JP5028127B2 - Motor driving method, apparatus, and crane apparatus - Google Patents

Description

  The present invention relates to a motor driving method and apparatus for driving a generator with an engine to generate electric power and driving a motor with electric power generated by the electric generator.

  Conventionally, in a crane or a vehicle, a three-phase AC generator is driven by a diesel engine to generate electric power, and the three-phase AC motor is driven by electric power generated by the generator. Hereinafter, the motor drive system using the engine and the generator is referred to as an engine drive power generation system.

  In this engine-driven power generation system, the engine is driven at a constant rotational speed in order to keep the frequency of power generated by the generator constant, that is, to keep the frequency of power supplied to the motor constant (Patent Literature). 1). For example, when the frequency of the power supplied to the motor is 60 Hz, the engine speed is 1800 rpm, and when the frequency is 50 Hz, 1500 rpm.

As a general feature, the fuel consumption rate per output (PS) of a diesel engine decreases as the engine speed decreases. For example, by reducing the rotational speed from 2000 rpm to 1400 rpm, the fuel consumption rate per output of the diesel engine is improved by about 5% (see FIG. 5A).
Further, the fuel consumption rate of the diesel engine becomes worse when the load factor falls below 75%, and at 50%, the fuel consumption rate becomes worse by about 10%.
Further, the output of the diesel engine increases as the rotational speed increases (see FIG. 5B), and reaches a maximum in the vicinity of 2000 rpm to 2200 rpm. It is known that when the engine speed exceeds 2200 rpm, the output generally decreases due to a rapid decrease in torque, and the generated noise and displacement increase as the engine speed increases.

  Considering the conventional engine-driven power generation method, in the conventional engine-driven power generation method, when the speed command from the controller to the motor changes and the target rotational speed corresponding to the speed command changes, the target Calculate the engine speed (necessary engine speed) required to change the motor speed up to the engine speed, and adjust the engine speed to the calculated required engine speed. Control is performed so that the rotational speed of the motor matches the target rotational speed corresponding to the command.

JP 2000-282897 A JP 2005-218225 A "Development of technology for practical application of matrix converter", [Searched on January 22, 2004], Internet <URL: http://www.fujielectric.co.jp/news/02121001/main.html>

However, in such a conventional technique, the frequency of the generated power from the generator greatly fluctuates in accordance with the change in the engine speed. There was a problem that it was necessary to cope with it, leading to an increase in the cost of the inverter.
The present invention is for solving such problems, and a motor driving method and apparatus capable of improving the fuel consumption rate and reducing the environmental load (suppressing noise and exhaust) while avoiding an increase in the cost of the inverter. And to provide a crane device.

In order to achieve such an object, a motor driving method according to the present invention generates electric power by driving a three-phase AC generator with an engine, and drives the motor with electric power generated by the three-phase AC generator. the motor driving method, the speed of the three-phase AC power a three-phase AC generator to generate a frequency conversion step of supplying the motor into a three-phase AC power of a predetermined frequency by an inverter, the operating device the rotational speed of the motor The required engine speed calculation step for calculating the required engine speed required for changing to the target speed corresponding to the command within the range of 1500 to 1800 rpm, the engine speed as the required engine speed, A rotational speed control step for adjusting the rotational speed to the target rotational speed.

  At this time, in the required engine speed calculation step, any one of a plurality of different engine speeds provided in advance within a range of 1500 to 1800 rpm may be selected as the required engine speed.

The motor drive device according to the present invention is a motor drive device that drives a motor by the power generated by the three-phase AC generator by driving a three-phase AC generator with an engine. an inverter supplying the motor into a three-phase AC power of three-phase AC power a predetermined frequency generator is generated, required to change to the target rotational speed of meeting the speed command from the operation unit the rotational speed of the motor Required engine speed calculating means for calculating the required engine speed of the engine within the range of 1500 to 1800 rpm, and the engine speed to match the required engine speed and the motor speed to the target speed. Control means.

  At this time, the required engine speed calculation means may select any one of a plurality of different engine speeds provided in advance within a range of 1500 to 1800 rpm as the required engine speed.

The crane apparatus according to the present invention is a crane apparatus in which a three-phase AC generator is driven by an electric motor driven by a three-phase AC generator to load and unload a load. The inverter that converts the three-phase AC power to be converted into three-phase AC power of a predetermined frequency and supplies it to the motor, and the engine required for changing the motor speed to the target speed corresponding to the crane operation command from the controller. A required engine speed calculating means for calculating the required engine speed within a range of 1500 to 1800 rpm; a speed control means for adjusting the engine speed to the required engine speed and the motor speed to the target speed; It has.

  At this time, the required engine speed calculation means may select any one of a plurality of different engine speeds provided in advance within a range of 1500 to 1800 rpm as the required engine speed.

  According to the present invention, it is possible to cope with frequency fluctuations of generated power by using a general-purpose inverter shared by 50/60 Hz, avoiding an increase in the cost of the inverter, and improving the fuel consumption rate and reducing the environmental load (noise and exhaust emissions). Suppression) can be realized. The latest experimental results show that in a crane device using a 300 KW class diesel engine, the engine rotational speed is variably controlled in the range of 1500 to 1800 rpm, resulting in 10 to 20% of fuel compared to the case where the speed is fixed at 1800 rpm. Consumption could be improved and noise could be reduced.

Next, embodiments of the present invention will be described with reference to the drawings.
[Embodiment 1]
FIG. 1 is a block diagram showing an example of a motor driving device used for carrying out a motor driving method according to the present invention. In the figure, reference numeral 1 denotes a diesel engine mounted on a crane or a vehicle, 2 denotes a three-phase AC generator driven by the engine 1, and 3 denotes three-phase AC power generated by the generator 2 at a predetermined frequency (for example, 50 Hz) is an inverter for converting into three-phase AC power, and 4 is a three-phase AC motor (power motor) driven by the three-phase AC power of a predetermined frequency converted by the inverter.

  The motor drive device 100 (100A) is provided with a control device 6 that receives a speed command from the controller 5 to the motor 4 and controls the overall operation. Moreover, in this motor drive device 100A, the inverter 3 includes an AC-DC converter 3-1 and a DC-AC converter 3-2, and uses the AC-DC-AC conversion method to supply power from the generator 2 to a predetermined level. Conversion to frequency power (frequency conversion means). The inverter 3 converts alternating current into direct current by the alternating current-direct current conversion section 3-1, and converts direct current into alternating current at the direct current-alternating current conversion section 3-2. Therefore, the inverter 3 has an input frequency (frequency of power from the generator 2). The stability of the output frequency (frequency of power to the motor 4) against fluctuation is high. In the present embodiment, a 50/60 Hz common-purpose inverter is used as the inverter 3.

FIG. 2 shows a functional block diagram of the control device 6. Hereinafter, an operation unique to the present embodiment will be described with the function of the control device 6.
A speed command from the controller 5 to the motor 4 is given to the control device 6 as a motor target rotational speed Nmtp. When the speed command from the controller 5 to the motor 4 is changed and the motor target rotational speed Nmtp is changed, the control device 6 has the power (in order to change the rotational speed of the motor 4 to the motor target rotational speed Nmtp). Necessary power) is calculated (block BL1).

  Then, the control device 6 calculates the engine speed (necessary engine speed) Nesp necessary for generating the necessary power calculated in the block BL1 (block BL2: required engine speed calculating means) The engine 1 is compared with the engine speed (current engine speed) Nepv (block BL3).

  At this time, the control device 6 calculates the necessary engine speed Nesp from the range of 1500 to 1800 rpm. When the required engine speed Nesp corresponding to the motor target speed Nmtp exceeds the range of 1500 to 1800 rpm, the value within this range and closest to the required engine speed Nesp corresponding to the motor target speed Nmtp. In addition, the necessary engine speed Nesp may be corrected. At this time, as the necessary engine speed Nesp, any one of the continuous values within the range of 1500 to 1800 rpm as described above may be used, and a plurality of different engines provided in advance within the range of 1500 to 1800 rpm. Any one of the rotational speeds may be selected.

  In particular, when the motor driving method and apparatus according to the present embodiment are applied to a crane, the necessary engine rotation is required for each weight of the load for each crane operation such as lifting, lowering, hanging support, traveling of the platform, and traversing. The number may be set individually in a range of 1500 to 1800 rpm, and the corresponding required engine speed may be selected according to the input crane operation. These required engine speeds may be registered as a table in a memory in the control device 6 or may be calculated based on a predetermined mathematical expression.

[Nepv> Nesp]
When the current engine speed Nepv is higher than the necessary engine speed Nesp (Nepv> Nesp), the control device 6 reduces the difference ΔNe = Nepv−Nesp between the current engine speed Nepv and the required engine speed Nesp by reducing the engine speed. At the same time as the command (engine speed command) is output to the engine 1 (block BL4), the motor target rotational speed Nmtp corresponding to the speed command from the operating device 5 is immediately output to the inverter 3 as the motor command rotational speed Nmsp (motor speed command). (Block BL5). Thus, the control device 6 adjusts the rotational speed of the engine 1 to the necessary engine rotational speed Nesp while receiving feedback of the current engine rotational speed Nepv from the engine 1. Further, while receiving feedback of the current motor rotation speed Nmpv from the motor 4, the inverter 3 adjusts the rotation speed of the motor 4 to the motor command rotation speed Nmsp (= Nmtp) (rotation speed control means).

[Nepv <Nesp]
When the current engine speed Nepv is lower than the required engine speed Nesp (when Nepv <Nesp), the controller 6 determines the difference ΔNe = Nesp−Nepv between the required engine speed Nesp and the current engine speed Nepv as the engine speed. A number increase command (engine speed command) is output to the engine 1 (block BL6). Thus, the control device 6 adjusts the rotational speed of the engine 1 to the required engine rotational speed Nesp while receiving feedback of the current engine rotational speed Nepv from the engine 1 (rotational speed control means).

  When the current engine speed Nepv is lower than the required engine speed Nesp, the control device 6 speeds up from the operating device 5 until the current engine speed Nepv and the required engine speed Nesp become equal (block BL7). The motor target rotational speed Nmtp corresponding to the command is reserved, and the motor 4 rotational speed (maximum motor rotational speed) Nmax that can be achieved at the current engine rotational speed Nepv is set as the motor command rotational speed Nmsp (motor speed command) to the inverter 3. Output (block BL8). If the current engine speed Nepv is equal to the required engine speed Nesp, the motor target speed Nmtp is output to the inverter 3 as a motor command speed Nmsp (motor speed command) (block BL5). Thus, the inverter 3 gradually adjusts the rotational speed of the motor 4 to the motor target rotational speed Nmtp while receiving feedback of the current motor rotational speed Nmpv from the motor 4 (rotational speed control means).

  In this embodiment, when the current engine speed Nepv is lower than the required engine speed Nesp, a time lag occurs until the engine 1 reaches the required engine speed Nesp, and power is insufficient for a short time. The rotation speed of the motor 4 cannot be immediately increased to the motor target rotation speed Nmtp. Therefore, in the present embodiment, the maximum motor rotation speed Nmax that can be achieved with the current engine rotation speed Nepv is calculated, and the calculated maximum motor rotation speed Nmax is calculated until the rotation speed of the engine 1 reaches the required engine rotation speed Nesp. This is used as the motor command rotational speed Nmsp to the inverter 3.

  In recent electronically controlled engines, the time for changing the rotational speed is short, and there is almost no problem in human sense. That is, when the engine 1 is an electronically controlled engine, the time lag until the rotational speed reaches the required engine rotational speed Nesp is slight, and there is almost no problem in human sense. In the present embodiment, it is assumed that a time lag occurs to some extent, and when the current engine speed Nepv is lower than the required engine speed Nesp, the motor target speed Nmtp corresponding to the speed command from the operating device 5 is reserved. However, if the time lag is very small, the motor target rotational speed Nmtp may be immediately used as the motor command rotational speed Nmsp to the inverter 3.

[Nepv = Nesp]
When the current engine speed Nepv is equal to the required engine speed Nesp (when Nepv = Nesp), the control device 6 determines the difference ΔNe = 0 between the current engine speed Nepv and the required engine speed Nesp as an engine speed current maintenance command. At the same time as outputting (engine speed command) to the engine 1 (block BL9), the motor target rotation speed Nmtp corresponding to the speed command from the operating device 5 is immediately output to the inverter 3 as the motor command rotation speed Nmsp (motor speed command) ( Block BL5).

(Generation voltage control)
The control device 5 monitors the generated voltage and current from the generator 2 to the inverter 3 and controls the generated voltage in the generator 2 to be constant (block BL10). When the rotational speed of the engine 1 decreases, the generated voltage of the generator 2 also decreases as it is. Therefore, in the present embodiment, the control device 5 generates the generated voltage so that the generated voltage of the generator 2 does not decrease even when the rotational speed of the engine 1 decreases, that is, the generated voltage of the generator 2 becomes constant. A control command is sent to control the field of the generator 2. This generator voltage control function may be provided in the generator 2 itself. In such a case, the control signal from the control device 5 and the voltage / electricity detection signal to the control device 5 become unnecessary.

  As can be seen from the above description, in this motor drive device 100A, the rotation speed of the engine 1 is not controlled so as to maintain a constant rotation speed (for example, 1800/1500 rpm), but only when necessary. Since the engine speed is controlled to the number of revolutions that can generate power (here, the number of revolutions in the range of 1500 to 1800 rpm), the load factor can be made almost constant regardless of the magnitude of the load. It is possible to reduce the number as much as possible while maintaining the load factor, and it is possible to improve the fuel consumption rate and reduce the environmental load (suppression of noise and exhaust).

  At this time, in the case of a three-phase AC generator, 60 Hz AC power is obtained at 1800 rpm, and 50 Hz AC power is obtained at 1500 rpm. Therefore, if the number of revolutions is controlled in the range of 1500-1800 rpm, the frequency of the AC power obtained is controlled between 50-60 Hz. For this reason, it is possible to cope with frequency fluctuations of 50 to 60 Hz of generated power with a general-purpose inverter shared by 50/60 Hz, and an increase in the cost of the inverter can be avoided.

[Embodiment 2]
In the first embodiment, when the current engine speed Nepv is lower than the required engine speed Nesp, a time lag occurs until the engine 1 reaches the required engine speed Nesp, and power is insufficient for a short time. , A response failure occurs that “the rotation speed of the motor 4 cannot be increased immediately to the motor target rotation speed Nmtp”.

  In the second embodiment, a secondary battery is used as a solution to this poor response. FIG. 3 shows an example of using a secondary battery. In this motor drive device 100 (100B), the positive terminal of the secondary battery 7 is connected to the AC-DC converter 3-1 and the DC-AC converter 3-2 in the inverter 3 via the charge controller 8. It is connected to the line (DC conversion part). As a result, the current from the secondary battery 7 flows into the DC conversion portion in the inverter 3 via the charge control device 8 against the power shortage that occurs when the current engine speed Nepv is lower than the required engine speed Nesp. The shortage of electric power until the rotational speed of the engine 1 reaches the required engine rotational speed Nesp is compensated.

  In the second embodiment, the discharge from the secondary battery 7 to the DC conversion portion in the inverter 3 only occurs for a short time. Therefore, the secondary battery 7 does not require a very large capacity. Further, the secondary battery 7 can be charged with a surplus power during the constant speed rotation or deceleration of the motor 4.

[Embodiment 3]
In cranes, vehicles, and the like, there are devices such as a motor cooling fan, an illumination lamp, and an air conditioner as auxiliary devices other than the motor 4 used as a power motor. These auxiliary machines are also driven by the electric power generated by the generator 2. In this case, it is conceivable that the electric power from the inverter 3 to the motor 4 is branched and used, but it is conceivable that the voltage and frequency change due to the load fluctuation of the motor 4. Moreover, as an auxiliary machine, the electric power of the phase number and frequency different from the motor 4 may be required.

  Therefore, in the third embodiment, a second inverter that sends power to the auxiliary machine is provided separately from the inverter (first inverter) 3 that sends power to the motor 4. FIG. 4 shows an example in which a second inverter is provided. In this motor drive device 100 (100C), an auxiliary inverter 9 is provided in addition to the inverter 3, and the three-phase AC power generated by the generator 2 by the inverter 9 is converted to AC power of a predetermined frequency (for example, 50 Hz). I am trying to convert it. The AC power from the inverter 9 is sent to auxiliary equipment such as the motor cooling fan 10, the illumination lamp 11, and the air conditioner 12. Further, it is also used as a control power source for the inverter 3. In addition, the inverter 9 converts the electric power from the generator 2 into the electric power of a predetermined frequency by the AC-DC-AC conversion system, like the inverter 3.

  According to the third embodiment, it is possible to stably supply power of a predetermined frequency to the auxiliary machine independently of the motor 4 used as the power motor. Further, as the power to the auxiliary machine, it is possible to supply power having a phase number or frequency different from that of the motor 4.

  In the case of cranes and the like, reducing the engine speed until now has led to stopping power generation, especially when power is supplied to night illumination lights, because it takes time to relight the lights (such as mercury lamps and In the case of sodium and the like, several minutes are required for relighting), and the engine speed could not be reduced even when there was no work for a long time. In the present embodiment, the power of these auxiliary machines is supplied from an auxiliary inverter 9 that is different from the inverter 3, so that the engine 1 can be kept in a standby state at a reduced speed.

  In the first and third embodiments (FIGS. 1 and 4), the inverter 3 converts the power from the generator 2 into power having a predetermined frequency by the AC-DC-AC conversion method. Instead of this, a matrix converter may be provided, and the power from the generator 2 may be converted into power of a predetermined frequency by an AC-AC direct conversion method. Further, the auxiliary inverter 9 shown in FIG. 4 may also be a matrix inverter, and frequency conversion may be performed by an AC-AC direct conversion method. Since the matrix converter is described in Non-Patent Document 1 and the like, description thereof is omitted here.

Moreover, in Embodiment 1-3 mentioned above, although the engine 1 was made into the diesel engine, it can be similarly applied also to other types of engines, such as a gasoline engine.
Moreover, in Embodiment 1-3 mentioned above, although the generator 2 was set as the three-phase alternating current generator and the motor 4 was set as the three-phase alternating current motor, various types, such as a single-phase alternating current generator and a single-phase alternating current motor, are used. Deformation is free. Moreover, the apparatus mounted is not restricted to a vehicle or a crane.

It is a block block diagram which shows an example (Embodiment 1) of the motor drive device used for implementation of the motor drive method which concerns on this invention. It is a functional block diagram of the control apparatus in this motor drive device. It is a block block diagram which shows the example (Embodiment 2) using a secondary battery as a solution of a response failure. It is a block block diagram which shows the example (Embodiment 3) which provided the inverter for auxiliary machines. It is a figure which shows the relationship between an engine speed and a fuel consumption rate, and the relationship between an engine speed and output horsepower.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Diesel engine (engine), 2 ... Three-phase alternating current generator (generator), 3 ... Inverter, 3-1 ... AC-DC conversion part, 3-2 ... DC-AC conversion part, 4 ... Three-phase AC motor (Motor), 5 ... operation device, 6 ... control device, 7 ... secondary battery, 8 ... charge control device, 9 ... inverter for auxiliary machinery, 10 ... motor cooling fan, 11 ... illumination lamp, 12 ... air conditioner, 100 (100A, 100B, 100C): Motor drive device.

Claims (6)

In a motor driving method for driving a three-phase alternating current generator with an engine to generate electric power and driving a motor with electric power generated by the three-phase alternating current generator,
A frequency conversion step of converting three-phase AC power generated by the three-phase AC generator into three-phase AC power having a predetermined frequency by an inverter and supplying the three-phase AC power to the motor;
A required engine speed calculation step of calculating a required engine speed required to change the motor speed to a target speed corresponding to a speed command from an operating device within a range of 1500 to 1800 rpm;
A motor drive method comprising: a rotation speed control step of adjusting the rotation speed of the engine to the required engine rotation speed and adjusting the rotation speed of the motor to the target rotation speed. The motor driving method according to claim 1,
The required engine speed calculating step selects any one of a plurality of different engine speeds provided in advance within a range of 1500 to 1800 rpm as the required engine speed. Method. In the motor drive device that drives the motor with the electric power generated by driving the three-phase AC generator with the engine and generating electric power,
An inverter that converts the three-phase AC power generated by the three-phase AC generator into three-phase AC power having a predetermined frequency and supplies the three-phase AC power to the motor;
A required engine speed calculating means for calculating a required engine speed of the engine required to change the speed of the motor to a target speed corresponding to a speed command from an operating device within a range of 1500 to 1800 rpm;
A motor drive device comprising: a rotation speed control means for adjusting the rotation speed of the engine to the required engine rotation speed and the rotation speed of the motor to the target rotation speed. In the motor drive device according to claim 3,
The required engine speed calculating means selects any one of a plurality of different engine speeds provided in advance within a range of 1500 to 1800 rpm as the required engine speed. apparatus. In a crane device that loads and unloads luggage by driving a motor with electric power generated by driving a three-phase AC generator with an engine,
An inverter that converts the three-phase AC power generated by the three-phase AC generator into three-phase AC power having a predetermined frequency and supplies the three-phase AC power to the motor;
A required engine speed calculating means for calculating a required engine speed of the engine within a range of 1500 to 1800 rpm, which is necessary for changing the motor speed to a target speed corresponding to a crane operation command from an operating device; ,
A crane apparatus comprising: a rotation speed control unit that adjusts the rotation speed of the engine to the required engine rotation speed and the rotation speed of the motor to the target rotation speed. In the crane apparatus according to claim 5,
The required engine speed calculating means selects any one of a plurality of different engine speeds provided in advance within a range of 1500 to 1800 rpm as the required engine speed. .

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