Thyristor starter

Patent metadata

Field	Value
Publication number	US-11277087-B2
Application number	US-201917059744-A
Country	US
Kind code	B2
Filing date	Jan 4, 2019
Priority date	Jan 4, 2019
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

In a thyristor starter, an inverter converts DC power provided from a converter through a DC reactor into AC power having a variable frequency, and supplies the AC power to a synchronous machine. A controller controls the inverter based on a phase control angle. A voltage regulator regulates an induced voltage of the synchronous machine by supplying a field current to the synchronous machine. When a rotation speed of the synchronous machine exceeds a reference rotation speed during acceleration of the synchronous machine, the voltage regulator controls the field current such that the induced voltage increases with an increase in the rotation speed of the synchronous machine. The controller decreases a rate of increase in the phase control angle relative to the rotation speed of the synchronous machine, as compared with when the rotation speed of the synchronous machine is less than the reference rotation speed.

First claim

The invention claimed is:

1. A thyristor starter that starts a synchronous machine, the thyristor comprising:
a converter that converts AC power into DC power;
a DC reactor that smooths the DC power;
an inverter that converts the DC power provided from the converter through the DC reactor into AC power having a variable frequency, and supplies the AC power to the synchronous machine;
a controller that controls the inverter based on a phase control angle; and
a voltage regulator that regulates an induced voltage of the synchronous machine by supplying a field current to the synchronous machine, wherein
when a rotation speed of the synchronous machine exceeds a reference rotation speed during acceleration of the synchronous machine,
the voltage regulator controls the field current such that the induced voltage increases with an increase in the rotation speed of the synchronous machine, and
the controller decreases a rate of increase in the phase control angle relative to the rotation speed of the synchronous machine, as compared with when the rotation speed of the synchronous machine is less than the reference rotation speed, and
the controller further sets the phase control angle according to the rotation speed of the synchronous machine such that a DC voltage that appears at an input terminal of the inverter is constant in spite of change in the rotation speed of the synchronous machine.

2. The thyristor starter according to claim 1 , wherein, when the rotation speed of the synchronous machine exceeds the reference rotation speed during acceleration of the synchronous machine, the controller sets the phase control angle based on a terminal voltage of the synchronous machine such that a product of the terminal voltage of the synchronous machine and a cosine function of an effective phase control lead angle of the synchronous machine has a constant value.

3. The thyristor starter according to claim 1 , wherein, when the rotation speed of the synchronous machine exceeds the reference rotation speed during acceleration of the synchronous machine, the controller sets the phase control angle according to the rotation speed of the synchronous machine such that a commutation margin time of a thyristor in the inverter is longer than a turn-off time of the thyristor in spite of change in the rotation speed of the synchronous machine.

4. The thyristor starter according to claim 2 , wherein, when the rotation speed of the synchronous machine exceeds the reference rotation speed during acceleration of the synchronous machine, the controller sets the phase control angle according to the rotation speed of the synchronous machine such that a commutation margin time of a thyristor in the inverter is longer than a turn-off time of the thyristor in spite of change in the rotation speed of the synchronous machine.

Assignees

• Toshiba Mitsubishi Electric Industrial Systems Corp

Inventors

• Ota Takahiro
• Kawaguchi Hironori
• Ogino Hiroshi
• Matsumoto Yasuaki
• Ando Akinobu

Classifications

• H02M5/271

  from a three phase input voltage · CPC title

• H02P6/20

  Arrangements for starting (H02P6/08 takes precedence) · CPC title

• H02P1/46

  for starting an individual synchronous motor {(H02P27/04 takes precedence)} · CPC title

• H02M7/48

  using discharge tubes with control electrode or semiconductor devices with control electrode · CPC title

• H02P27/06 Primary

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title