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Researchers Submit Patent Application, "Rotary Electric Machine Control Apparatus and Electric Power Steering System Using the Same", for Approval

August 29, 2014



By a News Reporter-Staff News Editor at Energy Weekly News -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors YAMANAKA, Takahiro (Kariya-city, JP); YAMAGUCHI, Nobuhisa (Nagoya-city, JP), filed on October 15, 2013, was made available online on August 14, 2014.

The patent's assignee is Denso Corporation.

News editors obtained the following quote from the background information supplied by the inventors: "A conventional rotary electric machine control apparatus controls driving of a rotary electric machine by detecting an electric current flowing in each phase coils by an electronic component such as a current sensor. In JP-A-2005-210871, for example, a phase current is detected by a shunt resistor, which is provided in each switching element pair corresponding to each phase of an inverter.

"The rotary electric machine includes inductive components and the like. A phase difference hence arises between a command current for driving the rotary electric machine and an actual current flowing in the coil of the rotary electric machine. The phase difference tends to cause that a torque outputted from the rotary electric machine does not attain a required torque level. For this reason, according to the conventional rotary electric machine control apparatus, the rotary electric machine is feedback-controlled. In the feedback control, the torque generated by the rotary electric machine is controlled by detecting the phase difference between the actual current flowing in the rotary electric machine and the command current and correcting the phase difference by a phase compensation control or the like.

"However, in a case that electronic components such as the shunt resistor for detecting the actual current are provided, the configuration of the control apparatus becomes complicated and large-sized."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "It is therefore an object to provide a rotary electric machine control apparatus, which is capable of detecting a direction of a current supplied to each phase coil of a rotary electric machine in a simple configuration, and an electric power steering system using the same.

"According to one aspect, a rotary electric machine control apparatus is provided for controlling driving of a rotary electric machine, which includes a winding set formed of plural coils corresponding to plural phases. The rotary electric machine control apparatus comprises an inverter and a control unit. The inverter includes switching elements forming plural switching element pairs, each of which corresponds to each phase of the coils and is formed of a first switching element provided at a high-potential side and a second switching element provided at a low-potential side. The control unit includes a terminal voltage acquisition part, a drive control part and a current flow direction determination part. The terminal voltage acquisition part acquires a terminal voltage developed at each junction point, which is between the first switching element and the second switching element and connected to one end of the coil of the corresponding phase. The drive control part controls the driving of the rotary electric machine by controlling ON-OFF operations of the switching elements based on a command current related to the driving of the rotary electric machine. The current flow direction determination part determines, at time of an ON-OFF switchover of the first switching element and the second switching element, a current flow direction of an actual current flowing in the coil of the phase corresponding to the terminal voltage based on the terminal voltage developed in a dead time period, in which the pair of the first switching element and the second switching element are both turned off.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a block diagram showing a rotary electric machine control apparatus according to a first embodiment;

"FIG. 2 is a schematic view showing an electric power steering system using the rotary electric machine control apparatus according to the first embodiment;

"FIGS. 3A and 3B are explanatory diagrams showing current flow directions of actual currents in the first embodiment;

"FIG. 4 is a time chart showing a method of determination of the flow direction according to the first embodiment; and

"FIG. 5 is a time chart showing a method of determination of the flow direction according to a second embodiment."

For additional information on this patent application, see: YAMANAKA, Takahiro; YAMAGUCHI, Nobuhisa. Rotary Electric Machine Control Apparatus and Electric Power Steering System Using the Same. Filed October 15, 2013 and posted August 14, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1338&p=27&f=G&l=50&d=PG01&S1=20140807.PD.&OS=PD/20140807&RS=PD/20140807

Keywords for this news article include: Energy, Electric Power, Denso Corporation.

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Source: Energy Weekly News


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