JPH0517151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for an AC elevator controlled by an inverter.

[Prior art]

Conventionally, in an AC elevator driven by a three-phase induction motor, power running torque is generated by controlling the primary voltage of the induction motor during acceleration, and DC braking torque is generated by controlling the DC current supplied to the primary winding of the induction motor during deceleration. Each adopted a speed feedback control method.

This method has the problem that the induction motor is controlled within a range of large slip during both acceleration and deceleration, resulting in large rotor loss and high power consumption.

As a means to solve this problem, if the speed of the elevator is controlled by changing the frequency of the voltage applied to the induction motor, the induction motor can be controlled within a range with small slippage and efficient operation can be achieved.

However, with this method, if electrical noise enters the inverter control device due to the influence of other equipment or for some other reason while the elevator is stopped, and the inverter operates, the induction motor for driving the elevator is in a locked state, so the inverter It was found that an excessive current flows through the inverter, destroying the transistors and gate turn-off thyristors that make up the inverter, and significantly impairing reliability.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a highly reliable control device for an AC elevator.

[Summary of the invention]

The feature of the present invention is that a device is provided to forcibly stop the inverter, the inverter is forcibly stopped by this device, and when the inverter is started, the forced stop of the inverter is canceled by the elevator operation start signal. However, the above problem can be solved by releasing the mechanical brake and starting the elevator, and when the elevator stops, applying the mechanical brake with the elevator stop command signal and forcibly stopping the inverter while the power is on. The goal is to eliminate the

〔Example〕

As is well known, the inverter needs to perform V/constant control so that the voltage V applied to the induction motor and the frequency have the relationship shown in FIG.

Therefore, in order to make the output voltage of the inverter proportional to its frequency and have the relationship shown in Figure 1, since the period is long in the low frequency region, half a cycle is required as shown in Figure 2. By increasing the number of pulses N _between
is the time between half cycles, and T _P is the pulse width). On the other hand, in the high frequency region, the period is short, so the number of pulses N is reduced as shown in Figure 3, and the pulse conductivity T _P /
Control T to be large. This is called pulse width modulation control (PWM control), and if the voltage applied to the induction motor is controlled using this method, the torque characteristics will be as shown in Figure 4.

The present invention uses this characteristic to control the speed of the elevator, and one embodiment of the present invention will be described in detail below with reference to FIG. 5.

In FIG. 5, a converter 2 converts a three-phase AC voltage into a DC voltage, which is supplied as a DC power source to an inverter 3.

_The converter 2 and the inverter 3 are well-known circuits as shown in _FIG . It is smoothed by capacitor C and becomes the DC voltage of inverter 3.

This voltage is converted into three-phase alternating current by an inverter 3 made up of transistors T _r1 to _{T r6} , and as shown in FIG. 1, the torque of the induction motor is controlled by controlling the frequency while keeping the ratio of voltage to frequency constant.

Note that the diodes D ₁ to _{D 6} of the inverter 3 are freewheeling diodes that charge the induced voltage of the induction motor to the capacitor C during regeneration, and the transistors T _r7 to _{T r12} of the converter 2 are used when the voltage of the capacitor C is higher than that of the AC power supply 1. When the voltage becomes high, the conduction of the transistors T _r7 to _{T r12} is controlled in accordance with the phase of the AC power source 1, and the regenerative power of the motor 5 is returned to the AC power source 1.

In FIG. 5, when the elevator is stopped, a signal is given from the sequence controller 22 to forcibly stop the converter 2 and inverter 3, and the inverter and converter are stopped.

Specifically, in FIG. 6, a contact _S1 of a relay (not shown) driven by the output of the sequence controller 22 is closed, and transistors T _r4 , _{T r5 ,} T _{r6 ,} T _r10 , T _r11 ,
The base and emitter of T _r12 are short-circuited to prevent the outputs of the pulse amplification circuit 16 that controls the inverter 3 and the pulse amplification circuit 20 that controls the converter 2 from being applied to the inverter 3 and converter 2.

When an elevator operation start signal is generated from the elevator sequence controller 22, contact _S1 in FIG. 6 is opened and the converter 2 and inverter 3 are activated.
is brought into a state where conduction control is possible, the electromagnetic brake 5 is released, and the speed command device 13 generates a speed command that increases as time increases.

The comparator 14 detects the difference between this speed command signal and the speed signal from the speed detection generator 12 connected to the three-phase induction motor 4 for driving the elevator, and uses this to generate a pulse for generating the PWM control pulse. input into the device 15;

This pulse generator 15 adjusts the number of pulses and the conduction rate to the speed command and the speed in order to control the transistor shown in FIG. 6 so that the ratio of the voltage and frequency applied to the induction motor 4 is constant. It is configured to output a pulse according to the difference between the signal and the signal.

The number of pulses is increased in the low frequency region to suppress low-order harmonics, suppress current ripple, and improve the drive characteristics of the motor.
On the other hand, in a high frequency region, the number of pulses is set to be small due to the limit of switching time of the main circuit transistor.

The output of this pulse generator 15 is amplified to a predetermined value by a pulse amplification circuit 16, which is applied to the base of the transistor of the inverter 3, and the frequency is gradually increased according to the speed control deviation to increase the power running torque of the motor 4. The elevator car 9 and counterweight 10 are accelerated and controlled via the reducer 6, sheep 7, and rope 8.

With this method, the elevator accelerates,
When the vehicle travels a predetermined distance and reaches a certain position before the landing point, the position from this position to the landing point is detected by a position detector 11 mounted on the car, and this is input to the speed command device 13.

The speed command device 13 generates a speed command that decreases according to the deceleration position of the elevator, and according to the difference between this and the speed signal, the pulse generator 15 controls the speed control deviation while keeping the voltage/frequency constant. The frequency is gradually decreased according to the induction motor 4.
The regenerative starting torque of the elevator is controlled to perform elevator deceleration control.

In order to return the regenerated power during deceleration to the power source, the DC voltage of the inverter 3 (the voltage of the capacitor C in FIG. 6) is detected by the voltage detection device 21, and the difference between this and the output of the reference value generator 17 is compared. The output of the voltage detection device 21 is detected by the reference value generator 1
7, the pulse generator 19 generates a pulse for PWM controlling the transistors T _r7 to _{T r12} of the converter 2 in accordance with the difference. Then, this is amplified to a predetermined value by the pulse amplifying device 20, and the transistor is controlled to be conductive, so that the regenerative power of the induction motor 5 is returned to the AC power source 1.

By the above method, when the elevator decelerates and reaches the landing point, this information (information on the position of the elevator car 9 and the speed of the elevator, etc.) is inputted to the sequence controller 22 and outputted from the sequence controller 22. The stop signal activates the electromagnetic brake 5, closes the contact _S1 in FIG. 6, and forcibly stops the converter 2 and inverter 3, thereby stopping and holding the elevator.

According to the embodiment of FIG. 5 of the present invention, an inverter and a converter (hereinafter abbreviated as an inverter device)
A forced stop device is provided that forcibly stops the inverter device by shorting the base and emitter of the transistor, and when the elevator is started, the electromagnetic brake is applied after the forced stop of the inverter device is released by the elevator operation start signal. is released to start the elevator, and when the elevator stops, the inverter device is forcibly stopped after applying the electromagnetic brake, so when the electric motor is locked, such as when the elevator is stopped, the inverter control device Even if electrical noise mixes into the inverter, malfunctions of the inverter device can be prevented, and the reliability of the device is significantly improved.

In addition, at startup, the electromagnetic brake is released after the forced stop of the inverter device is released, so no-load descent,
Since the car acceleration is reversed during operation, such as when the full load is increased, and the electromagnetic brake is applied when stopping, the inverter device is forcibly stopped later, which has the effect of reducing stopping shock and improving riding comfort.

In the embodiment of FIG. 6, the transistors T _r4 , T _r5 , T _r6 , T _r10 , T _r11 , T _r12 connected to the negative side
Although the base and emitter of the transistor were short-circuited to forcibly disable conduction, this may be done for all transistors. In this case, the method of disabling the transistor is not limited to the above method,
Any method may be used as long as the same effect can be obtained.

In addition, although we have described an example in which the regenerated power in the above embodiment is returned to the AC power source using a regenerative converter, this can also be done by connecting a resistor and a chopper device in parallel with the capacitor and causing the regenerated power to be consumed by the resistor. good. In this case, the chopper device may be forced to be inactive when the elevator is stopped.

Note that although the inverter has been described using a voltage type as an example, it may also be a current type, and furthermore, although a transistor is used as the semiconductor control element, it may also be a thyristor, a gate turn-off thyristor, or another device having the same function. .

Further, although the main power source of the elevator is a three-phase AC power source, it may be a DC power source using an engine generator or a battery.

〔Effect of the invention〕

As described above, according to the present invention, after the forced stop of the inverter is released, the mechanical brake is released and the elevator is started, and when the inverter is stopped, the mechanical brake is applied and then the inverter is forcibly stopped.
It is possible to prevent the inverter device from malfunctioning due to electrical noise, and it is also possible to improve riding comfort during startup and shutdown.

[Brief explanation of the drawing]

Figure 1 is a diagram of the relationship between the inverter's output frequency and output voltage, Figures 2 and 3 are output voltage waveform diagrams of the pulse width modulation type inverter, and Figure 4 shows the inverter control to achieve the characteristics shown in Figure 1. FIG. 5 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 6 is a diagram showing the main circuit configuration of FIG. 5. 1... Three-phase AC power supply, 2... Converter device,
3... Inverter device, 4... Three-phase induction motor,
5... Electromagnetic brake, 9... Car, 15, 19
... PWM pulse generator, 16, 20 ... Pulse amplification device, 22 ... Sequence controller,
T _r1 - _{T r12} ... Transistor, D ₁ - _{D 18} ... Diode, S ₁ ... Inverter and converter stop contact.

Claims (1)

[Scope of Claims] 1. An AC elevator equipped with an induction motor supplied with power by an inverter device and driven by the motor, comprising means for generating an operation start signal for the elevator, and a means for generating a stop command signal for the elevator. an inverter forced stop means for forcibly disabling the control elements constituting the inverter, and a mechanical brake for stopping and holding the elevator car, and forcibly stopping the inverter device when the power is turned on. is released by the elevator's operation start signal, the mechanical brake is released, and the mechanical brake is activated by the elevator's stop signal, and then the operation of the inverter device, which is still powered on, is forcibly stopped. What is claimed is: 1. A control device for an AC elevator, characterized in that it is equipped with means for 2. The control device for an AC elevator according to claim 1, wherein the inverter forced stop means has a function of cutting off a control signal of a control element constituting an inverter.