JPH033207A - Excitation device of lifting electric magnet - Google Patents

Abstract

PURPOSE:To eliminate the need for a power supply transformer with large capacity and to provide an excitation device of lifting electric magnet which achieves required initial excitation only by adding a simple circuit of short-time rating by constituting a booster circuit generating an output voltage which is added to the output voltage of a main excitation circuit for initial excitation using a switching element and a diode including a transformer with a small capacity. CONSTITUTION:Switching elements 31a and 31b of a booster circuit 3 conduct current by a controller 4 for initial excitation of a lifting electric magnet 1. Through a transformer 32, for example, the boosted alternate current generates a specified DC voltage using a parallel circuit of the switching elements 31a and 31b and diodes 30a and 30b. On the other hand, even in a main excitation circuit 2, the power rectifying circuit generates a specified excitation voltage. However, since the output side of the main excitation circuit 2 is connected to the output side of the booster circuit 3 in series, output voltage of the booster circuit 3 is added to the output voltage of a main excitation circuit 2, thus producing an overshoot voltage of a specified initial excitation voltage, which is applied to the coil of an electromagnet 1, thus increasing the leading edge of current flowing to the coil.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an excitation device for a suspended electromagnet, and more particularly to an excitation device having an overshoot function for efficient initial excitation.

[Prior Art] In general, lifting electromagnets use so-called overloading, which increases the current rise (-E) during initial excitation in order to obtain the current required to attract a predetermined lifted object in a short time to improve cargo handling efficiency. A shoot method is used. This initial overshoot excitation is performed, for example, by applying a voltage of 350 to 500 V for about 5 seconds to an electromagnet with a rating of 220 mm, thereby making the current rise steep.

For this reason, in the past, a power transformer was used to step up the voltage from the AC power source and supply it to the forward converter, and the forward converter controlled the initial excitation and the lifting of the lifted object up to the grounding. The excitation was changed to excitation for attraction (290 sq. compared to the rated 200 sq.), and then to rated voltage (200 V) excitation during lifting and transporting F objects after cutting the ground.

Therefore, a large-capacity power transformer is required only for initial excitation for a very short period of time, resulting in the disadvantage that the entire device becomes expensive and large.

[Problems to be Solved by the Invention] The present invention provides an excitation device for a suspended electromagnet that does not require a large-capacity power transformer and can perform predetermined initial excitation simply by adding a simple short-time rated circuit. The purpose is to provide

[Means for solving the problem] A forward conversion circuit and a booster circuit connected through a transformer are connected in series between both ends of a coil of a lifting electromagnet, and each is connected to an AC power source. The alternating current from the alternating current power supply is converted into direct current and supplied to the coil via a booster circuit, and the booster circuit includes a parallel circuit of a switching element and a diode.

[Function J] When the switching element is conductive, the output voltage of the booster circuit is added to the output voltage of the forward conversion circuit and supplied to the coil, and when the switching element is non-conductive, only the output voltage of the forward conversion circuit is added to the output voltage of the forward conversion circuit. is supplied to the coil.

[Example] An embodiment of the present invention will be described with reference to the drawings.

A booster circuit 3 and a main excitation circuit 2 are connected in series between both ends of the coil of the lifting electromagnet 1, and these booster circuits 2
and main excitation circuit 3 are each connected to alternating current power supply 5.

The main excitation circuit 2 is a known forward conversion circuit, and its control circuit is not shown.The booster circuit 3 serves as an auxiliary excitation circuit, and includes a parallel circuit of switching elements 31a, 31b and diodes 30a, 30b, and a transformer. 32, and is connected to the AC power supply 5 via this. Switching element 31. The conduction and non-conduction of a and 31b are controlled by the controller 4.

To explain the operation, the switching element 31a of the booster circuit 3 is activated by the controller 4 for initial excitation of the lifting electromagnet 1.
, 31b are made conductive. Via the transformer 32, e.g.
The boosted AC voltage is applied to switching elements 31a and 31b.
A predetermined DC voltage is generated by the parallel circuit of diodes 30a and 30b. On the other hand, the main excitation circuit 2 also generates a predetermined #magnetic voltage by its forward conversion circuit, but since the output side of the main excitation circuit 2 is connected in series to the output side of the booster circuit 3, the booster circuit 3 The output voltage of main 1a
It is added to the output voltage of the magnetic circuit 2, becomes an overshoot voltage of a predetermined initial excitation voltage, and is applied to the coil of the electromagnet. This increases the rise of the current flowing through the coil. After the overshoot ends, the switching elements 31a and 31b of the booster circuit 3 are rendered non-conductive. As a result, no output voltage is generated in the booster circuit 3, and only conduction is performed, so that only the output voltage of the main excitation circuit 2 is applied to the electromagnet 1 through the diodes 30a and 30b of the booster circuit 3. The output voltage of this main excitation circuit 2 is l191g&voltage for attracting the lifted object up to the ground cutting. Thereafter, after the ground breaking, the output voltage of the main excitation circuit 2 is adjusted by a control circuit (not shown) and switched to the rated excitation voltage for transferring the lifted object.

[Effects of the Invention] A booster circuit that generates an output voltage to be added to the output voltage of the main ID magnetic circuit for initial excitation is composed of a switching element including a small-capacity transformer if necessary, and a diode,
Since these require extremely short-time ratings, they are cheaper in price and smaller and simpler in structure than conventional large-capacity power transformers.

[Brief explanation of drawings]

The drawing is a block diagram of an embodiment of the invention. In the figure, 1. lifting electromagnet, 2. Main excitation circuit, 3. booster circuit,
4. controller, 5. AC power supply, 30a, 30b, diode, 31a, 31b, switching element, 32. transformer.

Claims (1)

[Claims] Consisting of a forward conversion circuit and a booster circuit connected in series between both ends of the coil of the lifting electromagnet and each connected to an AC power source, the forward conversion circuit converts the AC power from the AC power source into is converted into DC and supplied to the coil via the booster circuit, and the booster circuit includes a parallel circuit of a switching element and a diode that receives input from the AC power source via a transformer, and when the switching element is conductive, is a lifting device that adds the output voltage of the booster circuit to the output voltage of the forward conversion circuit and supplies the result to the coil, and when the switching element is non-conducting, supplies only the output voltage of the forward conversion circuit to the coil. Electromagnet exciter.