The invention relates to a frequency converter for an energy flow from a three-phase network to a consumer for medium and high output voltages, with variable frequency, current and voltage outputs, fed from secondary windings of a transformer with one or more cells per output phase (R, S, T). For each output phase, each identical cell has a diode input rectifier circuit, an active harmonic filter, an intermediate-circuit capacitance, and a three-point DC/AC converter on the output side.

A multi-phase voltage-controlled PWM frequency converter, comprising at least one control unit (23), at least one rectifier bridge (20) designed to be connected to a multi-phase supply network (U.sub.U, U.sub.V, U.sub.W), a direct-voltage intermediate circuit and at least one controlled inverter bridge (21) for feeding at least one multi-phase load (22) with an alternating voltage (U.sub.S, U.sub.R, U.sub.T) of varying magnitude and frequency. The inverter bridge has pulse width modulation-contr...

A trenching machine comprising a wheeled frame and a first motor mounted on the frame is provided. The first motor drives a digging chain carried on a chain guide extending from the machine. The chain guide is pivotally mounted coaxially with a drive chain drive sprocket. An actuating arm for pivotally moving the chain guide relative to the frame, a lock to lock the chain guide in a desired pivotal position, and a second motor mounted on the frame, are also provided. The second motor drives at l...

The present invention relates to a method for controlling a polyphase voltage inverter the inverter being designed to control a load in terms of pulse width modulation and to be connected upstream to a voltage source via a DC bus and downstream to an electrical load. It is connected to a control logic which implements said method. A geometric structure is produced while taking account of the constraints downstream and upstream of the inverter. More particularly, an upstream constraint relates to...

An ac-ac power converter system is provided for supplying power to an electrical load. The ac-ac power converter system provides an output voltage having variable amplitude and/or frequency. The ac-ac power converter system includes a boost inductor for applying a discontinuous current to an ac-ac power converter. The ac-ac power converter includes a rectifier circuit comprising of a first set of gate controllable active switches for converting an input ac power to a dc power and an inverter cir...

A Single-switched Resonant DC Link (SRDCL) converter is presented for a parallel resonant network with a single auxiliary power device for low conduction loss in single or poly-phase inverter and converter applications. The resonant network with an auxiliary power device is activated when the status of power devices coupled to the DC link changes. The resonant network forces the DC link voltage to drop to zero before any of the power devices coupled to the DC link are turned on. The auxiliary sw...

A system for generating an output power to a load is provided. The system comprises a generator configured for generating a variable frequency output power and a dual mode rectifier coupled to the generator and configured for being switched between a passive mode and an active mode. The dual mode rectifier comprises a passive rectifier coupled to output terminals of the generator and configured for operating in the passive mode and an active converter coupled to tappings from windings of the gen...

A multilevel converter-based, intelligent, universal transformer includes back-to-back, interconnected, multi-level converters coupled to a switched inverter circuit via a high-frequency transformer. The input of the universal transformer can be coupled to a high-voltage distribution system and the output of the universal transformer can be coupled to low-voltage applications. The universal transformer is smaller in size than conventional copper-and-iron based transformers, yet provides enhanced...

The electric power converter includes a series converter connected in series between an AC power supply 1 and a load 6, and having capacitors 30, 31 as a power supply for the converter, switching devices 12, 13, and diodes 16, 17; and a parallel converter connected in parallel to the AC power supply 1 and having the capacitors 30, 31, switching devices 10, 11, and diodes 14, 15. The series converter compensate the change in the voltage of the AC power supply 1 to feed a certain voltage to the lo...

An electric circuit for the conversion of a multiplicity of commercial power voltages to a predetermined supply voltage which is independent of the respective commercial power voltage, for a device with high electrical power requirements of high output, in the range up to 40 kW, such as a bobbin winding machine. The circuit contains a rectifier stage for generating a primary intermediate circuit DC voltage, a converter stage with power switches for generating a rectangular AC voltage, a high-pow...