JP2560537B2 - Inductance load power supply method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply method having a forward / reverse switching function of converting an AC power supply to a DC power by a thyristor and supplying the power to an inductance load such as a hanging electromagnet. In particular, the thyristor is ignited when power is resupplied after the supply of power from the AC power supply has been stopped for a long period of time, which may cause the control DC power supply to fall and become uncontrollable. The present invention relates to a reliable power supply method for an inductance load and a device therefor, which is correctly executed according to the information before the power failure, and therefore does not cause a short circuit accident due to simultaneous firing of the forward and reverse thyristors.

[Prior Art] Conventionally, in a hanging electromagnet or the like for transporting scrap iron materials, iron pipes, etc. by an overhead crane, an AC power source is supplied from a factory power source via a trolley to a power supply device mounted on the overhead crane. The power supply device is provided with power supply means for converting this alternating current into direct current by means of a thyristor, and supplies direct current power to an inductance load such as these hanging electromagnets.

In the hanging electromagnet used for the above-mentioned application which is an inductance load, the polarity of the electromagnet is reversed by changing the direction of the current supplied to the electromagnet in order to reliably release the adsorbed matter adsorbed to the electromagnet. Means may be used.

In order to change the direction of the current supplied to this electromagnet in order to reverse the polarity of the electromagnet as described above, the load current must be attenuated to the specified current value after stopping the current supply until the conversion time. After confirming, the electric current in the opposite direction is supplied after waiting for a certain time.

In addition, when the overhead crane travels, the trolley often separates, causing an instantaneous power failure of the power supply line to the power supply device for the electromagnet, etc., but the power failure may continue for a long time depending on the conditions of the power supply. is there. If such a long power failure occurs, the control power supply will drop and the contents of the control device in the control process will evaporate.Therefore, when the power supply is restored after the power failure, the relationship between the control command and the load status will be confused and correct. A short circuit accident may occur due to reverse simultaneous firing.

Next, in an example of a conventional power supply device for a hanging electromagnet which is used under such conditions, only a circuit function relevant to the present invention is extracted and shown as a third circuit configuration diagram for explanation. Shown in the figure.

In FIG. 3, a is a three-phase AC power source, 31 is a plurality of bridge-connected thyristors for supplying a positive direction current to the hanging electromagnet 33 which is an inductance load, and 32 is a reverse direction current for the electromagnet 33. In the thyristor 32, a resistor 34 is connected in series to each of the input side and the output side of the thyristor 32.

Further, 35 is a transformer for current value detection, 36 is a thyristor control device, 37 is a forward / reverse trigger pulse generator, and b is a control signal wiring with the control device body.

That is, in the forward / reverse trigger pulse generator 37, in addition to the control command signal from the control device main body, the thyristor based on the signal from the thyristor control device 36 indicating the thyristor to be fired by detecting the load condition and its trigger phase The trigger pulse of is output.

In addition, as shown in the figure, in order to prevent short-circuit current due to simultaneous firing of forward thyristor 31 and reverse thyristor 32 due to a trigger pulse output error after a momentary power failure or power failure, a resistor is connected in series with the reverse thyristor. Device 34 is connected.

[Problems to be Solved by the Invention] Although the DC voltage of the control power supply decreases when the power failure time becomes longer, the recovery of the thyristor adapted to the direction of the current still flowing to the load at the time of power failure recovery depends on the length of the power failure time. There is no guarantee that the operation will be executed, and the behavior of the thyristor after power restoration is unstable.

Therefore, in the conventional device as described above, the resistor is connected to prevent the circuit from being burnt out due to the short circuit current. However, mounting the resistor supplies the current in the reverse direction to the load. Sometimes the loss due to the resistor is large,
In order to absorb the required power, the volume of the resistor itself is required, and a measure for heat dissipation is required, which is an obstacle to downsizing of the device and cost reduction.

The present invention solves the above-mentioned problems of the prior art, and no matter what time a power failure occurs, a highly reliable inductance load that does not cause a short circuit accident due to simultaneous firing of thyristors in both the forward and reverse directions. It is an object of the present invention to provide a power supply method and a device therefor to eliminate the need for a resistor connected in series to a conventional thyristor.

[Means for Solving the Problems] In order to solve the above problems, a method for supplying power to an inductance load according to the present invention is a method for supplying DC power to an inductance load using a thyristor having a forward / reverse switching function. Detecting that the control device supply DC voltage used in the supply method has dropped below a predetermined constant value, and recording this detection information and the distinction between the forward and reverse directions of the current flowing at this detection timing, The thyristor is initially controlled according to the recorded information after the DC voltage supplied to the control device is restored.
Further, the power supply device for an inductance load according to the present invention is a direct current power supply device for an inductance load by a thyristor having a forward / reverse switching function, and the controller supply direct current voltage of the direct current power supply device has a predetermined predetermined value. A power failure detecting means for detecting that the value is less than or equal to a value, a means for recording the power failure detecting information and a current direction of the ignition side thyristor at the moment when the detecting means detects, and the recording after the control device supply DC voltage is restored. Means for controlling the thyristor according to the information recorded by the means.

[Operation] According to the present invention, in the power supply method for the inductance load, it is detected that the DC voltage for supplying the control device has become equal to or less than a predetermined value due to a cause such as a power failure, and the detection information is detected. And the current direction of the trigger side thyristor at the detection timing are recorded, and the thyristor is controlled according to the information recorded by the recording means after the DC voltage for supplying the control device is restored. It operates so that a current flows in the direction.

Further, in the power supply device of the inductance load, a power failure detection means for detecting that the DC voltage for supplying the control device has become equal to or less than a predetermined value, and the power failure information and the moment when this detection means detects the power failure information. Since the means for recording the current direction of the ignition side thyristor and the means for controlling the thyristor according to the information recorded by the recording means after restoration of the DC voltage for supplying the control device, are provided in an appropriate direction even after restoration of the power failure. It operates so that a current flows.

 Therefore, trouble such as a short circuit accident does not occur.

[Embodiment] Next, an embodiment in which the present invention is applied to a hanging electromagnet will be described in detail with reference to FIGS. 1 to 3.

FIG. 1 is a schematic flow chart of the operation at the time of a power failure and its restoration by the power supply method for an inductance load according to the present invention, and FIG. 2 corresponds to the power supply method for an inductance load described in FIG. FIG. 3 is a schematic block circuit diagram showing a main circuit that operates at the time of power failure and its restoration in the power supply device.

In the flow chart shown in FIG. 1, a power failure occurs in the power supply device of the hanging electromagnet, which is an inductive load during operation, due to some cause, and the output voltage from the DC power supply circuit to the control device decreases, which is predetermined. When a predetermined condition is met (step 1), a power failure flag is set in the power failure recording register provided in the control device and the power failure flag is set to 1
Is recorded (step 2).

Also, the control command signal at that timing is read by judging whether the hanging electromagnet, which is an inductance load, is excited in the forward direction or in the reverse direction. The recording register is set to zero, and when reverse excitation is performed, a reverse excitation flag is set in this forward / reverse recording register and 1 is recorded (step 3).

Next, when the power failure is recovered and the voltage of the DC power supply for the control device rises to establish the operable condition of each circuit (step 4), the control device reads the flag status of the above two registers.

In step 5, first, the power failure recording register is checked, and if the power failure recording register is not flagged, the normal operation immediately returns to the normal operation set in the control device. The flag of the reverse recording register is checked, and if the flag is not set in the forward / reverse recording register, that is, if the forward direction excitation command is before the power failure, the normal operation similarly set in the control device is returned to, When the reverse excitation flag is set,
That is, when the reverse excitation command is given before the power failure, the control device is instructed to perform the regenerative operation process for the reverse excitation thyristor.
Therefore, next, in step 7, the thyristor on the reverse excitation side performs regenerative operation to regenerate the electric power stored in the inductance load, and when this thyristor extinguishes, in step 8, the command signal input to the control device is input. Return to normal operation according to.

Each of the above registers has a time recording capability capable of completely discharging the stored power of the inductance of the load. For example, it is not always necessary when using a capacitor type memory that automatically resets after a few minutes of setting, If necessary due to a power failure, a reset may be applied when the power is restored (step 9).

Next, an example of a power supply device that concretely configures the above-described power supply method will be described with reference to FIG. 2 in which only main element circuits and devices are taken out and shown.

In FIG. 2, 1 is a thyristor circuit for forward direction excitation with three-phase bridge connection, 2 is a thyristor circuit for reverse direction excitation with three-phase bridge connection, 3 is a hanging electromagnet which is an inductance load, and a is A three-phase AC power supply is shown.

Reference numeral 20 denotes a DC power supply device for a control device which receives power from an AC power supply c obtained by extracting only a single phase from the three-phase AC power supply a described above, and is supplied to each circuit from a line e. Reference numeral 21 denotes a power supply monitoring circuit, which supplies a power failure signal before the power supply from the power supply c is stopped and a predetermined DC voltage cannot be supplied after a lapse of time determined by the time constant of the DC power supply device 20. When the power supply from the power supply c is restarted and a predetermined DC voltage can be supplied after the time determined by the time constant of the DC power supply device has passed, a power supply restart signal is sent to each element circuit and control device main body (to be described later). (Not shown)
Output to line d to.

Reference numeral 12 is a 1-bit register composed of a capacitor-type memory element having a time recording ability that allows the electromagnet 3 as an inductance load to completely discharge the accumulated power. Is set to.

Reference numeral 13 is a 1-bit register composed of a capacitor-type memory element having a time recording capability capable of completely discharging the electric power accumulated in the electromagnet 3, as will be described later by a power failure signal from the power supply monitoring circuit 21. The command signal of the drive thyristor set in the thyristor drive control circuit 15 is reset when the command signal is on the positive side, and is set to 1 when the drive thyristor is on the reverse side.

The power failure is restored, the DC power supply device for the control device described above is started up, a power supply restart signal is output from the power supply monitoring circuit 21, is input to the register 12, and the recording content of the register is 1, which will be described later. This signal is sent to the gate circuit 14.

Further, a power supply restart signal is input from the power supply monitoring circuit 21 to the register 13, and when the recorded content of the register 13 is 1, this signal is sent to the AND gate circuit 14.

If a signal of 1 is received from both the register 12 and the register 13 in the AND gate circuit 14, this AND gate circuit
An output is output from 14 and a signal is sent to the thyristor drive control circuit 15.

Since the signal is input to the thyristor drive control circuit 15 from the power supply monitoring circuit 21 described above, if there is no input from the AND gate 14 described above when the power supply restart signal from the power supply monitoring circuit 21 is input, The thyristor control signal as set to is output to the forward / reverse trigger pulse generator 7.

When a power supply restart signal is input from the power supply monitoring circuit 21 to the thyristor drive control circuit 15, the AND gate 14 described above
When there is an input from the thyristor on the opposite side, an output is output to the raw reverse trigger pulse generator 7 so that the thyristor on the opposite side performs a regenerative operation, and when the regenerative operation is completed and the thyristor extinguishes, the control device body (not shown) According to the signal b from, the operation according to the next command is performed.

In the above description, the output is not output when the set contents of each register are zero, but a zero signal can be output to the thyristor drive control circuit 15 depending on the circuit configuration.

Further, although it has been described that the output from each of the registers 12 and 13 is output according to the signal from the power supply monitoring circuit 21, the control device main body (not shown) which receives the signal from the power supply monitoring circuit 21 causes the registers 12 and 13 to output. It is also possible to issue a read signal to the device for reading.

Further, in the above description of the embodiment, it is described that the reverse regeneration processing or the normal processing is executed corresponding to the contents of each register when the power supply is restarted, but the load and the control device of the system to which the present invention is applied. Depending on the conditions, the processing function can be made appropriate for the system.

In addition, it corresponds to other functions necessary for the entire system including this device, for example, corresponding to the function sharing of the software processing of the computer and the function of the control device body (not shown),
Other circuit configurations capable of exerting the functions based on the present invention can also be used.

Further, the gate trigger pulse generation and thyristor control means in the above description can be appropriately set other than those described above by the function provided in the control device and the thyristor circuit.

Further, in the above description, the power supply method for exciting an electromagnet, which is a large inductance load device, and its device circuit have been described, but the present invention can be similarly applied to other inductance loads.

[Effects of the Invention] As described above, according to the present invention, the following effects can be obtained.

When the power is restored after a power failure, the power can be turned on again so that the current flows in an appropriate direction with respect to the current direction of the load.

Therefore, in a power supply device for an inductance load by a thyristor, which can supply current in both forward and reverse directions,
It is possible to obtain excellent reliability without causing a short-circuit current even after a power failure of such a length that the operation of the control DC power supply is stopped.

Therefore, since it is not necessary to connect a resistor in series with the thyristor, there is an excellent effect as described below.

B, there is no power loss due to resistors.

B, resistor and heat dissipation function and cost for mounting these are unnecessary.

It does not require a volume for mounting c, resistors and heat radiation functions.

Therefore, it can be said that the present invention is suitable as a power supply method and a power supply device for a large inductance load such as a hanging electromagnet.

[Brief description of drawings]

FIG. 1 is a schematic flow chart for a power failure countermeasure in an electric power supply method for an inductance load according to one embodiment of the present invention, and FIG. 2 is a schematic block circuit of an electric power supply device for an inductance load according to one embodiment of the present invention. FIG. 3 is a circuit configuration diagram of a power supply device for a hanging electromagnet, which is a typical example of a conventional inductance load. 1 ... Forward direction thyristor circuit, 2 ... Reverse direction thyristor circuit, 3 ... Inductance load, 7 ... Forward / reverse trigger pulse generator, 12 ... Register circuit, 13 ... Register circuit, 14 ... AND Gate circuit, 15 ... Thyristor drive control circuit, 21 ... Power supply monitoring circuit.

Claims (2)

(57) [Claims] 1. A DC power supply method for an inductance load using a thyristor having a forward / reverse switching function, wherein it is detected that a DC voltage supplied to a control device used in this DC power supply method has dropped below a predetermined constant value. However, this detection information and the distinction between the forward and reverse directions of the current flowing at this detection timing are recorded, and the initial control of the thyristor is performed according to the recorded information after the DC voltage supplied to the control device is restored. Power supply method for an inductance load. 2. A direct current power supply device for an inductance load using a thyristor having a forward / reverse switching function, detects that the direct current voltage supplied to a control device of the direct current power supply device is below a predetermined value. Power failure detection means, means for recording the power failure detection information and the current direction of the ignition side thyristor at the moment when the detection means detects, and control of the thyristor according to the information recorded by the recording means after restoration of the DC voltage supplied to the control device A power supply device for an inductance load, comprising: