JP2012016227A - Start control method and start control device of coil type induction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a start control method and a start control device which can improve a start torque of a coil type induction machine while allowing for the whole device to be small, light and reducing cost.SOLUTION: A first synchronization input mode, in which first and second opening and shutting means 31 and 32 which are connected to a first power source system 21 and a second power source system 22 of low voltage are turned off and a stator coil 11 is released to apply voltage to a rotor coil 12 by a power converter 34 and the inductive voltage of the stator coil 11 and the voltage of the power source system 22 are synchronized and the opening and shutting mean 32 is turned on to connect the power source system 22 to the stator coil 11, and a first acceleration mode, in which an induction machine 10 is accelerated by the power converter to a prescribed speed, and then the opening and shutting means 32 is turned off to release the stator coil 11, and a second synchronization input mode, in which the inductive voltage of the stator coil 11 and the voltage of the power source system 21 are synchronized and then the opening and shutting means 31 is turned on to connect the power source system 21 to the stator coil 11, are carried out sequentially to start the induction machine 10.

Description

  The present invention relates to a start control method for a wire-wound induction machine capable of controlling input / output power of the wire-wound induction machine by a power converter connected to a rotor winding, and a start control device for carrying out this method. It is about.

  The power input / output to / from the rotor winding of the winding induction machine has a characteristic that is approximately proportional to the product of the power input / output to / from the stator winding connected to the power supply system and the slip of the induction machine. For this reason, in applications where variable speed control is performed on a winding induction machine within a small slip range, a large capacity power converter for variable speed control can be controlled by a small capacity power converter connected to the rotor winding. is there. However, this requires a separate starting means for accelerating the winding induction machine to a small speed, that is, near the synchronous speed.

  As a starting control method for such a winding induction machine, Patent Document 1 discloses, as [Prior Art], a power converter in which a stator winding of a winding induction machine is short-circuited and connected to the rotor winding. Is used to start the wire-wound induction machine as a squirrel-cage induction machine, and further, the amplitude of the stator winding terminal voltage is converted into the voltage of the power supply system converted into the orthogonal two-axis amount on the rotor coordinates, A method is disclosed in which the stator windings are synchronously input to the power supply system by matching the phase and frequency.

  In Patent Document 2, a transformer called a booster transformer is connected between a rotor winding and two power converters, and these power converters are operated to increase the voltage of the rotor winding. Is described. Hereinafter, this conventional technique will be described in detail.

FIG. 9 shows a start-up control device for a wire-wound induction machine according to this prior art. In FIG. 9, 50 is a winding type induction machine (winding type induction generator motor), 51 is a stator winding connected to the power supply system 60 via a circuit breaker 61, and 52 is a rotor winding.
The rotor winding 52 is connected to power converters 76 and 77 via circuit breakers 71 and 73, respectively. The rotor winding 52 is connected to the power converter 76 via a booster transformer 75 and a circuit breaker 72, and is connected to the power converter 77 via a booster transformer 75 and a circuit breaker 74. .
78 is an AC output power converter, 79, 80, 81 are transformers connected between the power supply system 60 and the power converter 78, and 91 is a rotational phase angle detector attached to the rotor of the induction machine 50. , 92 is a rotational speed detector, 101 is a circuit breaker, and 102 is a three-phase short circuit for short-circuiting the stator winding 51 of the induction machine 50.

Explaining this operation, in the state where the stator winding 51 is short-circuited by the three-phase short circuit 102 at the start of the induction machine 50, the circuit breakers 71 and 73 are turned off and the circuit breakers 72 and 74 are turned on to convert the power. Devices 76 and 77 are connected to booster transformer 75. In this state, the power converters 76 and 77 are operated by a method such as vector control.
Thereby, since the output voltage of the power converter 76 and the output voltage of the power converter 77 are superimposed and applied to the rotor winding 52, the output voltage is increased as compared with the prior art described in Patent Document 1. . Therefore, a large starting torque can be obtained from the induction machine 50 during high-speed operation, and for example, a starting control device suitable for underwater starting of a generator turbine can be realized.

JP-A-1-198297 (page 1, lower right column, line 6 to page 3, upper left column, line 8, FIG. 2, FIG. 3, etc.) JP-A-7-7995 (paragraphs [0019] to [0021], FIG. 2 etc.)

The prior art described in Patent Document 1 and Patent Document 2 is a method for starting a wound-type induction machine, in which both the stator windings are short-circuited and a relatively small capacity power conversion connected to the rotor windings. This coincides with the point that the induction motor is started as a squirrel-cage induction machine.
On the other hand, in a winding induction machine, the ratio (turn ratio) between the number of turns of the stator winding and the number of turns of the rotor winding is often designed to be approximately 1. In this case, when variable speed control is performed in a range where the slip is about 0.1, assuming that the voltage of the power supply system is 3.3 [kV], for example, the maximum voltage of the rotor winding is about 330 [V]. A standard 400 [V] rated power converter can be used connected to the rotor winding. That is, since the rated voltage of the power converter may be low, the required capacity of the power converter is small.

  By the way, when either the rotor winding or the stator winding of the winding induction machine is short-circuited and the induction machine is accelerated by supplying power from the other winding, the maximum torque that the induction machine can output ( It is known that the (stationary torque) is approximately proportional to the square of the voltage applied to the induction machine. Therefore, for example, when the rotor winding is short-circuited and the upper limit value of the voltage applied to the stator winding is 1/10 of the rated voltage, the maximum torque at the synchronous speed is reduced to 1/100 of the rated torque. There's a problem.

Here, FIG. 10 shows the calculation result of the speed-torque characteristic when the stator winding is short-circuited using the following equivalent circuit constant.
Rated output: 1000 [kW]
Rated speed: 600 [r / min]
Power supply system: 3.3 [kV], 50 [Hz]
Number of poles: 10
Stator winding resistance: 2 [%] (0.183 [Ω])
Rotor winding resistance: 2 [%] (0.183 [Ω])
Stator leakage inductance: 10 [%] (2.92 [mH])
Rotor leakage inductance: 10 [%] (2.92 [mH])
Excitation inductance: 200 [%] (18.3 [mH])
Stator winding voltage upper limit: 400 [V]
Turns ratio: 1.3

According to FIG. 10, in the related art (characteristic line B1) according to Patent Document 1, the maximum torque at the synchronous speed (power frequency ω ₂ ) is about 3.5% of the rated torque. The maximum torque calculated from the equivalent circuit of the induction machine does not consider the effects of mechanical loss and iron loss. Therefore, in consideration of the effects of mechanical loss and iron loss that increase as the rotational speed increases, there is a problem that acceleration cannot be accelerated to the vicinity of the synchronization speed, and the time for acceleration to the vicinity of the synchronization speed (acceleration time) becomes unacceptably long Problem arises.
In FIG. 10, the characteristic line B2 is the speed-torque characteristic of the prior art according to Patent Document 2, and the characteristic line A is the speed-torque characteristic according to the embodiment of the present invention. These characteristic lines A, B1, B2 The comparison result will be described later.

  On the other hand, in Patent Document 2, in order to solve the above problem, a booster transformer 75 or the like is added to increase the maximum voltage applied to the rotor winding 52, but in order to start the induction machine 50, the booster transformer 75, two power converters 76 and 77, and transformers 79 and 80 are necessary, and there is a problem in that the apparatus volume is increased in size, weight, and cost.

  SUMMARY OF THE INVENTION Accordingly, a problem to be solved by the present invention is to provide a start-up control method and start-up control device for a wire-wound induction machine that can improve the starting torque of the wire-wound induction machine and reduce the overall size, weight and cost. It is in.

In order to solve the above-mentioned problem, a start control method according to claim 1 is connected to a first power supply system via a first opening / closing means and is connected to the first power supply system via a second opening / closing means. A start control method for a winding induction machine comprising: a stator winding connected to a second low-voltage power supply system; and a rotor winding connected to the first power supply system via a power converter In
A voltage is applied to the rotor winding by the power converter in a state where the first and second opening / closing means are turned off and the stator winding is opened, and an induced voltage of the stator winding and a second A first synchronous on mode in which the second switching means is turned on after the voltage of the power system is synchronized and the second power system is connected to the stator winding;
A first acceleration mode in which power is supplied to the rotor winding by the power converter to accelerate the induction machine to a predetermined speed, and then the second opening / closing means is turned off to open the stator winding. When,
A second synchronous input that synchronizes the induced voltage of the stator winding and the voltage of the first power supply system and then turns on the first switching means to connect the first power supply system to the stator winding. Are sequentially executed to start the induction machine.

  According to a second aspect of the present invention, there is provided a start control method in which the first and second opening / closing means are turned off with the rotor of the induction machine stationary before the first synchronous input mode according to the first aspect. In addition, the stator winding is short-circuited, the power is supplied to the rotor winding by the power converter, and the induction machine is accelerated to a predetermined speed, and then the short-circuited stator winding is opened. The acceleration mode is executed, and then the first synchronous input mode, the first acceleration mode, and the second synchronous input mode are sequentially executed.

The start control device according to claim 3 is a first opening and closing means connected between the first power supply system and the stator winding of the winding induction machine,
A second opening / closing means connected between a second power supply system having a lower voltage than the first power supply system and the stator winding;
A power converter connected between the first power system and the rotor winding of the wound induction machine;
Control means for controlling the first and second opening / closing means and the power converter,
The control means includes
The first and second switching means are turned off and a voltage is applied to the rotor winding by the power converter, and the induced voltage of the stator winding and the voltage of the second power supply system are synchronized. Turning on the second opening and closing means and connecting a second power supply system to the stator winding;
A first acceleration mode in which power is supplied to the rotor winding by the power converter to accelerate the induction machine and then the second opening / closing means is turned off to open the stator winding;
A second synchronous input mode in which the first switching means is turned on by synchronizing the induced voltage of the stator winding and the voltage of the first power supply system to connect the first power supply system to the stator winding. Are sequentially executed to start the induction machine.

The start control device according to claim 4 is the start control device for a wound induction machine according to claim 3,
Short-circuit means for short-circuiting the stator winding,
The control means includes
The rotor of the induction machine is stopped, the first and second opening / closing means are turned off, the stator winding is short-circuited by the short-circuit means, and power is supplied to the rotor winding by the power converter. The initial acceleration mode in which the stator winding in a short-circuit state is opened after the induction machine is accelerated to a predetermined speed is executed prior to the first synchronous input mode.

According to the invention according to claim 1 or claim 3, the starting torque characteristic at high speed is improved with respect to the conventional technique according to Patent Document 1, and the conventional technique according to Patent Document 2 is The winding-type induction machine can be started without using a booster transformer or two power converters, so that the entire apparatus can be reduced in size, weight, and cost.
According to the invention which concerns on Claim 2 or Claim 4, the torque characteristic from the stop state of an induction machine to the time of high speed rotation can be improved, and smooth acceleration can be implement | achieved.

1 is a configuration diagram of a start control device according to Embodiment 1. FIG. 3 is a flowchart illustrating an operation procedure of a start control method according to the first embodiment. It is a time-speed characteristic figure of the induction machine in Example 1. FIG. It is a flowchart which shows the operation procedure of the starting control method which concerns on a prior art. It is a time-speed characteristic figure of the induction machine in a prior art. FIG. 6 is a configuration diagram of a start control device according to a second embodiment. 7 is a flowchart illustrating an operation procedure of a start control method according to Embodiment 2. It is a time-speed characteristic figure of the induction machine in Example 2. FIG. It is a block diagram of the prior art which concerns on patent document 2. FIG. FIG. 6 is a speed-torque characteristic diagram of an induction machine according to an embodiment of the prior art and the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The embodiment of the present invention connects the stator winding of the wound-type induction machine to the low-voltage power supply system at the start of the induction machine, and uses the power converter connected to the rotor winding to input / output power of the induction machine. By controlling this, the speed-torque characteristics are improved as compared with the prior art. Examples 1 and 2 embodying this embodiment will be described below.

FIG. 1 is a configuration diagram of a first embodiment corresponding to claims 1 and 3, and shows, for example, a three-phase winding induction machine start control device connected to a three-phase power supply system in a single line diagram. .
In FIG. 1, 10 is a three-phase winding induction machine, 11 is a stator winding thereof, 12 is a rotor winding, 13 is a rotor, and a speed detector 14 is attached to the rotor 13. .

Reference numeral 21 denotes a first AC power supply system. The stator winding 11 of the induction machine 10 is connected to the power supply system 21 via a switch 31. Here, the “switch” is a switching means that does not have a large current interruption capability in the event of a failure, and is distinguished from a “breaker” that has a large current interruption capability. Regardless of the presence or absence of the switch, the switch may be either a switch or a circuit breaker because it simply functions as an opening / closing unit that opens and closes the electric circuit. Hereinafter, the term “switch” in each embodiment is used in a generic meaning of a switch and a circuit breaker.
Reference numeral 22 denotes a second AC power supply system having a lower voltage than the power supply system 21, and the stator winding 11 of the induction machine 10 is connected to the power supply system 22 via a switch 32.
The second power supply system 22 may be configured by connecting a low-voltage winding (secondary winding) of a step-down transformer 33 described below to the stator winding 11 via a switch 32. . That is, the second power supply system 22 is not necessarily a separate power supply system independent of the first power supply system 21 and may be configured by stepping down the first power supply system 21.

The primary side of the step-down transformer 33 is connected to the power supply system 21, and the secondary side is connected to the rotor winding 12 of the induction machine 10 via a power converter 34 such as an inverter or a matrix converter.
In the present embodiment, the power converter 34 connected to the first power supply system 21 controls the power supplied to the rotor winding 12, so that the stator winding 11 connected to the second power supply system 22. Controls input / output power. Here, FIG. 1 shows an example in which the speed detector 14 is attached to the shaft of the rotor 13 and feedback control of the speed is performed. However, the present invention does not detect the speed but controls V / f constant control or speed sensorless control. The present invention can also be applied to the case of starting by, for example.
A control device for performing opening / closing control of the first and second switches 31, 32 and drive control of the power converter 34 is not shown.

  Next, a starting control method for the induction machine 10 according to the first embodiment will be described with reference to FIGS. FIG. 2 is a flowchart showing an operation procedure of the start control method, and FIG. 3 is a time-speed characteristic diagram of the induction machine 10.

First, by keeping off the switch 31 at time _{t 0,} the initial state (step S1).

Next, in the first synchronous input mode of period t ₂ , first, a voltage is applied to the rotor winding 12 by the power converter 34 and the stator winding 11 is opened by turning off the switches 31 and 32. In this state, an induced voltage is generated in the stator winding 11, and control is performed to synchronize this induced voltage with the voltage of the second power supply system 22 (step S2).
That is, before the switch 32 is turned on, the amplitude and phase of the induced voltage of the stator winding 11 and the voltage of the power supply system 22 are matched to reduce shock when the switch 32 is turned on. Various methods for controlling the amplitude and phase of the voltage are known, such as voltage feedback control and PLL control, and the description thereof is omitted here.
When the amplitude and phase of the induced voltage of the stator winding 11 become equal to the amplitude and phase of the voltage of the power supply system 22, the switch 32 is turned on, and the stator winding 11 is connected to the power supply system 22 and synchronized. (Step S3).

Next, in the first acceleration mode period t _3, by a known vector control using the power converter 34 to accelerate the rotor 13 by applying a voltage to the rotor winding 12 (step S4). When the rotational speed reaches ω ₂ corresponding to the synchronous speed, the switch 32 is turned off and the stator winding 11 is opened (step S5).

Next, in the second synchronous input mode of period t ₄ , the induced voltage of the stator winding 11 is synchronized with the voltage of the power supply system 21 with the stator winding 11 open, as in the first synchronous input mode. After performing the control, the switch 31 is turned on, and the stator winding 11 is connected to the power supply system 21 (steps S6 and S7).

Then, in the second acceleration mode period t _5, the vector control of the power converter 34 as in the first acceleration mode, further accelerates the rotor 13. Here, the rotor 13 can be accelerated by the rated power. Then, as shown in FIG. 3, when the rotational speed reaches omega _3, the starting ends.

Hereinafter, for comparison with the first embodiment, a start control method of the conventional technique (see FIG. 9) according to Patent Document 2 described above will be described. FIG. 4 is a flowchart showing the procedure of the starting control method according to this prior art, and FIG. 5 is a time-speed characteristic diagram of the induction machine.
In the prior art, first, as an initial state at time t ₀ , the circuit breakers 71 and 73 in FIG. 9 are turned off, the circuit breakers 72 and 74 are turned on, and the power converters 76 and 77 are connected to the booster transformer 75 (step). S31). In addition, the circuit breaker 61 is turned off, the circuit breaker 101 is turned on, and the stator winding 51 is short-circuited by the three-phase short circuit 102 to configure the induction machine 50 as a general induction motor.

Next, in the acceleration mode of the period t ₁ , the power converters 76 and 77 are operated, and these output voltages are superimposed via the booster transformer 75 and applied to the rotor winding 52 of the induction machine 50 to thereby induce the induction machine. 50 is accelerated (step S32).
Thereafter, when the rotational speed becomes omega _2, turning off the circuit breaker 101 (step S33), thereafter the second synchronous loading mode in FIG. 2, similarly to the second acceleration mode, synchronous loading mode period t ₄ sequentially executes the acceleration mode period _{t 5} (step S34 to S36).

FIG. 6 is a configuration diagram of the second embodiment corresponding to claims 2 and 4. The same parts as those of the first embodiment shown in FIG. It demonstrates centering on a different part.
In the second embodiment, the stator winding 11 of the induction machine 10 is connected to the three-phase short circuit 36 via the switch 35.

The starting control apparatus according to the second embodiment starts by short-circuiting the stator winding 11 by the three-phase short circuit 36 until the rotational speed becomes ω ₁ (see FIG. 8) from the state where the rotor 13 is stationary. Is. The start control method according to the second embodiment will be described below with reference to the flowchart of FIG. 7 and the time-speed characteristic diagram of FIG.

First, as an initial state at time t ₀ , the switches 31 and 32 are turned off and the switch 35 is turned on while the rotor 13 is stationary (step S 11).

Next, in the initial acceleration mode of the period t _1, the stator winding 11 is short-circuited by the switch 35 and the three-phase short circuit 36 which are in the on state as described above, whereby the winding induction machine 10 is made to be a general induction motor. Configure as. Thereafter, power is supplied to the rotor winding 12 by known vector control using the power converter 34 to accelerate the rotor 13 (step S12). Rotational speed of the rotor 13 turns off the switch 35 When turned omega _1, to open the stator winding 11 which has been short-circuited (step S13).

Thereafter, in the state of the rotational speed ω ₁ , as in the first embodiment, the process shifts to the first synchronous input mode of the period t ₂ (steps S 14 and S 15), and the stator winding 11 is connected to the second power supply system 22. Synchronize. Since the subsequent operations (steps S16 to S20) are the same as those in the first embodiment, description thereof is omitted.

Here, FIG. 10 shows the speed of the induction machine according to the prior arts according to Patent Documents 1 and 2 (characteristic lines are B1 and B2, respectively) and Example 1 of the present invention (characteristic line is A). It is a torque characteristic figure, and is a thing at the time of using each starting control apparatus using the circuit constant of a certain winding type induction machine.
In Patent Document 1 to such a prior art (the characteristic line B1), the voltage limitation of the power converter, the fast time and approximately inversely proportional with the rotational speed and torque, as described above, the torque in the vicinity of the power supply frequency omega ₂ It is about 3.5 [%]. For this reason, if the friction loss or mechanical loss of the induction machine is large, it may not be possible to accelerate to the power frequency.
In the related art (characteristic line B2) according to Patent Document 2, it is possible to increase the torque by superimposing the voltage of the power converter on the rotor winding by a booster transformer. It is clear that the effect becomes smaller.

On the other hand, in Example 1 (characteristic line A) of the present invention, although the influence of the voltage limitation of the power converter appears at a low speed, a torque of at least about 7 [%] is obtained, so that the engine cannot be started. The possibility is low.
At high speeds, the vector sum of the stator winding voltage and the rotor winding voltage acts on the induction machine, and the rotor winding voltage frequency is reduced, resulting in less loss due to reactance. A large torque is obtained.
In general, according to the present invention, the starting torque characteristics at high speed can be improved, and the wound induction machine can be started with a small, lightweight and low-cost apparatus configuration without requiring a booster transformer or a plurality of power converters. In addition, smooth acceleration can be realized by improving the torque characteristics from the stationary state to the high speed rotation.

10: Winding induction machine 11: Stator winding 12: Rotor winding 13: Rotor 14: Speed detector 21, 22: AC power supply system 31, 32, 35: Switch 33: Step-down transformer 34: Power conversion 36: Three-phase short circuit

Claims (4)

A stator winding connected to the first power supply system via the first opening / closing means and connected to the second power supply system having a lower voltage than the first power supply system via the second opening / closing means; In the starting control method of the winding induction machine comprising a rotor winding connected to the first power supply system via a power converter,
A voltage is applied to the rotor winding by the power converter in a state where the first and second opening / closing means are turned off and the stator winding is opened, and an induced voltage of the stator winding and a second A first synchronous on mode in which the second switching means is turned on after the voltage of the power system is synchronized and the second power system is connected to the stator winding;
A first acceleration mode in which power is supplied to the rotor winding by the power converter to accelerate the induction machine to a predetermined speed, and then the second opening / closing means is turned off to open the stator winding. When,
A second synchronous input that synchronizes the induced voltage of the stator winding and the voltage of the first power supply system and then turns on the first switching means to connect the first power supply system to the stator winding. Mode,
Are sequentially executed to start the induction machine. A starting control method for a wound induction machine. Prior to the first synchronous input mode according to claim 1, the first and second opening / closing means are turned off and the stator winding is short-circuited with the rotor of the induction machine stationary. Performing an initial acceleration mode in which power is supplied to the rotor winding by the power converter to accelerate the induction machine to a predetermined speed and then open the short-circuited stator winding;
Then, the winding-type induction machine start control method characterized by sequentially executing the first synchronous input mode, the first acceleration mode, and the second synchronous input mode. First opening / closing means connected between the first power supply system and the stator winding of the wound induction machine;
A second opening / closing means connected between a second power supply system having a lower voltage than the first power supply system and the stator winding;
A power converter connected between the first power system and the rotor winding of the wound induction machine;
Control means for controlling the first and second switching means and the power converter;
With
The control means includes
The first and second switching means are turned off and a voltage is applied to the rotor winding by the power converter, and the induced voltage of the stator winding and the voltage of the second power supply system are synchronized. Turning on the second opening and closing means and connecting a second power supply system to the stator winding;
A first acceleration mode in which power is supplied to the rotor winding by the power converter to accelerate the induction machine and then the second opening / closing means is turned off to open the stator winding;
A second synchronous input mode in which the first switching means is turned on by synchronizing the induced voltage of the stator winding and the voltage of the second power supply system, and the first power supply system is connected to the stator winding. When,
And starting the induction machine in sequence. In the start-up control device for a winding induction machine according to claim 3,
Short-circuit means for short-circuiting the stator winding,
The control means includes
The rotor of the induction machine is stopped, the first and second opening / closing means are turned off, the stator winding is short-circuited by the short-circuit means, and power is supplied to the rotor winding by the power converter. Then, an initial acceleration mode in which the induction motor is accelerated to a predetermined speed and then the stator winding in a short-circuit state is opened is executed prior to the first synchronous input mode. Start control device.

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