JPS58186397A - Voltage controlling method for hysteresis motor - Google Patents

Abstract

PURPOSE:To equalize the electric characteristics of motor groups by temporarily interrupting the power supply to the motors to decelerate the motors, demagnetizing the remaining magnetic fluxes of the rotors, then reapplying the altered voltage, AC demagnetizing the remaining magnetic flux, and altering the voltage. CONSTITUTION:An inverter is connected through an electromagnetic contactor 6 to hysteresis motor groups, the output of the inverter 5 is compared with a set voltage 12, and the thyristor of a rectifier 2 is phase controlled through an integrator 14. The contactor 6 is opened during the operation, the motor group 7 is decelerated by natural speed reduction, the remaining magnetic fluxes of the rotors are demagnetized, the set voltage 12 is then switched, thereby decreasing the output voltage of the inverter, the contactor 6 is reclosed, the remaining magnetic fluxes are AC demagnetized with the altered voltage, thereby altering the voltage. Accordingly, the electric characteristics of the motor groups can be equalized, and the overload of the power sources at the voltage altering time can be alleviated.

Description

[Detailed description of the invention] (a) Explanation of technical field The present invention relates to a method for controlling a hysteresis motor.

In particular, it relates to a voltage control method for a hysteresis motor that changes the operating voltage.

(b) Description of the Prior Art A hysteresis motor (hereinafter abbreviated as HM) has a simple structure, is robust, and is suitable for high-speed rotation. In recent years, they have been increasingly used because they can operate at asynchronous speeds and are extremely easy to start. However, H
Due to its torque generation principle, M is only used in practical use at most IKW.1. For this reason, HM uses a large number of identical machines for industrial purposes, and these machines are
It is used for applications such as driving with M.

This application is applicable when only the rotational speed is a problem, and when H
There are cases where it is necessary to make the electrical characteristics (efficiency, maximum torque, heat generation amount) of M the same.

Especially in the latter case, where it is necessary to make the HM end terminal positive voltage variable, when changing the voltage, it is necessary to control a large number of HMs so that they all have the same electrical characteristics. . The reason for changing this voltage is, for example, to lower the voltage for high efficiency operation. ) (Due to its principle, M has lower efficiency than other electric motors.

This is because during synchronous operation, the load torque is a fraction of the maximum torque that the HM can produce, and because of its constant current characteristics, the input power factor is extremely low, and the stator loss accounts for a large proportion of the output. It depends on K.

The reason for this is that the HMFiM torque characteristic has no relation to the magnitude of slippage, and its output torque is almost equal to the maximum torque of the same synchronous machine, so when acceleration is taken into consideration, the difference between the maximum torque and the rated load torque becomes large. This results in low efficiency as described above. Now, even if the HM terminal voltage is lowered and the maximum torque is slightly larger than the load torque,
HM can be operated at synchronous speed, but on the other hand, the stator iron loss decreases in proportion to the first power of the voltage (γχ1.6 to 2.0), and the HMM power voltage decreases in proportion to the voltage. For,
Copper loss decreases in proportion to the square of the voltage. Highly efficient operation can be achieved by operating with the voltage reduced in this way. Conversely, when the voltage is increased, the stator loss of the HM increases. By changing the voltage in this way, it is possible to change the efficiency of the HM, and it is possible to provide optimal electrical characteristics to the other machine.

Conventionally, when changing the terminal voltage of the HM group, the output voltage of the drive power source (for example, an inverter device) is changed, and the H
A method of varying the terminal voltage of M has been used. However, in this case, it has been found that the following two problems occur.

Problem (1): If the terminal voltage of HM in synchronous operation is lowered, the characteristics of HM will change due to the overexcitation phenomenon and the electrical characteristics will improve), and if the voltage is increased, The characteristics of the HM change due to the de-excitation phenomenon (the electrical characteristics deteriorate). Since such an over-excitation/de-excitation state is a quasi-stable state for H to 1, it is gradually canceled due to disturbance etc., and eventually becomes the original electrical characteristic determined by the terminal voltage and load of HM. This change varies depending on the load condition, but it has been observed that it takes 2 to 3 days. These changes occur differently for each HMK, so in this transitional state, the characteristics of each HM are not uniform, so the performance of the partner machine cannot be fully demonstrated, and the product during this transition period This may lead to unevenness or a decrease in the efficiency of the system.

Problem (2): The above-mentioned decoys that are not in the over-excited or de-excited state have constant current characteristics, and the reactive component of the input direct current is proportional to the voltage, regardless of the load. In the case of HM, this reactive component is very large, so in actual operation, it is common to connect a power factor improvement capacitor to measure the decrease in power supply capacity. When changing the voltage, if the decoy is not overexcited or demagnetized, H
The reactive current of M is proportional to the voltage, and the compensation current of the capacitor is also proportional to the voltage, so the reactive current of the power supply output is proportional to the voltage.

No problems arise. However, when the voltage is lowered using the conventional method, the HM becomes over-excited. In this over-excitation state, the input power factor of the HM becomes very good and can be a power factor of IK%. Therefore, in the case of an overexcitation state, the compensation current of the capacitor becomes overcompensated, and the output current of the power supply increases, resulting in an overload of the power supply.

Moreover, in the case of de-energization, the reactive current of HM increases, resulting in insufficient compensation of the capacitor and overload of the power supply.

In the above-mentioned problem 1.2, the influence of de-energization is often smaller and tolerable than that of over-excitation.

As described above, the conventional method of changing the voltage has the above-mentioned drawbacks, and therefore has the disadvantage of being subject to severe limitations when actually applied.

(C) Purpose of the Invention The present invention was made based on the above reasons, and provides a voltage control method for a hysteresis motor that does not have the above-mentioned drawbacks, which makes the electrical characteristics of the HM group uniform, and reduces overcharge of the power supply when changing the voltage. The purpose is to

(d) Structure and operation of the invention The present invention will be described below based on an embodiment shown in the drawings. FIG. 1 shows the configuration of the present invention. Reference numeral 1 denotes an AC power supply that supplies power to an inverter device. This power supply IFi is converted from AC to DC by a rectifier 2, and is roughly composed of a DC reactor 3 and a DC capacitor 4. It is smoothed by a filter device and converted into a DC voltage with less ripple, which is further converted to a desired frequency txNv by an inverter circuit 5.
Changed to AC. This AC output VI NV is supplied to a hysteresis motor group 7 via an electromagnetic contactor 6 .

The reactive current of the HM group 7 is compensated by connecting an AC capacitor 8 in parallel to the HM group 7 via an electromagnetic contactor 9, and the output of the inverter device consisting of the rectifier 2, filter device, and inverter circuit 5 is Measure the capacity drop.

The output voltage of the inverter device is the transformer lO1 rectifier circuit 1
1, the return voltage VfVc for the control circuit is changed, and this Vf is controlled so as to be equal to the output Vr of the reference voltage setter 12. Vr and Vf are added by an adder 13 with the polarity shown, and e=Vr-Vf is input to an integrating circuit 14. The output Ec of the integrating circuit 14 enters a phase control circuit 15, which changes the firing phase of the thyristor constituting the rectifier 2 and controls the firing phase so that the output of the rectifier 2 is proportional to Rc. Let's do it. This will be explained using FIG.

Next, the operation shown in FIG. 1 will be explained with reference to FIG. 2.

In Fig. 2, (a) is the output voltage vt of the inverter device.
Return voltage Vf corresponding to NV, (b) terminal voltage vM of HM group 7, (C) output v of reference voltage setter 12
(d) and (e) show the open and closed states of the electromagnetic contactors 6 and 9, with the closed state shown as ON and the open state shown as OFF.

Note that the horizontal axis t indicates time, and between t=Q and tl, the electromagnetic contactors 6 and 9 are in a closed state, and the HM group 7 is driven by an inverter device. At this time, it is clear that VINV=
It is VM. At the time of t=tl, the electromagnetic contactors 6 and 9 are closed → open, and the HM group 7 is in the natural speed state, and the speed is 1.
The rotation speed is gradually lowered over time.

At this time, the output VtNv of the inverter device rises for a short period of time due to the load fluctuation, so that Vf)Vr
After that, vf=v. On the other hand, grab #7
The terminal voltage vM is not 0 due to the back electromotive force caused by the residual magnetic flux of the HM rotor, but is a constant value V, / (this is determined by the rotor material, but is usually determined by the power supply voltage I~ before disconnection). Become.) remain. Next, at the time t = tl,
The output Vr of the reference voltage setter 12 is changed to lower the output voltage VINV of the inverter device, and vI
becomes. VtNV is a control time constant and decreases to a value corresponding to vr'. In other words, Vf is Vf −Vr at the control time constant.
It decreases at 4.

Next, 1=1. At the time point, the electromagnetic contactors 6 and 9 change from open to close, and the load HM group 7 is applied again. From this point on, the HM group terminal voltage VM and the output voltage V of the inverter device are changed again.
ENT will be equal. At this time, the output voltage VINY of the inverter device causes a drop in mold pressure during the control time constant due to load fluctuation, so after reaching Vf (Vr, Vf=xVr
becomes. Now, the behavior of the HM group over this time period will be shown. First, until t=tl, the HM group 7 is driven by the inverter device, so the output frequency fI of the inverter device
It rotates in synchronization with NV. HM group 7 is t=tlO
At this point, the vehicle becomes at its natural speed, and at 1=13, the vehicle is driven again by the inverter device.

During this natural speed time T = t, -tl, the rotation speed of the HM group 7 decreases, and when it is driven again at t-ts, the rotation frequency fM of the HM group 70 is equal to the output frequency fnrv of the inverter device. On the other hand, it is in a tax situation. Therefore, after t-, the residual magnetic flux in each HM rotor of the HM group 7 is demagnetized by the same excursion as AC demagnetization by the slip frequency fs=frNV-fv, and the HM group 7 is accelerated again. When the synchronization state is reached, the magnetic flux within the HM rotor is determined according to the hysteresis loose determined by the output voltage 11 of the inverter device applied to the HhNI 17 after 1=1 s.

That is, 1=1. Hereinafter, the characteristics of the HM group 7 will be determined based on the output voltage v of the inverter device, regardless of the previous history.
Determined by rMV. Therefore, according to this operation, HM
All HMFis within $7 will have the same electrical characteristics, and the above problem (1) will be solved.

In addition, 1=1. Thereafter, since the reactive current compensation of the capacitor 8 is appropriate, the output current of the inverter device becomes an output corresponding to the synchronization escape output of the HM group 7.

This is a large value for the inverter, but in cases where the voltage is reduced as in this example (which is the case in most applications), this synchronous escape output is the square of the voltage. Since it is proportional, it is not a huge amount and can be kept within the rating including the overload of the inverter device3.
If the inverter device's rating is exceeded due to this operation, the HM group 7 is divided, and each divided group is sequentially turned on, accelerated, and synchronized to keep the inverter output current within the inverter's rating. be able to. At this time, the last group to be introduced has a long natural speed time, so
Although the slip frequency fts is large, it is not a problem because the HM's synchronization escape characteristic is slightly dependent on slip.

1st I! ! ! In IK, the output voltage of the inverter device was controlled by controlling the firing phase of the thyristor of the rectifier 2, but this can be similarly performed by voltage control using a chopper or inverter circuit soPWM control.

Furthermore, the present invention can be implemented in the same manner as in the present invention by providing a tapped transformer at the output of the inverter circuit 5 and switching the tap without changing Vr. Among these methods, especially the method using a tapped transformer, since the output KVA of the inverter device is constant even by voltage control, the inverter output current rating is equivalently increased, and it can be said to be optimal for carrying out the present invention.

FIG. 3K shows another embodiment of the invention. The same equipment as in FIG. 1 is given the same symbol and the description thereof will be omitted. In FIG. 3, the reference voltage setter 12 has three settings: a rated voltage setting, a desired change voltage setting, and a degaussing voltage setting. The operation shown in FIG. 3 will be explained below using FIG. 4. In the same figure, for the same amount of electricity and state as in Figure 2,
The same symbols will be used and the explanation will be omitted. In Figure 4 (C)
shows the time change of the inverter output current INv. The operation of this device is different from that shown in FIG. 1, as shown in FIG.

t=o%tl is a state in which the HM group 7 is in the rated operating state and is rotating in synchronization with the power supply frequency fINv. The reference voltage setter is 1=1. Switch the internal setting device with , and change the settings up to the degaussing voltage setting Vr using 12 internal time constants. Considering the overexcitation of the HM group 7, Vr is set to a value such that even in the overexcitation state, the synchronous escape output at that time is smaller than the load loss of the HM group 7. 1=1. DeV
As r decreases, the inverter output VI NV decreases, and the return voltage Vf corresponding to VI NV changes in the same way as Vr changes.

Since the change in Vf is the same as the change in Vr, the explanation will be omitted below.

As Vr decreases, the output VINY of the inverter device decreases, and as a result, as described above, the matching between HM fil 7 and the reactive current compensation capacitor 8 becomes f, so that the inverter output rectification is performed as shown in Ic). IINV increases. IINV becomes constant when Vr reaches a constant value yr, that is, when Vf reaches vf', but at this time, the maximum output of 8M (HM load loss is 1, so i(M starts to step out).
The inverter output current 11FtV is 1 FtV because it loses synchronization at the time of i = + l, and the overexcitation state is canceled when the inverter loses synchronization.
-1. In this state, Kt=t,
1, during this time the HM group 7 continues to speed while producing torque corresponding to the voltage value set at complete Kvr'.

Switch the internal setting of the reference voltage setter 12' at t=tl v
When r', Vr #iV: increases to v; with an internal time constant. Following this voltage increase, the output current lll1rv of the inverter device increases, and becomes a constant value tl.

Naturally, Vr' is selected so that the output of HM at this time is greater than the load loss of f(M), so the 8M group 7 is gradually accelerated and sequentially becomes synchronized. Therefore, the output of the inverter device 'The current starts to gradually decrease from +4, and at t
At the time l, it becomes an approximately constant value. This is 8M group 7 from +4
It is shown that each HM constituting the HM has started to synchronize, and almost all of them have entered synchronization at tj.

In this way, in this embodiment, if the capacity of the inverter device is sufficient, in order to disconnect the 8M group 7 which is the load, after demagnetizing the 8M group 7 by simply controlling the output voltage of the inverter device, Since the voltage can be set to a desired voltage, it is possible to perform control with nine voltage changes that are harmless to the user and have the same characteristics for each HM in the 8M group 7. Note that, in place of the output voltage control of the inverter device in this method, a tap voltage regulator or an induced voltage regulator may be used to perform the same implementation.

FIG. 5 shows another embodiment of the present invention, and the same reference numerals as in FIG. 1 are the same as 4, so a description thereof will be omitted. In the same figure, the HM group is divided into two parts 7(1) and 7(2), and the connections with the inverter device are 9(1) and 9+2 from the electromagnetic contactors 6+1> and 6(2)K, respectively. >, reactive current compensation AC capacitor 8 (1), 8
(2) connection is controlled. In this way, dividing the HM groups is often used because the HM groups are divided into groups and each group is sequentially accelerated to reduce the papermaking starting capacity.

The operation of FIG. 5 will be explained below. First, 8M group 7(1) is disconnected and in a natural speed state. For 8M group 7(2),
The voltage is transformed by the same control as in the apparatus of FIG. At this time, since the number of HMs in the load of the inverter device is small, even the increase in the output current between tt and tt corresponding to Fig. 4 does not exceed the capacity of the inverter device.
(2) is a characteristic determined by the change in voltage. Next, 8M group 7 (1), which is at natural speed, is introduced when the slip reaches the appropriate force value. Then, for 8M group 7(1),
8M group 7 (2
), the HMI% property is determined by the changing voltage. Therefore 8
The M groups 7 (1) and 7 (2) have HM characteristics determined by the cointegration change voltage. In this way, according to the present device, both of the above-mentioned problems (1) and (2) can be solved.
It is possible to control voltage changes. In the above description, an inverter device is used as a power source, but it is clear that a rotary generator can be used in the same manner.

+ Comprehensive Effects As described above, according to the present invention, when changing the voltage,
Each H is used to demagnetize the residual magnetic flux of the rotor under load.
It is possible to provide an effective voltage control method for a hysteresis motor that can perform voltage changes with the same characteristics of M, and also eliminate or reduce over-excitation and power supply overload.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
FIG. 3 is a configuration diagram showing another embodiment of the present invention; FIG. 4 is a state transition diagram explaining the operation of FIG. 3; FIG. 5 is another example of the present invention. FIG. l... AC power supply 2... Rectifier 3...
...DC reactor 4...Capacitor 5-...
・Inverter circuit 6, 6(1), 6f2), 9, 9(1), 9
(2)...Magnetic contactor 7...HM group 12.12...Reference voltage setting device (7317) Agent Patent attorney Noriyuki Chika (
(and 1 other person) Procedural amendment to Figure 1, Figure 2, Figure 3, Figure 5, Figure 2 (voluntary) 1948 Bi-Monday 5 3.29 Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office 1, Patent Application No. 1983-67183 2. Name of the invention Voltage control method for hysteresis motor 3. Relationship with the case of the person making the amendment Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. 4. Agent Address: 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100 Tokyo Shibaura Denki Co., Ltd., Tokyo Office 6, Contents of the Amendment (1) On page 7, line 8 of the specification, the phrase "with the same electrical characteristics" is corrected to "with the same electrical characteristics." (2) Delete "Explain using Figure 2" on page 8, line 16 of the specification. 0) “Short-time control (a)” on page 9, line 11 of the specification
"I! time, after the control time constant, Vf = Vr &b.", r Vr'<v
; then vQ = v;. (Close) +d+ (5)Amend Figures 2 and 4 of the attached drawings as shown in the attached sheet. el Figure 2 OHt3

Claims (4)

[Claims] (1) A hysteresis motor drive device comprising a hysteresis motor and a power supply device for driving the hysteresis motor, which includes a process of demagnetizing or demagnetizing the residual magnetic flux of the rotor of the hysteresis motor, and changing the voltage of the hysteresis motor. Voltage control method for electric motor. (2) In the process of demagnetizing or demagnetizing the residual magnetic flux, the power supply to the hysteresis motor is interrupted, the power is decelerated by natural flow, and then the residual magnetic flux of the rotor is turned on again with the changed voltage. A voltage control method for a hysteresis motor as claimed in claim 1, characterized in that the voltage is demagnetized by AC demagnetization. (3) The process of demagnetizing or demagnetizing the rotor residual magnetic flux reduces the power supply voltage to I! 2. A voltage control method for a hysteresis motor according to claim 1, wherein the hysteresis motor is stepped out and residual magnetic flux of the rotor is demagnetized by this adjustment. (4) When the process of demagnetizing or demagnetizing the rotor A residual magnetic flux divides the hysteresis motor group into two or more groups, the power supply to the hysteresis motor in one group is interrupted for one group, and the speed is naturally decelerated. After that, the voltage is turned on again with the changed voltage to demagnetize the residual magnetic flux of the rotor, and in the other group, the power supply voltage is reduced to cause the hysteresis motor to step out, and this step out demagnetizes the residual magnetic flux of the rotor, resulting in hysteresis. A voltage control method for a hysteresis motor according to claim 1, characterized in that the voltage of the motor is changed.