JP3278908B2 - Control method of commutatorless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a commutatorless motor, and more particularly to a control for starting a generator of a gas turbine power plant as a commutatorless motor without interrupting a current flowing through the motor. The present invention relates to a control device for a commutatorless motor that reduces a stress on a high-speed synchronous generator that becomes a commutatorless motor by being started.

[0002]

2. Description of the Related Art Conventionally, a method for controlling a commutatorless motor has been disclosed in Japanese Patent Publication No. 59-47956, in which the control angle of a motor-side power converter is set to a limit value necessary for commutation. The torque coefficient is adjusted to a maximum value, and the generated torque necessary for speed control is controlled by current control in adjusting the control angle of the power semiconductor converter on the AC power supply side. Further, as shown in the above-described known example, when the torque direction is reversed from the power running operation to the regenerative operation or from the target operation to the power running operation, the control angle of one power converter in the forward converter region is switched to the reverse conversion region. After confirming that the operation is in the reverse conversion region, the control angle of the power semiconductor converter in the other reverse conversion region is switched to the forward conversion region, and the power converter on the power supply side and the power semiconductor converter on the load side are switched. By switching the operations of the above, the torque direction is reversed without reducing the current to zero, and a smooth switching between the powering operation mode and the regenerative operation mode is realized. As described above, conventionally, the generated torque is controlled by adjusting the control angle of the power semiconductor converter on the AC power supply side, so that in the speed control when the load torque is small, the current flowing through the motor is continuous. Control is performed below the limit current value, that is, the current is operated in the intermittent mode.

However, in the case of a high-speed and long-axis rotating machine such as starting a generator of a gas turbine power plant as a commutatorless motor, the rotor has a cylindrical structure, and a cylindrical rotor slot and a hollow are inserted therein. Regarding the relationship with the rotor coil, there is a gap at the time of starting in consideration of thermal expansion due to a rise in the rotor coil temperature at the rated current flowing.
Therefore, when the current intermittent operation is performed at the time of starting as a non-commutator motor, the force applied to the rotor coil with a clearance between the rotor slot and the rotor coil changes due to a sudden change in the generated torque at that time, and the rotor slot and the There is a drawback that the rotor coil that hits inside may be hit and stresses the rotor. Therefore, conventionally, the motor was started by an electric motor connected to a generator via a torque converter. This method also makes it difficult to produce a torque converter for increasing the capacity.

[0004]

SUMMARY OF THE INVENTION As described above, when a gas turbine generator or the like, which is a high-speed rotating and long-axis rotating machine, is started as a commutatorless motor, the rotor accompanying the current intermittent operation is used. Unless the drawback of the control method of applying the above-mentioned stress is solved, the control method of starting the generator as a non-commutator motor cannot be used. Therefore, an object of the present invention is to provide speed control operation at a continuous limit current (I ₁ ) or more at which the motor current does not continue. In addition, since the speed control operation requires a power running operation and a regenerative operation, an object of the present invention is to provide a control method capable of performing the speed control operation at a continuous limit current (I ₁ ) or more in both the power running operation and the regenerative operation. I have.

[0005]

According to the present invention, as an electric motor control method for achieving the above object, an AC power supply is connected to a power supply.
Force of synchronous motor, which is a non-commutator motor, on the load side
During line operation, a forward conversion operation is performed, and the AC power
Also, during regenerative operation when the synchronous motor is on the power supply side,
The power-side power semiconductor converter that performs the switching operation is connected to the AC power supply.
During the power running operation, the reverse conversion operation is performed
Motor-side power semiconductor converter that performs forward conversion operation during operation
To the synchronous generator side, and the same
Rotation signal of the starting motor and the above
Input the current value signal from the power supply to the control circuit, and
Lower limit required for continuous limit current I ₁ where motor current is not interrupted
When the generated torque was T _1, it is calculated from the input signal
Generation torque is the motor except between -T ₁ through T ₁
Generate the control angle of the side power semiconductor converter.
Controlled to be, the generated torque between -T ₁ through T ₁
Torque coefficient generation as is the lower limit torque above T ₁
Control the above-mentioned motor-side power semiconductor converter to reduce
Speed control method. As another control method,
In between generated torque -T ₁ through T _1, the braking of the motor-side converter
The angle is set to a value that maximizes the generated torque coefficient at the commutation limit
As it is, the field current is reduced and the generated torque coefficient is reduced.
To control the speed without interrupting the current of the motor .

[0006]

According to the above control method of the present invention, the generated torque is controlled by adjusting the control angle of the motor-side power semiconductor converter while controlling the motor current to be equal to or higher than the continuous limit current (I ₁ ). Speed control. Alternatively, the generated torque can be speed-controlled by controlling the generated torque coefficient by adjusting the field current. Therefore, current continuous operation that can prevent stress on the rotor due to current discontinuity that occurs at low load, which is a problem when starting as a high-speed rotating, long-axis rotating machine such as a generator of a gas turbine power plant and a non-commutator motor, There is an effect that speed control can be performed.

[0007]

FIG. 1 is a block diagram showing a control apparatus using one embodiment of a method for controlling a commutatorless motor according to the present invention. In the figure, 1 is an AC power supply and 2 is a C for detecting a current.
T and 3 are thyristor converters which perform a forward conversion operation during power running and an inverse conversion operation during regeneration. Reference numeral 4 denotes a DCL for smoothing current, and a thyristor converter 5 performs an inverse conversion operation during power running and an inverse conversion operation during regeneration. Reference numeral 6 denotes a circuit breaker, 7 denotes a synchronous generator serving as a non-commutator motor, 8 denotes a field winding of the synchronous generator, 9 denotes a gas turbine directly connected to the synchronous motor, and 10 denotes a rotor and an armature of the generator. A position detector for detecting a relative position, 11 a speed detector, 1
Reference numeral 2 denotes a current detector for detecting a DC current based on the AC current detected by CT2, and a gate circuit 13 includes a thyristor converter 3
, Control of the thyristor of the thyristor converter 5, that is, the motor-side control angle β, and the gate circuits 9, 24 are non-rectified. Variable frequency automatic pulse phase shifter operating from zero to rated frequency of the slave motor 7 (Japanese Patent Publication No. 61-4835)
No. 3). Reference numeral 15 denotes a field current control circuit, and control circuit 16 denotes a circuit characteristic of the present invention, the details of which will be described later. Next, a detailed operation of the control circuit 16 which is a feature of the present invention will be described with reference to block diagrams of FIGS. 2 and 3, an operation time chart shown in FIG. 4, and operation explanatory diagrams shown in FIGS.

The speed calculation circuit 101 receives the output S _R of the command circuit 17 and the output S _F of the speed detector 11 and calculates so that the speed of the non-commutator motor 7 becomes S _R. Inverting circuit 1
Numeral 02 inverts the polarity of the output of the speed calculation circuit 101, and the output is used when a reverse torque is generated. The switching circuit 103 switches the output of the speed calculation circuit 101 for positive torque and the output of the reversal circuit 102 for reverse torque and outputs the output. The switching is performed by a switching signal. The lower limit circuit 104 is the switching circuit 10
Minimum current (I ₁ ) required to make the output value of 3 continuous
The lower limit for flowing the above is restricted. Switching circuit 1
05 is a switching circuit 1 when switching between powering operation and regenerative operation.
In the other cases, the output of the lower limit circuit 104 is switched and output in other cases, and is used as a current command. Its switching is performed by switching signal T _C. The current calculation circuit 106 is a switching circuit 105
, And the output I _FB of the current detection circuit 12 are input, the current flowing through the electric motor 7 is calculated to be a current command signal, and the input signal V
Outputs _Cα . 107 is a setter for setting a lower limit generated torque (T ₁ ) necessary for continuous current, and 108 is a switching circuit 10
The output of 3 is an arithmetic unit for calculating the deviation of the output of the setting unit 107. The output 109 is a calculation unit when the output of the arithmetic unit 108 is negative, that is, when the output of the switching circuit 103 is smaller than the lower limit torque (T ₁ ). calculator for outputting a negative value (-V _P), 1
10 is a polarity inversion circuit, and the function generation circuit 111 inputs S _F and outputs V ₀ + k · SF. Here, V ₀ is a value (k is a proportional constant) for giving the minimum advance control angle at which the thyristor converter 5 can commutate with the back electromotive force of the non-commutator motor 7, 1
12 is a polarity inversion circuit, 113 is a setter for setting a bias (−V ₁ ) corresponding to the advance control angle β = 0, and 114 is a bias corresponding to the advance control angle β = 180 ° (lag control angle α = 0). A setter 115 for setting (−V ₂ ), an adder circuit 115 calculates a control angle of the thyristor converter 5 at the time of positive torque and outputs a value of (V ₀ + k · SF−V ₁ + V _P ). (V ₀ + k · SF−V ₁ ) is a value corresponding to the control angle of the thyristor converter 5 which becomes the maximum generated torque coefficient at the continuous limit, and V _P
Is an adjustment signal for reducing the generated torque coefficient when the required generated torque is equal to or smaller than the limit generated torque (± T ₁ );
Reference numeral 6 denotes an adder circuit for calculating the control angle of the thyristor converter 5 at the time of reverse torque and outputting a value of (V ₂ −V ₀ −k · SF−V _P ). Is output by switching the output of the reverse torque addition circuit 116. Its switching is performed by switching signal T _beta. The arithmetic circuit 118 receives the output of the switching circuit 17 and
And outputs a fourth input signal V _C.beta. FIG. 3 shows a switching signal generator for generating the switching signals T _α , T _β , and T _C of FIG. In FIG. 3, a waveform shaping circuit 201 detects whether the output T ₁ of the speed calculation circuit 101 is positive or negative, and generates a T of “1” when the torque is positive. 202, 2
03,204 The signal inversion circuit, the detection circuit 205 is "1" when it becomes -e ₁ below corresponds to the control angle output V _{C alpha} of the current operation circuit 106 corresponds to the inverse transform operation region of the thyristor converter 3 Is output. Detection circuit 20
6 outputs a detection signal β ₁ which becomes “1” when V _Cβ becomes equal to or more than e ₂ corresponding to the forward conversion region of the thyristor converter 5. Detection circuit 207 outputs a detection signal B ₂ becomes "1" when V _C.beta becomes -e ₃ below (corresponding to the inverse transform domain). The OR circuit 208 is a circuit that performs an OR operation on the signals T, A, B ₁ and B ₂ , generates a signal that becomes “0” between t ₂ and t ₃ in FIG. Switching t ₃
~t NOR circuit 211 for generating the composed signals T _beta between "0" of ₆ to NOR signal inversion circuits 203 and 204, generates a signal which becomes "1" during t ₆ ~t ₈ in FIG. 4 . NOR
Circuit 210 generates a signal T _alpha which is between "0" of the t ₅ ~t _8. EOR circuits 212 EOR signals T and T _beta,
OR that generates "1" signal when switching between forward torque and reverse torque
The circuit 213 has a command T ₀ for stopping the generated torque and the E
And OR output of the OR circuit 212, generates a switching signal T _C. The method of controlling the current continuously will be described in detail with reference to FIGS. Relationship generated torque and motor current (motor current) of the control angle is when in generated torque coefficient constant is constant thyristor converter 5 becomes a characteristic shown in FIG. 5, occurs when the critical current I ₁ or more necessary to the continuous current Torque is T
₁ or more. FIG. 6 shows the relationship between the control angle of the thyristor converter 5 and the generated torque coefficient. Figure 7 of the motor current to generate torque required to load torque shown in (a) to control flow to I ₁ or more, the motor current is controlled as shown in FIG. (C) by a thyristor converter 3, the generated torque Control is performed as shown in FIG. Between the generated torque -T ₁ through T ₁ is controlled as shown in (d) of FIG under the control angle adjustment of the thyristor converter 5, except between -T ₁ through T ₁ is the torque generated by a constant value Figure (B) and the seed of FIG. (D), the torque can be controlled to the generated torque shown in FIG.

[0009] showing another embodiment in FIG. 8, differs from the embodiment of FIG. 2, the setting changing the field磁設value 109 output signal is an error signal generated when a torque T ₁ or less A subtractor 120 subtracts the field current command value V _Cf from the converter 119 to control the thyristor converter 5 to control the generated torque coefficient instead of controlling the generated torque coefficient. The relationship between the coefficients is shown in FIG. 9)
, The current is controlled to be equal to or greater than the continuous current, and the generated torque is controlled to correspond to the load torque as shown in FIG.

[0010]

According to the method for controlling a commutatorless motor described in the embodiments of FIGS. 2 to 7, when a thyristor of a gas turbine power plant is started as a commutatorless motor, a problem arises when a high-speed rotation becomes a problem. By adjusting the generated torque coefficient of the thyristor converter 5, the stress caused by the intermittent current to the rotor can be eliminated because the speed can be controlled at or above the limit current at which the motor current becomes continuous.
Further, even in the power running operation and the regenerative operation, the speed can be controlled with the current exceeding the limit current, and the stress on the rotor can be eliminated.

According to the control method of the commutatorless motor described in the embodiments of FIGS. 8 to 10, the motor armature current is controlled to the current continuous limit current value or more, and when the load torque is small, the field current is controlled. Speed can be controlled so as to reduce the generated torque coefficient, so that stress on the rotor can be eliminated.

[Brief description of the drawings]

FIG. 1 is an overall block diagram of one embodiment of the present invention.

FIG. 2 is a detailed circuit diagram of a control circuit of the present invention.

FIG. 3 is a detailed view of a switching signal generator of FIG. 2;

FIG. 4 is an operation time chart.

FIG. 5 is a diagram showing the relationship between motor current and generated torque.

FIG. 6 is a relationship diagram between a control angle of a thyristor converter and a generated torque coefficient.

FIG. 7: Load torque of continuous current limit within ± T ₁ range and ± T
FIG. 4 is a diagram illustrating generated torque control operation outside _one range.

FIG. 8 shows another embodiment.

FIG. 9 is a relationship diagram between a field current and a generated torque coefficient.

FIG. 10 is a diagram illustrating the generated torque control operation of the embodiment of FIG. 8;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... AC power supply, 3,5 ... Thyristor converter, 7 ... Synchronous generator which becomes a non-commutator motor, 9 ... Gas turbine, 13,
14: gate circuit, 16: control circuit of the present invention.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-32400 (JP, A) JP-A-58-99274 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 6/20 H02P 1/46

Claims (4)

(57) [Claims] 1. A forward conversion operation is performed during a power running operation in which an AC power supply is on the power supply side and a synchronous motor that is a non-rectifier motor is on the load side, and a regenerative operation in which the AC power supply is on the load side and the synchronous motor is on the power supply side. Sometimes, the power-side power semiconductor converter that performs the reverse conversion operation is connected to the AC power supply side, performs the reverse conversion operation during the power running operation, and performs the forward conversion operation during the regenerative operation. To the control circuit, and inputs the rotation speed signal of the synchronous motor detected by the speed detector and the current value signal from the AC power supply detected by the current detector to the control circuit, and the continuous limit current I in which the synchronous motor current is not interrupted. when the lower limit torque was T ₁ required for _one generation torque calculated from the input signal, -
T ₁ through T other than between ₁ controls so generated torque coefficient control angle of the motor-side power semiconductor converter is maximized, the lower limit torque T ₁ is the torque generated between -T ₁ through T ₁
A method for controlling a commutatorless motor, comprising controlling the speed of the motor-side power semiconductor converter so as to reduce the generated torque coefficient as described above. 2. The method for controlling a commutatorless motor according to claim 1, wherein the power supply-side electric power is supplied when the torque direction is changed from a power running operation to a regenerative operation or from a regenerative operation to a power running operation.
Forward conversion of semiconductor converter and motor-side power semiconductor converter
Conversely from the control angle of the power semiconductor converter in the operating side switched to the inverse transform operation, and to confirm that the phase signal for controlling the output voltage or the output voltage is reversed varying over operation
The control angle of a power semiconductor converter conversion operation side forward conversion
It is switched to the operation, the power source side power semiconductor converter and the collector
A method for controlling a commutatorless motor, characterized in that the operation with a motor- side power semiconductor converter is exchanged with each other to control the torque direction to be reversed. 3. A method of controlling a Brushless DC electric motor according to claim 1, wherein, in between generated torque -T ₁ through T _1, torque coefficient control angle commutation limit of the motor-side converter is maximum A method for controlling a commutatorless motor, wherein the speed is controlled without interrupting the current of the motor by reducing the field current and reducing the generated torque coefficient while keeping the value. 4. A method of controlling a Brushless DC electric motor according to claim 2, in between generated torque -T ₁ through T _1, torque coefficient control angle commutation limit of the motor-side converter is maximum A method for controlling a commutatorless motor, characterized in that the limit current is reduced while keeping the value, and the speed is controlled without interrupting the current of the motor by reducing the generated torque coefficient.