SI9012274A - Method and apparatus for propelling and retarding off-road haulers - Google Patents

Abstract

The invention relates to a process and apparatus for power and control operation of large diesel-electric off - road haulers of the type in which the tractor's drive wheels are driven and stopped by direct current electric motors to drive wheels that powered by tug-mounted generators as desired and DC and DC current amplifiers client networks. With the system presented, thyristor converters connected to the distribution network AC, utilizes to receive additional external energy from the DC power supply network flow and conduct it into the distribution network alternating current in bargaining mode. The use of these Thyristor converters allow the exploitation of additional of energy from the pantry without installation of special on-off equipment or controls equipment for supplying electric motors to DC current to drive the wheels when energized receives from the client network. Thyristor converters can also be used to supply current, created with motors to drive the wheels in regime stopping, stopping resistors, allowing that the initial electricity generated by the motors for drive the wheels, change the load on the diesel engine, thus achieving significant fuel savings.

Description

1

Marathon LeTourneau Company

Procedure and device for propelling and stopping terrain tractors

The present invention relates to a method and apparatus for driving and stopping diesel electric tugs. These tractors have very large self-loading off-road trailers with a carrying capacity of between 100 and 200 tonnes or more. They are most commonly used when working on daily digging, but are also useful when carrying large amounts of soil, rocks, etc.

Many of these tugs use diesel as a power source to power the vehicle today. Such systems typically consist of an electric generator driven by a (diesel) motor whose basic output is used to supply high-power direct current electric motors, which are connected to a group of drive wheels on both sides of the vehicle via gear wheels. Electricity is usually produced as alternating current (AC) and converted to direct current (DC), which is used by DC motors to drive the wheels. In order to obtain adequate power to drive the tugs, many control systems have been designed to regulate the power and speed of these engines. Since DC motors for wheel speed motors require variable voltage from zero to a maximum and variable current due to torque regulation, all control systems must include means to regulate these parameters.

The propulsion power must be provided when the tugs are operating on flat or sloping surfaces. When operating on sloping surfaces, power is not required to drive, but means must be provided to stop the tractor moving forward. Tome brakes are not suitable for this purpose because they would wear out too quickly due to the very large mass of these vehicles, especially when loaded. Although friction or similar braking systems are mounted on the tractors as the primary means of stopping, most of these tractors utilize DC electric motors 2 to drive the wheels to provide the continuous stopping torque required to perform downward slope movement. This is achieved by changing the direction of either the excitation current or the angle current, which creates a change in the torque direction of DC electric motors, which then act as direct current generators, which are driven by gearboxes through gearboxes. Resistance sources, called " stopping resistors ", are used to generate load so that the resistors use the current generated by the DC motors and emit it into the atmosphere in the form of heat. The amount of current consumed creates a corresponding load on the DC electric motors of the wheels, which, as a stopping torque, is transmitted to the drive wheels via gearboxes.

For known tractor units, even when operating at shutdown mode, it is imperative that basic diesel engines continue to generate sufficient power to meet the requirements for additional power and parasitic power on the tractor for needs such as eg. fan drive, hydraulic system power supply, excitation current generation for bicycle engines, air conditioning or heating power supply, etc. Also, unladen motor consumes fuel to compensate for losses due to compression, friction and the like. These additional and parasitic loads and losses in the engine cause significant fuel consumption in the engine even when the engine is at shutdown mode, generating and releasing significant amounts of energy into the atmosphere.

With some known tugs, such as The Marathon LeToumeau Model T-2000 TITAN Off-Road Vehicle is designed to recover, recover, at least some of the DC power generated by the DC electric motors of the wheels during standstill mode, to fully or partially reduces the load on the AC generator, and that the AC generator rotates as an AC synchronous motor, providing the engine with the power to fully or partially relieve the mechanical loads of the moto. However, due to the functional characteristics of the stopping and limiting resistors, such systems, from the standpoint of motor voltage and current, have not been able to supply primary DC generated by DC motors to the AC system, or consistently supply energy to the AC system throughout the stopping cycle. Therefore, even with the best existing projects, it is often imperative that the fuel be used to cover motor parasitic and additional loads, while the system completely emits large amounts of energy as heat from the stop resistors. 3

Due to the high prices of fossil fuels and the limitation of engine power, it is sometimes desirable for off-road tractors and similar vehicles to be driven by a pantograph system using an external power source such as a power supply for the DC electric motors of the wheels. air power supply network. Since the power source of the air network is a fixed voltage system, the control systems for voltage and current regulation required by the DC wheel motors must be installed. Electricity from the air network is often available only in the part of the area where the tugs are used (eg, power from air lines is only available on routes to or from the mine area, but not in the loading area or other parts of the daily mine itself). For this reason, it is imperative to continue to provide onboard tractor diesel power. Tractors can move with energy generated on their own in areas where there is no available energy from the air network, and in other parts of their load cycle they can switch to energy from the air network. This, in turn, requires a system to receive both the electricity generated on the tugboat and the DC power of a constant voltage from an external source, ie. air ducts. This mode of operation is commonly referred to as " current pantry support " because energy from air ducts or pantograph wires is only available in certain areas to support the operation of tugs.

Existing tugboats utilizing a pantograph support are provided with mechanical switching systems so that the tug-of-war DC electric motors are disconnected from and plugged into the vehicle's built-in diesel-electric system and controlled by another current control that regulates the supply voltage and mains current pantographs for DC electric motors of wheels. When power is not available from the pantograph wires, the DC wheel motor motors are reconnected to the built-in diesel system. This forms a work selection of " or-or " and places severe restrictions on work procedures. Mechanical coupling equipment and other control systems required for air duct work also increase capital and maintenance costs. In addition, the installed engine must continue to operate on existing pantograph systems, even when the tractor is powered by power from the pantograph to provide energy for the auxiliary functions of the vehicle.

Therefore, it is a primary object of the present invention to provide a system for propelling and stopping off-road tractors, in which the initial power generated during the shutdown mode can be returned to the AC system to accommodate loads otherwise borne by the internal combustion engine.

Another task is to create a system where essentially all the energy requirements of the internal combustion engine and the AC system are satisfied before any amount of energy generated in the shutdown mode is transmitted through the stop resistor.

It is a further task to create a system whereby energy from an auxiliary voltage source can be fed to the DC power supply system of the wheels without having to first disconnect the engines from the vehicle's built-in diesel system.

The next task is to create a system that can utilize the auxiliary energy from the air network over a wide range of fixed voltages from at least about 1000 to at least about 2000 V. Another task is to create such a system that energy from the pantograph network can be used to power DC electric motors of the wheels in propulsion mode to meet all other tractor's power needs, as well as to provide energy for the internal combustion engine, thereby freeing the engine from all auxiliary and parasitic loads, so that the engine during the period when the energy available from the pantograph is essentially fuel-free.

These and other objects and advantages of the present invention are apparent from the following detailed description and presentation and and subsequent drawings, in which the same numerals denote the same parts, and where FIG. 1 is a diagram of a known off-road tractor power and shutdown system, FIG. 2 is a schematic diagram of a system of the present invention for powering and stopping an off-road tractor, FIG. 3 is a diagram of an alternative system according to the present invention for powering and stopping an off-road tractor.

In FIG. 1 is a schematic representation of a known off-road tractor power and shutdown system 10, such as e.g. Marathon LeTourneau TITAN Off-Road Vehicle Model T-2000. The engine 12, 5 is powered by hydrocarbon fuel (preferably diesel), is the primary gearbox and is connected to the generator via the clutch 14. The generator is preferably a three-phase AC generator whose power is adapted to the engine according to the requirements of the system. that when it is driven by motor 12, it outputs the AC voltage of the desired voltage (preferably about 1000 V) to the AC switchgear such as e.g. AC grid shown by thicker lines 18. The system shown in FIG. 1, is fully integrated on the tractor and is adapted to operate in two modes: a driving mode in which it provides the tractor drive wheels with driving torque, and a stopping mode in which it provides a stopping moment on the tractor driving wheels to stop progressive movement tug on sloping surfaces.

Generator 16 is also adapted to receive AC energy from the AC distribution network when the system 10 is operating in stop mode and is driven as an AC synchronous motor, which transmits rotational energy to the motor 10 through the clutch 14. not shown, in addition to providing energy to drive the generatoy 16, the engine 12 must also provide power for various auxiliaries powered directly by the engine or powered by an AC power grid such as fans, water and fuel pump, hydraulic system pumps, etc. . The engine 12 must also provide the energy to overcome the internal loads generated by friction, fuel pressure and the like.

Electrically connected to the AC distribution network 18, a voltage regulator 20 is arranged, which regulates the AC voltage in the AC distribution network by regulating the flow of current to the excitation field in the rotor part of the AC generator 16, which is in FIG. 1 shows schematically a thread 22. Voltage regulators are preferably a three-phase half-wave control converter of a conventional construction. Thyristor converters 24 and 26 are also electrically connected to the AC distribution network, converting alternating current energy to direct current energy, which supplies a pair of DC motors 32 and 34 to drive wheels via DC lines 28 and 30. The engines 32 and 34, through the drive shafts 36 and 38 and the gear reducers 40, 42, in themselves, provide torque to the drive wheels 44, 46 to drive the tractor. The first wheel motor usually drives the drive wheels on the first side of the tractor and the second one drives the wheels on the other side of the tractor. 6

Thyristor converters 24, 26 The angles of the wheel motor are preferably three-phase, fully controlled, full-wave thyristor converters of the conventional construction used in DC drive systems. With such thyristor converters, the AC voltage is balanced and controlled by the proper synchronization of the selection pulses to the thyristor assembly. They have the ability to transfer energy from the AC source to the DC consumer in an infinitely variable manner from zero to the maximum DC voltage, but if the DC consumer becomes the source, which happens when the system 10 is in shutdown mode, Thyristor converters 24, 26 also have the ability to recover energy back from DC power to AC power. Most preferably, the 24.26 Thyristor Angular Converters are a three-phase, full-wave offset, or " six-pulse bridge inverters " comprising six thyristors connected to three AC phases in the bridge configuration. This is a kind of two-way converter that emits energy in one direction but can receive it in the opposite direction. This converter function, namely that it receives the DC power and transmits it to the AC distribution network, will be called " regeneration " or " regeneration ". An AC field converter 58 is also connected to the AC distribution network 18, which converts alternating current energy into direct current energy to bring it through the DC power lines 60 to the threads of the DC drive motors 32, 34 of the wheels. These excitation threads are shown schematically in FIG. 1 with electric threads 62, 64. The DC motor must also have excitation current and angle current to produce torque.

Also, the motor excitation converter 58 is a thyristor converter known to those skilled in the art. Preferably, this is a dual three-phase half-wave rectifier or a dual three-pulse converter with a center joint. It utilizes three thyristors connected to the three AC phases to ensure that the load current returns to neutral in one direction, and three thyristors connected in the opposite direction to the three AC phases to provide the load current returned in the opposite direction. Since each three-phase segment can supply energy in one direction and receive it back in the opposite direction (regeneration), this is often called a four-quadrant converter. The reverse motion of the current through the excitation fields of the motor performs a change in the direction of the torque of the motor, which allows the whole motor system to operate in four quadrants (drive and stop in the forward and reverse direction and drive and stop in the opposite direction). 7

Through the dc circuit are connected the groups of arresting resistors 48, 50 and the pair of arresting diodes 52, 54 shown by lines 28 and 30. The arresting resistors are a group of variable-rate DC power resistors capable of dissipating large quantities of electricity in heat when the system 10 operates in stop mode. The resistors are equipped with cooling fans (not shown), which are driven by electric motors 56. A single motor 56 can supply energy to drive the cooling fans of both groups of stop resistors 48, 50. When the system is in the drive mode, the stop diodes are 52, 54 designed to block energy for stop resistors.

The system is controlled by a controller 66, which is connected to the voltage regulator 20, the excitation converter 58 and the angled converters 24, 26 by electrical lines 68, 70, 72 and 74. The controller can be of any suitable construction. It receives input signals from the driver about speed, direction selection, forward or stop commands, engine speed and generator power. The controller also receives system feedback signals representing the motor voltage, anchor current, excitation motor current, generator voltage, motor speed / ac frequency and motor speed. Optionally, additional driver commands, feedback signals and other control features can be integrated into the controller.

As a control and computational part of the system, the controller 66 provides logic pulses of the control loops and routing pulses to control all the outputs of the inverters. It consists of arrays and combinations of proportional, integral and derivative control circuits with a transfer function described by conventional control system theory and feedback. These control circuits can be created by amplifier-type working circuits (analog) or transmission equations calculated by microprocessor circuits (digital). The specific nature of the controllable system, as well as the requirements for strong integration, lead to the specific design of custom loops instead of using the standard computer and control systems available. Preferably, the control system is based on closed control loops, where the response to the command level is fed back to controller 66 to become part of the control process. An external or common loop is the response of the steering system to the speed of the driver-controlled vehicle. Inside this loop are sub-loops that control motor speed and generator voltage, and internal loops that control motor voltage and current parameters that generate motor torque, and therefore motor speed. The timing constants and transfer functions of the control loops are coordinated for correct synchronization and response. The main output of the controller 66 8 is a properly synchronized selection pulse for the various thyristor converters to obtain the required anchor current, excitation current and stop current of the inverter as well as the corresponding voltages.

System 10, as described, can be used to either propel or stop the off-road tractor. When operating in the drive mode, the diesel engine 12 is used to drive the AC generator 16. When the generator 16 is excited and the AC voltage starts to rise, the voltage regulator 20 maintains AC voltage control by regulating the current until the generator 22 is excited. Controller 66 monitors the voltage and frequency of the generator to maintain proper levels. While the driver determines the speed and direction of the vehicle, the controller 66 provides the thyristors to the excitation converter 58 and the inverted 24, 26 angles of the motor to the selection pulses. These converters then transmit DC power to DC motors 32, 34 wheels and the excitation thread 62, 64 of the motor. Controller 66 maintains the correct torque and speed of the motor 32 by monitoring various feedback signals that measure anchor current, excitation current, voltages, and motor speed, and which maintain the correct levels in the inverters by adjusting the thyristor choices accordingly. When the shutdown mode is activated in order to slow or stop the tractor, the excitation converter 58 regenerates the existing excitation energy back to the AC distribution network 18 and then emits the exciter current in the opposite direction. This changes the direction of the torque and the polarity of the voltage on the motors 32, 34, which then operate as DC generators. Alternatively, the excitation current can remain unchanged, and the direction of current in the angle of each of the engines 32, 34 wheels is changed, again causing them to act as DC generators.

In the case of negative motor voltage, the stop diodes 52, 54 are inverted and the direct current generated by the motors 32, 34 flows through the stop resistors 48, 50, where electricity is converted to heat. To blow ambient air through resistors or through heat exchange fins or the like associated with resistors, fans are arranged to dissipate the heat generated. The fans are driven by an electric motor 56, a serially wound DC motor connected via a portion of the stop resistor 48. As the stopping voltage increases, the speed of the fan motor 56 is also increased, so that more cooling air is automatically supplied through the stop resistors 48, 50.

The angular converter 24, 26 can be adjusted so that a portion of the direct current generated by the wheel motors 9 is regenerated back to the AC distribution network 18. The sum of the energy transferred to the stop resistors 48, 50 and the energy recovered to the AC network through angular converters 24, 26, represents the total stopping load by which the engines 32, 34 are actuated on the drive wheels 44, 46 of the tractor. The AC energy supplied to the AC distribution network 18 from the angular converters 24, 26 is consumable for replacing the AC energy consumed by the excitation converter 58 to establish the excitation currents 62, 64, the voltage regulator 20 in establishing the excitation 22 of the generator and other AC consumers in the system. In addition, the AC generator 16 can be controlled so that when it has enough alternating current energy from the inverters 24, 26, it acts as a synchronous motor, which drives the motor 12 through the clutch 14, to accommodate the loads exerted on the auxiliary equipment engine, and parasitic loads, thus significantly reducing the amount of engine fuel required. However, the engine must be able to operate at idle speed, even when operating at " no load " to maintain the proper voltage and frequency of the generator and, if necessary, ready to power the system.

The power level for stopping and distributing energy to the motors 32, 34 of the wheels is regulated by controller 66. However, there are restrictions on the distribution of energy generated during the stopping because the stopping resistors 48, 50 are a group of steady-state resistors of fixed values, voltage and current generated by the motors 32 , 34, however, are limited by the design constraints of the engines themselves. The stopping power, which as a power (in watts) must be mechanically generated in motors 32, 34 of the wheels, is electrically a function of the product of voltage and current, and mechanically it is a function of the product of moment and speed. The design of the commutator, motor windings and other magnetic conditions limit the maximum voltage and the amount of current that can be switched (transferred from the brushes to the commutator) in the motors. Therefore, when selecting the value for the groups of step resistors 48, 50, the current and voltage limits of the motor must be observed. The chosen resistance values are, when the full range of engine speed is examined, a compromise at best. At maximum motor voltage, resistors 48, 50 produce an anchor current, and the motor structure establishes a working speed that can commute with this current. At this operating speed, all current generated by the 32, 34 wheel motors must flow through the selected resistors in order to generate maximum stopping force (or voltage). If no maximum stopping force is required, the motor voltage can be reduced by reducing the current through resistors 48, 50, which allows a portion of the motor current to be regenerated 10 back to the AC distribution network 18 via the angular converters 24, 26. higher currents and less effect at the same stopping force than if the voltage can be kept at maximum value and the current reduced. At engine speeds less than the aforementioned operating speed, energy is recovered into the AC distribution network only after the selected stopping resistors have absorbed their maximum load for this voltage. Also, the second regeneration at lower stopping forces can be accomplished by further lowering the motor voltage, but this results in higher currents and less effect than if the engines are maintained at maximum voltage. When regeneration occurs, the fact that no more energy is recovered than the AC grid can absorb must also be taken into account. On the contrary, if the engines of the wheels operate at speeds higher than the selected one, the current must be reduced due to the good motor commutation. The voltage must be lowered in order to reduce the current, meaning that the stopping force is reduced in proportion to the square of the required current reduction instead of linear, which would be the case where the maximum voltage value could be retained and the current alone reduced.

As a result of these limitations, an additional supply current through the inverters 24, 26 of the AC mains is only available at certain levels of stopping power. The remaining time requires additional fuel to be consumed in the engine 12 to power the engine to overcome parasitic or additional loads and to drive the generator 16 even when the system is in shutdown mode, while the resistors 48, 50 supply significant amounts of energy and dissipate as heat. It would be more efficient if the first energy generated by the engines 32, 34 when in shutdown mode could be routed directly back to the AC network via the converter to replace AC network loads and / or auxiliary and parasitic engine loads before any the amount of energy dissipates over the stop resistors. However, due to the previously stated system functional limitations, it is not possible with the existing propulsion and steering systems of the tractor units.

In FIG. 2 shows an improved traction drive and shutdown system 110 of the present invention that allows the initial energy generated during the shutdown to be regenerated in the AC grid to regenerate all diesel engine loads before any amount of energy is transmitted to the resistors. In the enhanced system 110, most of the components are the same or substantially the same as the corresponding parts and components shown and described in connection with the known system of FIG. 1, with the corresponding Reference Numbers preceded by the " P. Thus, motor 112 in system 110 corresponds to diesel engine 12 of the known system 10, AC generator 116 corresponds to AC generator 16, etc.

In system 110, the stop resistors 48, 50 are removed from the DC circuit connected to the motors 32, 34 and replaced by the stop resistors 176 having a similar function and the same capacity as the combined resistors 48, 50 of FIG. 1. Resistors 176 are connected to a direct current circuit shown by the supply lines 180, 182 for direct current, which are themselves electrically connected to the stop converter 184. The stop converter 184 is operably connected to the AC distribution network 118 and via the control line 186. with controller 166.

The stopping converter 184 is of a thyristor type and is preferably a three-phase, full-wave rectifier utilizing six thyristors connected to three alternating-phase phases in a bridge configuration, similar to angled converters 124, 126, but with a correspondingly increased capacity. In the drive mode, system 110 operates in essentially the same manner as the known system 10 (Fig. 1). The AC energy generated in the AC generator 116 driven by the motor 112 is fed to the thyristor anchor converters 124, 126 to convert the DC power to the DC motors 132, 134 wheels and transmitted through the drive shafts. 136, 138 and gear reducers 140, 142 to tractor wheels 144, 146 of tractor. The stopping converter does not activate during the drive, so it does not supply the stopping resistor.

When the shutdown mode is activated, it regenerates the excitation converter 58 to the existing excitation energy back into the AC grid, and then emits the excitation current in the opposite direction. This changes the direction of the motor torque, whereby the DC motors 132, 134 of the wheels act as DC generators driven by the tractor wheels 144, 146 of the tractor. Alternatively, instead of changing the direction of the excitation current, the direction of the angular current can be changed in the motors 132, 134 of the wheels, using dual angular converters instead of the angular converters 124, 126. Angular converters 124, 126 are configured to recover energy into the AC grid. In order to maintain the commanded speed of the vehicle, the amount of stopping energy generated is controlled by controller 166. Since there are no longer stopping resistors in the circuits 128, 130 DC of the motor, all the energy generated by the motors is regenerated via thyristor 12 converters to the AC distribution network 118. Regenerated energy is first used to power all other loads in the AC grid, such as the excitation converter 158 and the voltage regulator 120. This relieves the AC generator 116 and reduces the fuel consumption of the engine 112. As the additional power generated is available from the engines 132, 134, it supplies the session to the AC generator 116 so that it starts to act as an AC synchronous motor, which drives the engine 112. This completely relieves the engine 112, since the energy from the generator 116 is available to meet all additional and parasitic energy needs of the engine 112, thereby substantially reducing fuel consumption to zero. At this point, all the additional energy generated by the engines 132, 134 wheels, due to conversion to direct current energy and consumption in the stop resistors 176, is transmitted via the AC distribution network 118 to the stop converter 184. The fan motor 156 is driven, as in the system of FIG. 1, cooling fan (not shown) due to dissipation of generated heat into the atmosphere.

Controller 166 monitors the amount of regenerative stopping energy input to the AC circuit, the engine speed and frequency, and the voltage of the AC generator as well as other relevant parameters of the drive motor, by properly managing the overall functioning of the system. The presence of a thyristor converter 184 for shutdown associated with an AC power system allows for an infinitely variable delivery of excess stopping energy to the stopping resistors 176. Because the angled converters 124, 126 allow all the stopping energy generated by the motors 132, 134 to be regenerated into an AC network , motors 132, 134 can be operated at maximum voltage and current limits over their full speed range, providing maximum torque and stopping power. This eliminates the functional constraints imposed by known systems with steady-state stop resistors of fixed capacity, connected via DC motors to drive motors.

The system 110 is also adapted to receive and utilize DC energy from a source outside the tractor, such as e.g. conventional dual air lines of direct current pantographs. As in FIG. 2 illustrated by dashed lines, a client unit 188 may be added to the hauler if desired, comprising elements such as pantograph or pantograph bars, which are schematically indicated by code 190 and which can be optionally connected to the DC pantograph line. The client unit 188 also comprises elements for electrical connection through the lines 180, 182 DC with the DC side of the stop 13 of the converter 184. The stop resistor 176 has been added stop to diode 178. The client unit is adapted to be connected to voltage terminals opposite to those of which are common on stop resistors 176 such that diode 178 is normally oriented in reverse and isolates stop resistors 176, thereby preventing the energy from the client network from being drawn into the resistors.

Where available on the client power grid, a device 190 for connection to the air network can be activated, either by the driver or an automatic device, thereby connecting the system 110 to the client power supply network. When controller 166 detects that client unit 188 is turned on, the thyristors in the stop converter 184 (which now functions as a combined current collector / stop converter) are adjusted so that the energy is regenerated into the AC distribution network 118. The regenerated energy is consumed by? power to all AC consumers on the tractor in the drive mode, including the required energy for the drive motors 132, 134, the excitation converter 158 and the voltage regulator 120. Additional AC power from the stop converter 174 is available to drive the AC generator 116 as a synchronous motor for complete unloading of the 112 engine, reducing fuel consumption to practically zero. In order to maintain the desired system voltage, the controller 166 continues to control the voltage regulator 120.

For system 110, energy can be supplied to the AC grid simultaneously from the client unit 188 via the converter 184 and from the AC generator 116 driven by the motor 112. Therefore, it is not necessary to switch off or interrupt the built-in diesel electrical system before connecting to an external client power grid. energy generation. When available from the client network, it automatically replaces AC energy from the AC generator, thereby reducing and ultimately eliminating the load on the engine 112. Conversely, when the tractor is leaving the area where client network energy is available, the device 190 to connect to the client network, it switches off and stops supplying power from the client unit to the AC system. Controller 166 detects power loss from the client unit and automatically releases additional fuel into the engine 112 to generate the required propulsion energy through the AC generator 116. All this is done without the use of a coiled electrical start-up equipment or a special control system for regulating voltage and current, which is fed from the client network to the DC drive motors 132, 134.

In the system of FIG. 2, the maximum voltage of the client network is not required to be much higher than the 14 maximum voltage normally generated by the generator 116 in the AC distribution system 118 for the thyristors to function properly. The DC voltage supplied to the respective DC electric motor 132, 134 via the angle converters 124, 126 is numerically approximately the same as the AC voltage. For a DC electric motor designed for 5 operation at a maximum of about 1000 V, FIG. 2 shows a system suitable for use with a supply network of up to 1000 V. There are a number of facilities for supporting pantographs in mines around the world that use pantograph lines to supply DC power from 1000 to 1200 V and which are deployed as an additional source of energy for diesel tugs operating on steeply sloped 10 surfaces. A power and shutdown system as shown in FIG. 2, which uses 1000 V propulsion engines and would provide significant advantages over known systems.

Other installations for supporting pantographs, however, generate voltages in client 15 grids in the range of 2000 to 2200 V and may not be suitable for use with tractors having parallel motors of wheels to a DC voltage of 1000 V as shown in fig. 2. For this reason, an alternative embodiment of the invention provides a method and apparatus for propelling and stopping off-road tractors that can utilize additional energy from the client network over a wide DC voltage range from about 1000 20 to about 2200 V. This embodiment shown in FIG. 3, comprises a system 210 having many of the same components as the system 110 shown in FIG. 2. The corresponding parts and functions are indicated by the corresponding reference numbers, with the first digit of each component number changed from " 1 " v '' 2 ". Thus, engine 212 of FIG. 3 is substantially the same as the internal combustion engine 112 of FIG. 2, AC generator 216 is the same as AC generator 116, etc. 25

In system 210, the AC generator 216 is adapted to generate alternating current at a voltage of about 2000 V, whose thyristor angular converter 224 converts to direct current of the same voltage to supply DC motors 232, 234 to the wheels. However, since the drive motors 232, 234 are coupled in series each receives only a maximum of about 1000 V each, allowing the use of 30 conventional 1000 V motors to drive the tractor's wheels. With this configuration, unit 228 of the pantograph can use DC power from the air line up to about 2000 to 2200 V. As the client / stop converter 284 15 recovers all DC voltage obtained from the client unit into the AC power supply at the desired higher voltage (eg 2000 V), this system can also be used with existing 1000 V DC client lines without modification in the tractor's drive and stop assembly.

Since both the drive motors 232, 234 and the motor excitations 262, 264 are serially coupled, each of the motors 232, 234 gives essentially the same torque to the tractor wheels 244, 246. In some cases, such as slippery conditions, it may be desirable to give the drive wheels on one side of the tractor less torque than those on the other, thereby controlling the slip of the wheels. This objective is optionally achieved by incorporating an additional thyristor excitation converter 292 into a system constructed in the same way as excitation converter 258. The excitation converter 292 may be electrically connected to the AC distribution network as shown and connected to the controller 266 via a control line 294. An additional conduit 296 of direct current connects the second converter 292 to the second excitation winding 264, both excitation windings 262, 264 being separately grounded as shown. Controller 266 can then be used to independently control the excitation current for the engines 232, 234, thereby individually adjusting the size of the driving or stopping torque generated by each of the motors.

Performance and benefits of the 210 propulsion system the stops are essentially the same as those described in connection with the system 110 shown in FIG. 2, except that the client unit 288 can automatically receive the voltage of the client network from about 1000 to about 2200 V without the need to change the connectors, introduce the on-off devices or make other changes to the system. The voltage of the AC generator is automatically maintained at the desired altitude of about 2000 VAC by the operation of the voltage regulator 220. Higher AC power generators can be installed in the system, which gives a proportionally larger range of maximum voltage to the client network.

The foregoing presentation and description is provided for illustrative purposes only, and various changes in system configuration, operation and control are possible without departing from the scope of protection presented in the appended claims. It is obvious to experts that e.g. a thyristor converter can be used to supply AC power to the distribution network from another external DC power source, regardless of whether 16 16 10 external energy is supplied through the stop converter, as shown in FIG. 2 or 3, whether the energy is supplied through a dedicated inverter connected to the current pantograph unit. In this way, known systems such as the one in FIG. 1, it may modify whether existing tugs are supplemented to take advantage of the current pantograph by adding a device to be connected to the client network which is connected to the AC power supply via thyristor converters. The functional advantages of supplying power from the client line to the AC distribution network via a thyristor converter are realized regardless of whether the stopping resistors are connected to the AC supply network, as shown in FIG. 2 and 3, or to the line of DC motors as shown in FIG. 1. It is further apparent from the previous presentation and description of the present invention that the known system of FIG. 1 modifies to receive power from the client network through a 2000 V thyristor converter so that the 32 34-wheel motor in the known system can be serially coupled and the other components modified to receive about 2000 V AC in the AC power network 18. For all of these modifications as described, as well as others apparent to those skilled in the art, are considered to be within the scope of the present invention.

Marathon LeToumeau Company

LJUBLJANA, ČOPOVA 14

Claims (2)

17 Claims An off-road tractor start and stop system, characterized in that it comprises an internal combustion engine, an alternator, which, in order to generate an alternating current adapted to drive the said motor, is an alternating current mains for alternating current. the current generated by said generator, the AC voltage regulator, the DC motor wheel for transferring the driving power to the drive wheel of said tractor, an angular thyristor converter adapted to receive AC power from the AC power supply network and to supply DC power to said electric motor dc to drive wheels, exciter generator zl generating dc exciters for dc motor to drive wheels, thyristor exciter converter to receive alternating current from said ac mains and supply dc to said genes alternator, device for connection to a current client network for the selective connection of said system to DC power from a source outside said tractor, a thyristor converter of current client network for receiving DC power from said device for connection to the client network and for supplying AC power to said AC power grid, a control device for controlling the operation of a voltage regulator, an angular thyristor converter, a thyristor excitation current converter and a thyristor converter of the client network, said field tractor being able to selectively move with the energy generated on the tractor itself by means of said tractor current, or direct current from said source outside said tractor. The system of claim 1, characterized in that said alternator is adapted to act as an alternating current motor driving said tractor motor motor when the system is powered by a source outside said tractor. said direct current from a source outside the tractor may be used to eliminate the load on said tractor engine in order to substantially reduce the fuel consumption of that tractor engine. The system of claim 1, characterized in that the angular thyristor converter comprises a single thyristor converter connected to said AC power grid, and that the AC motor comprises a pair of DC motors for driving the wheels, which are connected in series on the DC side of said anchor thyristor converter. The system of claim 3, characterized in that said thyristor excitation current converter comprises two thyristor excitation currents connected to the alternating current distribution network, and said said excitation current generator comprises two windings of excitation current, each of these windings of excitation current being electrically connected to one of the two thyristor excitation currents and connected to one of the two serially coupled DC motors to drive the wheels, each of these two thyristor excitation current converters being independently controlled by said control device to independently regulate the excitation the current in each of the windings of the excitation current as well as the magnitude of the torque generated by each of the said DC motors for driving the wheels. An off-road tractor propulsion system in which an internal combustion engine drives an alternator for alternating current production, the alternating current distribution network distributing this alternating current and the first thyristor converter receiving alternating current from the alternating current distribution network and supplying direct current to the electric motor to direct current for driving a wheel which itself transmits propulsion energy to the drive wheel of said tractor, characterized in that it comprises an air network communication device for selectively connecting to a DC power network from a system outside said tractor, as well as a second thyristor converter for receiving a direct current from an air supply network communication device and supplying an alternating current to said alternating current network, wherein the electrical current from a source outside said tractor can be used selectively to replace the alternating current obtained from said alternating current generator ka, thus reducing the fuel consumption of said internal combustion engine. System according to claim 5, characterized in that said air link device 19 comprises means for electrically connecting said tractor to the air client line. A system capable of operating selectively in the propulsion and stopping mode due to the selective propulsion and stopping of the off-road tractor, characterized in that it comprises an internal combustion engine, an AC generator adapted to give when driven in propulsion mode said motor to generate alternating current and adapted to act as an alternating current electric motor when the system is in shutdown mode and to supply power to said internal combustion engine, alternating current mains adapted to, when the system operates in the drive mode, conducts electricity generated by said generator and is adapted to supply an alternating current to said generator when that system is in stop mode, a voltage regulator for regulating the voltage of said alternating current, a DC motor to drive wheels adapted to that when this system is running in drive mode, transmits the drive torque to the drive wheel of said tractor, and adapted to act as a direct current generator when receiving this power from the drive drive wheel of said tractor and to generate a direct electric drive. a current, thereby acting with a stopping torque on said drive wheel, an angular thyristor converter adapted to receive alternating current from said AC power supply when the system is in drive mode and to supply a direct current to said motor at and is adapted to receive, when this system is in stop mode, to receive DC generated by said motor for DC power and to supply AC power to said AC power supply, a device for generating excitation current. to generate a direct excitation current for the aforementioned i a DC motor for driving the wheels, a thyristor excitation converter for receiving alternating current from the AC power supply network and supplying a direct current to said excitation generator, a device for selectively driving said DC motor to drive the wheels to operate as an engine when this system is activated in the drive mode and as a direct current generator when the system is operating in stop mode 20, a stopping resistor adapted to, when the system is in stop mode, consume the electricity generated by said DC motor for propulsion wheels, a thyristor stop converter for receiving alternating current from said AC mains supply and supplying direct current to said stopping resistance, and a control device with said voltage regulator, an thyristor converter, a thyristor exciter converter and a thyristor follower of stopping resistance, thereby controlling the direction and magnitude of the driving and stopping torque occurring on said DC motor for driving the wheels, whereby, when said system operates in said stopping mode, the electricity generated by said the DC motor may first utilize to reduce the energy required for said internal combustion engine, the excess electricity generated by said DC motor being supplied to the stopping resistor. The system of claim 2, further comprising a connection device for selectively connecting this system to a direct current from a source outside said tractor and supplying said external direct current to the direct current side of said thyristor stopping resistor, wherein the direct current from the said foreign source can be converted to alternating current by means of this thyristor stop-current converter and fed to the alternating current mains to replace the direct current generated by said alternator and to reduce the energy required for said internal combustion engine. System according to claim 8, characterized in that said device for connection to the air network is connected to this system at a DC voltage opposite to that which usually exists at said stopping resistor and further comprises a diode connected to this system between the device for connecting to the air network and said stopping resistor, said external DC power source being connected to this system via said device for connecting to the air line, said opposite polarity of this DC power line 21 changing the orientation of that diode and blocking direct current from the air mains so that it flows into said stopping resistor while allowing the direct current to flow from the air mains into said thyristor stop current resistor for conversion to alternating current. System according to claim 7, characterized in that said means selectively causes said DC motor to act as a motor when the system is operating in drive mode and as a direct current generator when that system is operated in said stop mode due to the selective change in direction of said DC excitation current. The system according to claims 7, 8, 9 or 10, characterized in that said angular thyristor converter comprises a single thyristor angular converter connected to said AC power distribution system, wherein said DC motor comprises a pair of motors to DC, which are serially coupled to the DC side of said angled thyristor converter. System according to claim 11, characterized in that said thyristor excitation current converter comprises a single thyristor excitation current converter and said excitation current generator comprises two windings of excitation current, connected in series to the direct current side of said thyristor excitation current converter, and is connected to it. said pairs of direct-current electric motors for wheel propulsion, wherein these direct-current electric motors for wheel propulsion operate to deliver substantially the same torque values when the system is in drive mode and generate substantially the same stopping torque when this system operates in stop mode. System according to claim 11, characterized in that said thyristor excitation current converter comprises two thyristor excitation current converters connected to the alternating current distribution network, and said said excitation current generator comprises two excitation current windings, the excitation current coils being electrically connected one of said thyristor excitation current converters connected 22 to one of the two serially coupled DC motors to drive the wheels, each of the thyristor excitation current converters being independently controlled by said control device, thereby regulating the amount of current in each of excitation current windings by regulating the independent torque magnitude generated by direct current motors for wheel propulsion. The system according to claim 7, 8, 9 or 10, characterized in that said angular thyristor converter comprises several angular thyristor transducers connected in parallel with the AC power grid, and said said DC motor comprises several DC motors for driving wheels , whereby the vsk of these DC motors is electrically coupled to one of the angular thyristor converters. The system of claim 7, characterized in that said stopping resistor comprises multiple stage resistors adapted to convert the excess electricity generated in that system into heat, and comprises additional heat dissipation elements generated by said resistors. A system for selectively driving and stopping an off-road tractor, characterized in that it comprises an internal combustion engine, an alternator that is mechanically connected to said engine, an AC power grid that is electrically connected to that alternator, a voltage regulator, which is electrically connected to said AC mains due to the regulation of AC voltage in this AC mains, an thyristor converter which is electrically connected to this AC mains, a DC motor for driving a wheel electrically connected therewith angular thyristor converters, a drive wheel of said off-road tractor mechanically coupled to this DC motor to drive the wheel, electric winding to create a direct excitation current for this DC motor to drive the wheel, a thyristor DC exciter converter ktric connected to said winding and to the aforementioned alternating current distribution network, multiple stop resistors for dissipation of excess electricity generated in this system, a thyristor stop resistance converter electrically connected to said multiple stop resistors and electrically connected to an alternating current line 23, wherein the system may operate in a drive mode in which said internal combustion engine drives said alternator to produce alternating current to supply the alternating current distribution network, said angular thyristor converter converting alternating current to direct current for said electric motor to DC the current for the drive of the wheel, and this DC motor for direct drive of the wheel, with the desired driving torque, acts on said drive wheel, and that this system can also operate in stop mode, where the direction of current is in the field of excitation current and in the said electric motor u to DC for driving a reverse polarity wheel, and this tractor drive wheel drives this electric motor to DC for driving the wheel, causing said DC motor to generate electrical current which is converted to the said thyristor inverter by and supplying it to the AC power grid, wherein the AC generator receives AC power from said AC power system, causing the AC generator to act as an AC motor that drives said internal combustion engine by reducing the required amount of fuel for that engine, and the excess AC generated by said DC motor to drive a wheel that is not required to reduce the fuel consumption of said engine is consumed by said stopping resistors and dissipated as heat. The system of claim 16, further comprising a device for connecting to an air line that can selectively connect to a DC power source outside said tractor, and is electrically connected to the DC side of said thyristor stop resistor, wherein the electricity from said external source can be selectively fed into this system. The system of claim 17, further comprising a power diode which is electrically incorporated into this system between said connection device and said stopping resistors, said connection device being adapted to supply direct current from this external source to this system. a system with a polarity opposite to that normally supplied to these arresting resistors, thereby automatically preventing said diode from supplying DC power to 24 arresting resistors. System according to claim 16, 17 or 18, characterized in that two electric motors are arranged on a single current drive for the wheels and two angular thyristor inverters, each of the motors for driving the wheels being connected to the drive wheel of said tractor and to the angular thyristor inverter , wherein these angled thyristor converters are connected in parallel to the alternating current distribution system, each of the DC motors being able to operate at a maximum voltage approximately equal to the maximum voltage supplied by said alternator. A system according to claim 16, 17 or 18, characterized in that a pair of DC motors is arranged to drive the wheels, each of these DC motors being connected to the drive wheel of said tractor, said pair being direct current electric motors for wheel drive electrically connected in series to a single thyristor converter, each of these direct current electric motors being able to operate at a maximum voltage equal to about half the maximum voltage supplied by the alternator. System according to claim 20, characterized in that said thyristor excitation current converter comprises a single thyristor excitation current converter and said electric winding comprises two windings of excitation current, serially connected to the DC side of said thyristor exciter current converter and connected to said electrical exciter current converter dc to drive wheels, wherein these two dc motors operate to emit a driving torque of essentially the same size when the system is in stop mode and to obsolete a stopping torque of essentially the same size when the system is in stop mode. The system of claim 20, characterized in that said thyristor excitation current converter comprises a pair of thyristor excitation current converters connected in parallel to the alternating current distribution network, and said electric winding for generating a direct excitation current comprises a pair of such electrical windings, 25 wherein electrical winding in each case electrically coupled to one of the thyristor excitation current converters and connected to one of said serially coupled DC motors to drive the wheels, each of these thyristor excitation current converters being independently controlled by said control device, thereby controls the amount of current in each of said electrical threads due to the independent control of the torque magnitude generated by each of said pair of DC motors to drive the wheels. The process of handling an electrically powered off-road tractor that selectively utilizes the electricity generated on the tractor itself and the electricity from an external source, characterized in that it comprises activating the internal combustion engine on said tractor as the main drive, driving the alternator current generator engine for generating AC power at the desired voltage, supplying AC power from this AC generator to the AC power supply network, supplying AC power from AC power supply to at least one angular thyristor converter, converting AC power to DC an thyristor converter, supplying a direct current from said angular thyristor converter to at least one DC motor for wheel drive, driving at least one tractor drive wheel with said DC motor with a wheel drive, selectively supplying a second thyristor inverter arranged on said tractor, direct current from said external source, converting direct current from said external source to alternating current in said second thyristor converter, supplying alternating current from said second thyristor inverter and utilizing the alternating current supplied to the alternating current supply from said external source to supply said electric motor to direct current for wheel propulsion to replace the alternating current generated by said alternator and reduce fuel consumption of the said internal combustion engine. The method of claim 23, further comprising utilizing an alternating current 26 supplied to an AC power source from an external source to drive the alternator as an AC motor, and drive said internal combustion engine by means of an alternator which acts as an AC motor, thereby reducing the fuel consumption of this internal combustion engine. 25. A method according to claim 23, characterized in that it comprises additional steps of establishing an excitation current with the desired polarity for said electric motor for wheel propulsion, selectively changing the polarity of said excitation current when it is intended to inhibit the forward motion of said tractor to cause it to this direct current electric motor to drive the wheel acts as a generator of direct current, to drive that electric motor to direct current to drive the wheels with the drive wheel of the tractor to produce direct current, to supply a single current generated by this electric motor to drive the wheel, to said anchor thyristor converter, converting this direct current to alternating current in said anchor thyristor converter, supplying alternating current from that angled thyristor converter to said alternating current mains, utilizing this alternating current from this an angular thyristor converter for driving an alternator as an alternating current motor to supply said internal combustion engine with energy and reduce fuel requirements for it, supplying additional alternating electricity from said angular thyristor converter to electrical resistors for heat conversion, and the dissipation of heat generated by these electrical resistors, thereby stopping the forward movement of said tractor. Marathon LeTourneau Company For: 22180PP0.IV-VII / 95