JPH0747425Y2 - AC elevator control device - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of an AC elevator control device of a slip frequency vector control system.

[0002]

2. Description of the Related Art In recent years, with advances in power electronics and microelectronics, AC motors have come to be used in many fields where DC motors have been used exclusively for control performance.

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

However, the conventional means for controlling 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 or the like. Had a limit.

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

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 for converting three-phase AC into DC, 3 is a capacitor for smoothing the pulsating current rectified by the converter, and 4 is an inverter for converting DC into AC. Reference numeral 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 an elevator hoist, and 8 A main rope for connecting the basket 9 and the counterweight 10, a speed command generator 11 for generating an ideal speed command signal ω _r ^* of the elevator,

Reference numeral 12 is a current detector which detects the output current of the inverter 4 and outputs a current detection signal S12, 13 is a load detector which detects the load in the elevator car 9 and outputs a load signal S13, and 20 is a load detector. This is a well-known microcomputer, and this microcomputer 20 is a speed command signal ω _r.
^* , Interface circuits 21, 22 and 23 for taking in velocity signal ω _r and load signal S13, microprocessor 24, and ROM 25 and RAM for storing data and programs for operating this microprocessor 24
26, and a D / A converter 27 for converting the digital quantity into an analog quantity and outputting the instantaneous current command S20 of the induction motor 5.
It consists of and.

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 a subsequent stage. In the base drive circuit 32, a base signal of a 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 the approximate 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 torque T generated by the induction motor 5 is generated by the electromagnetic force acting between the secondary magnetic flux Φ ₂ and the secondary current I _{2. When the} primary current I _{1 is} passed through the induction motor 5, it is generated. , The secondary magnetic flux (exciting current) component Φ ₂ and the secondary current (torque current) component I _{2 which} are orthogonal to each other as shown in FIG. 3, the generated torque T becomes T = Φ ₂ × I ₂ , and the hatched rectangle Area.

Therefore, in order to perform speed control in which the magnetic flux, which is similar to that of a 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 frequency I It is necessary to control the advancing angle with respect to the secondary magnetic flux Φ ₂ rotating at. This is the principle of vector control.

Therefore, in order to carry out vector control, the following condition should 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 the exciting current I _m and the secondary current I ₂
Is given by the vector sum of. As a result, the basic vector control block configuration is represented 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, M is a mutual inductance of the induction motor 5, L ₂ is a secondary self-inductance of the induction motor 5, R ₂ is a secondary resistance of the induction motor 5, I _m ^* is an exciting current command, I ₂ ^* is a secondary current command, and 50 is a three-phase sinusoidal current command generator. Then, the U-phase primary current command I _U ^* , V-phase primary current command I _V ^* , W-phase primary current command I of the induction motor 5
_It outputs _W ^* respectively.

[0015]

A pulse encoder is generally used to detect the speed of a hoisting electric motor, but particularly in the case of an AC gearless machine, accurate and quick speed detection is required even at low speeds. Therefore, a high-resolution encoder (which outputs 1000 pulses per rotation) is used, and the signal frequency is increased over the entire speed range via the speed-increasing pulley.

However, since the friction drive mechanism is used, an error of about 0.5% occurs in detecting the rotational position of the rotor. This rotational position detection error is of a level that causes almost no problem in speed control, but when vector control is performed based on rotor position information, the aforementioned angle θ cannot be controlled well, It was found that the separation control of the excitation component and the torque component could not be performed well, and as a result the vibration of the torque and the magnetic flux resulted in significant deterioration of the control function, such as deterioration of riding comfort and occurrence of overcurrent, especially in the middle and high speed regions. In the low speed region, there is no problematic effect.

On the other hand, when the pulse encoder is directly connected to the main shaft of the AC gearless hoisting machine, there is no error in detecting the rotational position of the rotor, and there is no problem peculiar to vector control. In order to ensure speed detection accuracy in control, that is, in the low speed region, a very expensive high resolution encoder is required. In that case, high accuracy mounting is also required, and it is not applicable to AC gearless machines. It will be difficult. That is, each of the friction drive encoder and the direct coupling encoder has merits and demerits, and it was not possible to perform good control in all speed regions by using the sliding frequency vector control type AC elevator as a speed detection device alone.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a control device for an AC elevator having good control performance in both low speed and medium and high speed ranges.

[0019]

According to the present invention, a torque current component and an exciting current component of a primary current supplied to an AC motor are based on a comparison signal between an elevator speed command signal and an elevator hoisting speed signal. And a hoisting machine in a slip frequency vector control elevator for independently controlling the magnitude and phase of the primary current and for frictionally driving the hoisting machine to generate a first speed signal. And a second speed detecting device that is directly connected to the hoist and outputs a second speed signal. When the hoist is low, the first speed signal is output. A switching device for switching and selecting is provided.

[0020]

With the above-mentioned structure, the slip frequency control is smoothly performed regardless of the speed of the hoisting machine.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partial block diagram of a control device showing an embodiment of the present invention. 2 and FIG. 5 are the same, but PE1 is a pulse encoder directly connected to the shaft of the sheave 7 or the main shaft of an AC gearless hoist, and PE2 is an AC gearless hoist. A friction drive pulse encoder frictionally driven via a speed increasing pulley 40 attached to the main shaft of the machine or the shaft of the sheave 7.

Reference numeral 41 is _a microcomputer 20 based on the pulse signal PE1 _a obtained from the pulse encoder PE1.
Is a speed calculation means for calculating the speed of the elevator car 9 by 42, 42 is a speed calculation means for calculating the speed of the elevator car 9 by the microcomputer 20 based on the pulse signal PE2 _a obtained from the pulse encoder PE2, and 43 is the speed of the elevator car 9 A switching device in which the terminal b and the terminal c are connected at low speed and the terminal a and the terminal c are connected at medium and high speed, and the speed signal guided to the terminal c is transmitted to a known speed control unit and vector control unit.

In the first place, since the influence of the position detection error increases in proportion to the rotation speed of the AC gearless hoisting machine, the friction drive encoder PE has a high resolution but contains an error at low speed.
2 is used, while the system is configured to use the axis direct coupling type encoder PE1 which does not include a position detection error at medium and high speeds.

A simple encoder such as a slit plate and a pulse sensor can be used as the direct encoder PE1. Even with an encoder having a relatively low position resolution, the pulse signal frequency becomes sufficiently high at medium and high speeds. The speed can be detected quickly.

The influence of the switching of the encoder used by the switching device 43 on the riding comfort of the elevator does not cause a problem because the deviation between the two signals at the time of switching is sufficiently small.

[0026]

As described above, according to the present invention, the friction drive encoder including the error is used only at the low speed where the influence of the position detection error hardly appears, and the error is generated at the middle and high speeds when the position detection error has the influence. Since a direct-coupled encoder that does not have a pin is used, good vector control can be performed in all speed regions, and good control performance can always be maintained. Further, the work of calibrating the encoder pulse number, which had been performed at the time of factory shipment and at the time of adjusting the field operation, becomes unnecessary, and the effect of reducing man-hours is exerted.

[0027]

[Brief description of drawings]

FIG. 1 is a partial configuration diagram of a control device showing an embodiment of 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] Secondary magnetic flux Φ ₂ and secondary current I due to 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.

[Explanation of symbols]

11 Speed command generator ω _r ^* Speed command signal 5 Induction motor 6 Speed detector ω _r Speed signal I ₁ Primary current I ₂ Secondary current Φ ₂ Secondary magnetic flux I _m Excitation current θ Phase angle PE1 Axis direct connection pulse encoder PE1 _a First speed signal PE2 Friction drive encoder PE2 _a Second speed signal 43 Switching device

Claims (1)

[Scope of utility model registration request] 1. A torque current component and an excitation current component of a primary current supplied to an AC motor are independently commanded on the basis of a comparison signal between an elevator speed command signal and a speed signal of an elevator hoisting machine. In a slip frequency vector control elevator for controlling the magnitude and phase of the next current, a first speed detection device that frictionally drives the elevator hoist to generate a first speed signal and a direct drive for the elevator hoist And a second speed detecting device that emits a second speed signal, and selects the first speed signal as the speed signal when the elevator hoisting machine is in a low speed,
A control device for an AC elevator, comprising a switching device for switching and selecting the second speed signal as the speed signal at medium and high speeds.