JPH0540715Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Purpose of the invention] (Field of industrial application) This invention is applicable to AC variable speed inverters, AC and
This invention relates to inverter control devices used in DC servos, etc.

(Prior Art) Inverter control devices used for AC variable speed inverters, AC and DC servos, etc., operate after a certain time limit when AC power 1 is supplied, as shown in Fig. 3. The circuit is configured such that the electromagnetic contactor 3 is operated by the contacts.

On the other hand, when AC power 1 is supplied, the rectifier 4 exchanges the AC into DC. The capacitor 6 is charged with direct current, but until the electromagnetic contactor 3 operates, it is charged through the resistor 5, so the charging current is suppressed and the rectifier 4 is protected from overcurrent.
The smoothed DC power is inversely converted into AC voltage by an inverter unit 10 and drives an AC motor 11 .

The inverter section 10 is a well-known technology, so the description thereof will be omitted. When the AC motor 11 is to be decelerated and stopped, the inertial energy of the motor load is regenerated to the DC power supply section via the inverter section 10.
This inertial energy is charged in the capacitor 6 and the DC power supply voltage increases.

Generally, when the DC voltage rises to a value with some margin above the rated voltage of the inverter elements, it is detected by the main DC voltage detection unit 8, the transistor 9 is turned on, and current flows through the resistor 7. That is, when the regenerated energy due to deceleration of the motor exceeds a certain voltage, the transistor 9 turns on and is consumed by the resistor 7.

Note that a diode 12 is added to prevent the transistor 9 from being destroyed due to the generation of surge voltage when the transistor 9 is operated due to the reactance of the resistor 7 and the connecting wire.

(Problem to be solved by the invention) In this way, in the conventional inverter control device, since the charging current suppression resistor 5 and the regenerative energy consumption resistor 7 are separately provided in the same circuit, the power consumption of the entire circuit is reduced. Due to the large number of components and the reduction in the number of parts, there was a desire for the entire device to be smaller and lower in price.

The purpose of the present invention is to provide an inverter control device that achieves miniaturization and cost reduction of the entire device by configuring a circuit in which one resistor is used for both charging current suppression and regenerative energy consumption. .

[Structure of the invention] (Means for solving the problems) In order to achieve the above object, the present invention includes a rectifier that converts an AC voltage of a power supply into a DC voltage, and a rectifier that is charged by the DC voltage. In a device equipped with a capacitor and a power conversion circuit that converts DC voltage smoothed by the capacitor into variable voltage power to drive a motor, the circuit is closed for a certain period of time after the power is turned on, and the DC output of the rectifier is closed. a contact connecting between one end of the side and one end of the capacitor, a series circuit of a resistor and a diode forming a parallel circuit with the contact, a series connection point of the resistor and the diode, and the other end of the DC output side of the rectifier. A transistor is provided between the capacitor and the capacitor, which becomes conductive when the voltage of the capacitor is equal to or higher than a predetermined voltage.

(Function) With the above configuration, when the power is turned on, the capacitor is charged through the resistor and the diode. Therefore, the charging current can be suppressed and the rectifier can be protected from overcurrent.

Further, when a certain period of time has elapsed since the power was turned on, the contacts are closed and the inertial energy of the load is regenerated during operation of the motor, the voltage of the capacitor rises and the transistor becomes conductive. At this time, the diode becomes reverse biased, and the discharge current of the capacitor flows into the resistor through the contact. Therefore, regenerative energy is consumed by the resistor, and the resistor can be used both for suppressing charging current and absorbing regenerative energy.

(Example) The present invention will be described below with reference to an example shown in FIGS. 1 and 2. In both figures, the same reference numerals as in FIG. 3 indicate the same parts, so the explanation thereof will be omitted.

In FIG. 1, the circuit configuration of the inverter control device of the present invention is the same as that in FIG.
The difference from the figure is that the resistor 5 is omitted and a resistor 7 is connected in parallel to the series circuit of the contact 3A of the electromagnetic contactor 3 and the diode 12.

Next, the operation of the inverter device of the present invention will be explained. The AC power supplied from input power source 1 is
The capacitor 6 is charged through the resistor 7 and the diode 12, which are converted into DC by the rectifier 4. This charging current is suppressed by the resistor 7. After a certain time period, when the electromagnetic contactor 3 operates and the contact point 3A turns ON, this state will be maintained without going through the resistor 7 and diode 12.

On the other hand, when the electric motor 11 is decelerated, regenerated energy is regenerated to the main DC section and the DC voltage increases as described above. Similarly to the above, after the main DC voltage detection unit 8 operates and the transistor 9 is turned on, regenerative energy is consumed by the resistor 7 through the contact 3A of the electromagnetic contactor 3.

Moreover, FIG. 2 shows a modified example. What is different from the above is that a two-pole type electromagnetic contactor 3 is used in which a contact 3B is added, and the charging current is charged to the capacitor 6 from the contact 3B through the resistor 7. After a certain time period, when the electromagnetic contactor 3 operates and the contacts 3A and 3B turn ON to the dotted line state, the capacitor 6 is charged without passing through the resistor 7, and the resistor 7 is connected to the regeneration transistor 9.

On the other hand, regenerative energy from the motor 11 passes through the resistor 7, the dotted line of the contact 3B, and the regenerative transistor 9, and is consumed in the resistor 7.

Incidentally, as the capacity of the motor increases, the regenerative energy consumption resistance also increases in proportion, and since the capacitor in the main DC section also increases in size, the charging current suppression resistance also inevitably increases. Therefore, it is possible to use the regenerative energy consuming resistor as a charging current suppressing resistor.

[Effects of the invention] As explained above, according to the invention, the circuit configuration is such that the capacitor charging current suppressing resistor and the regenerative energy consumption resistor are used by switching the same resistance, thereby reducing the size and cost of the device. Pricing becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the inverter control device of the present invention, Fig. 2 is a circuit diagram showing another embodiment of the present invention, and Fig. 3 is a circuit diagram showing a conventional inverter control device. . 1... Input power supply, 2... Time-limited relay (timer), 3... Magnetic contactor, 4... Rectifier, 5...
Charging current suppression resistor, 6... Capacitor, 7... Regenerative energy consumption resistor, 8... DC voltage detection section,
9...Transistor, 10...Inverter section, 1
1...Electric motor, 12...Diode, 3A...A contact of electromagnetic contactor 3, 3B...B of electromagnetic contactor 3
contact.

Claims (1)

[Scope of utility model registration request] A rectifier that converts AC voltage of a power supply into DC voltage, a capacitor that is charged by the DC voltage, and a power conversion circuit that converts the DC voltage smoothed by the capacitor into variable voltage power to drive a motor. A device comprising: a contact that closes after a certain period of time after the power is turned on and connects one end of the DC output side of the rectifier and one end of the capacitor; and a series resistor and diode forming a parallel circuit with the contact. An inverter control device characterized in that a transistor is provided between the circuit, a series connection point of the resistor and the diode, and the other end of the DC output side of the rectifier, which becomes conductive when the voltage of the capacitor is equal to or higher than a predetermined voltage. .