JPS5899812A - Voltage controller of electric power supply unit - Google Patents

Abstract

PURPOSE:To prevent an erroneous compensating operation, by adding a means for giving a single polarity transfer characteristic, such as a diode, etc., to a voltage controller of an electric power supply unit provided with an automatic voltage controller and a line drop compensating circuit. CONSTITUTION:In an input part of an automatic voltage controller 3 attached to an electric power supply unit 2, output voltage detected by a voltage detector 11 connected to an output terminal A is compared with a set value of a setting device 5. Also, as a line drop compensating circuit, a comparing means 14 for deriving a difference between an output of a voltage detecting circuit 12 provided on the output terminal A, and an output of a voltage detecting circuit 13 provided on a load terminal B is provided. Also, a diode 15 for setting an output of the comparing means 14 to an auxiliary set value as to only its single polarity, and leading it to a comparing point of the input part of the automatic voltage controller 3 is provided. In this way, a negative output generated by the comparing means 14 is cut by the diode 15, therefore, an erroneous compensating operation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes an automatic voltage control device that detects the output terminal voltage of a power supply device and compares it with a voltage setting value to adjust the output terminal voltage. A line drop compensation circuit is provided for compensating for line drop voltage between the output end of the power supply device and the load end by giving an auxiliary setting value to the automatic voltage control device according to the deviation between the output end of the power supply device and the load end voltage. The present invention relates to a voltage control device for a power supply device.

When power is supplied to a load that requires high voltage accuracy, it is preferable that the voltage detection value to be fed back to the automatic voltage control device of the power supply device is taken out from the load end. By doing so, the load end voltage can be maintained with high accuracy without considering the line drop voltage between the output end of the power supply device and the load end. However, especially when performing parallel power supply using multiple power supplies, each power supply is connected and disconnected in parallel via a circuit breaker, so the output voltage of each power supply must be adjusted in advance when synchronizing. Therefore, the voltage detection point must be placed at the output end of the power supply. For this reason, a line drop compensation circuit as mentioned at the beginning is required.

However, it has been found that when the conventional line drop compensation circuit as described above is provided, the voltage control system may become unstable and the output voltage may drop abnormally instead of compensating for the line drop voltage.

The inventors of the present invention have conducted various studies to investigate the cause of this problem, and have found that the cause is that the voltage exceeds the load end voltage due to a mismatch in the characteristics between the output end voltage detector and the load end voltage detector. We have discovered that there are cases where false detections are being made as if there is a problem. Therefore, when the output deviation of both detectors corresponds to the state described above, we inserted a diode to prevent this from being given to the automatic voltage control device as an auxiliary setting value, and the abnormal drop as described above disappeared, and it fell within the allowable range. The results show that the compensation circuit works effectively and can sufficiently compensate for line drop voltages that exceed .

Therefore, it is an object of the present invention to avoid erroneous operation of the line drop compensation circuit despite detector errors. Of course, in this case, the objective is to be achieved without impairing the original line drop compensation effect.

A feature of the present invention that achieves this object is that in the control device for a power supply device as described at the beginning, when the auxiliary set value has a polarity that equivalently lowers the voltage set value, the auxiliary set value The point is that means is provided to prevent the voltage from being applied to the automatic voltage control device.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In the figure, 1 is a load, 2 is a power supply device such as a static power converter, 3 is an automatic voltage control device attached thereto, and 4 is a breaker. At the input section of this automatic voltage control device, the output voltage detected by the voltage detector 11 connected to the output terminal is compared with the setting value of the setting device 5.

Further, as a line drop compensation circuit, a comparing means 14 for calculating the difference between the detected output of the voltage detector 12 provided at the output end and the detected output of the voltage detector 13 provided at the load end B, and the output of this comparing means are provided. , a diode 15 which leads to a comparison point at the input of the automatic voltage control device 3 as an auxiliary setting value only for unipolarity is provided. As a result, as mentioned earlier, due to the uneven transfer characteristics of the voltage detectors 12 and 13, when the line trop voltage is small, such as at a light negative end, the output of the detector 13 is transferred to the detector 12. Even if an erroneous detection is made that the output exceeds the output of The negative output of the comparison means 14 is directly led to the automatic voltage control device 3 as an auxiliary set value. As a result, the voltage setting value is equivalently lowered, so the automatic voltage control device 3 gives a command to the power supply device 2 to lower the output voltage. In particular, the unevenness of the characteristics of the voltage detectors 12 and 13 is a steady characteristic (
In other words, when the breaker 4 is closed (proportional gain), the output voltage gradually decreases when the breaker 4 is turned on, and eventually an undervoltage relay (not shown) operates to open the breaker 4, which is a protective operation. There may also be situations where this is not possible.

By adding a simple means such as a diode 15 to provide unipolar transfer characteristics, the present invention can tolerate variations in voltage detector characteristics within the normal range.

Note that although the voltage detectors 11 to 13 are not shown in detail, they are constructed of an instrument transformer, a rectifier, and a smoothing filter as usual. Furthermore, even if the detection polarity is correct, the detection error means 14
It is effective to add a diode limiter circuit 16 that limits the output of the circuit.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Load, 2... Power supply device, 3... Automatic voltage control device, 4... Breaker, 5... Voltage setting device, 11
-13... Voltage detector, 14... Comparison means, 15.
...Diode, 16...Limiter circuit.

Claims (1)

[Claims] 1) Equipped with an automatic voltage control device that detects the output terminal voltage of the power supply device, compares it with a voltage setting value, and adjusts the output terminal voltage, and also according to the deviation between the output terminal voltage of the power supply device and the load terminal voltage. In the voltage control device for a power supply device, the voltage control device for a power supply device includes a line drop compensation circuit that compensates for a line drop voltage between an output leakage of the power supply device and a load end by giving an auxiliary setting value to the automatic voltage control device. A voltage control device for a power supply device, comprising means for preventing the auxiliary set value from being applied to the automatic voltage control device when the set value has a polarity that equivalently lowers the voltage set value.