JP4577542B2 - Series load power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a series load power supply apparatus that supplies power to a plurality of loads connected in series like a constant current supply apparatus for a marker lamp at an airport.
[Prior art]
Conventionally, a constant current supply device for an indicator lamp at an airport includes a phase control device, and detects a load current and controls a conduction phase of the phase control device so that the detection signal is constant. In addition, power is supplied to the load via a saturable insulating transformer. As a result, if the load is opened, such as when the load is disconnected, the magnetic core of the saturable transformer is saturated, the primary impedance is lowered, and power can be supplied to another load (insulation transformer) connected in series. Yes.
[0002]
In addition, it has been proposed that an abnormal state such as an open load is detected by detecting distortion on a phase control voltage waveform that appears when a saturable magnetic core is saturated. That is, the presence / absence of load abnormality is detected based on whether or not distortion occurs within a specific phase range of the phase control voltage waveform.
[Problems to be solved by the invention]
In the prior art, a voltage waveform whose phase is controlled for constant current output is output, which originally includes a distortion component. Therefore, detecting the strain that appears when the saturable magnetic core is saturated when the load is abnormal and detecting the abnormality actually requires a complicated filter circuit and a determination circuit, which is one factor in increasing the price. Also, when using a transformer with an intermediate tap at the output stage of the constant current supply device and dimming lighting by switching the tap, the distortion generation phase and distortion component differ depending on the tap, making it difficult to detect abnormalities with high accuracy. Met.
[0003]
An object of this invention is to provide the series load electric power feeder which can detect the abnormal state of load with a simple structure with high precision.
[Means for Solving the Problems]
The invention according to claim 1 is a constant-current power supply device that outputs a low-frequency, non-phase-controlled, substantially sinusoidal voltage; and the primary windings are connected in series with each other and supplied with the output of the constant-current power supply device. A plurality of saturable transformers supplying power to each load from the secondary winding; and detecting a signal corresponding to the current flowing in the primary winding of the saturable transformer connected in series, Current control means for controlling the output of the constant current power supply so that the flowing current is constant even when some of the loads are released; the output current waveform and output voltage waveform of the constant current power supply Load abnormality detection means for detecting at least one of the detected waveforms and a difference between the detected waveform and the sine wave waveform or a differential value of the detected waveform to detect an abnormality when a part of the loads is released ; It is characterized by having.
[0004]
In the invention described in claim 1 and the following invention, unless otherwise specified, each component and each term are defined as follows.
As the constant current power supply device, a high frequency generator such as an inverter or a chopper can be mainly configured. In this case, electronic components such as semiconductor switching elements can be mainly formed, which is advantageous for reduction in size and weight. The low frequency of the constant current power supply device is preferably set in the range of several Hz to 1 KHz centering on commercial frequencies of 50 Hz and 60 Hz. That is, a saturable transformer can be used if it is several Hz or more, and if it is 1 KHz or less, the problem of voltage drop due to stray capacitance and inductive impedance associated with wiring installed over a long distance can be reduced.
[0005]
The load abnormality detection means detects at least one of the output current waveform and the output voltage waveform of the constant current power supply device. In short, the detection waveform and sine wave when a part of the load is opened are used. Or the differential value of the detected waveform may be detected. Accordingly, it is not necessary to strictly detect the current waveform and voltage waveform between the output terminals of the constant current power supply device, and the detection location is not particularly limited. In addition, as a method of obtaining the difference between the detection waveform and the sine wave waveform or the differential value of the detection waveform, a method for obtaining the difference between the detection waveform and the reference sine wave waveform, the detection waveform is input to the sine wave blocking filter, and the output is obtained. A method for monitoring, a method for differentiating the detected waveform, and the like are conceivable. Moreover, you may make it detect only whether a peak value exceeds predetermined value.
[0006]
According to the first aspect of the present invention , when a part of the load is opened, the saturable transformer corresponding to the load is saturated and power can be supplied to another load. However, when the load is released, the output current of the constant current power supply does not substantially flow until the transformer changes from non-saturated to saturated, so the waveform changes from unsaturated to saturated compared to the sine waveform. It becomes a waveform that is cut off until it is done. The output voltage is a large value until the transformer changes from non-saturation to saturation, and after the transformer is saturated, the output voltage is normal. The load abnormality detecting means obtains a difference or differential value from the sine waveform for these waveforms, detects and notifies the load abnormality, and records it as necessary. In this case, the output current waveform and the output voltage waveform when the load of the constant current power supply device is normal are substantially sine waves, so that the above difference can be clearly detected, and the output waveform of the constant current power supply device depends on the characteristics of the saturable transformer. The differential value becomes large due to a sudden change and can be clearly detected. Accordingly, the circuit configuration can be simplified and the detection accuracy can be improved. Even when the load is abnormal, the constant current power supply device can supply a constant current in terms of average value or effective value to other loads.
[0007]
The invention according to claim 2 is a DC power supply device; a high-frequency generator that switches the output of the DC power supply device and outputs a high-frequency voltage that is PWM-controlled so as to correspond to a low-frequency substantially sinusoidal component; Filter means for removing a high-frequency component from the output of the high-frequency generator and outputting a substantially sinusoidal voltage; primary windings connected in series with each other and supplied with the output of the filter means; And detecting a signal corresponding to the current flowing in the primary winding of the saturable transformer connected in series, and supplying the current flowing in the primary winding to one of the loads. high frequency generator and a current control means for PWM controlling the high-frequency voltage of the device to a constant reduction even when the load is open parts; transformer powered by the current waveform of the saturable type, detecting at least one of the voltage waveform , Part of the load of the each load in accordance with the differential value of the difference or the detected waveform with these detected waveform and the sine waveform and the abnormal load detection means for detecting an abnormality when opened; that comprises a It is characterized by.
[0008]
In the second aspect of the invention, the means for detecting a signal corresponding to the current of the current control means may also be used as the current waveform detection means of the load abnormality detection means. In this case, the number of parts can be reduced to reduce the size, weight and cost.
[0009]
According to the invention of claim 2, the high frequency voltage of the high frequency generator is PWM-controlled by the current control means in accordance with the current flowing through the saturable transformer. Therefore, the current supplied to the saturable transformer (load) connected in series via the filter means is constant. When the load becomes abnormal, the load abnormality detection means detects the load abnormality as in the first aspect of the invention. Further, when the constant current control by PWM control is performed in an average value or an effective value, a constant current can be continuously supplied to other loads.
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to FIG. 1 and FIG.
FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining the operation. Reference numeral 1 denotes a constant current power supply device that outputs, for example, a 50 Hz sine wave AC voltage. In FIG. 1, a DC power supply device 2, an output variable high frequency generator 3 for switching the output of the DC power supply device 2, and a filter means 4 for removing a high frequency component from the output of the high frequency generator 3 are provided. . The high frequency generator 3 is controlled in switching by the oscillation control means 5 and can change its output. The oscillation control means 5 changes its output in response to a feedback signal described later, details of which will be described later.
[0010]
The output of the filter means 4 is supplied to a plurality of saturable transformers (current transformers) 7 and 7 connected in series via an output transformer 6. Loads 8 and 8 are connected to the saturable transformers 7 and 7, respectively. In FIG. 1, the loads 8 and 8 indicate a light bulb. However, when used as a constant current power supply device for a marker lamp at an airport, the loads 8 and 8 are embedded in the ground or installed on the ground. It becomes a beacon light.
[0011]
Next, a configuration for feedback control of the oscillation control means 5 will be described. A current transformer as a current detecting means 9 is inserted on the secondary winding side of the signal output transformer 6 to detect the current of the secondary winding, that is, the current flowing through the loads 8 and 8. The output of the current detection means 9 is input to the negative terminal of the error amplifier 11 via the effective value conversion means 10. A reference signal source 12 is connected to the positive terminal of the error amplifier 11, and its output is inputted to one input terminal of the multiplier 13. A signal from the reference sine wave signal source 14 is input to the other input terminal of the multiplier 13, and the oscillation control means 5 is controlled by a signal multiplied by the output of the error amplifier 12.
[0012]
The detection signal of the current detection means 9 is also input to the load abnormality detection means 15. The load abnormality detection unit 15 includes a rectification unit 16, a differential calculation unit 17, a comparison unit 19, a latch unit 20, and a notification unit 21 that compare the output of the differential calculation unit 17 and the output from the reference signal source 18. .
[0013]
Next, the operation of this embodiment will be described. When the loads 8 and 8 are normal, a constant sine wave voltage as shown in FIG. 2 (a) is output from the constant current power supply 1 and is passed through each of the saturable transformers 7 and 7. Are supplied to each load 8,8. The load current at this time is detected by the current detection means 9, and an error from the reference signal is detected by the error amplifier 11, and is input to the multiplier 13. The multiplier 13 inputs the signal multiplied by the reference sine wave signal to the oscillation control means 5 and controls the oscillation control means 5. Therefore, the high frequency generator 3 changes the output, and as a result, the amplitude of the sine wave voltage is controlled in the output of the filter means 4 and the currents of the loads 8 and 8 are made constant.
[0014]
The detection signal of the current detection means 9 is also input to the load abnormality detection means 15. When the loads 8 and 8 are normal, the current waveform is a substantially sine wave as shown in FIG. 2 (a), so the output of the differential calculation means 17 is zero or minute and does not detect a load abnormality. . When any one of the loads 8, 8 is in an abnormal state such as an open state, the saturable transformer connected to the abnormal load repeats the state change from the non-saturated state to the saturated state every half cycle of the AC voltage. Therefore, the current waveform detected by the current detection means 9 is as shown in FIG. When the waveform as shown in FIG. 2 (b) is input, the output of the differential calculation means 17 increases, and when the signal of the reference signal source 18 is exceeded, the comparison means 19 outputs a load abnormality signal, and the notification means 21 Notifying and latching by the latch means 20.
[0015]
FIG. 3 is a circuit diagram showing an embodiment of the high-frequency generator. FIG. 4 is a simplified waveform diagram showing the output voltage waveform of the high frequency generator and the output voltage waveform of the filter means. The high-frequency generator shown in FIG. 3 mainly includes four switching devices 31, 32, 33, and 34 that are bridge-connected. The switching devices 31, 32, 33, and 34 are conductivity modulation type field effect transistors (IGBT). These switching devices 31, 32, 33 and 34 are controlled to be turned on / off by the oscillation control means 5. In the present embodiment, the switching devices 31 and 34 are synchronized and the other switching devices 32 and 33 are synchronized and turned on and off, and the switching devices 31 and 34 are switched on and off with the switching devices 32 and 33. Are controlled to be reversed. Then, a high-frequency voltage that is PWM-controlled so as to include a low-frequency substantially sine wave component is output. FIG. 4A shows such a high-frequency voltage. The ON period is large in the portion where the crest value of the sine wave voltage (FIG. 4B) is large, and the ON period is small in the portion where the peak value is small. Even in the negative half cycle of the sine wave ((b) in the figure), the controlled high frequency voltage is obtained. Such a high-frequency voltage is input to the filter means 4, and the high-frequency component is removed and output as a substantially sine wave voltage as shown in FIG.
【The invention's effect】
According to the first and second aspects of the present invention, the load current value is stabilized at a predetermined value while supplying a low-frequency substantially sinusoidal voltage to the load, and the output voltage waveform, the output current are stabilized. Since at least one of the waveforms is detected and an abnormality at the time of load release is detected according to the difference between the detected waveform and the sine waveform or the differential value of the detected waveform, the configuration of the filter circuit, judgment circuit, etc. is simplified The price can be reduced to improve the accuracy of abnormality detection.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of the present invention. FIG. 2 is a waveform diagram for explaining the operation. FIG. 3 is a circuit diagram showing an embodiment of a high-frequency generator according to the present invention. Waveform diagram showing simplified output voltage waveform and output voltage waveform of filter means
DESCRIPTION OF SYMBOLS 1 ... Constant current power supply device, 3 ... High frequency generator, 4 ... Filter means, 5 ... Oscillation control means, 6 ... Output transformer, 7 ... Saturable type transformer, 8 ... Load, 15 ... Load abnormality detection means.

Claims (2)

A constant-current power supply device that outputs a low-frequency, non-phase controlled, substantially sinusoidal voltage;
A plurality of saturable transformers in which primary windings are connected in series with each other and supplied with an output of a constant current power supply, and each secondary winding supplies power to each load;
A signal corresponding to the current flowing in the primary winding of a saturable transformer connected in series is detected, and the current flowing in the primary winding is made constant even when some of the loads are opened. Current control means for controlling the output of the constant current power supply device;
At least one of the output current waveform and output voltage waveform of the constant current power supply is detected, and some of the loads are opened according to the difference between the detected waveform and sine waveform or the differential value of the detected waveform . A load abnormality detecting means for detecting an abnormality at the time ; and a series load power supply device. A DC power supply;
A high-frequency generator that outputs a high-frequency voltage that is PWM-controlled so as to correspond to a low-frequency substantially sine wave component;
Filter means for removing a high frequency component from the output of the high frequency generator and outputting a substantially sinusoidal voltage;
A plurality of saturable transformers having primary windings connected in series with each other and supplied with the output of the filter means to feed each load from each secondary winding;
A signal corresponding to the current flowing in the primary winding of a saturable transformer connected in series is detected, and the current flowing in the primary winding is made constant even when some of the loads are opened. Current control means for PWM-controlling the high-frequency voltage of the high-frequency generator;
At least one of the current waveform and voltage waveform supplied to the saturable transformer is detected. Depending on the difference between the detected waveform and sine waveform or the differential value of the detected waveform , some of the loads A load abnormality detecting means for detecting an abnormality when opened ; and a series load power supply device.

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