# US 8,786,225 B2 · Inverter power generator

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- Number: US 8,786,225 B2
- Document ID: US8786225B2
- Status: Granted
- Kind: B2
- Application number: 13/416,696
- Filed: 2012-03-09
- Published: 2012-09-13
- Granted: 2014-07-22
- Earliest claimed: 2011-03-11
- Assignees: Toshiba Kikai Kabushiki Kaisha
- Applicants: Narutoshi Yokokawa; Tomoyuki Hoshikawa; Kazumi Murata; Junichi Kanai; Naoyuki Mashima
- Inventors: Narutoshi Yokokawa; Tomoyuki Hoshikawa; Kazumi Murata; Junichi Kanai; Naoyuki Mashima
- Web page: https://patentgrep.com/patent/US8786225B2

## CPC

- H02P 9/48: Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle (H02P9/04 - H02P9/46 take precedence)
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

An inverter power generator includes a current controller 14a setting a current limit ratio according to a rotation speed of a synchronous motor 13 and controls a converter current according to the current limit ratio. The current controller sets the current limit ratio to 70% if the synchronous motor is at a rotational speed equal to an idle speed of an engine 11. Until the rotational speed of the synchronous motor reaches a rated speed, the output current limiter linearly increases the current limit ratio up to 100%. With this, the rotational speed of the engine becomes reasonably increasable even if a sudden load increase occurs when the engine is operating at low speed.

## Claims

### Claim 1

An inverter power generator comprising:
a prime mover;
a synchronous motor coupled with the prime mover, wherein the prime mover is configured to rotate the synchronous motor to generate AC power;
a converter connected to the synchronous motor, the converter configured to convert the AC power from the synchronous motor into DC power;
an inverter connected to the converter, the inverter configured to invert the DC power from the converter into AC power of a required frequency; and
a capacitor arranged between the converter and the inverter, wherein:
the converter includes a current controller configured to set a current limit ratio according to a rotation speed of the synchronous motor and to limit a converter current according to the current limit ratio; and
the current controller is configured to set the current limit ratio lower than 100% when the synchronous motor is at a predetermined rotation speed lower than a rated rotation speed and linearly increase the current limit ratio up to 100% according to an increase in the rotational speed of the synchronous motor, wherein:
the converter includes a current command generator configured to generate a current command value according to a difference between a set PN voltage value serving as a voltage command value to charge the capacitor and a feedback PN voltage value from the capacitor;
the current controller includes:
a current limiter that is connected after the current command generator, the current limiter including a current limit ratio table indicating a relationship between rotation speed of the synchronous motor and current limit ratio, the current limiter configured to determine a current limit ratio according to a given rotation speed of the synchronous motor and the current limit ratio table and limit the current command value of the current command generator with the determined current limit ratio; and
a current driver configured to control an output current according to the limited current command value from the current limiter; and
the current limit ratio table is configured to specify a current limit ratio lower than 100% if the synchronous motor is at the predetermined rotation speed lower than the rated rotational speed and linearly increase the current limit ratio up to 100% according to an increase in the rotational speed of the synchronous motor.