JP2006149135A - Power conversion device and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion device, along with its control method, of which convenience is improved than before when driving a plurality of objects using the power conversion device. <P>SOLUTION: The electric power rectified by a converter part which is a forward conversion part of a power conversion device is supplied to a plurality of smoothing parts and an inverter part that is a reverse conversion part and connected to them. The reverse inversion parts drive motors that are connected to be driven. In short, a plurality of smoothing part and reverse conversion parts share the forward conversion part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for providing a power conversion device.

  Patent Document 1 discloses a power conversion device.

JP 2001-268987 A

  In Patent Document 1, the regenerative power of the AC motor can be used effectively even if the forward conversion device of the power conversion device does not have a regeneration function.

  For this purpose, a secondary battery such as a sodium-sulfur battery is provided, and the secondary battery is charged and recovered with regenerative power of an AC motor.

  Therefore, providing a secondary battery may cause a problem in space saving.

  Based on the above, it is an object of the present invention to provide a power conversion device that is more convenient than the conventional one for a regenerative operation when the electric motor to be driven is driven by the power conversion device, and a control method thereof. To do.

  In response to the above problem, in the present invention, the power rectified by the converter unit that is a forward conversion unit of the power conversion device is supplied to a plurality of smoothing units and an inverter unit that is an inverse conversion unit connected thereto, The inverse conversion unit drives a connected electric motor, motor, or the like to be driven. That is, the forward conversion unit is shared by a plurality of smoothing units and inverse conversion units.

  In the above configuration, when there are a first smoothing unit, an inverse conversion unit, an electric motor and a second smoothing unit, an inverse conversion unit, and an electric motor, control is performed by the following control method.

  When the first electric motor is rotating backward in a free run, it is necessary to first brake and stop it in order to rotate it forward. At this time, regenerative power is generated from the first electric motor and flows to the first reverse converter, and this regenerative power is converted into DC power by the first reverse converter and supplied to the first smoothing unit. .

  However, when the common forward conversion unit connected to the first smoothing unit is configured by a simple rectifier circuit that does not have a system linkage function, DC power cannot be reversely flowed to the commercial power source.

  As a result, the DC power from the first inverse conversion unit is stored in the first and second smoothing units. As a result, the DC potential rises and exceeds the allowable potentials of the smoothing unit and the inverse conversion unit. , Is expected to be a problem.

  In general, assuming such a situation, a regenerative circuit is provided, and the DC power generated by the first inverse conversion unit is converted to heat by a regenerative resistor and consumed, so that the potential of the smoothing unit is It is known not to exceed the allowable potential. However, the regenerative resistance is inconvenient because it causes an increase in the price and size of the device.

  Therefore, in the above case, the DC power from the first inverse conversion unit is supplied to the second smoothing unit, the inverse conversion unit, and the electric motor via the first smoothing unit. In this way, the supplied DC power from the first reverse conversion unit is converted into drive power for driving the second electric motor in the second reverse conversion unit, and is consumed by driving the second electric motor. Is done. Therefore, it is possible to cope with problems such as a potential increase in the first smoothing section.

  Further, by adopting the above-described configuration and control method, the regenerative electric power generated in the first motor when the first motor is braked drives the second motor through the second reverse conversion unit. Can be consumed. Therefore, the first electric motor can be braked and stopped without using a regenerative resistor or the like as in the prior art.

  The regenerative power from the first motor is converted to DC power by the first reverse conversion unit, and when supplied to the smoothing unit, the potential of the DC unit rises and is higher than the potential of the forward conversion unit shared. If it becomes higher, power will not flow from the common conversion unit, so there is no problem even if the common conversion unit, the first smoothing unit, and the second smoothing unit are connected.

  Accordingly, when the second motor is driven with the regenerative power of the first motor in carrying out the control method, the connection between the forward conversion unit, the first smoothing unit, and the second smoothing unit is performed. There is no need to provide a switch for disconnecting. Alternatively, the process and control for disconnecting the connection between the forward conversion unit and the first smoothing unit and the second smoothing unit may not be performed.

  However, in the implementation of the control method, it is denied that the process and control for disconnecting the connection between the forward conversion unit and the first smoothing unit and the second smoothing unit, and the provision of the switch for disconnecting are provided. is not. As another configuration, a connection line for supplying DC power from the first reverse conversion unit to the second reverse conversion unit is provided. By providing the connection line, the regenerative power generated in the first electric motor can be consumed by the second electric motor from the first reverse conversion unit through the second reverse conversion unit.

  In the above description, the first smoothing unit and the second smoothing unit may be shared.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the power converter device which improved the convenience conventionally, and its control method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. In each figure, the common code | symbol shows the same thing.

  FIG. 1 shows a configuration of a power conversion device according to an embodiment of the present invention, FIG. 2 shows a configuration when the power conversion device and control method according to the embodiment of the present invention are used in a fan filter unit of a clean room, and FIG. 3 shows an embodiment of the present invention. The flowchart of the control method which starts all the motors to the normal rotation side without a regenerative circuit when all the motors by are rotated in the free run state by the external force to the reverse rotation side is shown.

  In FIG. 1, a commercial power source 50 is connected to a forward conversion unit 40 (which may have a noise filter as shown in the figure) on which a rectifier diode is mounted, and supplies AC power. The electric power rectified to direct current by the forward conversion unit 40 is supplied by a cable 41 to the controller 10 on which the first smoothing unit 11, the first reverse conversion unit 12, and the first motor control circuit 13 are mounted.

  Furthermore, the power rectified to direct current by the forward conversion unit 40 is supplied by a cable 41 to the controller 20 on which the second smoothing unit 21, the second inverse conversion unit 22, and the second motor control circuit 23 are mounted.

  In response to an instruction from the host controller 60, the controllers 10 and 20 supply and drive DC power from the inverse converters 12 and 22 to the first and second motors 14 and 24, respectively.

  Here, the number of controllers that can be connected to the forward conversion unit 40 may be two or more, and in that case, a capacity that can supply the total power required for the controllers connected to the forward conversion unit 40. The forward conversion unit 40 needs to be equipped with the rectifier diode.

  The feature of FIG. 1 resides in that a plurality of controllers 10 and 20 are connected to the forward conversion unit 40 by a DC unit after rectification. In the controller 10, the smoothing unit 11 is arranged as close as possible to the inverse conversion unit 12 and the motor control circuit 13 so that the motor 14 can be driven stably.

  Further, the smoothing unit 11 is configured to absorb the voltage fluctuation of the DC unit due to the operation of the inverse conversion unit 12 and suppress the mutual influence on the other controller 20. Furthermore, even when the distance between the forward conversion unit 40 and the controller becomes long, the smoothing unit 11 also has an effect of suppressing the voltage jump due to the inductance of the cable 41. Of course, the smoothing part 21 also performs the same function.

  The capacity of the smoothing unit 11 mounted on the controller 10 is set to a capacity necessary for driving the motor 14 and the motor control circuit 13. That is, if the number of controllers that share and connect the direct current section increases, a smoothing section having a necessary capacity is secured in response to the increase.

  On the other hand, it is desirable from the viewpoint of cost or effect that suppression of harmonics flowing out to the commercial power supply side, or lightning surge noise entering from the commercial power supply, etc., should be concentrated in one place connected to the commercial power supply. Accordingly, the forward conversion unit 40 shown in FIG.

  By connecting the DC unit between the forward conversion unit 40 and the smoothing unit 11 and the smoothing unit 21, the regenerative power generated when the first motor 14 is regenerated is used as the driving power for the second motor 24. It becomes possible. Of course, the reverse is also possible.

  Specifically, when the commercial power source is 200V, the DC voltage rectified by the forward conversion unit is about DC288V. When both the motor 14 and the motor 24 are operating at the rated load, regenerative power may be generated depending on the load condition, such as when inertia is large when the motor 14 is braked. Work in the direction to raise.

  Since the commercial power source flows to the smoothing unit only when the voltage rectified by the rectifying diode of the forward conversion unit becomes higher than the increased DC unit, it does not flow when the regenerative power is large, that is, when the DC voltage of the DC unit is high. At this time, all the electric power necessary for driving the motor 24 is covered by the regenerative electric power of the motor 14.

  That is, the controller 10 and the controller 20 can supply either regenerative power to the other, and only the insufficient power is supplied from the forward conversion unit.

  However, in this case, when all the motors sharing the DC unit are braked, regenerative power cannot be consumed, so an overvoltage abnormality occurs. A method for dealing with this will be described in the operation method of the fan filter unit described later.

  FIG. 2 shows the structure of a clean room 200 such as a semiconductor manufacturing factory and the installed state of the fan filter units 210, 220, and 230 installed there. Since the fan filter unit is installed on the entire ceiling of the clean room, a large-scale unit can have a scale of hundreds to thousands in one system.

  The fan filter unit is usually managed by the host controller 270 as a set of several to several tens. Each fan filter unit includes fan motors 212, 222, and 232, which are controlled at variable speeds by controllers 211, 221, and 231.

  Under normal operating conditions, all the fans blow out air from the ceiling duct 201 through the filter 202 below the fan filter unit, blow out the dust from the ceiling in the clean room, and generate a downflow 203 that flows from the ceiling to the floor. Then, it is sucked into the floor slit 204 together with dust in the room. The duct 205 under the floor is connected to the ceiling via the air conditioner 206 and is constantly circulated.

  Here, when the drive of one fan motor 212 is stopped for maintenance or the like, the stopped fan is rotated in the reverse rotation direction in a free-running state due to the pressure difference between the ceiling and the clean room.

  Usually, air is blown into the clean room by a fan from the back of the ceiling. Accordingly, the atmospheric pressure difference between the back of the ceiling and the clean room is higher in the clean room than in the back of the ceiling, although there is a difference in degree. In this case, the drive power is not supplied, and the fan in the free-run state rotates in the reverse direction because air flows from the clean room to the back of the ceiling based on the pressure difference.

  If it is attempted to start again from this state, it is necessary to overcome the reverse rotation torque due to the inertia of the fan and the atmospheric pressure, brake the motor, once stop the reverse rotation, and then start in the forward rotation direction.

  At this time, regenerative electric power is generated when stopping the reverse-run free run, so that the voltage of the direct current section rises and a general controller may not be able to brake due to an overvoltage abnormality.

  In this case, the fans are forcibly stopped by a mechanical brake or a regenerative circuit, or all other fans 223 and 233 need to be operated at low speed in order to reduce the pressure difference.

  None of these methods is desirable because a new device such as a mechanical brake or a regenerative circuit is provided to brake the motor 212, or the cleanliness of the clean room is lowered due to a decrease in the air circulation rate.

  Here, if the DC section of the plurality of fan motors 212, 222, 232 is shared in the same configuration as in FIG. 1 according to the embodiment of the present invention, the regenerative power generated by the motor 212 to be braked is the motor 222 that is rotating forward. , 232 can be consumed as driving power, so that the voltage rise in the DC section can be effectively suppressed, and the motor 212 rotating in the reverse direction can be reliably braked.

  When all the motors are stopped simultaneously, the supply of commercial power may be stopped.

  In addition, if all the fan motors 212, 222, and 232 that share the DC section in this configuration are rotated in reverse by the pressure difference, regenerative power cannot be consumed and the overvoltage abnormality occurs if the motor is simply braked. End up.

  In this case, the regenerative power necessary for braking one motor 212 is consumed by the motors 222 and 232 that share the other DC unit, and the necessary regenerative power is the number of the other motors 222 and 232. Dividing by (two in this embodiment), all the other motors 222, 232 may be further accelerated to the reverse rotation side so that the power is consumed.

  As a result, the braking of one motor 212 is completed in a short time, and immediately after stopping, this one 212 is driven in the forward rotation direction, and at the same time, the reverse rotation driving of the other motors 222 and 232 is stopped and the free run state is achieved. To do.

  In this state, among a plurality of motors sharing the DC part, one motor is powering in the forward rotation direction. Therefore, the regenerative power for stopping braking of the next motor (222 or 232) from the reverse rotation is It can be consumed by the operation of the motor 212.

  Even if the number of motors is large, the same procedure can be used to consume regenerative power that matches the total motor drive power during forward operation. Repeat this procedure while increasing the number of motors to be braked sequentially. Thus, it is possible to start all the motors from the reverse free-run state to the forward power running state.

  FIG. 3 shows a flowchart of a procedure for starting the motor in the reverse free run from the host command device.

  The host command device shown in FIGS. 1 and 2 first checks the operating status of all the motors sharing the DC unit (step 301). Here, when all the motors are in reverse rotation and free running, processing from step 321 to step 326 is added. If some of the motors are running in the normal direction, all the motors are started in the forward direction by repeating the processing from step 311 to step 315.

  First, the case where all the motors are free running with reverse rotation will be described below.

The host controller first selects an arbitrary one to stop braking (step 321).
At the same time as braking the motor, all other motors are powered in the direction of the reverse rotational speed further than the current rotational speed of the reverse rotational free run (step 322). The braking torque of the motor to be braked at this time and the power running torque of all the motors to be powered in the other reverse direction are set so that the sum of the regenerative power and the reverse power running power is equal, thereby suppressing an increase in DC voltage ( Step 323).

  The state of step 323 is maintained until the braked motor is stopped.

  When the motor stops, it is immediately started to the forward rotation side, and at the same time, the power running of the other reverse rotation motors is stopped.

  As a result, one motor is in the forward power running and the other motor is in the reverse rotation free run (step 326). The subsequent processing is the same as the processing after the determination in step 302.

  If some of the motors that share the DC section are powering in the forward direction, Pt is the total power during the forward powering, and the total regenerative power of the motor to be braked If Pg, the number of motors to be braked is determined so that Pt ≧ Pg (step 311).

  At this time, the braking torque of all the motors to be braked is set so that the sum of the regenerative power is balanced with the sum of the forward running power (step 312).

  The motor that has been braked and stopped immediately starts forward rotation (step 314).

  Here, the host controller confirms whether or not all motors are rotating forward, and if there is one that has not yet been rotated forward, the process from step 311 is repeated again.

  According to this method, there is no limit to the number of motors sharing the DC section, and finally all the motors are braked from the reverse rotation free-run state without using a means such as a regenerative circuit, and the forward rotation power running operation is performed. be able to.

  Next, an example of a large heat exchanger installed outdoors will be described with reference to FIG.

  Inside the housing of the heat exchanger 410, there are a heat exchanger 404 and exhaust fans 402, 403. In normal operation, outside air is introduced into the interior from the intake duct 405 by the exhaust fan, and the exhaust duct is passed through the heat exchanger. Heat is exchanged by exhausting from 401.

  Here, when the operation of the heat exchanger is stopped, depending on the direction of the wind, the wind enters from the exhaust duct 401 to rotate the fan motors 402 and 403 in the reverse direction, and passes through the heat exchanger in the reverse direction. The duct 405 may come off. Especially in the case of a typhoon or the like, the wind speed reaches several tens of meters, so the above phenomenon may occur.

  When starting operation of the heat exchanger in this state, it is necessary to operate in the forward direction after braking and stopping the motors 412 and 413 in the reverse rotation free-run state by the wind entering from the exhaust duct. There is. At this time, as with the fan filter unit described above, a means for consuming regenerative power is required.

  Here, when the DC part of FIG. 1 according to the embodiment of the present invention is configured to be shared by the motors 412 and 413, the host controller 420 that controls these fan motors has both motors in the reverse direction before operation. When it is recognized that the vehicle is running in a free run, one motor, for example, the motor 412 is further powered in the reverse direction, and at the same time, the other motor 413 is started to be braked.

  At this time, the reverse rotation command rotational speed is in a range in which the induced voltage of the motor can be controlled. That is, if the vehicle is already rotating backward beyond the control range, it should be determined as an abnormal strong wind and should not be started for safety.

  The pressure Pout 431 inside the exhaust duct is reduced by the reverse rotation of the motor 412, and the pressure Po 432 inside the exhaust fan duct is increased by the pushing pressure of the fan 402. This works in the direction of braking the reverse rotation of the fan 403 and thus works in the direction of assisting the braking of the motor 413.

  Therefore, braking of the motor 413 is completed in a short time, and power running in the forward rotation direction can be started. If one unit is powered in the forward rotation direction, the other regenerative power can be consumed by the power consumption, so that the motor 412 can be braked.

  Therefore, according to this control method, it is possible to brake the motor and start it in the forward rotation direction without using a means such as providing a regenerative circuit even when strong wind enters from the exhaust duct. .

The block diagram of the power converter device which shared the direct current | flow part by the Example of this invention. The figure explaining the driving | operation of the fan filter unit system to which the Example of this invention is applied. The flowchart which shows the control method of the power converter device by the Example of this invention. The figure explaining the operating method of the heat exchanger to which the Example of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st controller, 11 ... 1st smoothing part, 12 ... 1st inversion part, 13 ... 1st motor control circuit part, 14 ... 1st motor, 20 ... 2nd controller, 21 ... 2nd smoothing part, 22 ... 2nd reverse conversion part, 23 ... 2nd motor control circuit part, 24 ... 2nd motor, 40 ... Forward conversion part, 41 ... Cable, 50 ... Commercial power supply, 60 ... Host Control device, 200 ... clean room, 201 ... ceiling duct, 202 ... filter, 203 ... down flow, 204 ... floor slit, 205 ... underfloor duct, 206 ... air conditioner, 207 ... semiconductor manufacturing equipment, etc. 210 ... first fan Filter unit, 211 ... first fan motor controller, 212 ... first fan drive motor, 213 ... first fan, 210 ... first fan filter unit, 211 ... first fan Controller 212, first fan driving motor, 213, first fan, 220, second fan filter unit, 221, second fan motor controller, 222, second fan driving motor 223 ... 2nd fan, 230 ... 3rd fan filter unit, 231 ... 3rd fan motor controller, 232 ... 3rd fan drive motor, 233 ... 3rd fan, 270 ... fan filter unit system Upper control device, 271 ... operation command cable, 301-326 ... flowchart, 401 ... exhaust duct, 402 ... first exhaust fan, 403 ... second exhaust fan, 404 ... heat exchanger, 405 ... intake duct, 410 ... heat exchanger housing, 412 ... first fan driving motor, 413 ... second fan driving motor, 42 ... heat exchanger main body control unit, 430 ... first fan reverse drive of the air flow, 431 ... exhaust duct pressure, 432 ... heat exchanger secondary side pressure, 433 ... heat exchanger primary side pressure.

Claims (4)

A forward conversion unit for converting supplied AC power into DC power;
A first smoothing unit to which an output from the forward conversion unit is connected;
A first inverse transform unit to which an output of the first smoothing unit is connected;
A second smoothing unit to which an output from the forward conversion unit is connected;
And a second inverse conversion unit to which an output of the second smoothing unit is connected. A forward converter that converts the supplied AC to DC power;
A smoothing unit to which an output from the forward conversion unit is connected;
A first inverse transform unit to which an output of the smoothing unit is connected;
And a second inverse conversion unit to which the output of the smoothing unit is connected. In the control method of the power conversion device in which the first inverse conversion unit and the second inverse conversion unit are electrically connected,
After the regenerative power generated by the first motor is converted to DC power by the first reverse conversion unit, power is supplied to the second reverse conversion unit, and the supplied DC power is supplied to the second reverse conversion unit. A method for controlling a power converter, wherein the converter converts the electric power to drive the second electric motor and then supplies the electric power to the second electric motor to drive the second electric motor. In the control method of the power conversion device in which the first inverse conversion unit and the second inverse conversion unit are electrically connected,
When braking the first motor,
After the regenerative power generated by the first electric motor is converted to DC power by the first reverse conversion unit,
After power is supplied to the second inverse conversion unit, the supplied direct-current power is converted into electric power for driving the second electric motor by the second reverse conversion unit,
By supplying the second motor and driving the second motor,
A method for controlling a power converter, wherein the first electric motor is stopped.

Images