JP6013073B2 - Electric motor drive device and operation method thereof - Google Patents

Description

  The present invention relates to an electric motor drive device that drives an electric motor with two different power sources and an operation method thereof.

  In an electric motor drive device used in the field of vehicles, ships, etc., a common load may be driven by a plurality of electric motors, and these electric motors may be driven by individual power converters. And the power supply of each of these power converters may be supplied from the insulated separate power supply. As such an example, a method has been proposed in which two large and small electric motors having different rated outputs are provided, and the operating range of each motor is separated into a low speed region and a high speed region (see, for example, Patent Document 1).

Special table 2003-517253 gazette (the whole)

  In the method disclosed in Patent Document 1, since two motors have different rated outputs and load sharing is performed according to the operation region, when a DC power supply is provided individually, the power supply with the lower voltage is used. A suitable driving | operation becomes possible by connecting with the electric motor of the low speed area | region side. However, there is no mention of an operation method in the case of a device having a motor with the same rated output and simultaneously operating two motors in the same operation region, and connected according to the voltage of the DC power supply. When switching, it is necessary to stop the apparatus once. When a DC power source such as a battery is used as the power source, an imbalance occurs in the power source voltage depending on the operation status of each device. When an imbalance occurs, the power supply side device having a low voltage cannot operate in the high-speed rotation region of the motor.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electric motor drive device and an operation method in which an operation region is not limited to a device on the side where the power supply voltage is low.

To achieve the above object, a motor driving device and a driving method of the present invention, and two battery, and two voltage detectors the voltage of these two battery respectively detected, are respectively connected to said storage battery Two inverters that convert DC power into AC power, two AC motors that are driven by the inverter and drive a common load, a rotation detector that detects the rotational speed of the AC motor, and A common control unit that gives a current command to each of the two inverters, and the common control unit controls the deviation between the rotational speed detection value output from the rotation detector and the rotational speed command to be small. And the total current command, which is the output of the speed control means, is distributed to the two inverters, and the inverters corresponding to the detection voltages of the two voltage detectors are distributed . Current command distribution means having means for calculating an allowable maximum current, and the current command distribution means is connected to a storage battery that detects a higher voltage of the detection voltages of the two voltage detectors. When the distribution ratio of the total current command given to the inverter is 50% or more and the ratio of the allowable maximum current of the inverter to the total current command is 100% or more, the distribution ratio of the total current command given to the inverter 100% or more, and the inverter connected to the storage battery in which the lower voltage is detected is regeneratively operated .

  According to the present invention, it is possible to provide an electric motor drive device and an operation method in which an operation region is not limited to a device having a lower voltage.

The block block diagram of the electric motor drive device which concerns on Example 1 of this invention. 1 is a block configuration diagram of a current command distribution unit of an electric motor drive device according to Embodiment 1 of the present invention. An example of the operation | movement flowchart of the electric current command distribution part of the electric motor drive device which concerns on Example 1 of this invention. The block block diagram of the electric current command distribution part of the electric motor drive device which concerns on Example 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, an electric motor drive device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

  1 is a block configuration diagram of an electric motor drive device according to Embodiment 1 of the present invention, and FIG. 2 is a block configuration diagram of a current command distribution unit of the electric motor drive device according to Embodiment 1 of the present invention.

  In FIG. 1, AC motors 1A and 1B are driven by outputs of inverters 12A and 12B, respectively, and drive a common load 3 connected by the same output shaft. The rotation speeds of the AC motors 1A and 1B are the same, and the rotation speed is detected by the rotation detector 2.

  Inverters 12A and 12B convert DC power supplied from DC power supplies 11A and 11B to AC power, respectively. The inverters 12 </ b> A and 12 </ b> B perform current control based on the respective current commands given from the current command distribution unit 22 of the common control unit 13.

  The speed control unit 23 of the common control unit 13 generates a total current command so as to reduce a deviation between a speed command (not shown) and a rotation speed feedback given from the rotation detector 2. The voltage detectors 21A and 21B detect the voltages of the DC power supplies 11A and 11B, respectively, and give the detected voltage value to the current command distribution unit 22. The current command distribution unit 22 determines the current command value (distribution ratio of all current commands) to be supplied to the inverters 12A and 12B from the voltages of the DC power supplies 11A and 11B, the voltage difference between them, the magnitude of the total current command, and the like. .

  For example, when batteries or the like are used as the DC power supplies 11A and 11B, an imbalance occurs between the two power supply voltages if there is a load offset. When the voltage of the DC power supply 11A is lower than the DC power supply 11B, increase the current command value to the inverter 11A having the higher power supply voltage and decrease the current command value to the inverter 11B having the lower power supply voltage. Thus, the voltage difference between the two can be reduced.

  In the internal configuration of the current command distribution unit 22 shown in FIG. 2, the current command ratio calculation unit 31 gives each of the inverters 12A and 12B from the detected voltages of the voltage detectors 21A and 21B and the total current command value. A current command to be given to the inverters 12A and 12B is generated by calculating the current command sharing ratio and multiplying the calculated current ratio by the total current command value output from the speed control unit 23. In this way, by adjusting the current command of the two inverters, the load sharing can be adjusted to balance the two DC power supply voltages.

  FIG. 3 is an example of a flowchart for obtaining the sharing ratio of the current command. An example of the internal operation of the current command ratio calculation unit 31 in FIG. 2 will be described with reference to this flowchart.

  First, the DC voltage and total current command value It * values of the two DC power supplies are read (step ST1). Next, the allowable maximum current Ihm of the high DC voltage inverter of the two inverters is calculated (step ST2). In this calculation, it is basically possible to obtain an approximate value by calculation from a DC voltage value, but it may be obtained by referring to an easy table in advance. Next, it is calculated what percentage of the total current command value It * the allowable maximum current Ihm is, and this ratio R is obtained (step ST3). Next, it is determined whether the ratio R is 50% or more (step ST4). Further, it is determined whether the ratio R is 100% or more (step ST5). If the ratio R is less than 50% in step ST4, it is difficult to continue the operation, and some abnormal process such as alarm generation is performed (step ST6). This abnormality process may be determined in step ST1 when the value of the higher DC voltage is equal to or less than a predetermined value.

  If the ratio R is 100% or less in step ST5, the current distribution ratio of the two inverters 12A and 12B is determined according to the difference in DC voltage between the two DC power supplies 21A and 21B (step ST7). In this determination method, for example, an additional amount of 50% or more of the sharing ratio of the high DC voltage inverter may be determined in proportion to the DC voltage difference. When the DC voltage difference is a predetermined value or more, a high DC voltage is determined. The sharing ratio of the voltage inverter may be set to the ratio R or a constant value close thereto.

  If the ratio R is greater than 100% in step ST5, it is confirmed whether or not the regenerative operation is performed (step ST8). This confirmation may be performed, for example, based on whether there is such an operation signal, or may be automatically determined based on whether the voltage value of the low DC voltage inverter is equal to or lower than a predetermined value. In step ST8, if the regenerative operation is not performed, the process proceeds to step ST7. If the regenerative operation is performed, the charging current ratio α is determined based on the voltage difference between both inverters, the ratio R, etc. The storage battery is charged by performing a regenerative operation of the low DC voltage inverter with the current command sharing ratio of (100 + α)% and the low DC voltage inverter sharing ratio of (−α)%.

  Hereinafter, an electric motor driving apparatus according to Embodiment 2 of the present invention will be described with reference to FIG.

  FIG. 4 is a block diagram of the current command distribution unit of the electric motor drive device according to the second embodiment of the present invention. In the second embodiment, the same parts as those of the current command distribution section of the electric motor driving apparatus according to the second embodiment of the present invention shown in FIG. The second embodiment is different from the first embodiment in that the current command distribution unit 22A includes a mode switch 32, charging current reference setting devices 33A and 33B, and current reference switching devices 34A and 34B.

  As described in the first embodiment, when the two DC power supplies 11A and 11B are storage batteries, the ratio R is more than 100%, and the inverter with the higher power supply voltage is power-running, and the inverter with the lower power supply voltage is operated. In regenerative operation, the charging current may not be constant. In general, it is preferable to charge the storage battery at a constant charge current. Therefore, as shown in FIG. 4, when the condition for regenerative operation of the inverter having the lower power supply voltage is prepared, the current reference ratio calculator 31A switches the mode. A command for regenerative operation of the inverter having the lower power supply voltage is given to the unit 32. In accordance with this command, the mode switch 32 switches either the current reference switch 34A or 34B to the charge current reference setter 33A or 33B side. As a result, the storage battery of the inverter having the lower power supply voltage is charged with a constant current set by the charging current reference setting device 33A or 33B.

  Even if the current command distribution unit 22 shown in FIG. 2 is maintained, the above function can be achieved by setting a constant current sharing ratio when conditions for regenerative operation of the inverter having the lower power supply voltage are satisfied. is there.

  Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, two or more inverters may be connected to one electric motor. In this case, the same control as in the case of the two inverters shown in FIG. 1 can be performed by making the current command to the N inverters connected to the same motor equal to 1 / N. it can.

  Further, the winding configuration of the motor is not limited to the three-phase winding, but may be a multi-phase winding and the inverter may be a multi-phase output, and the same control can be performed.

  Further, in order to prevent the influence of noise or the like, the previous share ratio from the current command distribution unit may be stored, and a command for a change from the previous value may be given. You may make it give through filters, such as a delay circuit.

1A, 1B AC motor 2 Rotation detector 3 Load 11A, 11B DC power supply 12A, 12B Inverter 13 Common control unit 21A, 21B Voltage detector 22, 22A Current command distribution unit 23 Speed control unit 31, 31A Current reference ratio calculator 32 Mode switch 33A, 33B Fixed current reference generator

Claims (5)

Two storage batteries,
Two voltage detectors for detecting the voltages of these two storage batteries ,
Two inverters each connected to the storage battery and converting DC power to AC power;
Two AC motors driven by the inverter and driving a common load;
A rotation detector for detecting a rotation speed of the AC motor;
A common control unit for giving a current command to each of the two inverters;
The common control unit includes:
Speed control means for controlling the deviation between the rotation speed detection value output from the rotation detector and the rotation speed command to be small;
A means for distributing a total current command, which is an output of the speed control means, to the two inverters and calculating an allowable maximum current of each inverter corresponding to a detection voltage of the two voltage detectors; and a current instruction distribution means has,
The current command distribution means includes
The distribution ratio of the total current command given to the inverter connected to the storage battery that has detected the higher voltage of the detection voltages of the two voltage detectors is 50% or more , and
When the ratio of the maximum allowable current of the inverter to the total current command is 100% or more, the power distribution operation is performed with the distribution ratio of the total current command given to the inverter being 100% or more, and the lower voltage is detected and connected to the storage battery An electric motor driving device characterized in that the inverter is regeneratively operated . The current command distribution means includes
The ratio of the allowable maximum current of the inverter connected to the storage battery that has detected the higher voltage of the detection voltages of the two voltage detectors to the total current command that is the output of the speed control means is less than 50% 2. The electric motor drive device according to claim 1, wherein abnormality processing such as generation of an alarm is performed in some cases. By the current command of the inverter regenerative operation constant, the motor driving apparatus according to claim 1, characterized in that so as to charge the storage battery at a constant current. The motor driving device according to any one of claims 1 to 3 , wherein the electric motor is a multiphase winding, and the inverter is a multiphase output. Two storage batteries,
Two voltage detectors for detecting the voltages of these two storage batteries ,
Two inverters each connected to the storage battery and converting DC power to AC power;
Two AC motors driven by the inverter and driving a common load;
A rotation detector for detecting a rotation speed of the AC motor;
A common control unit for giving a current command to each of the two inverters;
The common control unit includes:
Speed control means for controlling the deviation between the rotation speed detection value output from the rotation detector and the rotation speed command to be small;
A means for distributing a total current command, which is an output of the speed control means, to the two inverters and calculating an allowable maximum current of each inverter corresponding to a detection voltage of the two voltage detectors; current command distributing means has
A method of operating an electric motor drive device having
The current command distribution means includes
The distribution ratio of the total current command given to the inverter connected to the storage battery that has detected the higher voltage of the detection voltages of the two voltage detectors is 50% or more , and
When the ratio of the maximum allowable current of the inverter to the total current command is 100% or more, the power distribution operation is performed with the distribution ratio of the total current command given to the inverter being 100% or more, and the lower voltage is detected and connected to the storage battery A method for operating an electric motor drive device, wherein the inverter is regeneratively operated .

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