Yaskawa America, Inc.
|Yaskawa America, Inc. Patent applications|
|Patent application number||Title||Published|
|20150115854||MOTOR SPEED CONTROL WITH SPEED FOLDBACK FOR PHASE IMBALANCE PROTECTION - A variable frequency motor drive comprises a converter including a rectifier having an input for connection to an AC power source and converting the AC power to DC power. A DC bus is connected to the rectifier circuit. At least one bus capacitor is across the DC bus. An inverter receives DC power from the DC bus and converts the DC power to AC power to drive a motor. A controller is operatively connected to the converter. The controller comprises a speed control controlling the inverter responsive to a speed command to maintain a desired motor speed. A speed foldback control measures DC bus ripple voltage and regulates the speed command responsive to the measured DC bus ripple voltage.||04-30-2015|
|20150054443||ENERGY SAVING METHOD FOR USE WITH ACTIVE PWM RECTIFIERS IN REGENERATIVE DRIVES - As described herein, a drive circuit for a three phase AC motor comprises an AC/AC converter. The converter has an input for receiving multiphase AC power from an AC source and converting the AC power to variable voltage and variable frequency from the AC source for driving the AC motor. A filter circuit is connected to the AC/AC converter and comprises at least one inductor per phase and at least one capacitor per phase. The capacitors are connected in a broken wye configuration with one side connected to one of the inductors and an opposite side connected via a three phase diode bridge rectifier to a switch. The switch is controlled by a converter control to selectively open or short a neutral point of the broken wye capacitor configuration.||02-26-2015|
|20140313800||BALANCED FLUX ISOLATION TRANSFORMER BASED EIGHTEEN PULSE RECTIFICATION SCHEME FOR USE WITH VARIABLE FREQUENCY DRIVES - An AC/DC converter system comprises an input circuit for connection to a three-phase AC source. An isolation transformer comprises a symmetrical core with a set of primary windings and first and second sets of secondary windings wound on the symmetrical core providing balanced flux in all three phases and magnetically coupling to the set of primary windings. The first and second sets of secondary windings are phase shifted by select amounts from the set of primary windings. The set of primary windings is connected to the input circuit. An AC/DC converter comprises first, second and third three-phase rectifiers, the first three-phase rectifier is powered by the first set of secondary windings, the second three-phase rectifier is powered by the second set of secondary windings, and the third three-phase rectifier is powered by the input circuit. An output circuit is connected between the AC/DC converter and a DC load.||10-23-2014|
|20140198542||SINGLE-PHASE ACTIVE FRONT END RECTIFIER SYSTEM FOR USE WITH THREE-PHASE VARIABLE FREQUENCY DRIVES - A voltage source inverter comprises a rectifier having an input for receiving single-phase AC power from an AC source and converting the AC power to DC power on a DC bus. The DC bus has first and second rails to provide a relatively fixed DC voltage. A DC bus capacitor is across the first and second rails to smooth voltage ripple. An inverter receives DC power from the DC bus and converts the DC power to AC power. An active front end circuit comprises a pair of filter capacitors in series across the first and second rails to create a midpoint. A bidirectional switch is connected between the rectifier input and the midpoint. The bidirectional switch is controlled to inject current into the midpoint of the DC bus.||07-17-2014|
|20140146584||ELECTRONICALLY ISOLATED METHOD FOR AN AUTO TRANSFORMER BASED 12-PULSE RECTIFICATION SCHEME SUITABLE FOR USE WITH VARIABLE FREQUENCY DRIVES - An AC/DC converter system comprises an input circuit for connection to a 3-phase AC source. An autotransformer is coupled to the input circuit for developing first and second phase shifted AC supplies. A first AC/DC converter has a first rectifier connected to the first phase shifted AC supply converting AC power to DC power across a first DC bus having a first DC bus capacitor. A second AC/DC converter has a second rectifier connected to the second phase shifted AC supply converting AC power to DC power across a second DC bus having a second DC bus capacitor. First and second sets of switches are connected between the respective first and second DC buses and a main DC bus having a main DC bus capacitor. The first and second sets of switches are controlled so that only one of the first and the second DC buses is connected to the main DC bus to charge the main DC bus capacitor.||05-29-2014|
|20140043870||THREE PHASE BOOST CONVERTER TO ACHIEVE UNITY POWER FACTOR AND LOW INPUT CURRENT HARMONICS FOR USE WITH AC TO DC RECTIFIERS - A voltage source inverter comprises a zigzag transformer providing a neutral point. A rectifier unit comprises three single phase boost converters each connected to one of the three phases of AC power and the neutral point and comprising a bridge rectifier converting single phase AC power to DC power and using a boost inductor with a boost switch and blocking diode to develop a DC output. An inverter receives DC power and converts DC power to AC power. A link circuit is connected between each boost converter DC output and the inverter circuit and comprises a DC bus having first and second rails to provide a relatively fixed DC voltage for the inverter and a DC bus capacitance across the first and second rails to smooth voltage ripple. A switch controller controls operation of the boost switches using average current control for each of the boost converters.||02-13-2014|
|20130208515||AC SIDE SOFT CHARGE CIRCUIT FOR VARIABLE FREQUENCY DRIVES - A voltage source inverter comprises a rectifier having an input for connection to a multi-phase AC power source and converting the AC power to DC power at an output. An inverter receives DC power and converts the DC power to AC power. A DC bus is connected between the rectifier circuit and the inverter circuit to provide a relatively fixed DC voltage for the inverter. A bus capacitor is across the DC bus. A soft charge circuit limits inrush current to the bus capacitor. The soft charge circuit comprises an input inductor for each phase connected between the rectifier input and the AC power source and a clamping circuit across each input inductor to limit DC bus voltage.||08-15-2013|
Patent applications by Yaskawa America, Inc.