JPS6316690Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an elevator speed control device.

FIG. 1 shows a block diagram of elevator speed control based on speed control of an induction motor. An acceleration command is given when the car 1 starts going up or down, and a deceleration command is given when it approaches a stop floor.The speed pattern generation circuit 2 generates a constant speed pattern that accelerates to a constant speed, then decelerates to a constant speed and then stops. do. a speed detection signal of an induction motor 6 that constitutes a drive device for the car 1 together with a sheave 3, a counterweight 4, and a transmission 5;
That is, the detection signal of the speed detector 7 such as a speed generator is
The two signals are compared as a feedback signal to the speed setting signal which becomes the pattern output of the speed pattern generating circuit 2. The speed control amplifier 8, which receives the difference between the two signals as input, has a proportional-integral characteristic and performs speed calculation with a predetermined gain, and its output is used as a phase control signal for the phase control circuit 9. The output of the phase control circuit 9 is used for thyristor control of a power control unit 10 having a thyristor switch as a main circuit, and when accelerating and driving the electric motor 6, phase control is performed with each phase being balanced.
Dynamic brake control is performed during deceleration and braking.

In such a speed control device, the speed control amplifier 8 generally has a circuit configuration shown in FIG.
The speed setting value Ns of the speed pattern generation circuit 2 and the speed detection value N _F of the speed detector 7 are calculated using resistances Rin and Rf.
Subtract by, feedback resistor R _G and feedback capacitor C
Proportional and integral calculations with first-order delay characteristics are performed by the operational amplifier OA.

In the speed control device having this speed control amplifier 8, the speed followability of the electric motor 6 (car 1) with respect to the speed setting transitioning from full load increase (drive traveling) to deceleration is shown in FIG. 3a, and the control at that time is shown. The change in the output of the amplifier 8 is shown in FIG. As shown in this figure, when the elevator is decelerated by dynamic braking, a follow-up delay occurs at the deceleration start point. This is because when performing elevator deceleration control using dynamic braking, stability cannot be achieved unless the gain of the deceleration control amplifier 8 is significantly lowered compared to that during drive control, and by lowering the gain, the speed set value This is because the tracking ability of the speed detection value Nf with respect to Ns deteriorates.

In addition, the elevator drive mechanism includes many mechanical vibration elements such as springs for balancing the rope and load, and cushion springs for softening the shock when the elevator stops. When improving tracking performance, resonance is likely to occur due to these vibration elements, and for this reason, it is desirable to improve the apparent response of the control system without increasing the gain of the speed control amplifier.

In addition, unlike ordinary machines, elevators place great importance on the sensory element of riding comfort, and it is important not only to have good follow-up performance, but also to provide shock control at inflection points, such as when switching from constant speed to deceleration. Smooth speed changes are required, and for this purpose, it is desired that the speed control amplifier has control characteristics that take into account not only the quick response of the speed control system, but also shocks caused by expansion and contraction of the machine's spring system.

In view of these circumstances, the present invention was devised.The speed control amplifier is divided into a proportional element and an integral element, and the integral element has a circuit configuration in which its integral constant can be adjusted, so that the output of the integral element corresponds to the deceleration torque. To provide an elevator speed control device which improves followability of a deceleration start point by increasing the gain of the entire control system transiently by adjusting the integral constant depending on whether the output is constant or not. With the goal.

FIG. 4 is a main circuit diagram showing an embodiment of the present invention. The speed control amplifier 11 includes a proportional element 11A that amplifies the deviation between the speed setting value Ns and the detected speed value Nf with a predetermined gain, and an integral element that receives the output of the proportional element 11A and whose integral constant can be switched. 11B. Proportional element 11
A is the resistor R ₁ and R ₂ and the feedback resistor R ₃ of the operational amplifier OA ₁
The gain is set according to the ratio. The integral element 11B is connected to the feedback capacitor C of the operational amplifier OA ₂ and the grounding resistor R ₄ .
The integration constant is set by the time constant of the series circuit of R ₅ ,
The integral constant is switched by providing a short-circuiting analog switch AS to the resistor _R3 .

A comparator 12 determines whether the output of the speed control amplifier 11, that is, the output V _OUT of the integral element 11B, which is converted into a phase control signal, has positive polarity (braking output) and is above a certain value. The comparator 12 is provided with a variable resistor VR for the comparison reference setting of the operational amplifier OA ₃ which has a positive feedback resistor R ₆ to provide hysteresis characteristics, and when the output of the integral element 11B exceeds the comparison reference setting value, it becomes high level. Get an inverted output at the logic level from to low level. The hysteresis width and reference voltage of the comparator 12 are set so that once the output is inverted, the inverted state is maintained even though the output of the integral element 11B decreases as long as the subsequent deceleration control continues.

The output of the comparator 12 is logically ANDed with the deceleration command D by an AND gate 13, and only during the period when the deceleration command D is given, the analog switch AS of the integral element 11B can be controlled, that is, the integral constant can be switched.

Waveforms of various parts during elevator braking in such a speed control circuit are shown in FIG. Figure a
At the point td when the speed setting value Ns shown by the solid line enters deceleration from constant speed, the deceleration command D shown in b is applied to AND gate 1.
3 is given logic “1” to open its gate. At this time, since the control system is in constant speed drive, the output V _OUT of the integral element 11B has negative polarity as shown in c in the figure, so the output of the comparator 12 shown in d
V _OUT is at a high level (logic "1"), and at the same time as the deceleration command D is given, the analog switch AS closes as shown in e to reduce the integral time constant of the integral element 11B. Therefore, at the deceleration start time td, the response of the integral element 11B becomes extremely faster than in normal times, and the output V _OUT of the integral element 11B rises quickly to the braking side (positive polarity side). This output
When V _OUT reaches the comparison reference voltage that limits the comparator 12, at this point td ₁ , the comparator 12
The output returns to low level and the analog switch
AS is opened and the integral element 11B returns to its normal integral time constant.

Therefore, during the deceleration period from the start of deceleration to a certain level set in the comparator 12, it is possible to obtain a speed control amount (speed detected value Nf) that relatively well follows the speed set value Ns with good responsiveness of the speed control amplifier 11. Compared to conventional control using constant proportional and integral gains, constant deceleration control can be entered without recovering the follow-up delay at the deceleration starting point midway. In FIGS. 5a, c, and f, two-dot chain lines indicate the detected speed values Nf', V _OUT ', and acceleration changes g' in this embodiment, and broken lines indicate the respective changes in the conventional device.

Note that the shape of the elevator speed pattern is generally constant, and the required torque after entering deceleration control is determined by the inertia (GD ² ) of the mechanical system rather than the magnitude of the load, and is determined by the setting of the comparator 12. Even if the value (VR) is kept constant, almost constant deceleration characteristics can be obtained regardless of load changes. However, even better deceleration characteristics can be obtained by switching the operating point (VR) in multiple stages or continuously in an elevator equipped with a load detection device.

Also, the speed at which the output V _OUT of the integral element 11B changes from driving to braking greatly affects the rise characteristics of acceleration, but the resistance R ₄ should be set to the optimum value according to the mechanical system, or adjusted using a variable resistor. Therefore, the response characteristics during normal control can be easily adjusted to an arbitrary optimum value without changing them.

As described above, according to the present invention, the integral time constant is reduced for a short period of time at the deceleration start point to increase responsiveness, so it is possible to obtain control characteristics with good followability over the entire control range and with good stability. . In addition, since there is little follow-up delay at the deceleration start point, there is no large acceleration change that occurs when trying to forcefully catch up with the speed setting value, and the acceleration change g during deceleration is almost constant, resulting in a control characteristic with good riding comfort. The error in the landing position can be reduced. In addition, due to the vibration elements of the elevator, resonance with the mechanical system is likely to occur depending on the motor torque change rate, and uncompensated control based only on speed settings and feedback values causes the mechanical system to change slowly even though the control output changes slowly. The deceleration tends to be unstable and oscillatory due to the influence of vibration, but in this invention, the response is temporarily accelerated, making it less susceptible to the influence of the mechanical system, and stable deceleration characteristics can be obtained. .

[Brief explanation of drawings]

Fig. 1 is a control block diagram of the elevator, Fig. 2 is a circuit diagram of the conventional speed control amplifier shown in Fig. 1, Fig. 3 is a waveform diagram for explaining the response characteristics of the speed control amplifier to the speed setting value, and Fig. FIG. 4 is a speed control amplifier circuit diagram showing an embodiment of the present invention, and FIG. 5 is a waveform diagram for explaining the operation of FIG. 4. 2... Speed pattern generation circuit, 6... Induction motor, 8, 11... Speed control amplifier, 11A... Proportional element, 11B... Integral element, 12... Comparator, AS... Analog switch.

Claims (1)

[Scope of utility model registration request] In a speed control device that controls the speed of an elevator car by a speed control amplifier whose input is a comparison between a speed setting value of a fixed pattern of acceleration, constant speed, and deceleration and a speed detection value of the elevator, the speed control amplifier comprises: A proportional element that amplifies the deviation between the speed setting value and the detected speed value with a constant gain, an integral element that integrates the output of this proportional element with an integration time constant switching circuit, and an integral element that integrates the above integral element in response to an elevator deceleration command. An elevator speed control device comprising: a circuit that sets a small time constant and returns the integral time constant to its original value when the output of the integral element reaches a predetermined level of braking output.