JP2695699B2 - Elevator control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elevator control device, and more particularly, to a device for driving an induction motor using an inverter constituted by a voltage-driven semiconductor element, in which high-speed switching is performed. The present invention relates to an elevator control device with reduced adverse effects.

[Prior art] In recent years, inverters are composed of voltage-driven semiconductor elements such as MOSFETs and IGBTs, and the high-speed switching that is a feature of the inverter is used to increase the frequency of the inverter, so that the magnetic noise of the motor can be heard by humans. Noise can be reduced by increasing the frequency.

FIG. 2 is a block diagram showing a conventional elevator control device. In FIG. 2, (1) is a converter for converting a three-phase AC power source consisting of an R phase, an S phase, and a T phase into DC, and (2) is a converter. A smoothing capacitor connected between the output terminals of the converter (1) for smoothing the DC output; (3) a three-phase induction motor that converts the DC smoothed by the smoothing capacitor (2) into a three-phase AC power supply; An inverter that supplies and drives (4) and (5) is an IGBT that constitutes inverter (3)
Is a gate drive circuit connected to and driving this gate. Although not shown, a hoist is connected to the three-phase induction motor (4), and a car and a counterweight suspended by wires wound around the hoist are moved up and down. Conventionally, as shown in FIG. 3, a voltage-driven semiconductor device constituting an inverter (3) such as an IGBT
A gate input resistor (7) is fixedly inserted into the gate of (6) to keep the switching speed of the IGBT (6) constant.

[Problems to be Solved by the Invention] In order to increase the frequency of the inverter, it is necessary to perform high-speed switching. However, if the switching speed of the semiconductor element forming the inverter is slow, the heat generation of the semiconductor element increases, On the contrary, if the switching speed of the semiconductor element is fast, the heat generated by the snubber circuit included in the inverter increases, and the insulation of the inverter and the motor deteriorates. And a problem such as an increase in harmonic interference. Further, the allowable amount of heat generated by the semiconductor element is determined by the capacity of the heat radiation fin, which is determined by the maximum starting frequency of the elevator.

However, the conventional elevator control device uses a resistor (7) so as to follow the elevator even if the activation frequency is high.
Is set to a constant value. For this reason, heat generated by the semiconductor element increases, and the switching speed of the semiconductor element is increased to suppress the heat generation. Then, when the activation frequency of the elevator decreases, the heat generation of the semiconductor element decreases, but the switching speed of the semiconductor element remains unchanged because the value of the resistor (7) is constant. As a result, there are problems such as increased heat generation of the snubber circuit, accelerated insulation deterioration of the inverter and the motor, and increased harmonic interference.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an elevator control device that can reduce the adverse effects when the activation frequency of the elevator is low.

Means for Solving the Problems An elevator control device according to the present invention is an elevator control device that drives a car by generating an arbitrary AC power by an inverter and supplying the AC power to an induction motor. Detecting means for detecting the amount of heat generated by the semiconductor element constituting the inverter; and changing the value of a gate input resistance connected between the gate of the semiconductor element and the gate drive circuit according to the amount of heat generated. Means for changing the rise time of the gate voltage of the semiconductor element.

[Operation] In the present invention, the activation frequency of the elevator is high,
When the inverter is not thermally suffering, the switching speed of the semiconductor element is increased to reduce the switching loss, the heat generation of the semiconductor element is suppressed, the starting frequency is low, and when the inverter is not thermally suffering, the upper and lower short circuit prevention time is allowed. In this case, the switching speed of the semiconductor element is reduced within a certain range to suppress problems such as occurrence of harmonic interference.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention, and (5)
(7) are the same as described above. (8) is a thermosensitive element whose resistance value changes with temperature, for example, a thermistor, and (9) is a protection resistor for preventing the gate input resistance from becoming zero. The thermistor (8) is electrically connected in series with the resistor (9), and this series circuit is connected in parallel with the resistor (7). The thermistor (8) is mechanically mounted on a heat dissipation fin or the like of the IGBT (6).

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described. When the startup frequency of the elevator is high and the temperature of the radiation fin is high, the resistance value of the thermistor (8) decreases, the gate input resistance decreases, and the IGBT
(6) The switching speed is increased. Therefore, IGBT
(6) The switching loss is reduced, and the inverter can cope with a high starting frequency of the elevator.

When the activation frequency of the elevator is low and the temperature of the heat radiation fin is low, the resistance value of the thermistor (8) increases,
The gate input resistance increases and the switching speed of the IGBT (6) decreases. Therefore, heat generation of the snubber circuit, insulation deterioration of the inverter and the electric motor, occurrence of harmonic interference, and the like are suppressed, and an elevator control device with higher quality than when the switching speed is fixed at a high speed can be obtained.

[Effects of the Invention] As described above, according to the present invention, in an elevator control device that drives a car by generating an arbitrary AC power by an inverter and supplying the AC power to an induction motor, Detecting means for detecting the amount of heat generated by the semiconductor element to be constituted; and changing the value of a gate input resistance connected between the gate of the semiconductor element and a gate drive circuit in accordance with the amount of heat generated, thereby forming the semiconductor element. Means for changing the rise time of the gate voltage of the inverter, so that the heat generation of the snubber circuit, the insulation deterioration of the inverter and the motor, the occurrence of harmonic interference, etc., which occur when the startup frequency of the elevator is low, are suppressed, and the switching speed is reduced. There is an effect that a high-quality elevator control device can be obtained as compared with a case where the fixing device is fixed quickly.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional elevator control device, and FIG. 3 is a circuit diagram showing a conventional gate input unit. In the figure, (3) is an inverter, (4) is a three-phase induction motor, (6) is an IGBT, and (8) is a thermistor. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] An elevator control device for driving a car by generating an arbitrary AC power by an inverter and supplying the AC power to an induction motor, wherein a heat generation amount of a semiconductor element constituting the elevator is detected. Detecting means for changing a value of a gate input resistance connected between a gate of the semiconductor element and a gate drive circuit according to the heat generation amount, thereby changing a rise time of a gate voltage of the semiconductor element. A control device for an elevator, comprising: