JPS5895960A - Preventing method for overheat of armature coil for dc electric machine - Google Patents

Abstract

PURPOSE:To accurately obtain the temperature of a coil by applying a load current during operation a voltage between the terminal of the coil, rotating speed and a field current at that time at the prescribed interval to a computer and obtaining the armature coil temperature. CONSTITUTION:A rotating speed N and a field current If are applied to a computer, which then obtains a counterelectromotive force E=k.N.f(If). Then, the counterelectromotive force E, a voltage V between armature coil, and a load current I are applied to the computer, which then obtains a coil resistance R=(V-E)/I. Then, the coil temperature t=R/R0.(t+234.5)-234.5 is obtained, where R0 designates the coil resistance at the temperature t0. These calculations are performed by the computer, thereby accurately obtaining the temperature of the coil, and preventing in advance the abnormal overheat of the coil.

Description

[Detailed description of the invention] The present invention is for temperature detection of armature windings.

Since the armature winding is a rotor, in order to measure the temperature during operation, it is necessary to embed a search coil or thermistor in the winding and extract the signal from this through a slip ring. Not only does the rotor have a complicated structure, but since the slip ring has contact points, constant maintenance is required, and there are also problems in terms of reliability.

The main objective of the present invention is to use the latest advances in microcomputer technology to control the rotating machine and use numerical values taken from operating records to calculate the most important armature winding temperature through simple calculations. An object of the present invention is to provide a method for preventing abnormal overheating of windings.

Figure 1 shows a search coil 2 embedded in an armature winding 1 using the conventional method, and a lead wire connected to a slip ring 4 through a hole in a shaft 3 to extract signals from the rotating search coil. There is.

FIG. 2 shows an embodiment according to the invention.

Here, I: Load current, v: Voltage between electric machine pre-windings (voltage between brushes), N: Rotational speed, It: Field current, and these values are the values necessary to control the DC machine. Therefore, it is generally incorporated into the control panel. By inputting this value into a computer (microcomputer) and performing the calculations below, the momentary winding temperature can be determined.

E=kNXf (If) R=(V-E)/I where Le. is the reading temperature t. It is the resistance value at the time, and is included in the calculation formula as a constant.

According to the present invention, the average height of the windings can be determined accurately through calculation, thereby eliminating hardware failures and improving reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a rotor when a conventional search coil is attached, and FIG. 2 is a calculation flow according to the present invention.

Claims (1)

[Claims] 1゜The load current during operation, the voltage between the terminals of the winding at that time, the rotational speed, and the field current are input into a computer at regular intervals, and the temperature of the winding is calculated moment by moment.
A method for preventing overheating of the armature winding of a DC machine, which is characterized by controlling.