Hitachi, Ltd.

Hitachi Appliances, Inc

Tatsuo Ando

Yoshiaki Kurita

Yoshitaka Iwaji

Tsunehiro Endo

Hiroshi Fujii

Yasuo Notohara

Takahiro Suzuki

Chikara Tanaka

Noriaki Yamada

Kuniaki Takatuka

Satoshi Furusawa

Hiroyuki Tomita

Toshiaki Okuyama

Seiji Ishida

Keijiro Sakai

Yuhachi Takakura

Hideo Kimura

A converter includes a converter circuithaving a plurality of bridge-connected semiconductor switching devices for converting AC power into DC power, a smoothing condenser connected in parallel to the DC side of the converter circuit and a current detector provided in a condenser circuit to control a condenser current flowing through the smoothing condenser to be a set value. The condenser current is controlled to be the set value (e.g. zero) to thereby reduce the capacity of the smoothing condenser and make the converter small.

Converter and power converter that becomes it with the converter

An inverter device for variably controlling an operating frequency of an electric motor, which drives a compressor in a refrigerating cycle. the inverter includes a box-like resin case, having a metal film for shielding being applied or plated on a surface thereof and having a step portion on which a terminal block for the motor is arranged. A first substrate having mounted thereon power semiconductor devices constituting a converter and an inverter so as to be immersed in gel, and the first substrate is mounted in the case and brought into proximity of radiation fins at a reverse surface thereof. A second substrate having mounted thereon interface connectors into which signals from detection sensors for temperatures and pressures in the refrigerating cycle are input and photo-couplers for transmitting the input signals, and the second substrate is mounted in the case above the first substrate.

Inverter device

A refrigerating apparatus comprises: a first substrate, on one surface of which an active converter and an inverter are mounted, and on a reverse surface of which a radiation fin is closely fixed; a second substrate, on which a microcomputer, a current detecting mechanism, and a terminal block are mounted; a resin casing covering sides of the first and second substrates and provided with a step permitting the terminal block to be arranged thereon; and a third substrate, on which an interface connector and a photo-coupler are mounted. The first substrate, the second substrate, and the third substrate are layered in this order on a bottom surface of the casing. Gel is filled up to a power semiconductor surface of the first substrate, and a resin is filled up to an upper surface of the second substrate.

Refrigerating apparatus and an inverter device used therein

In detecting an output current of a power converter based on a DC current Idc of the power converter, the pulse width of the DC current Idc becomes narrower when the pulse width of a line voltage is narrower, and its detection becomes difficult. A voltage command correction unit according to the present invention corrects voltage commands such that pulse width of a line voltage becomes zero when the pulse width of the line voltage is less than the minimum pulse width, not to output a line pulse, and an error generated by the correction is integrated. This integrated error is added to the line voltage in the next time, and the integrated pulse width of the line voltage is outputted when the pulse width becomes larger than or equal to the minimum pulse width.

Pulse width modulation method, pulse width modulator and power converter

The present invention provides a control algorithm which instantaneously detects magnetic pole positions in the inside of a motor including polarities of the motor. A controller applies a minute voltage change vhd to a voltage command on a dc axis which constitutes an estimation magnetic pole axis of the motor , detects electric currents Idc, Iqc of a motor and discriminates the polarities of the magnetic pole axes by making use of the difference between a cycle in which ripple components of the electric currents Idc, Iqc become positive and a cycle in which the ripple components become negative or the difference between positive-side and negative-side current change rates. Further, the minute voltage change vhd with respect to the above-mentioned voltage command is generated on both of the dc axis and the qc axis rectangular thereto, and the magnetic pole positions of the motor are directly estimated based on the current ripple components on the respective axes. Without separately providing a cycle for discriminating the polarities of the magnetic poles, the cycle from the turning-on of a power source to the starting of the motor can be shortened so that the high-speed starting of the motor can be realized.

Driving system of AC motor

Growing community of inventors

Shimizu, Japan

Tatsuo Ando