JPS647948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for a high-speed elevator using a three-phase induction motor as a drive motor whose speed is controlled by a variable frequency power source.

Conventionally, DC motors have been mainly used as elevator drive motors from the viewpoint of easy speed control.

However, DC motors, in principle, require a commutator and brushes, so they are difficult to maintain and have the disadvantage of being high in cost.

Therefore, an AC motor, such as an induction motor, is used as the drive motor for the elevator, and control during deceleration is performed by DC braking.
DB control elevators have come into use, but this method is difficult to apply to high-speed elevators because its synchronous speed is limited by the characteristics required for acceleration and deceleration of the drive motor. There were flaws.

Therefore, in order to obtain a high-speed elevator using an induction motor as a driving motor, a method has been proposed in which a variable frequency power source such as an inverter or a cycloconverter is used, and an example thereof is shown in FIG.

In the figure, 1 is a commercial power supply, 2 is an inverter,
A variable frequency power supply device such as a cycloconverter (hereinafter referred to as a power supply device), 3 is a gate signal that controls the thyristor of the power supply device 2, 4 is a three-phase induction motor for driving an elevator (hereinafter referred to as IM), 5 is a
A traction sheave (hereinafter simply referred to as sheave) that is directly connected to IM4 or driven via a reduction gear, 6 is the main rope of the elevator, 7 is the elevator car, 8 is a counterweight, 9 is the shaft of IM4,
Alternatively, a generator (referred to as PG) for detecting rotational speed attached to the shaft of the sheave 5, 10 is a speed signal, 1
1 is a phase control device (PH
), 12 is a speed command generator, and 13 is a speed command signal.

The power supply device 2 is controlled by the gate signal 3 from the PH 11, and functions to frequency convert the power from the commercial power supply 1 and supply it to the IM 4.

A speed command generation device 12 generates a speed command signal 13 that is a desired speed value for the car 7 in response to an elevator call or the like.

Therefore, the PH11 compares the speed command signal 13 and the speed signal 10 representing the actual speed of the car 7, generates a gate signal 3 according to the difference between them, changes the output frequency of the power supply device 2, and changes the output frequency of the power supply device 2. Control is performed so that the speed of the car 7 matches the target value given by the speed command signal 13 by changing the rotational speed of the car.

According to the system shown in FIG. 1, it is possible to drive the elevator at a fairly high speed using an AC motor such as a three-phase induction motor.

By the way, in this method, it is necessary to control the output frequency of the power supply device 2 to an extremely low frequency range at the start of acceleration of the elevator or at the end of deceleration. However, devices such as the inverter or cycloconverter that make up the power supply 2 have the disadvantage that their operation becomes extremely unstable at low frequencies, and commutation failures are likely to occur, making detailed control difficult. Ta.

In addition, equipment such as elevators must be operated at a considerably low speed during test runs after installation work is completed, or during maintenance and inspection. Therefore, it was difficult to operate the system directly all the time, and a back-up power supply was required for this purpose.

Furthermore, in principle, when power supplies such as inverters or cycloconverters are operated at low frequencies, the power supply waveform contains many harmonic components, which increases the pulsation in the motor torque and increases power supply noise. There were disadvantages such as a decrease in the rate of use.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, even when an induction motor driven by a variable frequency power supply is used as an elevator drive motor, even when the elevator starts accelerating or at the end of deceleration. To provide an elevator speed control device which enables stable control with less pulsation and allows direct and easy operation at low speeds.

In order to achieve this object, the present invention uses a two-winding pole-converting induction motor as a drive motor, and applies a variable frequency voltage to the winding with the smaller number of poles of the motor, and applies a variable frequency voltage to the winding of the motor with the smaller number of poles. It is characterized in that the speed is controlled by supplying a variable voltage to each of the windings.

Embodiments of an elevator speed control device according to the present invention will be described below with reference to the drawings.

Fig. 2 shows an embodiment of the present invention, including a commercial power supply 1, a power supply device 2, a gate signal 3, a sheave 5, a main rope 6, a car 7, a counterweight 8, a PG 9, a speed signal 10, a PH 11, and a speed command generation. The device 12, speed command signal 13, etc. are the same as in the conventional example shown in FIG.
Furthermore, in the figure, 20 is a two-winding pole-converting induction motor (called IM), 21 is the winding with fewer poles (called high-speed winding), and 22 is the winding with more poles (low-speed winding). 23 is a variable voltage power supply (referred to as a low-speed power supply), 24 is a gate signal, 2
5 is a phase control device (referred to as PH), 26 is a comparison switch (referred to as COM), and 27 and 28 are speed signals.

The two-winding pole-converting type IM20 has a high-speed winding 21 and a low-speed winding 22 independently, and when driven by the high-speed winding 21, it has, for example, a four-pole armature structure and has a relatively high synchronous speed. When operated at low speed and driven by the slow winding 22, the armature structure is, for example, 16 poles, and is adapted to operate at a fairly low synchronous speed.

The low-speed power supply 23 is composed of a thyristor or the like, and functions to output the AC power from the commercial power supply 1 as three-phase AC or DC at an arbitrary voltage through phase control or the like.

The PH 25 functions to compare the speed command signal 13 and the speed signal 28 and generate a gate signal 24 according to the difference between them.

The COM26 inputs the speed signal 10 from the PG9 and compares it with a predetermined reference value, and when the speed signal 10 is less than the reference value, it puts the PH25 into the operating state, outputs this speed signal 10 as the speed signal 28 to the PH25, and then outputs it as the speed signal 28. When is above the standard value, the PH
11 into the operating state and outputs a speed signal 27 to the PH11.

Next, FIG. 3 shows an embodiment of a power supply device 2 (hereinafter referred to as a high-speed power supply) and a low-speed power supply 23.

The high-speed power supply 2 has thyristors TH ₁ ~ TH ₆ , TH ₁₁ ~
It consists of an inverter consisting of a TH ₁₆ and a Chiyoke coil CH, and the three-phase AC supplied from the commercial power supply 1 is rectified by the thyristors TH ₁ to _{TH 6} , smoothed by the Chiyoke coil CH to become DC, and the thyristor
At TH ₁₁ to _{TH 16} , it is converted to three-phase AC with a frequency different from that of the commercial power supply 1, and the terminals U ₁ , V ₁ , W of the high-speed winding (21 in Fig. 2) of the two-winding pole number conversion type IM20 are converted. Supply to ₁ . At this time, the DC voltage is controlled by phase control using the gate signal supplied to the thyristors TH ₁ to _{TH 6} , and the thyristors TH ₁₁ to _{TH 16}
The output frequency is controlled by a gate signal supplied to.

The low-speed power supply 23 consists of thyristors TH ₂₁ to _{TH 24} and a switching relay that switches between acceleration control and deceleration control. Only contacts L ₁ to _{L 5} of this switching relay are shown, and among these, contacts L ₁ and L ₂ and _L5 are normally open contacts, and contacts _L3 and _L4 are normally closed contacts. and,
This switching relay turns ON during acceleration control and turns OFF during deceleration control. Therefore, since only contacts L ₁ , L ₂ , and L ₅ are closed during acceleration control, terminals U ₂ , V ₂ , and W ₂ of the low-speed winding (22 in Figure 2) of the IM are connected to three-phase AC from the commercial power supply 1. is supplied, and its voltage is controlled by the gate signal 24 supplied to the thyristors TH ₂₁ to _{TH 24} .

In addition, since only contacts L ₃ and L ₄ are closed during speed control, direct current from the commercial power supply 1 rectified by the thyristors TH ₂₁ to TH ₂₄ is supplied between the terminals U ₂ and V ₂ of the low-speed winding 22 of the IM 20. DC braking is performed, and the strength of the DC braking is controlled by the gate signal 24 supplied to the thyristors TH ₂₁ to _{TH 24} .

Next, FIG. 4 shows the operating characteristic curve of the elevator in the embodiment of the present invention, and the time t
represents the speed v of the car with respect to the curve S ₁ ,
S ₂ and S ₃ represent the respective characteristics when the mileage is different. Further, the speed v _T represents the speed when the aforementioned speed signal 10 (FIG. 2) becomes a predetermined reference value, and the speed v _R represents the rated speed of this elevator. In the figure, the hatched area indicates the area where voltage is applied to the low-speed winding 22 and control is performed, and the other areas are areas where voltage is applied to the high-speed winding 21 and control is performed. It shows the area where the winding is being carried out, and the double hatched area is the low speed winding 2.
Although it is a control area according to No. 2, it shows that it is an area where DB control (deceleration control using DC braking) for deceleration is performed.

Next, the operation will be explained with reference to FIGS. 2 to 4.

When an elevator call is registered and a start command is issued, a speed command generator 12 generates a speed command signal 13.

At this time, COM26 receives the speed signal 1 from PG9.
Since 0 is 0 and the reference value corresponding to the speed v _T has not been reached, the PH 25 is brought into operation and the speed signal 10 is supplied thereto as the low speed speed signal 28 .

Therefore, the PH25 outputs a gate signal 24 in response to the speed command signal 13 and the speed signal 28, controls each thyristor of the low voltage power supply 23, and supplies three-phase AC at the frequency of commercial AC to the low voltage winding 22 of the IM20. It operates in a voltage control mode in which the voltage is supplied and the voltage is controlled to perform speed control, and the elevator car 7 is gradually accelerated in accordance with the speed command signal 13.

When the speed of the car 7 eventually reaches a predetermined speed v _T , the COM 26 stops the operation of the PH 26, and
The PH 11 is brought into operation and the speed signal 10 is switched to be supplied to the PH 11 as a high speed signal 27. As a result, the low speed winding 2 of IM20
2 is open, and on the other hand, three-phase alternating current is applied to the high-speed winding 21 from the high-speed power supply 2.

Therefore, from this point on, PH11 starts operating, supplies gate signal 3 corresponding to speed command signal 13 and speed signal 27 (same as 10) to high-speed power supply 2, controls its frequency, and thereby controls IM20. The car 7 starts operating in a frequency control mode, and increases the frequency of the three-phase alternating current supplied to the high-speed winding 21 in response to the speed command signal 13, increasing the speed of the car 7. When the position (floor of the building) at which the elevator car 7 should be stopped is detected, the speed command generator 12 stops increasing the speed command signal 13, and after keeping the voltage value constant for a certain period of time, , a decreasing voltage is generated as the speed command signal 13.

In general, such an elevator speed command signal increases according to a fixed time function during acceleration, but when decelerating it increases according to a predetermined value corresponding to the distance between the current position of the car 7 and the stopped floor. It is configured to take a form that decreases according to a distance function such that deceleration is obtained.

Therefore, the PH11 decreases the output frequency of the high-speed power supply 2 in accordance with the speed command signal 13 whose voltage value decreases, and the IM20 decreases the output frequency of the high-speed winding 23.
As the frequency of the three-phase alternating current supplied to the elevator decreases, a deceleration torque is generated and the speed of the elevator decreases.

Eventually, the speed of the elevator reaches a predetermined value v _T (Figure 4)
and when it is detected by COM26
The operation by the PH11 is stopped and the mode is switched to the voltage control mode in which the PH25 is operated again. Further, at this time, since the vehicle is in a deceleration state, the switching relay of the low-speed power supply 23 is switched to DB control.

Therefore, at this time, DC of a predetermined voltage is supplied between the two phases of the low-speed winding 22 of the IM 20 in accordance with the decreasing speed command signal 13 and the low-speed speed signal 28, and the operation is started in the DB control mode. Elevator deceleration control is performed.

Then, when car 7 arrives at its destination floor,
The speed command signal 13 becomes zero and the mechanical brake is activated to stop the elevator.

Therefore, according to this embodiment, when the speed of the elevator car is lower than the location value v _T , the drive motor operates with a relatively large number of poles due to the low speed winding, that is, the synchronous speed is sufficiently low. Because I will,
Voltage control allows for sufficiently stable and smooth speed control even at fairly low speeds.On the other hand, when the elevator speed exceeds a predetermined value _v Since the high-speed power supply operates at a sufficiently high synchronous speed, the high-speed power supply does not need to operate at a very low frequency, so it can operate sufficiently stably, and the elevator can be operated at a high speed.

Note that in the above embodiments, the variable frequency power supply device serving as a high-speed power supply is configured with an inverter, but it may also be configured with a cycloconverter, and almost the same effect can be expected with this.

Furthermore, in the above embodiment, as is clear from FIG. 4, switching from voltage control mode to frequency control mode or switching from frequency control mode to DB control mode is performed simultaneously at a predetermined speed v _T. However, both control modes may be performed with some overlap in the vicinity of the predetermined speed v _T .

According to this, it is possible to reduce the risk of sudden speed changes occurring at the time of switching, and improve the riding comfort of the elevator.

As explained above, according to the present invention, there is no need to operate the variable frequency power supply in a low frequency range, so the operation is stable, the torque pulsation of the motor is reduced, and the range of change in the rotational speed of the drive motor is wide. You can get a high-speed elevator from
Since the synchronous speed is sufficiently low at low speeds, voltage control can easily perform stable and smooth control at extremely low speeds, and large acceleration/deceleration torques can be obtained, eliminating the drawbacks of conventional technology. However, an elevator speed control device with high performance can be provided at relatively low cost.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional example of an elevator speed control device using a variable frequency power supply, Fig. 2 is a block diagram showing an embodiment of an elevator speed control device according to the present invention, and Fig. 3 is a block diagram showing an example of an elevator speed control device according to the present invention. FIG. 4 is a circuit diagram showing an embodiment of a variable frequency power supply and a variable voltage power supply in FIG. 4, and FIG. 4 is a curve diagram for explaining the operation of the embodiment of the present invention shown in FIG. 2... Variable frequency power supply device (high speed power supply), 11,
25... Phase controller, 20... 2-winding pole number conversion type induction motor, 21... High speed winding, 22... Low speed winding, 23... Variable voltage power supply device (low speed power supply), 2
6... Comparison switch.

Claims (1)

[Claims] 1. In an elevator that is equipped with a variable frequency power source and that controls speed by changing the frequency of the voltage to be supplied to the drive motor, the first number of turns that provides a relatively high synchronous speed and the A two-winding pole-converting drive motor is provided with a second winding that provides a low synchronous speed, and a variable voltage power supply. A variable frequency voltage is supplied to the winding to perform speed control, and when the speed of the elevator is below a predetermined value, a variable voltage is supplied to the second winding of the drive motor to perform speed control. An elevator speed control device characterized by: 2. In claim 1, means is provided for supplying a DC voltage to a second winding of the drive motor, and deceleration control is performed by DC braking in a region where the speed of the elevator is below a predetermined value. An elevator speed control device characterized by comprising: 3. In claim 1, means is provided for simultaneously supplying the variable frequency voltage and the variable voltage to the first and second windings of the drive motor, and the speed of the elevator is close to the predetermined value. 1. A speed control device for an elevator, characterized in that speed control is performed redundantly by a plurality of control means.