JPH0158116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device for controlling an elevator driven by an AC motor.

An induction motor is used as the motor for driving an elevator car, and AC power of variable voltage and frequency is supplied to the induction motor to control the speed of the motor. This is shown in FIG.

In the diagram, R, S, and T are three-phase AC power supplies, 1A, 1B
2 is a smoothing capacitor connected to the DC side of the converters 1A, 1B to smooth the DC output; 3 is a smoothing capacitor connected to both ends of the smoothing capacitor 2. 4 is a three-phase induction motor connected to the AC side of the inverter 3, and 5 is a hoisting machine driven by the electric motor 4. A driving sheave, 6, is a main rope that is wound around the sheave 5 and has a car 7 and a counterweight 8 connected to both ends, respectively;
9 is a speedometer generator that is directly connected to the motor and generates a speed signal; 10 is a speed command generation circuit that generates a speed command signal; 11 is a voltage detection circuit that detects the voltage across the smoothing capacitor; 12 is a speed command signal and speed Converter 1 from the signal and the above voltage detection circuit output
This is a speed control circuit that gives firing commands to A, 1B and the inverter 3 to control voltage and frequency.

FIG. 2 shows an example of the speed control circuit 12. In the figure, V _P and V _T are a speed command signal and a speed signal, respectively, V _FB is a voltage detection signal across the smoothing capacitor, 2a is a slip calculation circuit that calculates a slip command signal V _S from V _P and V _T , and V _F is a frequency command signal formed by adding V _S and V _T ; 2b is an inverter control circuit that controls the firing pulse of the inverter in response to V _F ;
2d is the command value V _R of the converter voltage in response to V _F
The converter voltage command calculation circuit 2e that generates
This is a converter firing control circuit that controls the converter's firing pulse in response to the deviation of V _R and V _FB .

That is, a speed command signal is sent to the speed control circuit 12.
When V _P is added, the slip calculation circuit 2a outputs V _P ,
In response to the deviation of V _T , a slip command signal V _S proportional to the torque to be generated by the drive motor 4 is generated. The slip command signal V _S is added to the speed signal V _T to become the AC power frequency command signal V F to be applied to the motor 4, which is applied to the inverter control circuit and the converter control circuit, respectively, and becomes the frequency command signal V _F to be applied to the inverter and converter. Controls the ignition pulse. These ignition pulses adjust the voltage and frequency of the AC power to be applied to the motor 4 via the converters 1A, 1B, the smoothing capacitor 2, and the inverter 3. The speed, that is, the traveling speed of the car 7 is automatically controlled with high precision.

However, if the thyristor converter or smoothing capacitor deteriorates or breaks down, for example, when the motor is in power running, the voltage across the smoothing capacitor will drop abnormally, causing the motor to generate the specified torque according to the speed command signal. In the worst case, it becomes impossible to generate torque commensurate with the unbalanced torque of the load applied to the motor. In this case, either the basket or the counterweight, whichever is heavier, begins to fall. Furthermore, when the motor is in regenerative operation, power cannot be regenerated to the commercial AC power source due to a converter failure, resulting in a problem that the smoothing capacitor is charged to a voltage higher than the rated voltage.

This invention was made to improve the above-mentioned problem, and the voltage across the smoothing capacitor is a predetermined value lower than the voltage value calculated from the commercial AC power supply voltage and the phase of the ignition pulse applied to the converter. If the value is higher or lower than this, the purpose is to stop the elevator immediately to prevent serious accidents such as those mentioned above.

Hereinafter, this invention will be explained in detail using the drawings.

FIG. 3 is a circuit diagram showing an embodiment according to the present invention, in which 13 is a voltage detection circuit that detects the voltage of a commercial AC power source and is composed of, for example, a three-phase transformer and a diode bridge; 14 is a voltage detection circuit of the voltage detection circuit 13; From the output signal 13a, the firing pulse of the thyristor converter, and the power supply synchronization signal for converter firing control (not shown), for example, V = V _IN COS θ - V〓 However, V _IN : Voltage detection circuit output 13a θ: Point Arc pulse phase V〓: A circuit that calculates the voltage value to be applied to the smoothing capacitor according to the formula of forward voltage drop of the diode bridge, 15 is the voltage calculation output V
14a and the voltage 11a across the smoothing capacitor, and outputs a detection signal 15a when the detected voltage 11a is larger or smaller than the voltage calculation output 14a by a predetermined value or more.

The drive motor 4 is in power running, that is, the converter 1
Consider the case where A is operating. converter 1a
When both the smoothing capacitor 2 and the smoothing capacitor 2 are normal, the smoothing capacitor 2 is charged to a predetermined voltage determined by the commercial AC voltage and the firing phase of the thyristor converter. Therefore, at this time, the voltage detection output 11a of the smoothing capacitor and the voltage calculation circuit output 14a are approximately equal, and the voltage comparison circuit does not detect any abnormality.
However, if, for example, converter 1A fails and cannot generate a predetermined voltage according to the phase of ignition pulse 12a, the smoothing capacitor continues to flow load current to the drive motor, causing the voltage at both ends to drop. The voltage drop across the smoothing capacitor is fed back to the converter control circuit 2c by the voltage detection circuit 11.
This feedback signal 11a is transmitted to the converter ignition control circuit 2.
The ignition pulse is controlled so that the phase of the ignition pulse e is further advanced, that is, the output voltage of the converter is further increased. As a result, the output 14a of the voltage calculation circuit 14 becomes larger than the voltage detection output 11a of the smoothing capacitor, and when it exceeds a predetermined value, the voltage comparison circuit 15 operates the elevator safety circuit (not shown). A detection output 15a is output for safely stopping the elevator.

Similarly, even when the drive motor 4 is in regenerative operation, that is, when the converter 1B is operating, for example, if the converter 1B fails, a predetermined regenerative power according to the phase of the ignition pulse is transferred to the commercial AC power source. When it becomes impossible to return to
is rapidly charged by the regenerated power of the drive motor. As a result, when the voltage calculation circuit output 14a becomes larger than the voltage detection output 11a of the smoothing capacitor by a predetermined value or more, the voltage comparison circuit 15 operates to safely stop the elevator.

As explained above, according to the present invention, the voltage value to be applied to the smoothing capacitor is calculated from the value of the commercial AC voltage and the phase angle of the firing pulse applied to the thyristor converter, and this voltage calculation value is applied to the smoothing capacitor. By comparing the voltage actually applied across the thyristor converter or smoothing capacitor, if the thyristor converter or smoothing capacitor fails, the failure can be detected as soon as possible and the elevator can be stopped safely.

[Brief explanation of drawings]

1 and 2 are block diagrams showing a conventional AC elevator control device, and FIG. 3 is a block diagram showing an embodiment of the AC elevator control device according to the present invention. 1A, 1B...Converter, 2...Capacitor, 3...Inverter, 4...Three-phase induction motor,
5... Drive sheave, 6... Main rope, 7... Car, 8...
... Weight, 9 ... Speedometer engine, 10 ... Speed command generation circuit, 11 ... Voltage detection circuit, 13 ...
Speed control circuit, 13... Voltage detection circuit, 14...
Voltage calculation circuit, 15... Voltage comparison circuit. Note that the same or equivalent parts in the figures are indicated using the same symbols.

Claims (1)

[Claims] 1. Convert commercial AC power to DC using a thyristor converter, smooth this DC using a smoothing capacitor, convert it to variable frequency AC power using an inverter, and use the converted AC power to drive an AC motor. In an elevator that operates the car by driving the car, the voltage of the commercial power supply is detected, and the voltage is applied to the smoothing capacitor based on the relationship between the detected power supply voltage value and the phase of the firing pulse given to the thyristor converter. a circuit that calculates a voltage value to be calculated, and a circuit that compares the voltage across the smoothing capacitor with the output of the calculation circuit, and the capacitor voltage detection output is larger or smaller than the output of the calculation circuit by a predetermined value or more. A control device for an AC elevator, which is characterized by detecting that the car is suddenly stopped.