In the particular embodiments described, an unlimited voltage static power converter includes an array of multi-level phase drivers consisting of a plurality of H-bridge power modules connected in series. The midpoint node of the series-connected power semiconductors is connected to corresponding midpoint nodes in adjacent H-bridges to achieve a desired high output voltage using available power switch ratings. A three-dimensional multi-level, multi-phase, multi-circuit array of H-bridges permits the use of the static power converter for high power applications, while providing a high degree of power quality. The power semiconductor switches are operated in accordance with a two-dimensional interleaved pulse width modulation algorithm which produces a waveform with a switching frequency that can be more than an order of magnitude higher than the switching frequency of a single power switch. PWM complementary triangle carrier waves are used for individual PWM control of each H-bridge in each multi-level phase driver, resulting in a two-dimensional interleaved control algorithm. Injection of harmonic or non-harmonic content into the PWM reference waveform further reduces harmonic and non-harmonic content of the output voltage waveforms. Part-load efficiency is increased using unique load partitioning methods, five of which are described herein.

Modular static power converter connected in a multi-level, multi-phase, multi-circuit configuration

A modular transformer arrangement providing power to a multi-level power converter includes a plurality of three phase transformers having delta or extended delta connected primary windings and delta or extended delta or wye or zig zag wye connected secondary windings and the multi-level power converter has full bridge power modules inputs connected to isolated secondaries of the transformer modules and outputs connected in series and/or in parallel to provide increased voltage and/or current or multiple phases which can be phase shifted with respect to the input to the transformer.

Modular transformer arrangement for use with multi-level power converter

In a current type GTO inverter, commutation surge voltage is inevitably generated from an inductive load whenever each GTO is turned off. The commutation surge voltage thus generated is once stored in a capacitor (C 1 ) through a diode surge voltage rectifier (5) and then restored to the DC source terminals (3A, 3B) of the GTO bridge-connected inverter (3) through a pair of other GTOs (G 7 , G 8 ) turned on during steady state intervals of inverter commutation. Magnetic energy stored in a reactor (Lr 1 , Lr 2 ) in motor-driving operation is recharged to the capacitor (C 1 ) through the diode surge voltage rectifier (5) after the GTOs (G 7 , G 8 ) have been turned off; the motor kinetic energy stored in the capacitor (C 1 ) through diodes (D 8 , D 9 ) in motor-braking operation is regenerated to the AC source side of the inverter (3) through a pair of other GTOs (G 9 , G 10 ) when the voltage across the capacitor (C 1 ) exceeds a predetermined value, and magnetic energy stored in the reactor (Lr 1 , Lr 2 ) in motor-braking operation is recharged to the capacitor (C 1 ) through diodes (D 12 , D 13 ) after the GTOs (G 9 , G 10 ) have been turned off. The circuit operation is stable at higher frequency range because no vibration circuits are provided, and the energy conversion efficiency is high because every energy loss is effectively restored to the inverter or the power source side.

Current-type GTO inverter with surge energy restoration

A three-phase converter for polyphase induction motors has an input transformer with primary windings and at least two secondary windings associated with each primary winding, and controlled power semiconductors. Groups of power semiconductors are connected to the secondary windings such that the power semiconductors operate in series with the motor phases.

Three-phase converter for polyphase induction motors

A simultaneous recovery commutation current source inverter is provided by connecting three AC output terminals of a main inverter and an auxiliary inverter in parallel with each other and to three terminals of an induction motor, providing a high AC impedance DC current source through inductors connected in series to a variable DC electric source so that DC electric power is supplied to both sides of a main DC bus of the main inverter, providing a low AC impedance DC voltage source by supplying DC electric power to both sides of an auxiliary DC bus of the auxiliary inverter through a rectifying circuit from the respective connecting points of the main inverter, auxiliary inverter and the three motor terminals. Snubber circuits may be added to the respective semiconductor elements for safe switching operation.

Simultaneous recovery commutation current source inverter for AC motors drives

Circuit arrangement for inverters with three stage self-commutation suitable for large outputs and for parallel connection of main thyristors and separating reactors.

Circuit arrangement for self-commutated inverters

Inverted current rectifier with self commutation for smaller and medium output and three-stage commutation in which the disconnection of thyristors of the inverted rectifier and the current commutation in the phases are separated and the accumulated power of capacitors of the inverted rectifier is, without losses, discharged to the current source and thus to the load of the inverted rectifier.

Circuit arrangement of an inverted current rectifier with self commutation

Schaltung fuer einen stromwechselrichter mit eigener kommutierung

The invention relates to an electrical invertor circuit which is supplied from an electrical power source (1 DEG ), has self-commutation and contains a supply rectifier block (3 DEG ), an invertor block, a supply capacitor block (4 DEG ) and an auxiliary storage block (6 DEG ), as well as overshoot reactors (7 DEG , 8 DEG ), a recharging source, a block (9 DEG ) of commutation pulses and a recharging inductor (10 DEG ). For switching relatively low and medium power, three-stage commutation is used, the switching-off of the invertor thyristors and the current commutation being isolated in the phases, and the stored energy of the invertor capacitors being dissipated without losses into the electrical power source and thus into the invertor load. The invention can be used advantageously for both single-motor and multi-motor drives having asynchronous motors and synchronous motors and, furthermore, also for other types of load impedances.

Krtek Jan

Papers

Circuit arrangement for self-commutated inverters

Circuit arrangement of an inverted current rectifier with self commutation

Schaltung fuer einen stromwechselrichter mit eigener kommutierung

Electrical invertor circuit having self-commutation