Kabushiki Kaisha Toshiba

Toshiba Mitsubishi-electric Industrial Systems Corporation

Toshiba Industrial Products and Systems Corporation

Tatsuya Hirose

Tetsuo Yoshimitsu

Satoshi Hiroshima

Takayuki Sakurai

Hiroyuki Ogawa

Yuji Yamamoto

Hiroshi Mochikawa

Masayuki Hikita

Masahiro Kozako

Takahisa Ueno

Tomomi Ikegami

Taki Horiguchi

A partial discharge measurement device includes: an impulse voltage application unit; a measurement control unit; and first and second partial discharge detection unit. The measurement control unit includes: a first and a second detector level partial discharge counting unit; and a partial discharge resistance evaluation unit. Each of the first and the second detector level partial discharge counting units outputs a first or second detection signal when the first or second detection signal exceeds a predetermined specified value. The partial discharge resistance evaluation unit counts the number of occurrences of partial discharge based on an output from the first and second detector level partial discharge counting unit, and regards the impulse voltage value at which the count value has reached a predetermined value as a partial discharge inception voltage under the repeated impulse voltage application.

Partial discharge measurement device

An impulse voltage generator uses a predetermined rectangular waveform signal and a high voltage to generate an impulse voltage. The high voltage is obtained by boosting an instruction voltage of the rectangular waveform signal on a per-cycle basis. A partial discharge frequency calculation section receives detection signals based on partial discharges occurring in an object to be measured by the application of the impulse voltage and counts the detection signal on a per-cycle basis as a partial discharge frequency. An application voltage signal observation circuit observes an application voltage signal indicating the impulse voltage applied to the object to be measured. In a first cycle in which the partial discharge frequency reaches a specified frequency or more, a voltage value acquiring section sets, as a partial discharge starting voltage, the peak value of the voltage indicated by the application voltage signal output from the application voltage signal observation circuit.

Partial discharge measurement system and partial discharge measurement method by repeated impulse voltage

A signal generator generates a combined signal that is generated only in the period where supply of a pulse signal is effected, a pulse signal whose frequency is of a higher impulse repetition frequency than the frequency of the period setting signal and whose amplitude represents a voltage value that is lower than the high voltage HVDC value. A semiconductor switch accumulates electric charge on a capacitative element by means of the high voltage HVDC from the high voltage generator when the voltage value of the combined signal is lower than the set gate voltage value and generates an impulse voltage whose peak value is the value of the high voltage HVDC, by means of the electric charge that is discharged from the capacitative element when the voltage value of the combined signal exceeds the set gate voltage value.

Impulse voltage generation device

In an inverter in which six switching elements of an inverter main circuit is controlled to be turned on and off under a switching pattern in which a voltage space vector composed of adjacent two of six fundamental voltage vectors out of phase from one another by an electrical angle of .pi./3 and a zero vector figures a circular locus so that a three-phase substantially sinusoidal voltage is obtained, a three-phase PWM signal generating device includes a circuit in which two switching patterns of the same kind are formed before and after the formation of the switching pattern corresponding to the zero vector, respectively, a circuit in which the switching pattern corresponding to the zero vector is held for half of its holding time when the voltage space vector passes an intermediate phase position between the two adjacent fundamental voltage vectors, and a circuit in which when the magnitude of the command voltage vector exceeds the region of a circular locus figured by the fundamental voltage vector, the command voltage vector is converted to a new command voltage vector so as to meet the region.

Three-phase PWM inverter providing an improved output sinusoidal waveform

Growing community of inventors

Inagi, Japan

Tatsuya Hirose