JPH0519268U - AC elevator controller - Google Patents

Abstract

(57) [Summary] [Purpose] In all speed regions, without cost
To obtain a control device for an AC elevator equipped with a speed detection device that can perform good slip frequency vector control and is maintenance-free. A detector is provided for directly detecting the rotation of an elevator hoisting machine, and a correction means for correcting a speed signal based on a pulse signal obtained from a friction drive encoder by an output signal of the detector is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a slip frequency vector control type AC elevator control device.

[0002]

[Prior Art]

 With the recent advances in power electronics and microelectronics, AC motors have come to be used in many fields where DC motors were used exclusively for control performance.

In the field of elevators, an AC elevator using an induction motor has recently come into practical use instead of a DC elevator using a DC motor having a separately excited field winding.

However, the conventional control means for an AC elevator using an induction motor is a so-called primary voltage control method in which the magnitude of the primary winding voltage of the induction motor is simply controlled by using a thyristor, etc. He had his own limits.

Therefore, various control devices configured to perform variable voltage / variable frequency control have been proposed as a control device for an AC elevator that can improve the control performance and further reduce power consumption and power source equipment capacity. Has been done.

FIG. 2 is a block diagram showing an example of the configuration of a speed control device for an AC elevator that performs variable voltage / variable frequency control using a microcomputer.

In the figure, 1 is a three-phase AC power supply, 2 is a converter that converts three-phase AC into DC, 3 is a capacitor for smoothing the pulsating flow rectified by a converter, and 4 is DC conversion into AC. An inverter, 5 is an induction motor used as a motor for hoisting an elevator, 6 is a speed detection device such as a pulse encoder that detects the speed of the elevator and outputs a speed signal ω _r , 7 is a sheave of the elevator hoist, 8 is a main rope for connecting the car 9 and the counterweight 10, and 11 is a speed command generator for generating an ideal speed command signal ω _r ^* of the elevator,

Reference numeral 12 is a current detector that detects the output current of the inverter 4 and outputs a current detection signal S12. Reference numeral 13 is a load detector that detects the load in the elevator car 9 and outputs a load signal S13. Is a well-known microcomputer. The microcomputer 20 has interface circuits 21, 22 and 23 for receiving the speed command signal ω _r ^* , the speed signal ω _r and the load signal S13, a microprocessor 24, and this microcomputer. It is composed of a ROM 25 and a RAM 26 for storing data and a program for operating the processor 24, and a D / A converter 27 for converting a digital amount into an analog amount and outputting an instantaneous current command S20 of the induction motor 5.

Reference numeral 31 is a PWM circuit for calculating a deviation between the instantaneous current command S20 and the current detection signal S12, and inputting a well-known pulse width modulation signal S31 for making the deviation zero to a base drive circuit 32 in the subsequent stage. In this base drive circuit 32, the base signal of the transistor forming the inverter 4 is generated based on the pulse width modulation signal S31 generated by the PWM circuit 31, and the on-time of the transistor is controlled. As a result, an AC voltage having an arbitrary voltage and frequency of a similar sine wave is applied to the induction motor 5.

Here, the principle of vector control will be briefly described for the following description.

First, the generated torque T of the induction motor 5 is generated by the electromagnetic force acting between the secondary magnetic flux Φ ₂ and the secondary current I ₂ , but when the primary current I _{1 is} passed through the induction motor 5, It is decomposed into a secondary magnetic flux (exciting current) component Φ ₂ and a secondary current (torque current) component I ₂ which are orthogonal to each other as shown in FIG. 3, and the generated torque T becomes T = Φ ₂ × I ₂ , and the shaded portion It is a rectangular area.

Therefore, in order to perform the speed control in which the magnetic flux similar to that of the DC motor is always kept constant, as shown in FIG. 4, the magnitude of the primary current I ₁ and the phase angle θ (primary current I ₁ It is necessary to control the advancing angle with respect to the secondary magnetic flux Φ ₂ rotating at the frequency. This is the principle of vector control.

Therefore, in order to carry out vector control, the following condition may be satisfied, and the secondary magnetic flux Φ ₂ rotates at the primary frequency f ₁ . The primary frequency f ₁ = rotor rotation frequency _fr + slip frequency f _s . The primary current I ₁ rotates at an angle that leads the secondary magnetic flux Φ ₂ by θ. The magnitude of the primary current I ₁ is given by the vector sum of the exciting current I _m and the secondary current I ₂ . Thereby, the basic vector control block configuration is expressed as shown in FIG.

That is, in the figure, the same reference numerals as those in FIG. 2 indicate the same elements, but ASR is a speed controller, ACR is a current controller, T _M ^* is a torque command, and M is a mutual inductance of the induction motor 5. , L ₂ is the secondary self-inductance of the induction motor 5, R ₂ is the secondary resistance of the induction motor 5, I _m ^* is the exciting current command, I ₂ ^* is the secondary current command, and 50 is the three-phase sinusoidal current command. The generator outputs the U-phase primary current command I _U ^* , the V-phase primary current command I _V ^* , and the W-phase primary current command I _W ^* of the induction motor 5, respectively.

[0015]

[Problems to be solved by the device]

By the way, a pulse encoder is generally used to detect the speed of the hoisting motor, but especially in the case of an AC gearless machine, accurate and quick speed detection is required even at low speeds. The encoder PE1 with high resolution (which outputs 1000 pulses per rotation) is used, and the signal frequency of the pulse signal PE1 _a is further increased through the speed-increasing pulley 40 over the entire speed range. In the speed calculation portion, the speed signal ω _r is calculated by the pulse setting device 61 and the speed calculator 62 for each rotation of the induction motor 5. That is, it becomes a mechanism for obtaining the ratio of the count value of the pulse signal PE1 _a between the timing pulses generated in the microcomputer 20 and the setting signal 61a of the pulse setter 61 and calculating it as the speed signal ω _r. There is.

However, since the friction drive mechanism is used for vector control, an error of about 0.5% occurs in the detection of the rotational position of the rotor. When vector control is performed based on the rotor position information, if the error in detection of the rotational position occurs, the above-mentioned angle θ control cannot be performed satisfactorily, so the separation control of the excitation component and the torque component is not performed. It was found that it could not be performed well, and the vibration of torque and magnetic flux resulted in the deterioration of riding comfort and the occurrence of overcurrent, resulting in significant deterioration of the control function. In addition, there is a problem that smooth torque control cannot be performed due to errors that occur due to variations in speedup.

On the other hand, when the pulse encoder is directly connected to the main shaft of the AC gearless hoisting machine, the error in detecting the rotational position of the rotor does not occur and the problem peculiar to vector control does not occur. In order to secure the speed detection accuracy in the speed control of, that is, in the low speed region, a very expensive encoder with high resolution is required. In that case, highly accurate mounting is required, and the AC gearless machine is required. The situation is difficult to apply to. In other words, the friction drive encoder and the direct-coupled encoder each have drawbacks, and some sort of ingenuity was required to use it as a speed detection device for a slip frequency vector control type AC elevator.

The present invention has been made in view of the above points, and an object of the present invention is to provide a control device for an AC elevator equipped with a speed detection device that does not cause inconvenience even with vector control.

[0019]

[Means for Solving the Problems]

 The present invention independently commands the torque current component and the exciting current component of the primary current supplied to the AC motor based on the comparison signal of the speed command signal of the elevator and the speed signal of the elevator hoist, and Slip frequency vector control that controls the magnitude and phase of current In an elevator, a pulse encoder that is friction-driven to the elevator hoist to generate a pulse signal, a detector that directly detects the rotation of the elevator hoist, and a pulse A speed calculation means for calculating a speed signal based on a pulse signal generated by the encoder is provided, and a correction means for correcting the speed signal by the output signal of the detector is provided.

[0020]

[Action]

 With the configuration as described above, the slip frequency control can be performed extremely smoothly.

[0021]

【Example】

FIG. 1 is a diagram showing an example of arrangement of a speed detecting device according to the present invention, and FIG. 7 is a partial configuration diagram of a control device showing an embodiment of the present invention. In the drawings, the same reference numerals as those in FIGS. 2, 5 and 6 indicate the same elements, but PE is a friction frictionally driven via a speed increasing pulley 40 attached to a shaft 7a of a sheave 7 or the like. The drive pulse encoder does not have to have a high resolution like the pulse encoder PE1 described above. Reference numeral 50 denotes a detector that emits a detection signal 50a each time the shaft 7a makes one revolution, and is composed of, for example, a photoelectric device including a light emitting diode and a photodiode, and outputs a signal each time it opposes a light shielding plate 7a ₁ fixed to the shaft 7a. Is to be emitted. Of course, it may be something like a magnetically sensitive device.

Reference numeral 51 is a counter for counting the actual number of pulses per revolution of the induction motor 5 based on the pulse signal PEa emitted by the pulse encoder PE and the detection signal 50a emitted by the detector 50. The correction signal 51a is output to the pulse setter 61 'which sets the number of pulses per rotation of 5 in FIG. Then, the pulse setter 61 ′ inputs the corrected set signal 61 ′ a corresponding to the number of pulses per revolution of the induction motor 5 to the speed calculator 62. This speed calculator 62 calculates the speed of the elevator car 9 based on the pulse signal PEa of the pulse encoder PE and the setting signal 61'a of the pulse setter 61 ', as in the conventional device shown in FIG. Then, the speed signal ω _r is transmitted to the known speed control unit and vector control unit.

Since it has been known that the influence of the position detection error increases in proportion to the rotation speed of the AC gearless hoisting machine, the correction signal 51a of the counter 51 constituting the correction means is changed to the pulse setter at low speed. A switch may be inserted in the output stage of the counter 51 so that it is not input to 61 ′ but is input only at medium and high speeds. The pulse setter 61 'is preset to a number of pulses that does not cause any particular problem during low-speed operation when the elevator is initially installed.

[0024]

[Effect of the device]

 As described above, since the present invention performs correction by the detector, even if a friction drive type pulse encoder that can be configured at low cost is used, the effect of position detection error can be minimized and all speeds can be reduced. Very good vector control can be performed in the region, and good control performance can always be maintained. And this detector can be constructed with a very simple device. In addition, the speed-up ratio correction and encoder pulse calibration that were performed at the time of factory shipment, initial adjustment, and periodic field operation adjustments are no longer necessary, and the effect of reducing man-hours is also demonstrated.

[0025]

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an arrangement of a speed detection device according to the present invention.

FIG. 2 is a block diagram showing a configuration example of a speed control device for an AC elevator that performs variable voltage / variable frequency control using a microcomputer.

FIG. 3 shows the secondary magnetic flux Φ ₂ and the secondary current I due to the primary current I _1.
FIG. 3 is a diagram showing a generation state of ₂ .

FIG. 4 is a principle diagram showing a principle of vector control.

FIG. 5 is a diagram showing a block configuration of vector control.

FIG. 6 is an explanatory diagram illustrating a conventional means for calculating a speed signal ω _r .

FIG. 7 is a partial configuration diagram of a control device showing an embodiment of the present invention.

[Explanation of symbols]

11 speed command generator ω _r ^* speed command signal 5 induction motor 6 speed detection device ω _r speed signal I ₁ primary current I ₂ secondary current Φ ₂ secondary magnetic flux I _m exciting current θ phase angle PE pulse encoder PEa pulse signal 40 Speed-up pulley 41 Counter 50 Detector 50a Detection signal 51 Counter 51a Correction signal 62 Speed calculator 61, 61 'Pulse setter

Claims (2)

[Scope of utility model registration request] 1. A torque current component and an exciting current component of a primary current supplied to an AC motor are independently commanded based on a comparison signal of an elevator speed command signal and an elevator hoisting machine speed signal, and the 1 In a slip frequency vector control elevator that controls the magnitude and phase of the next current, a pulse encoder that is frictionally driven with respect to the elevator hoist to emit a pulse signal, and a detector that directly detects the rotation of the elevator hoist, A control of an AC elevator comprising: a speed calculation means for calculating the speed signal based on the pulse signal generated by the pulse encoder; and a correction means for correcting the speed signal according to an output signal of the detector. apparatus. 2. The control device for an AC elevator according to claim 1, wherein the output stage of the correction means is provided with a switch that opens when the elevator hoisting machine is low speed and closes when the elevator hoisting machine is low speed.