TWI505629B - Method for adjusting the efficiency of a synchronous machine - Google Patents

Description

Method for adjusting the efficiency of an alternating current synchronous motor

The present invention relates to a method of adjusting the efficiency of an AC synchronous motor, and more particularly to an AC synchronous motor in which the wound rotor is used as an electric traction.

The adjustment control of the AC synchronous motor can be advantageously combined with the adjustment of the torque or speed of the AC synchronous motor according to the patent of Angelo Gaetani (IT 1329820). In the field of electric traction motion, it is known to use a direct current motor in series, parallel or separate excitation so that the torque or speed can be completely adjusted and controlled. Although these motors have excellent speed control or torque drive, the above motors have considerable problems in power distribution. Because the current value on the brush must ensure a limited value, and measures taken due to safety conditions, to avoid current sparking on the brush. In addition, this motor cannot adjust the control efficiency, which depends on the structural characteristics and operating conditions of the motor, and therefore cannot maintain performance under different operating conditions, which has a negative impact on the energy consumption of the motor.

An alternative to current motors can use so-called brushless motors that simulate a continuous current motor through appropriate techniques, associated application and vector control techniques. In fact, its mechanical structure, the so-called brushless motor, consists essentially of the composition of an AC synchronous motor (with an external armature and internal inductor), a position converter and a static matrix switching stator winding supply. Appropriate control of the stator windings enables a perfect orthogonality in the field of excitation current and reaction, and in addition, instantaneously, simulating the operation of the DC motor. Although this motor exhibits high dynamic performance and handling flexibility, it also has limitations. In fact, especially the structure of the motor is very fragile, which limits the rotational speed below a certain threshold during the rotation beyond the centrifugal force, which may result in permanent Magnetic force and thus damage the motor. Finally, another problem is that the motor is unable to make any adjustment control of the flow field current. In addition, the motor cannot adjust the control efficiency, especially the ability to maintain a certain efficiency under different operating conditions.

The driving method using electric traction is also called AC synchronous motor winding rotor driving. The rotor winding is externally connected through the brush and the electric ring, and the stator winding is externally connected through the terminal. These motors are particularly suitable for drives that require high power because of their high efficiency, high overload capability, and good performance in the weak magnetic zone.

At the same time, this motor does not have the function of adjusting the control efficiency, and it is necessary to maintain constant efficiency under different operating conditions, so as to minimize the energy loss of the motor.

Accordingly, in order to effectively solve the above problems, one of the objects of the present invention is to provide a method for adjusting the efficiency of an AC synchronous motor, in particular an AC synchronous motor, to adjust the control motor to maintain maximum efficiency and in different operating conditions. Maintain a constant power.

To achieve the above object, the present invention provides a method for adjusting the efficiency of an AC synchronous motor and maintaining constant power under different operating conditions, the method comprising: calculating the efficiency of the AC synchronous motor under a predetermined operating condition, and Measuring the phase current of one of the stator windings of the AC synchronous motor under a preset operation condition, and calculating the angle between the phase voltage of the stator winding and the induced electromotive force in the AC synchronous motor under a preset operation condition, In an operation case, the phase current of the stator winding in the AC synchronous motor is measured, wherein the phase current measured under the foregoing operation is different from the phase current measured under the preset operation, and in the operation, the AC synchronous motor is calculated. The angle between the phase voltage of the stator winding and the induced electromotive force, wherein the magnitude of the calculated angle in the foregoing operation is different from the magnitude of the calculated angle in the preset operation, and the operation is adjusted by using the above operation. The phase voltage and the value of the phase current recover the angle calculated under the operating condition Under operating conditions the predetermined angle calculated.

Therefore, through the invention, it is possible to preset the efficiency value of an AC synchronous motor and maintain the efficiency value under different operating conditions, thereby optimizing the energy consumption of the motor under various conditions.

V‧‧‧ phase voltage

E‧‧‧Induction electromotive force

R‧‧‧winding resistance, resistance

Xs‧‧‧Synchronous reactance

I, I’‧‧‧ phase current

α, α’‧‧‧ angle

Figure 1 is a vector diagram showing a power vector of a wound rotor AC synchronous motor in each phase stator winding; Figure 2 is a schematic diagram showing the dependence of the motor synchronous reactance on the magnetic induction value; A schematic diagram showing how to change the vector diagram of Figure 1 to the current variation in the stator windings.

The above object of the present invention, as well as its structural and functional features, will be described in accordance with the preferred embodiments of the drawings.

Referring to FIG. 1 , the present invention provides a method for adjusting the efficiency of an AC synchronous motor. In FIG. 1 , a vector diagram showing a power vector of a wound rotor AC synchronous motor in each phase stator winding. . In this figure we get the following formula: V = E + (R + jXs) I (1) where V is the phase voltage, E is the induced electromotive force, R is the resistance of the phase winding, and Xs is the synchronous reactance of the phase winding, I is Phase current.

(1) can also be written as V = E + ZsI, where Zs = R + jXs is the impedance of the synchronous phase winding.

Alternatively, according to the vector diagram of Fig. 1, the efficiency of the AC synchronous motor and the phase voltage (V) are inversely proportional to the angle (α) between the induced electromotive forces (E). In other words, the efficiency of an AC synchronous motor increases as the angle decreases, and vice versa. The magnitude of the angle (α) depends on the value of the synchronous impedance, that is, the value of the resistance (R) and the synchronous reactance (Xs), and the value of the phase current (I). The value of the resistance (R) depends on the nature and geometry of the winding material, while the value of the synchronous reactance (Xs) depends on the value of the magnetic induction (B), which is related to the excitation current, and decreases as the value of the magnetic induction (B) increases. And by changing the torque and / or motor revolutions, that is, changing the power of the motor, if maintaining a constant voltage (V), changing the phase current (I) and angle (α) and AC Synchronous motor efficiency, as shown in Figure 3, theoretically leads to an increase in power, i.e., an increase in phase current value (I').

Moreover, as can be seen from the third figure, the increase of the phase current causes the angle (α') to increase and the motor performance to decrease. Therefore, according to the invention, the AC synchronous motor stator power can be expected under different power supplies. Or a change in the field current. In order to maintain the performance of an AC synchronous motor, especially for an AC synchronous motor, the motor efficiency can be maintained by maintaining the angle (α) between the phase voltage (V) and the induced electromotive force (E) at each stator winding. In other words, by changing the power absorbed by the AC synchronous motor to adjust the supply voltage and the excitation current, the vector triangle in Figure 1 maintains a similar value even if the size changes.

Furthermore, that is, by measuring the power supply voltage (V), the phase current (I) of the stator winding, the winding resistance (R) and the synchronous reactance (Xs), the latter can be determined by the aforementioned method, for example, by vacuum Test and short-circuit the machine in the environment, and a preset operating condition (or preset operating conditions) to get the exact angular size. For example, the preset operating state can be the maximum efficiency (or maximization) of the AC synchronous motor. This operating condition (or operating condition) can be experimentally determined by calculating the AC synchronous motor performance in a variety of different operating environments.

After determining the angle (α) value in the preset operation, the power supply voltage (V) and the excitation current can be adjusted under different operating conditions (or operating conditions) of the AC synchronous motor, so that the power supply can be maintained. Angle (α) size value, and the motor performance will be the same as in the preset operation. In order to obtain this result under different AC synchronous motor operating conditions (or operating conditions), the phase current (I) of the stator winding is measured, and the power supply voltage (V) and the exciting current are adjusted to maintain The angle (α) between the voltage (V) and the induced electromotive force (E) does not change. And in different AC synchronous motor operations, such as the operation of the motor, that means different torque resistance and / or motor speed, which in turn represents different motors to absorb power. Thanks to this invention, it is possible to maintain a stable AC synchronous motor efficiency under different operating conditions, thereby enabling optimization of efficiency and energy saving.

It is to be understood that the above-described methods, shapes, configurations, and devices of the present invention are intended to be included within the scope of the present invention.

Claims (2)

A method for adjusting the efficiency of an AC synchronous motor is applied to a synchronous motor, comprising: calculating an efficiency of an AC synchronous motor under a preset operation condition; and measuring one of the stators of the AC synchronous motor under the preset operation condition The phase current of the winding; in the case of the preset operation, determining the synchronous reactance of the AC synchronous motor; in the case of the preset operation, calculating an angle between the phase voltage of the stator winding and the induced electromotive force in the AC synchronous motor The size of the phase current of the stator winding in the AC synchronous motor is measured under an operating condition, wherein the phase current measured under the foregoing operation is different from the phase current measured under the preset operation; in the case of the operation, Calculating an angle between the phase voltage of the stator winding and the induced electromotive force in the alternating current synchronous motor, wherein the magnitude of the calculated angle in the foregoing operation is different from the magnitude of the calculated angle in the preset operation; and utilizing Adjusting the phase voltage and the value of the phase current in the above operation case, and calculating the operation condition Angle return to default operation of the angle calculated. The method for adjusting the efficiency of the synchronous synchronous motor according to the first aspect of the patent application includes: determining the maximum efficiency of the AC synchronous motor in an operating condition to synchronize with the calculated AC under the preset operation. The efficiency of the motor is the same.