A variable speed wind turbine employing a rotor (103) connected to a multiplicity of synchronous generators (106 - 112) with wound field or permanent magnet rotors. A passive rectifier (114 - 120) and an inverter (136 - 142) are used for power transfer back to the grid. A Turbine Control Unit (TCU) (132) commands a required generator torque based on rotor speed and power output of the turbine inverters. Torque is controlled by regulating the DC current by control of the inverter. A main-shaft-damping filter is provided by measurement of the DC bus voltage. In high winds the turbine remains at a constant average output power through a constant torque command and a varying pitch command to a rotor pitch servo system (102). A set point is fixed at the inverter output such that output VAR load is minimized running the turbine at very nearly unity power factor. Dynamic VAR and power factor control is provided by a separate VAR apparatus.

Variable speed distributed drive train wind turbine system

A three stage power source for an electric arc welding process comprising an input stage having an AC input and a first DC output signal; a second stage in the form of an unregulated DC to DC converter having an input connected to the first DC output signal, a network of switches switched at a high frequency with a given duty cycle to convert the input into a first internal AC signal, an isolation transformer with a primary winding driven by the first internal high frequency AC signal and a secondary winding for creating a second internal high frequency AC signal and a rectifier to convert the second internal AC signal into a second DC output signal of the second stage, with a magnitude related to the duty cycle of the switches; and, a third stage to convert the second DC output signal to a welding output for welding wherein the input stage has a regulated DC to DC converter with a boost power switch having an active soft switching circuit.

Three stage power source for electric ARC welding

The invention features a centralized control architecture for a closely-coupled plasma arc system, in which the “intelligence” of the system is integrated into a single controller. The closely-coupled plasma arc system includes a power source, an automatic process controller and a torch-height controller, where each of these components individually has a closed-loop dynamic relationship with the controller.

Centralized control architecture for a plasma arc system

A plasma arc cutting power supply, and method of providing plasma cutting power, is disclosed. It includes a source of power having, preferably an engine or transformer based power source, that provides a main power output and an auxiliary power output. A two-state configuration circuit is in electrical communication with the auxiliary power output. The auxiliary power output receives voltage of a first magnitude with a non-floating ground when the configuration circuit is in its first state. The auxiliary power output receives voltage of a second magnitude, preferably different than the first magnitude, with a floating ground, when the configuration circuit is in its second state. When a plasma cutting circuit is connected to the auxiliary power output the configuration circuit is set in its second state. The plasma cutting circuit includes at least one chopper. A safety circuit that disables the plasma output includes a GFI or optical isolator.

Plasma cutter for auxiliary power output of a power source

A vehicle motor-generator apparatus based on a field winding type of synchronous machine coupled to a power inverter and a battery, wherein the synchronous machine is controlled to operate as a motor to perform engine starting and thereafter be driven by the engine as an electrical generator, wherein during a short time interval at the commencement of engine starting, the armature winding of the synchronous machine is driven by a current such that magnetic flux is produced by the armature winding acting in the same direction as magnetic flux produced by the field winding, to thereby achieve increased torque during the time when maximum torque is required. In addition, the supplied field current is set at a maximum value during only an initial period when engine starting begins, until the first compression stroke of the engine has been completed, and thereafter set to a reduced value until the completion of engine starting, thereby reducing the amount temperature rise within the field winding during engine starting, while ensuring a sufficiently high value of initial torque.

Vehicle motor-generator apparatus utilizing synchronous machine having field winding

A method and apparatus for welding with an engine driven inverter power supply includes generating an ac output with an engine and generator. The output is rectified and inverted to provide an ac inverter output. The engine is controlled using feedback indicative of a welding output operating parameter. The feedback may also be taken from the inverter or generator, and the generator may be controlled instead of or in addition to the engine. Engine parameters that may be controlled include engine speed, selecting between an idle speed and a run speed, a throttle position, a fuel pump, an injection timer, a fuel to air ratio, fuel consumption and ignition timing. Another aspect of the invention is having the feedback be responsive to one or more of the welding current, welding voltage, welding power, or functions thereof. The feedback may be responsive to the current, voltage, power, ripple and functions thereof. An aux power output is derived directly from the generator and feedback from the aux load is used to determine if the engine should be idling or running at high speed.

Engine driven inverter welding power supply

A power supply, such as a plasma cutting power supply or a welding power supply, that provides an output to a pair of output terminals is disclosed. The power supply includes a source of voltage and a plurality of choppers. The choppers are connected in parallel between the voltage source output terminals. A controller controls the choppers so that they are out-of-phase with respect to each of the other of the plurality of choppers. The choppers preferably include a freewheeling diode, an inductor and a switch. The number of choppers is approximately equal to the ratio of the open circuit voltage to the output load voltage.

Plasma cutting or arc welding power supply with phase staggered secondary switchers

A method and apparatus for controlling and maintaining a continuous flow of pilot arc current in a plasma cutting torch includes a pilot circuit, a current sensing circuit, and a control circuit. The control circuit maintains a continuous flow of pilot current through the pilot circuit both before and after a cutting arc has been generated. The control circuit further controls the magnitude of the pilot current in response to the sensing circuit indicating the absence or presence of the cutting arc.

Plasma pilot arc control

Engine driven converter with feedback control

A method and apparatus for welding with an engine driven inverter power supply includes generating an ac output with an engine and generator. The output is rectified and inverted to provide an ac inverter output. The engine is controlled using feedback indicative of a welding output operating parameter. The feedback may also be taken from the inverter or generator, and the generator may be controlled instead of or in addition to the engine. Engine parameters that may be controlled include engine speed, selecting between an idle speed and a run speed, a throttle position, a fuel pump, an injection timer, a fuel to-air ratio, fuel consumption and ignition timing. Another aspect of the invention is having the feedback be responsive to one or more of the welding current, welding voltage, welding power, or functions thereof. The feedback may be responsive to the current, voltage, power, ripple and functions thereof. An aux power output is derived directly from the generator and feedback from the aux load is used to determine if the engine should be idling or running at high speed.

Stephen Li

Papers

Engine driven inverter welding power supply

Plasma cutting or arc welding power supply with phase staggered secondary switchers

Plasma pilot arc control

Engine driven converter with feedback control

Welding power supply