JP4237451B2 - Power control power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control power supply apparatus that approximates a constant power control power supply that outputs a load power fluctuation caused by a voltage fluctuation.
[0002]
[Prior art]
FIG. 5 is a circuit diagram of a conventional constant power control power supply device. For a discharge lamp such as a xenon lamp, the impedance of the lamp increases at the end of its life, the load voltage rises, the power consumption becomes excessive, and the lamp may burst. In order to prevent this destruction and not to shorten the service life, a constant power control power supply device that controls the load power to a constant power has been used. However, the constant power control increases the number of parts of the control circuit, which increases the manufacturing cost. It was expensive.
[0003]
As shown in FIG. 5, the power of the commercial power source 1 is connected to the input terminals 2a and 2b, and the DC power rectified by the DC power source 3 is controlled by the DC-DC converter 4 and supplied to the load 6. . When the load 6 has a negative impedance characteristic like a discharge lamp, it is necessary to stabilize power consumption. The DC-DC converter 4 includes an inverter 4a, a transformer 4b, and a rectifier circuit 4c. 5p is an output terminal (positive), 5n is an output terminal (negative), and a load (lamp) 6 is connected. Reference numeral 11 denotes a current detector that detects a current flowing through the load 6. A voltage detection circuit 12 detects a voltage applied to the load 6. The current signal and the voltage signal detected by the current detector 11 and the voltage detection circuit 12 are connected to the multiplier 13, and the result of the arithmetic processing by the multiplier 13 is detected as a power signal. The output signal of the error amplifier 14 is supplied to the PWM signal generator 15 so that feedback control is performed to compare the output signal of the multiplier 13 with the built-in reference power signal and to make the error zero. A signal for driving the control element of the DC-DC converter 4 is generated. In addition, a power supply device (not shown) that supplies the load 6 with constant power control of the AC output of the inverter 4a has also been manufactured by a power signal detection method using a multiplier similar to the above. Since the power controlled in this way is controlled to be equal to the value of the built-in reference power signal, it is possible to achieve a constant power with high constant power so that the output is constant power.
[0004]
However, since the multiplier that calculates the product of the detected voltage and current converts the analog signal into a digital signal and stores it, it calculates by repeatedly adding the stored signal to calculate this product. Many memory elements and semiconductor elements for calculation were required. As the number of parts of this multiplier increased, the reliability was lowered. The environment in which such a power supply is installed is often used in a hot and humid environment with a lot of dust, so there is a strong demand for few failures, and even if the accuracy of constant power control is low, the power There has been a strong demand for a control technology that can provide the device at a low cost.
[0005]
[Problems to be solved by the invention]
Constant power control may have a substantially constant power characteristic that prevents excessive power, and the challenge is to meet demands for reducing the number of parts to achieve high reliability and low cost. It is an object of the present invention to provide a power supply device that outputs constant power.
[0006]
[Means for Solving the Problems]
Experiments focused on obtaining signals approximating power detection by eliminating arithmetic processing by the multipliers described above, and as a result of technical studies, created voltage approximation detection means, without using multipliers. By adding the current detection signal and the approximate voltage detection signal with an adder to make the error from the reference voltage zero, the approximate power control characteristic can be obtained.
[0007]
The invention of claim 1 is a load having a negative impedance characteristic such as a discharge lamp, a current detector for detecting a current supplied to the load, a voltage approximation detecting means for detecting a voltage supplied to the load, An addition amplifier circuit that amplifies an error by comparing an output signal of the current detector and an output signal of the voltage approximation detecting means with a reference voltage signal as an input signal, and an output signal of the addition amplifier circuit as an input signal of a PWM signal generator In the power control power supply apparatus comprising the PWM signal generator for driving the converter as the voltage approximate detection means, the voltage approximation detection means is the first to sixth resistors, and the emitter and collector are the fifth and sixth resistors, respectively. A transistor connected in series to one terminal, a voltage obtained by dividing a voltage supplied to the load by the first resistor and the second resistor, and the third resistor The voltage is divided by the fourth resistor and connected to the base of the transistor, and a series connection comprising the fifth resistor, the sixth resistor, and the transistor is in parallel with the second resistor, and The output voltage between the other terminal of the fifth resistor and the other terminal of the sixth resistor is connected in series with the first resistor, and two straight lines having different slopes and the curve of the transistor A characteristic is that the two straight lines are smoothly connected in the vicinity of the connection point due to the rising characteristics .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment according to the present invention will be described. FIG. 1 is a circuit diagram according to an embodiment of the present invention. A DC power source unit 3 is connected to the input terminals 2a and 2b connected to the commercial power source 1, and a DC-DC converter 4 is connected thereto. The DC-DC converter includes an inverter 4a, a transformer 4b, and a rectifier circuit 4c, to which a 5p output terminal (positive) and a 5n output terminal (negative) are connected. A load 6 is a discharge lamp having a negative impedance such as a high-pressure mercury lamp.
[0013]
A current detector 11 detects the amount of current flowing through the load 6. Reference numeral 121 denotes voltage approximation detection means for detecting the voltage applied to the load 6. The output signals of the current detector 11 and the voltage approximation detection means 121 are input signals to the summing amplifier circuit 131. The addition amplifier circuit 131 adds the voltage detection value and the current detection value, amplifies the error from the built-in reference value, supplies the amplified output signal to the PWM signal generator 15 as an input signal, and outputs the PWM signal. A function of driving the inverter 4a with the output signal of the generator 15 to control substantially constant power and supplying it to the load is provided.
[0014]
2 is an internal circuit diagram of the voltage approximation detection means 121, 51p is an input terminal (positive) of the approximation detection means, 51n is an input terminal (negative) of the approximation detection means, 52p is an output terminal (positive) of the approximation detection means. ), 52n are output terminals (negative) of the approximate detection means. Q1 is a transistor, R1 is a first resistor, R2 is a second resistor, R3 is a third resistor, R4 is a fourth resistor, R5 is a fifth resistor, and R6 is a sixth resistor.
[0015]
In the voltage approximation detection means, a voltage obtained by dividing the voltage supplied to the load 6 by the first resistor R1 and the second resistor R2 appears at both ends of the second resistor R2. The divided voltage is further divided by the third resistor R3 and the fourth resistor R4 and connected to the base of the transistor Q1, and the fifth resistor R5 and the second resistor R5 are connected in series to the emitter and collector of the transistor Q1, respectively. A series connection body to which one terminal of the six resistors R6 is connected is connected in parallel to the second resistor R2 and in series to the first resistor R1. A linear change in the voltage supplied to the load 6 between the other terminal of the fifth resistor R5 and the other terminal of the sixth resistor R6, that is, the voltage output to both ends of the series connection body is curvilinear. The property output as change was used. Improvement of the broken line approximation that connects two voltage lines having different gradients and correcting the bent portion of the two voltage lines into a curve has been realized by using the curved rising characteristics of the transistor Q1.
[0016]
FIG. 3A is a relationship curve between the input voltage Vi and the output voltage Vd of the voltage approximation detecting unit 121 of FIG. This curve is formed by smoothly connecting two curves having different gradients described in FIG. 4 in the vicinity of the connection point. FIG. 3B shows the output voltage of the power supply device obtained when the control power supply device of FIG. 1 is activated by adding the voltage detection value and the current detection value when the voltage detection is made by connecting the bent portions with a curve. The relationship of output current is shown. Before explaining the characteristic curve of FIG. 3B, FIG. 4 will be described as a prelude to the explanation.
[0017]
Here, the approximate constant power characteristic will be described. FIG. 4A is a voltage detection characteristic curve obtained by detecting the output voltage of the power supply device through a specific circuit. Here, it is a characteristic curve composed of two straight lines with different gradients connected at the bending point P1. In this case, the voltage detection value and the current detection value are added, and the output voltage of the power supply device obtained when the control power supply device of FIG. 1 is activated by error amplification between the added signal and the built-in reference value. FIG. 4B shows the relationship between the output currents. The output characteristic in such a case will be referred to as an approximate constant power characteristic by two-line broken line approximation. In the vicinity of the inflection point P2 of the output characteristic of FIG.
[0018]
Returning to FIG. 3 and continuing the description, the curve in FIG. 3A is a relationship curve between the input voltage Vi and the output voltage Vd of the voltage approximation detecting means 121. This curve is obtained by smoothly connecting the two straight lines described in FIG. 4 in the vicinity of the connection point. The output of this voltage detection is a characteristic that appears between the output terminals 52p and 52n when the input terminals 51p and 51n of the voltage approximate detection means 121 shown in FIG. 2 are connected to the output terminals 5p and 5n of the power supply device of FIG. And the vicinity of the bending point P is corrected.
[0019]
In this case, the voltage detection value and the current detection value are added, and the relationship between the output voltage and the output current of the power supply device obtained when the control power supply device of FIG. The actual measurement value is shown by the plot in FIG. While there is shown a characteristic of constant power output of theory with a dotted line, and the measured value is reflected in between dotted dashed and negative 7W of 150W plus 7W of this theory. If voltage approximate detection means obtained by correcting the voltage detection value as indicated by the above actual measurement values is used, an output signal to be supplied to the PWM signal generator can be obtained by the addition amplifier circuit without using a multiplier. There was found.
[0020]
Although not shown, the same control can be performed even with a power supply device that replaces the DC-DC converter with an inverter and supplies alternating current to the load. For discharge lamps that are economical to operate with high-frequency alternating current, inverters that output higher frequency power than commercial power supplies are used.
[0021]
【The invention's effect】
According to the present invention, it is possible to manufacture a control power supply device that can be inexpensively approximated to constant power control by eliminating the multipliers that require a large number of parts and thus disadvantageous in reliability, and thus installing a large number of discharge lamps. The facility has low equipment costs, has few failures even in adverse environments, reduces the burden of maintenance costs, prevents troubles such as explosion of the discharge lamp, prolongs lamp life, and contributes to resource saving. Great value.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a power supply device according to an embodiment of the present invention.
FIG. 2 is a circuit diagram for explaining a main part according to an embodiment of the present invention.
3A and 3B are characteristic diagrams according to the embodiment of the present invention.
4A and 4B are characteristic diagrams for explaining the principle of operation.
FIG. 5 is a circuit diagram of a conventional power supply device.
[Explanation of symbols]
1 commercial power supply,
2a input terminal 2b input terminal 3 DC power supply unit 4 DC-DC converter 4a inverter 4b transformer 4c rectifier circuit 5p output terminal (positive)
5n Output terminal (negative)
6 Load (lamp)
DESCRIPTION OF SYMBOLS 11 Current detector 12 Voltage detection circuit 13 Multiplier 131 Addition amplifier circuit 14 Error amplifier 15 PWM signal generator 121 Voltage approximate detection means 51p Input terminal (positive) of approximate detection means
51n Input terminal of approximate detection means (negative)
52p Output terminal of approximate detection means (positive)
52n Output terminal of approximate detection means (negative)
Q1 Transistors R1, R2, R3, R4, R5, R6 Resistance Vi Input voltage Vd of voltage approximation detection means Output voltage of voltage approximation detection means

Claims (1)

A load having a negative impedance characteristic such as a discharge lamp; a current detector for detecting a current supplied to the load; a voltage approximation detecting means for detecting a voltage supplied to the load; and an output signal of the current detector And an addition amplification circuit that amplifies the error by comparing the output signal of the voltage approximation detection means with the reference voltage signal as an input signal, and a PWM signal that drives the converter with the output signal of the addition amplification circuit as an input signal of the PWM signal generator In the power control power supply apparatus comprising the generator, the voltage approximation detection means includes a first to sixth resistors, and an emitter and a collector connected in series to one terminal of the fifth and sixth resistors, respectively. A voltage obtained by dividing the voltage supplied to the load by the transistor, the first resistor, and the second resistor is divided by the third resistor and the fourth resistor. And a series connection comprising the fifth resistor, the sixth resistor, and the transistor is connected in parallel with the second resistor and in series with the first resistor. The output voltage between the other terminal of the fifth resistor and the other terminal of the sixth resistor has two straight lines with different slopes and the two straight lines due to the curved rising characteristics of the transistor. A power control power supply device characterized by comprising a curve smoothly connected in the vicinity of a connection point .

Images