HRP930418A2 - Method and apparatus for propelling and retarding off - road haulers - Google Patents

Description

The presented invention relates to a method and device for starting and decelerating diesel-electric tractors. These tractors have very large off-road dump trailers, which usually have a load capacity of 100 to 200 tons and even more. They are most often used for working on open pits and for other applications when very large quantities of earth, stone, etc. have to be transported.

Many of these tractors today use a diesel-electric drive as their own source of power to propel the vehicle. Such systems usually consist of an electric generator driven by a (diesel) engine, the main output of which is used to power the wheels on both sides of the vehicle. Usually, electricity is produced as alternating current and converted to direct current which is used by direct current motors to drive the wheels. Many control systems have been designed to regulate the power and speed of these engines, in order to provide adequate power to start the tractor. As DC motors to drive the wheels require a variable voltage from zero to some maximum with increasing wheel speed, and some variable current to regulate the torque, all control systems must include means to regulate these parameters.

Starting power must be provided when tractors are operating on level or uphill surfaces. When operating on downhill sloping surfaces, no starting power is required, but means must be provided to slow down the forward movement of the tractor. Friction brakes are not suitable for this purpose, as they would wear out quickly due to the very large mass of these vehicles, especially when they are loaded. Although friction or similar braking systems are installed on tractors as a primary means of stopping, most of these tractors use direct current motors (hereafter referred to as DC electric motors) to drive the wheels to provide the continuous retarding torque required when moving on a downhill grade. . This is achieved by changing the direction of either the excitation current or the armature current, which causes a change in the direction of the torque (DC) of the electric motors, which now work as direct current generators, which get their drive through a reducer from the drive wheels. Sources of resistance, called "comparative resistors" are used to create a load, so that the resistors consume the current generated by the DC electric motors and dissipate it to the atmosphere as heat. The amount of current consumed creates a corresponding load on the DC electric motors of the wheels, which is transmitted via the reducer to the drive wheels as a deceleration torque.

Even when operating on deceleration mode, it is necessary for existing tractors that the basic diesel engines continue to generate sufficient power to meet the requirements for additional power and parasitic power on the tractor, for purposes such as fan drive, hydraulic system power, excitation current generation for wheel motors, powering air conditioning or heating, etc. And so, even an unloaded engine consumes fuel to compensate for losses due to compression, friction and the like. These additional and parasitic loads and losses in the engine cause considerable fuel consumption by the engine even when the tractor is operating in deceleration mode when it generates and dissipates to the atmosphere considerable amounts of energy.

In some well-known tractors, such as the Marathon LeTourneau Model T-2000 TITAN cargo vehicle, devices are provided to recuperate, recover, at least part of the direct current energy produced by the DC electric motors of the wheels when they are working in the deceleration mode, in the alternating current energy system, so to completely or partially reduce the load on the AC generator, it is started as an AC synchronous motor that will provide the motor with the power to relieve it completely, or partially, of the mechanical loads on the motor. However, such systems to date have not been able to introduce the primary current generated by the drive DC electric motors into the AC system, or consistently feed energy into the AC system throughout the deceleration cycle, due to the functional characteristics of the deceleration resistors and motor voltage and current limitations. Because of this, even with the best existing designs, it is often necessary to consume fuel to cover engine parasitics and additional loads, while the system as a whole wastes large amounts of energy as heat from the deceleration resistors.

Because of the high prices of phosphine fuels, and because of engine power limitations, it is sometimes desirable for off-road tractors and similar vehicles to be powered by a trolling system, in which some external source of electrical power, such as an aerial power grid, is used to power the wheel's DC electric motors . Since the power source of the aerial network is a constant voltage system, control systems must be installed to regulate the voltage and current required by the DC electric motors of the wheels. Electricity from the overhead grid is often only available in the part of the area where the tractors are used (for example, power from the overhead lines may only be available on the roads to or from the pit area, but not in the loading area or other parts of the day mine itself ). That is why it is necessary to continue with the provision of built-in diesel-electric energy on tractors. Tugs can be powered by self-generated power in an area where overhead power is not available, and switched to overhead power in other parts of their load cycle. This requires a system to accept both electricity generated on the tractor, and direct current electricity of constant voltage and an external source, i.e. overhead lines. This type of operation is commonly referred to as "troll assisted" since power from the overhead lines, or troll wires, is only available in certain areas to assist the operation of the tug.

On existing tugs using trolling support, mechanical systems are provided so that the DC electric motors of the tug wheels are disconnected from the vehicle's on-board diesel-electric system and switched on, and controlled, by another current control device that regulates the voltage and current from the trolling network supply for DC electric wheel motors. When there is no power available from the trolling wires, the DC electric motors of the wheels are reconnected to the on-board diesel-electric system. This creates an either/or operative choice and places strict constraints on operative procedures. The mechanical coupling equipment and other control system required to operate the overhead lines also add to the capital cost of maintenance. In addition, with existing troll-assisted systems, even when the tractor is running on power from the trolling network, the onboard engine must still be running to provide some of the power for the vehicle's auxiliary functions.

Therefore, the primary goal of the presented invention is the realization of a system for starting and decelerating all-terrain tractors, where the initial power generated in the deceleration mode could be returned to the electrical system of alternating current, in order to accept the load normally carried by the internal combustion engine.

Another goal is to achieve a system where at the core all energy requirements from the internal combustion engine and from the alternating current system will be met before any amount of energy generated in the deceleration mode is dissipated through the deceleration resistor.

The next goal is the realization of such a system where energy from an auxiliary source with a constant voltage can be introduced into the power supply system of the DC electric motors of the wheels, without the motors first having to be disconnected from the built-in diesel electrical system of the vehicle.

The next goal is to realize such a system that will be able to use auxiliary energy from the aerial network in a wide range of constant voltages, from at least approximately 1000 to at least approximately 2000 V.

Another goal is the realization of such a system in which the energy from the trolling network can be used to power the DC electric motors of the wheels in the starting mode, then to meet all the other needs of the tractor for electricity, as well as to provide energy for the internal combustion engine so that the engine of all auxiliary and parasitic loads, so that essentially the engine does not need fuel in periods when energy from the trolling network is available.

These and other objects and advantages of the presented invention will be apparent from the following detailed description and description and from the following drawings, in which the same numbers denote the same parts, whereby:

- picture 1 shows schematically, a well-known system for powering and decelerating an all-terrain tractor,

- figure 2 shows, schematically, one system for powering and decelerating an off-road tractor according to the presented invention, and

- figure 3 shows, schematically, an alternative system for powering and decelerating an off-road tractor according to the presented invention.

Figure 1 schematically shows a known system 10 for powering and decelerating an all-terrain tractor such as the Marathon LeTourneau TITAN vehicle model T-2000. Engine 12, powered by some hydrocarbon fuel (recommended diesel fuel) is the basic mover and is connected by connector 14 to generator 16. The generator is, preferably, a three-phase alternating current generator, the power of which is adapted to engine 12 according to system requirements. The generator is adapted to, when the motor 12 is started, supply an alternating current of a desired voltage (preferably about 1000 V) to some alternating current distribution device, such as the alternating current grid shown in thick lines 18. The system shown in Figure 1 is located entirely on the tractor and is adapted to work in two modes: the starting mode, in which it provides the driving torque to the driving wheels of the tractor, and in the deceleration mode, in which it provides the decelerating moment to the driving wheels of the tractor, so as to slow down the forward movement of the tractor on downhill inclined surfaces.

The generator 16 is also adapted so that, when the system 10 is operating in the deceleration mode, it accepts AC power from the AC distribution network, and is driven as an AC synchronous motor, which provides rotary power through the coupling 14 to the motor 10.

Although not shown in the drawing, the engine 12, in addition to providing power for driving the generator 16, must also provide power for various auxiliary devices that are directly driven by the engine or powered from the AC mains, such as fans, water and fuel pumps, hydraulic system pumps, and the like. The engine 12 must also provide energy to overcome internal loads that create friction, fuel pressure, and the like. A voltage regulator 20 is installed electrically connected to the alternating current distribution network 18, which regulates the alternating current voltage in the alternating current distribution network by regulating the current flow to the excitation field in the rotor part of the alternating current generator 16, shown in Figure 1 with a schematic thread 22. It is desirable that the voltage regulator be a three-phase half-wave controlled converter of conventional construction.

Also electrically connected to the alternating current distribution network are two thyristor converters 24 and 26, which convert alternating current energy into direct current energy for feeding via direct current lines 28 and 30 a pair of DC electric motors 32 and 34 for wheel drive. Drive shaft motors 36, 38 and gear reducers 40, 42 drive wheels 44, 46 to drive the tractor. Typically, one wheel motor drives the drive wheels on one side of the tractor and the other wheel motor drives the wheels on the other side of the tractor.

The wheel motor armature thyristor converters 24, 26 are preferably three-phase, fully controlled, wave thyristor converters of conventional construction, used in DC motor drive systems. In such thyristor converters, the AC voltage is rectified and regulated by appropriately synchronizing the selector pulses to a single thyristor circuit. They have the ability to transfer energy from the source of alternating current to the consumer of direct current in an infinitely variable manner from zero to the maximum voltage of direct current, and if the consumer of direct current becomes a source, which happens when the system 10 operates in the deceleration mode, the thyristor converters 24, 26 have also the ability to return energy back, from a direct current system to an alternating current system. Most preferably, thyristor armature converters 24, 26 are three-phase, full-wave controlled rectifier, or "six-pulse bridge converters" using six thyristors connected to three phases of alternating current in a bridge configuration. This is one type of two-square converter that delivers energy in one direction and can receive energy in the opposite direction. This function of the converter to receive energy from the DC side and deliver energy to the DC distribution network will be called "regeneration" or "regeneration".

Also connected to the AC distribution network 18 is a motor excitation field converter 58, which converts AC energy into DC energy for delivery via DC power lines 60 to the excitation windings of the DC drive motors 32, 34. These excitation windings are shown schematically in Figure 1 by electrical windings 62, 64. A DC motor must have both an excitation current and an armature current in order to produce torque.

The motor excitation converter 58 is also a thyristor converter known to those skilled in the art. It is preferable that it be a double three-phase half-wave controlled rectifier, or a double three-pulse converter with a central junction. It uses three thyristors connected to three phases of alternating current to ensure that the load current returns to neutral in one direction, and three thyristors connected in the opposite direction to three phases of alternating current to ensure that the load current returns to neutral in the opposite direction. As each three-phase segment can deliver energy in one direction and receive energy back in the opposite direction (regeneration), it is often called a four-square converter. The return movement of the current through the excitation fields of the motor changes the direction of the motor's torque, which enables the overall motor system to operate in four quadrants (starts and slows down in the forward direction and starts and slows down in the opposite direction).

Also connected via the DC circuit, shown by lines 28 and 30, are two sets of retarding resistors 48, 50 and a pair of retarding diodes 52, 54. Deceleration resistors are a group of high power DC step resistors capable of dissipating large amounts of electrical energy in the form of heat when the system 10 is operating in the deceleration mode. The resistors are equipped with cooling fans (not shown) that are driven by electric motors 56. A single motor 56 can provide power to drive the cooling fans of both groups of retarders 48, 50. The retarder diodes 52, 54 serve to block power to the retarder resistors when the system is operating in the boot mode.

The system is controlled by a controller 66 which is connected by electrical lines 68, 70, 72, 74 to a voltage regulator 20, an excitation converter 58 and armature converters 24, 26. The controller can be of any suitable construction. It receives input signals from the vehicle controller for speed control, direction selection, forward movement or deceleration of engine speed and generator power. The controller also receives system feedback signals representing motor voltage, armature current, motor excitation current, generator voltage, motor speed/AC frequency, and motor speed. Additional operator commands, feedback signals to other control features can be incorporated into the controller, if desired. As the control and computing part of the system, the controller 66 provides logic pulses, control loop pulses and directional pulses to regulate all inverter outputs. It consists of series and combinations of proportional, integral and derivative control circuits, with a converter function described by conventional control system theory and feedback. They can be realized by the operational circuits of the amplifier team (analog), or by conversion equations calculated in the microprocessor assembly (digital). The specialized nature of the controlled system, as well as the requirements for strong integration, lead to the custom design of circuits rather than the use of standard off-the-shelf computing and control systems. It is recommended that the control system be based on closed control nodes, or loops, by which the response to a single command level is fed back to the controller 66 to become part of the control process. The external or total node is the response of the control system to the speed of the vehicle controlled by the driver.

Within that node, or circuit, are sub-circuits that control motor speed and generator voltage, and internal circuits that control motor voltage and current parameters that produce motor coupling and thus motor speed. The time constants and conversion functions of the control circuits are coordinates for proper synchronization and response. The main output of the controller 66 is the properly synchronized selector pulses for the various thyristor converters to produce the required armature, excitation and buck converter currents as well as the corresponding voltages.

System 10, as described, can be used either to start or to decelerate the off-road tractor. When operating in the start mode, the diesel engine 12 is used to start the AC generator 16. After the generator 16 is energized and the AC voltage begins to rise, the voltage regulator 20 maintains control of the AC voltage by regulating the flow of current to the generator to maintain the appropriate level. As the vehicle operator determines the speed and direction of the vehicle, the controller 66 provides selection pulses to the thyristors of the excitation converter 58 and the motor armature converters 24 and 26. These converters then provide direct current to the DC electric motors 32, 34 of the wheels and the windings 62, 64 of the motor excitation. Controller 66 maintains proper torque and speed of motor 32, 34 by monitoring various feedback signals that measure armature current, excitation current, motor voltage and motor speed, and maintains proper levels by conveniently adjusting thyristor selections in converters. When the deceleration mode is activated to slow or stop the tractor, the excitation converter 58 regenerates the existing excitation energy back into the AC distribution network 18 and then provides excitation current in the opposite direction. This changes the direction of the torque and the polarity of the voltage on motors 32 and 34, which then work as direct current generators. Alternatively, the excitation current can be left unchanged while the direction of the armature current in each of the wheel motors 32, 34 is reversed, again causing them to operate as DC generators.

At a negative motor voltage, the retarder diodes 52, 54 are forward biased and the DC current generated by the motors 32, 34 flows through the retarder resistors 48, 50, where the electrical energy is converted to heat. Fans (not shown) are provided to blow ambient air over the resistors or over heat exchange fins, or the like, connected to the resistors to dissipate the generated heat. The fans are powered by electric motor 56, a series wound DC motor connected across a portion of retarder 48. As the deceleration voltage increases, the speed of the fan motor 56 increases, so that more cooling air is automatically supplied through the deceleration resistors 48, 50.

The armature converters 24, 26 can be adjusted so that part of the direct current energy, generated by the wheel motors, is regenerated back into the alternating current distribution network 18. The sum of the energy transmitted by the resistors 48, 50 for deceleration and the energy regenerated in the alternating current network through the deceleration by which the engines 32, 34 act on the driving wheels 44, 46 of the tractor. establishment of excitation currents 62, 64, from voltage regulator 20 when establishing excitation 22 of the generator, and from other consumers of alternating current in the system. In addition, the AC generator 16 can be controlled to operate, when there is sufficient AC power from the armature converters 24, 26, as a synchronous motor driving the motor 12 via the coupling 14, so as to accept the loads imposed on the motor by auxiliary equipment and parasitic load, so that the required amount of fuel for the engine is significantly reduced. However, the engine must be kept idling at operating speed, even when operating in a "no-load" condition, to maintain proper generator voltage and frequency, and be ready to supply power to the system as needed.

The level of deceleration power, and the distribution of the energy generated by the wheel motors 32, 34, is regulated by the controller 66. However, there are limitations to the distribution of the energy generated during the deceleration operation, because the deceleration resistors 48, 50 are groups of stepped resistors, of fixed values. , and the voltage and current produced by motors 32 and 34 are limited by the design limitations of the motors themselves. The retarding power that must be generated mechanically as power in watts, in 32, 34 wheel motors, is an electrical function of the product of voltage and current, and mechanically a function of the product of torque and speed. The construction of commutators, motor windings, and other magnetic conditions limit the maximum voltage and magnitude of current that can be commutated (transferred from the brushes to the commutator) in motors. Therefore, the current and voltage limitations of the motor must be considered when selecting values for the step resistor groups 48, 50. The selected resistance values are compromises at best when considering the full range of motor speeds. At maximum motor voltage, resistors 48, 50 establish the armature current, and the motor construction establishes the operating speed that can switch that current. At that operating speed, all the current generated by the wheel motors 32, 34 must flow through the selected resistors in order to achieve the maximum deceleration force (or effort). If the maximum deceleration force is not required, the motor voltage can be lowered, so that the current through the resistors 48, 50 is reduced, which allows a portion of the motor current to be regenerated back into the AC distribution network 18 via the armature converters 24, 26. This means a greater current and lower efficiency for the same deceleration force, than when the voltage can be maintained at the maximum value, and the current can be reduced. At motor speeds lower than the aforementioned operating speed, energy will be regenerated into the AC distribution network, or only after the selected deceleration resistors have absorbed their maximum load for that voltage.

Another regeneration can also be achieved with lower deceleration forces by further lowering the motor voltage, but this means higher currents and lower efficiency than when the motors are maintained at maximum voltage. Also, when regeneration occurs, care must be taken not to regenerate more energy than the AC network can absorb. Conversely, if the wheel motors are running at speeds higher than selected, the current must be reduced for good motor commutation. The voltage must be reduced to reduce the current, which means that the retarding force is reduced proportionally to the square of the required reduction in current, instead of linearly, which would be the case if the maximum voltage value could be maintained and only the current reduced.

As a result of these limitations, additional current to feed through the AC mains converter 24, 26 is only available at certain levels of deceleration effort (or force). At other times, additional fuel must 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 operating in the deceleration mode and substantial amounts of electricity are fed into the resistors 48, 50 and dissipated as warmth. It would be more efficient if the first energy generated by motors 32, 34 when operating in deceleration mode could be fed directly back to the AC grid via an inverter to replace AC grid loads and/or auxiliary and parasitic motor loads, before what amount of power is dissipated across the retarding resistor. However, this is not possible with existing tugboat propulsion and control systems, due to the systemic operational limitations discussed above.

Figure 2 shows an improved tractor starting and decelerating system 110 in accordance with the disclosed invention, which allows the initial energy generated during the deceleration cycle to be regenerated into the AC network to regenerate all diesel engine loads before any amount of supply energy to the resistors. In the improved 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 prior art system of Figure 1, and have been assigned corresponding numbers preceded by a "1". Thus engine 112 in system 110 corresponds to diesel engine 12 in known system 10, AC generator 116 corresponds to AC generator 16, and so on.

In system 110, the retarding resistors 48, 50 have been removed from the DC circuits connected to the motors 32, 34 and have been replaced with retarding resistors 176 having a similar function and the same capacitance as the combined resistors 48, 50 of Figure 1. The resistors 176 are connected via a single DC circuit shown by DC supply lines 180, 182, which are in turn electrically connected to a single deceleration converter 184. Deceleration converter 184 is conveniently electrically connected to AC distribution network 118, and via control line 186 to controller 166.

Buck converter 184 is of the thyristor type and is preferably a three-phase, half-wave controlled rectifier, using six thyristors connected to three AC phases in a bridge configuration, similar to armature converters 124, 126, but with correspondingly increased capacity.

In boot mode, system 110 operates in substantially the same manner as known system 10 (Figure 1). The alternating current energy, generated in the alternating current generator 116, driven by the motor 112, is supplied via the alternating current network 118 to the thyristor armature converters 124, 126 for conversion into direct current energy. Energy is supplied to the DC electric motors 132, 134 of the wheels, and is transmitted via drive shafts 136, 138 and gear reducers 140, 142 to the drive wheels 144, 146 of the tractor. During startup mode, the deceleration converter is not activated, so no power is supplied to the deceleration resistors.

When the deceleration mode is activated, the excitation converter 58 regenerates the existing excitation energy back into the AC network and then provides excitation current in the opposite direction. This changes the direction of the motor torque, and the DC electric motors 132, 134 of the wheels will work as direct current generators, which receive power from the drive wheels 144, 146 of the tractor. Alternatively, instead of changing the direction of the excitation current, the direction of the armature current (armature current) in the wheel motors 132, 134 can be changed by using dual armature converters instead of the armature converters 124, 126. The armature converters 124, 126 are adjusted so that the energy is regenerated into the grid alternating current. The amount of deceleration energy generated is regulated by controller 66 to maintain the commanded vehicle speed. Since there are no longer any retarding resistors on the wheels 128, 130 of the DC motors, all the energy generated by the motors is regenerated via the thyristor converters into the AC distribution network 118. The regenerated energy is first used to power all other loads in the AC network, such as the excitation converter 158 and the voltage regulator 120 . This relieves the load on the AC generator 116 and reduces the fuel consumption of the motor 112. As additional generated power is available from the motors 132, 134, power is supplied to the AC generator 116 so that it begins to operate as an AC synchronous motor driving the motor 112 .This completely relieves the engine 112, since power from the generator 116 is available to meet all the additional and parasitic power needs of the engine 112, reducing fuel consumption to essentially zero.

At that point, any additional power generated by the wheel motors 132, 134 will be transferred via the AC distribution grid 118 to the deceleration converter 184 for conversion to DC power and consumption in the deceleration resistors 176. As with the system of Figure 1, the fan motor 156 drives the cooling fans (not shown) to dissipate the generated heat to the atmosphere.

The controller 166 monitors the amount of regenerated deceleration energy input to the AC circuit, the engine RPM, and the frequency and voltage of the AC generator, as well as other relevant drive motor parameters, so as to properly manage the overall operation of the system. The presence of a thyristor buck converter 184 coupled to the AC power system allows infinitely variable delivery of excess buck energy to the buck resistors 176 . As armature converters 124, 126 allow all deceleration energy generated by motors 132, 134 to be regenerated into the AC grid, motors 132, 134 can operate at maximum voltage and current limits throughout their speed range, providing maximum torque and deceleration power. This eliminates the operational limitations imposed by known systems that have stepwise retarding resistors of constant capacity connected across the DC circuit of the drive motors.

System 110 is also adapted to receive and use DC power from a source external to the tug, such as conventional dual overhead DC trolling lines. As shown in broken lines in Figure 2, a single trolling unit 188 can be added to the tug, if desired, which includes elements such as a pantograph or trolling rods, shown schematically at 190, which can optionally be connected to a direct current trolling line. electricity. The control unit 188 also includes elements for electrical connection to the DC side of the inverter 184 for retarding via the retarding lines 184 for retarding via the direct current lines 180, 182.

The retarder diode 178 is connected in series to connect to voltage poles opposite to those normally realized on the retarder resistors 176, so that the diode 178 is normally oppositely biased and isolates the retarder resistors 176, thereby preventing power from the trolling network from being fed into the resistors .

In locations where a power grid is available, the overhead grid connection device 190 may be activated either by the vehicle operator or by a suitable automatic device to connect the system 110 to the power grid. When the controller 166 senses that the trolling unit 188 is on, the thyristors in the retarding converter 184 (which now functions as a combined trolling/retarding converter) are adjusted so that power is regenerated into the AC distribution network 118 . The regenerated energy is used to power all the AC consumers on the tractor in the starting mode, including the necessary energy for the drive motors 132, 134, the excitation converter 158, and the voltage regenerator 120. The additional AC energy from the deceleration converter 174 is available to drive the AC generator 116 as a synchronous motor to completely relieve the motor 112, thereby reducing fuel consumption to virtually zero. Controller 166 will continue to regulate voltage regulator 120 to maintain the desired system voltage.

With system 110, power can be supplied to the AC network simultaneously from the trolling unit 188 via the converter 184 and from the AC generator 116, driven by the motor 112. Therefore, it is not necessary to turn off, or interrupt the operation of, the built-in diesel power generation system before connecting to external trolling network for power supply. When trawl power is available, it will automatically replace AC power from the AC generator to reduce and eventually eliminate the load on the engine 112. Conversely, when the tug leaves an area where trawl power is available, the trolling grid connection device 190 will shut down and power to the AC system from the trolling unit will cease. The controller 166 will detect the loss of power from the trolling unit and will automatically direct additional fuel to the engine 112 to generate the necessary driving energy via the AC generator 116. All this is achieved without the use of complex electrical switching-on equipment or a special control system for regulating the voltage and current that is supplied from the trolling network to the DC drive motors 132, 134. In the system from Figure 2, the maximum voltage of the trolling network should not be much higher from the maximum voltage that is normally generated in the alternating current distribution system 118 by the generator 116, in order for the thyristors to work properly. Roughly numerically, the DC voltage supplied to each wheel DC electric motor 132, 134 via the armature converters 124, 126 is the same as the AC voltage. For DC electric wheel motors, designed to operate at a maximum of about 1000 V, the system shown in Figure 2 will be suitable for use with a trolling network for a supply of only about 1000 V.

There are a number of trolling support facilities in mines around the world, which use 1000 to 1200 V DC power trolling lines installed as a supplemental power source for diesel-electric haulers operating on uphill inclines. For such plants, a power and deceleration system such as that shown in Figure 2, using 1000 V drive motors, would be suitable and would provide significant advantages over known systems.

Other trolling support plants, however, generate trolling line voltages in the range of 2000 to 2200 V, and may not be suitable for use with tugs having parallel-connected 1000 V DC wheel motors, as shown in Figure 2. Therefore, in one alternative embodiment of the invention, a procedure and a device for starting and decelerating off-road tractors that can use additional energy from the trolling network in a wide range of direct current voltage, from about 1000 to about 2200 V, have been realized. This embodiment, shown in Figure 3, includes system 210 which has many of the same components as system 110, shown in Figure 2. Corresponding parts and functions are identified by a corresponding reference number system, where the first digit of each component number is changed from "1" to "2". Thus, the engine 212 of Figure 3 is essentially the same as the internal combustion engine 112 of Figure 2, the AC generator 216 is the same as the AC generator 116, and so on.

In system 210, AC generator 216 is adapted to generate AC voltage of approximately 2000 V, which will be treated by armature converter 224 to DC current of the same voltage to power DC electric motors 232, 234 wheels. However, since the drive motors 232, 234 are connected in series, each will receive a maximum of about 1000 V. [this enables the use of conventional 1000 V motors to drive tractor wheels.

With this configuration, the trolling unit 228 can use overhead DC power up to about 2000 to 2200 V. As the trolling/retarder converter 284 will regenerate all of the lower voltage DC power received from the trolling unit to the AC power grid at the desired higher voltage (for example 2000 V), the system can also be used with existing 1000 V DC power supply trolling lines without modifications to the tug's start and deceleration system.

Since both motors 232, 234 and motor drives 262, 262 are connected in series, each of the motors 232, 234 will provide essentially equal torque to the drive wheels 244, 246 of the tractor. In some cases, such as slippery road conditions, it may be desirable for the drive wheels on one side of the tractor to provide less torque than those on the other side, in order to control wheel slip. If desired, this goal can be achieved by incorporating in the system 210 one additional thyristor excitation converter 292, of the same construction as the 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 DC line 296 connects the second converter 292 to the second excitation coil 264, both excitation coils 262 and 264 specially grounded, as shown. Controller 266 can then be used to independently control the excitation current for motors 232 and 234 to individually adjust the amount of starting torque or decelerating torque generated by each motor.

The operation and advantages of the starting and decelerating system 210 are essentially the same as those described in connection with the system 110 shown in FIG. 2, except that the trolling unit 288 can automatically accept a trolling line voltage of about 1000 to about 2200 V without the need for changing connections, introducing on-off devices or other changes to the system. The alternating current generator voltage will automatically be maintained at the desired level of 2000 V alternating current by the operation of the voltage regulator 22. Generators of higher voltage alternating current can be installed in the system, which gives a proportionally larger range of the maximum voltage of the trolling net.

The foregoing depiction and description is provided by way of illustration only, and various changes may be made in the configuration, operation, and management of the system without departing from the scope of the invention set forth in the appended claims. For example, as will be appreciated by those skilled in the art, a thyristor converter can be used to power an AC distribution network from some external DC power source, regardless of whether the external power is supplied via a buck converter, as shown in figures 2 or 3, or the energy is supplied via a separate trolling converter connected to the trolling unit. In this way, known systems, such as that shown in Figure 1, can be modified, or existing tugs modified, to use trolling support by adding a device for connecting to the trolling network connected to the AC supply network via thyristor converters. The operational advantages of introducing power from the trolling line into the AC distribution network via a thyristor converter will be realized regardless of whether the retarding resistors are connected to the AC supply network, as shown in Figure 1. Further, if the known system of Figure 1 is modified to receive power from the trolling network via a thyristor converter at 2000 V, it is obvious from the foregoing description and description of the disclosed invention that the wheel motors 32, 34 in the known system can be connected in series and other components modified to accept approximately 2000 V a.c. currents in the supply network 18 alternating currents. All of these described modifications and variations of the starting and decelerating system, as well as others that will be considered by those skilled in the art, are believed to be within the scope of the disclosed invention.

Claims (20)

1. Electric drive and distribution system for a vehicle that includes: - alternating current network (118, 218); - an alternating current generator (116, 216) connected to said alternating current network and adapted for connection to an internal combustion engine (112, 212); - DC motor (132, 232), which has a coil (162, 262) and an armature - a current converter (158, 258) for supplying electricity from said alternating current network to the coil of the direct current motor that responds to the input control signal; - an armature converter (124, 224) for directing current from said alternating current network to the armature of a DC motor that responds to the input control signal and a control center (106, 206) for monitoring said converters; characterized by the fact that: - a contact conductor converter (184, 284) having direct current connections, an input control circuit and having alternating current connections connected to said alternating current network, for changing the direct current applied to said direct current connections and directing the changed direct current to said an alternating current network which responds by monitoring signals received at the input control circuit of said contact conductor pole converter; and where - said controller (166, 266) has outputs connected to the input control circuit of said contact conductor converter, to the input control circuit of said pole converter and to the input control circuit of said armature converter, said controller also has an input for sensing the direct current applied to said terminals of the direct current of said converter of the contact lead pole, said regulator for monitoring said pole converter and said armature converter for directing current from said alternating current network to said coil, i.e. the armature and for opening said converter of the contact lead pole in such a way as to direct the changed direct current to said alternating current network simultaneously with said alternating current generator directing alternating current to said alternating current network. 2. The system according to claim 1, characterized in that said regulator has inputs for receiving commands on the speed of the machine, armature current and coil current, so that said regulator is also for monitoring said contact conductor pole converter in such a way that responding to said coil converters and the armature provides enough current from said alternating current network, that said alternating current network provides current to said alternating current generator as a synchronous motor. 3. The system according to claim 1, characterized in that said contact conductor pole converter comprises a three-phase full-wave regulated thyristor rectifier. 4. The system according to claim 1, characterized in that it further comprises an electric power network (188, 288) for connecting said DC connections to the upper line of the DC contact conductor pole. 5. A system according to claim 4, characterized in that said alternator is adapted to act as an alternator electric motor which supplies current to an internal combustion engine when electrical energy is received at the direct current connections, so that the energy of the contact conductor pole direct line is used to remove loads on an internal combustion engine. 6. The system according to claim 1, characterized in that said armature converter comprises one thyristor armature converter (224) connected to said AC network and with said DC motor comprises a pair of DC rotating motors (232, 234) connected in series to the DC side of said single thyristor anchor converter. 7. The system according to claim 6, characterized in that said electric field converter comprises: a pair of current coils (262, 264), each of said current coils being electrically connected to a respective electric current converter and connected to one of said pair of DC rotary motors connected in series so that said controller can independently monitor each of said thyristor electric current converters. 8. Procedure for the operation of an electric drive system and a distribution system for a vehicle, said vehicle includes an internal combustion engine (112, 212), an alternating current generator (116, 216) for generating alternating current from said engine and applying it to the alternating current network ( 118, 218), a contact conductor pole converter (184, 284) connected to said alternating network and to direct current connections (190, 290) where external direct current is received and an electric motor (132, 232) connected to said alternating network via field converters (158, 258) and armature converters (124, 224), characterized by the fact that it includes stages: - sensing the presence of direct current applied to said direct connections - changing said direct current applied to said direct current connections to alternating current with said contact conductor pole converter; - opening of the said converter of the contact conductor pole in order to apply the said changed direct current to the said alternating current network simultaneously and together with the alternating current from the said alternating current generator; and - power supply of said electric motor with said changed direct current together with alternating current from said alternating generator. 9. The method according to claim 8, indicated by the fact that the additional stage is the power supply of said alternating current generator as a synchronous motor with said changed direct current. 10. The method according to claim 8, characterized in that the additional stages are: activating the stop monitoring of said motor converter so as to energize said AC network supplied with said motor to power said generator as a synchronous motor; and - connecting the decelerating assembly (176, 276) to the AC network during the said stop in order to dissipate the excess energy obtained on the said AC generator with the said motor. 11. The method according to claim 10, characterized in that the binding stage includes: - connecting said decelerating assembly via said DC connections. 12. The method according to claim 8, characterized in that the power supply stage includes: - delivering alternating current from said alternating current generator to the alternating current network; - supplying alternating current from the alternating network to the first thyristor converter (158, 258; 124, 224); - converting alternating current into direct current in said first thyristor converter; - delivering direct current from said first thyristor converter to said electrically driven motor. 13. The method according to claim 12, characterized in that it includes additional stages: - use of the changed direct current for the operation of said alternating current generator as an alternating current motor; and - power supply of the internal combustion machine from the said AC generator that works as an AC motor. 14. Electric drive and distribution system for a vehicle that includes: - alternating current network (118, 218); - an alternating current generator (116, 216) connected to said alternating current network and adapted for connection to an internal combustion engine (112, 212); - direct current motor (132, 232), which has a coil (162, 262) and an armature; - converters (124, 224; 158, 258) for directing current from said alternating current network to the coil and armature of a DC motor that responds to the input control signal and a regulator (166, 266) for monitoring said converters; characterized by the fact that: - the deceleration circuit (176, 276) is connected via said direct current connections; and - the contact rod/retarder converter (184, 284) has DC connections, has an input control circuit, and has AC connections connected to said AC network, for changing the applied DC current to said DC connections and applying the changed DC current to said AC network in response by monitoring the signals received at the input control circuit of said converter contact conductive pole/deceleration; - said regulator (166, 266) having outputs connected to the input control circuit of said inverter contact lead/deceleration to the input control circuit of said converter, said regulator also having an input for sensing the applied direct current to said DC terminals of said converter contact lead/ retarder, said regulator for monitoring said converter to apply current from said AC network to said coil and armature, and for opening said converter contact rod/retarder in such a way as to apply the changed direct current to said AC network; and - where said regulator, in slow mode, is also for monitoring said converter to apply reverse current to the DC motor so that the applied current is applied to said AC network in such a way that said AC network provides current to said AC generator as a synchronous motor, and also for regulating of the said converter contact rod/retarder in such a way that the said retarder circuit receives current from the said alternating network. 15. The system according to claim 14, characterized in that said retarding circuit comprises a resistor (176, 276) and a diode (178, 278) connected in series between said DC terminals in such a way that said diode is reverse biased when DC current is applied to said DC terminals. connections. 16. System according to claim 14, characterized in that said converters include: - a field converter (158, 258) for applying energy from said alternating network to the coil of a DC motor that responds to signals received at the input control circuit; and - armature converter (124, 224) for applying energy from said alternating network to the armature of a DC motor which responds to signals received at the input control circuit; and - when said controller is in slow mode, it controls said converter to apply reverse current to the coil so that said armature converter applies current to said AC network. 17. The system according to claim 14, characterized in that said deceleration assembly comprises: - A deceleration resistor (176, 276) adapted to consume electrical energy generated with said DC motor when said system operates in deceleration mode; - thyristor converter of retarding resistors (184, 284) electrically connected to said alternating network and to said retarding resistors, said thyristor converter of retarding resistors includes parts for receiving alternating electric current from said alternating network and delivering direct current to said retarding resistors; - and with said regulator is also electrically connected to said thyristor converter of deceleration displacements, in order to monitor the operation of said thyristor converters of decelerating resistors in order to monitor the direction and amount of deceleration moment expressed with said direct current motor so that when said system operates in said decelerated mode, the electrical energy generated by said A DC motor can be used to reduce the power requirements of an internal combustion engine, with excess power generated by said DC motor being supplied to said retarding resistor. 18. A system according to claim 17, characterized in that: an electrical power network (188) for selectively connecting said system to a DC power line outside the vehicle and for supplying said external DC power line to the DC side of said thyristor converter of retarding resistors, so that the external DC power line can be converted to AC power with said retarding resistor thyristor converter supplied to said AC grid to replace the AC power generated by said AC generator and to reduce the power requirement of the internal combustion engine. 19. The system according to claim 18, characterized in that said parts of the electrical network are connected at a DC voltage of opposite polarity to that which normally exists across said retarding resistors and additionally includes an electrical energy diode (178, 278) connected between said lines of the power network and said retarding resistor so that when an external DC power line is connected to said system via said power grid line, the opposite polarity of the DC power line will reverse the polarization of the diode and block the DC power line from supplying the retarding resistors allowing said DC power line to energy to supply said retarding resistor thyristor converter for conversion to alternating electrical energy. 20. The system according to claim 17, characterized in that the retarding resistor comprises: - a greater number of resistors adapted to the conversion of excess electricity generated into heat; and - a device (156, 256) for dissipating the heat produced by said resistors.