JP2647668B2 - Voltage controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage control device used for an emergency light or the like that uses a battery to turn on an incandescent lamp or the like.

[Conventional technology]

As shown in FIG. 7, a conventional emergency light lighting device rectifies an AC voltage of an AC power supply E by a full-wave rectifier DB via a step-down transformer T, and converts the obtained full-wave rectified voltage to a resistor R. It is smoothed by a resistor R ₆₅ of the capacitor C ₁₁ and its discharge through _51. Smoothed voltage appearing across the capacitor C ₁₁ charges the battery B through the diode D _2, and also supplies the operating power to the operational amplifier OP _7, OP ₈ through a resistor R ₅₈ and diode D _3, further operational amplifier OP ₇ Resistor R at the non-inverting input of
Voltage is applied through ₅₈ and diode D _4.

Voltage applied to the non-inverting input of the operational amplifier OP ₇ is sufficiently high, thus the voltage applied to the inverting input of operational amplifier OP ₇ is output from the operational amplifier OP ₈ is outputted from the triangular wave generating circuit OS in a non-inverting sufficiently higher than the voltage applied to the input terminal of the operational amplifier OP _8, the voltage input is output from the operational amplifier OP ₈ to the base of the transistor Q ₂ is always to maintain a low level . As a result, the transistor Q ₂ are transistors ₁ also normally off normally off, not powered the load L consisting of incandescent lamps, the load L does not emit light.

_{Incidentally, R 55 ~R 57, R 61} , R 62, R 63 are each resistor.
The triangular wave generation circuit OS is composed of inverting amplifiers I ₄ , I ₅ , I ₆ , capacitors C ₁₃ , C ₁₄ and resistors R ₅₉ , R _60, and the frequency is set to 100 Hz or more.

Next, when the alternating-current power supply E is power failure, the electric charge of the capacitor C ₁₁ is discharged through the resistor R _65, etc., as a result the capacitor C
The voltage at both ends of ₁₁ gradually decreases. Capacitor C ₁₁
Of the voltage across decreases, calculating the voltage at the non-inverting input of amplifier OP ₇ also decreases, thus the voltage applied to the inverting input terminal of the output from the operational amplifier OP ₇ and the operational amplifier OP ₈ is also decreased it becomes lower than the output voltage of the triangular wave generating circuit OS, the output voltage of the operational amplifier OP ₈ is a high level conducting transistor Q ₂ is the transistor Q ₁ becomes to conduct, the power supply from the battery B to the load L Is started,
The incandescent lamp which is the load L is turned on. At this time,
Also it decreases the voltage across the capacitor C _11, via a resistor R ₆₄ and a Zener diode ZD ₅ from the battery B operational amplifier
Since the supply of the operating power to OP ₇ and OP ₈ is continued, the operational amplifiers OP ₇ and OP ₈ operate without any trouble.

When a load L incandescent lamp lights, instead of the voltage across the capacitor C _11, the voltage that the voltage across the load L resistors R _52, R _53, R ₅₄ and to the partial pressure and mean at the capacitor C ₁₂ It applied to the non-inverting input of the operational amplifier OP _7,
After this voltage is amplified at the amplification determined by the resistors R ₅₅ and R ₅₆ , it is applied to the inverting input terminal of the operational amplifier OP ₈ .

In the operational amplifier OP _8, it compares the voltage corresponding to the average value of the voltage across the load L to the non-inverting triangular wave voltage applied to the input terminal and applied to the inverting input, and an output when the former is larger in high level The transistors Q ₂ and Q ₁ are turned on to supply power to the load L, and when the latter is large, the transistors Q ₂ and Q ₁
And shut off the power supply. As a result, when the average value of the voltage between both ends of the load L is large, the on-time of the transistors Q ₂ and Q ₁ is shortened and the off time is lengthened, and when the average value of the voltage between both ends of the load L is small, the transistor Q ₂ , the shorter the off time with the on-time for Q ₁ becomes longer, the change in the on-off operation of the transistor Q _2, Q _1, the average value of the voltage across or pulse voltage of the load L is controlled to be constant.

Conventional emergency lamp lighting apparatus described above for [invention attempt to resolve the problem to] detects the average value of the pulse voltage applied across the load L, and the on-off control of the transistor Q ₁ as the average value is constant I was going. In this case, in FIG. 8, the on-time voltage V _ON to the load L the transistor Q ₁ is turned on is applied T
And _ON, as T _OFF OFF time of the voltage applied to the load L the transistor Q ₁ is turned off becomes zero, the duty ratio D of the pulse _{voltage, D = T ON / (T} ON + T OFF) ... .., The average value V _AVE of the pulse voltage applied to both ends of the load L is represented by V _AVE = D · V _ON. The average value V _{AVE of the} pulse voltage is controlled to be constant.

By the way, when a pulse voltage is applied to the load L, the power P supplied to the load L is P = D · I _ON · V _ON when the current flowing through the load L by the voltage V _ON is I _ON. Becomes

If the load L is a constant load with a resistance value R, V _ON = R · I _ON ... Holds, so that the power consumption P is P = D · I _ON · V _ON = D · V _ON. (V _ON / R) = V _AVE · (V _ON / R) ... However, V _AVE and R are constant.

According to the above equation, a change in the voltage V _ON appears in the power consumption P,
Even if the average value of the pulse voltage is controlled to be constant, the power supplied to the load L is not constant, and when the load L is an incandescent lamp, the brightness changes due to a decrease in the voltage of the battery B. became.

In order to keep the power P supplied to the load L constant, it is necessary to detect the power supplied to the load L and compare it with a reference value. When the load L is a constant load, the effective value of the pulse voltage or the effective value of the pulse current is detected, and if the value is controlled so as to be constant, the power supplied to the load L can be kept constant. Can be.

However, detecting the effective value of the power, pulse voltage, and pulse current requires a complicated arithmetic circuit.
There is a problem that the cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a voltage control device capable of constantly controlling power supplied to a load with a simple and inexpensive configuration.

[Means for solving the problem]

In the voltage control device of the present invention, a switching element for supplying power from the battery to the load in a pulsed manner is inserted between the battery and the load driven by the battery, and the switching element is turned on and off by a switching control circuit. Further, the first and second detection circuits respectively detect different first and second detection items among the detection items of the peak value, the average value, and the duty ratio of the pulse voltage applied to the load, and perform switching control. The detection output of the first detection circuit follows the target value by changing the ratio between the on time and the off time of the switching element according to the difference between the detection output of the first detection circuit and the target value. Control. Further, the first value in the condition that the effective value is constant in the arithmetic circuit
The value of the first detection item corresponding to the detection output of the second detection circuit is calculated in accordance with the relationship between the first detection item and the second detection item, and is given as a target value from the arithmetic circuit to the switching control circuit.

[Action]

According to the configuration of the present invention, different first and second detection items among the detection items of the peak value, the average value, and the duty ratio of the pulse voltage applied to the load are determined by the first and second detection circuits. The detection output of the first detection circuit is detected by the switching control circuit, and the ratio between the on time and the off time of the switching element is changed according to the difference between the detection output of the first detection circuit and the target value. Is controlled so as to follow the target value, and the first detection item corresponding to the detection output of the second detection circuit in accordance with the relationship between the first and second detection items under the condition that the effective value is constant in the arithmetic circuit. Is calculated, and given as a target value from the arithmetic circuit to the switching control circuit, the power supplied to the load can be controlled to be constant.

Further, the first and second detection circuits only need to detect different first and second detection items among the detection items of the peak value, the average value, and the duty ratio of the pulse voltage applied to the load, It is possible to perform constant control of the power supplied to the load, and it is simple in construction and can be manufactured at low cost.

〔Example〕

One embodiment of the present invention will be described with reference to FIGS. This voltage control device, as shown in FIG.
Load L consisting of an incandescent lamp driven by battery B and battery B
A switching element I for supplying power from the battery B to the load L in a pulsed manner is interposed therebetween, and the switching element I is turned on and off by a switching control circuit IV. Further, among the detection items of the peak value, the average value, and the duty ratio of the pulse voltage applied to the load L, different first and second detection items are defined as first and second detection circuits I and II.
I and III, respectively, and the switching control circuit IV changes the ratio between the on-time and off-time of the switching element I according to the difference between the detection output of the first detection circuit II and the target value. Control is performed so that the detection output of the first detection circuit II follows the target value. Further, the arithmetic circuit V calculates the value of the first detection item corresponding to the detection output of the second detection circuit III according to the relationship between the first and second detection items under the condition that the effective value is constant, and calculates The circuit V gives the switching control circuit IV a target value.

In this case, the switching element I is turned on / off in accordance with the pulse signal given from the switching control circuit IV, so that the voltage applied to the load L is intermittent.

The first and second detection circuits II and III are provided, for example, when the first detection circuit II is configured to detect the peak value of the pulse voltage applied to the load L.
Is configured to detect either the average value of the pulse voltage applied to the load L or the duty ratio. Further, when the first detection circuit II is configured to detect the average value of the pulse voltage applied to the load L, the second detection circuit III
Is configured to detect any one of the peak value and the duty ratio of the pulse voltage applied to the load L. further,
When the first detection circuit II is configured to detect the duty ratio of the pulse voltage applied to the load L, the second detection circuit III detects the peak value and the average value of the pulse voltage applied to the load L. It becomes the structure which detects either one.

The switching control circuit IV includes a first detection circuit II.
And the output voltage of the arithmetic circuit V are input. If the output voltage of the first detection circuit II is larger than the output voltage of the arithmetic circuit V, the duty ratio D of the output pulse signal is reduced, that is, the switching element I Shorten the on-time and increase the off-time. If the output voltage of the first detection circuit II is smaller than the output voltage of the arithmetic circuit V, the duty ratio of the output pulse signal is increased, that is, the ON time of the switching element I is lengthened and the OFF time is shortened. Control operation.

Here, a specific configuration example of the first and second detection circuits II and III will be described with reference to FIG. First, the detection circuit DT ₁ for detecting an average value of the pulse voltage is a series circuit of the load L connected in parallel a resistor R ₄₁ and capacitor C _7, and obtains the average value by the integral operation, resistor R ₄₁ and capacitor voltage value corresponding to the average value of the pulse voltage from the connection point of the C ₇ is obtained.

Then, the detection circuit DT ₂ for detecting the duty ratio of the pulse voltage is composed of parallel connected resistor R ₄₂ and a Zener diode series circuit of ZD ₄ and Zener diode ZD ₄ connected in parallel with a capacitor C ₈ Metropolitan load L. Then, is set lower than the peak value of the pulse voltage applied to the Zener voltage V ₂ of the Zener diode ZD ₄ the load L. As a result, smoothed voltage value becomes D · V ₂ by the capacitor C _8. Therefore, the voltage value corresponding to the duty ratio of the resistors R ₄₂ and zener diode pulse voltage from the connection point of ZD ₄ are obtained.

Then, the detection circuit DT ₃ for detecting a peak value, a series circuit of a diode D ₁ and the resistor R ₄₃ connected in parallel to the load L, a capacitor C ₉ Metropolitan connected in parallel to the resistor _43. This circuit, since the cut off discharge loop to the load L with a diode D _1, it is possible to obtain a voltage value corresponding to the peak value of the pulse voltage from the connection point of the diodes D ₁ and the resistor R _43.

Next, the detection circuit DT ₄ for detecting the peak value is composed of a series circuit of resistors R ₄₄ and R ₄₅ connected in parallel to the battery B.
From the connection point of R ₄₄ and R ₄₅ , the voltage of the battery B, that is, the voltage corresponding to the peak value of the pulse voltage can be obtained.

Further, as described above, the arithmetic circuit V calculates the value of the first detection item corresponding to the detection output of the second detection circuit III in accordance with the relationship between the first and second detection items under the condition that the effective value is constant. Is calculated. Hereinafter, the arithmetic circuit V will be described in detail.

Effective value V of pulse voltage applied to both ends of load L
_RMS is represented by the following equations.

V _RMS = D ^1/2 · V _ON …… V _RMS = (V _AVE · V _ON ) ^1/2 …… V _RMS = V _AVE / (D ^1/2 )… Now, the effective value of the pulse voltage V _RMS Is constant, that is, V _RMS = C..., D = C ² / V _ON ² ... V _AVE = C ² / V _ON ... D = V _AVE / C ^2. Become. Therefore, if any one of the peak value, the average value, and the duty ratio of the pulse voltage applied to the load L satisfies one of the above expressions, the power supplied to the load L becomes constant. The arithmetic circuit V operates according to the detection items of the first and second detection circuits II and III.
, Or an expression based on any one of the expressions.

FIG. 3 is a graph in which the equation is calculated with a constant effective value within a certain voltage section, and the voltage V _ON applied to the load L when the pulse voltage is at a high level under the condition that the effective value is constant.
5 shows the relationship with the average value V _AVE of the pulse voltage applied to the load L. In this graph, assuming that the battery voltage range in which the power to the load L can be controlled to be constant is, for example, 3.3 V to 4.5 V, when the voltage V _ON is 3.3 V, the average value of the pulse voltage V _AVE
To 3.3 V, and the average value V of the pulse voltage when the voltage V _ON is 3.6 V
_If the average value of the pulse voltage V _AVE is controlled so that _AVE is 3.0 V and the average value V _AVE of the pulse voltage is 2.8 V when the voltage V _ON is 3.9 V, the effective value of the pulse voltage is constant. It indicates that you can do it.

FIG. 4 is a graph in which the equation is calculated with a constant effective value within a certain voltage section, and the voltage V _ON applied to the load L when the pulse voltage is at a high level under the condition that the effective value is constant.
And the duty ratio D of the pulse voltage applied to the load L. In this graph, when the battery voltage range in which the power can be controlled to be constant to the load L is, for example, 3.3 V to 4.5 V, when the voltage V _ON is 3.3 V, the duty ratio D of the pulse voltage is set to 100%, If the duty ratio D of the pulse voltage is controlled so that the duty ratio D of the pulse voltage becomes 85% when V _ON is 3.6V and the duty ratio D of the pulse voltage becomes 72% when the voltage V _ON is 3.9V, And that the effective value of the pulse voltage can be made constant.

Now, if the first detection circuit II detects the average value V _AVE of the pulse voltage and the second detection circuit III detects the _peak value of the pulse voltage, that is, the voltage V _ON , the arithmetic circuit V becomes Calculates the effective value V _RMS for the current voltage V _ON
Is calculated so that the average value _VAVE of the pulse voltage becomes constant (see FIG. 3).

The first detection circuit II detects the duty ratio D of the pulse voltage, when the second detection circuit III is configured to detect the peak value or voltage V _ON of the pulse voltage, the arithmetic circuit V the calculation of the formula The effective value V with respect to the current voltage V _ON
The target value of the duty ratio D of the pulse voltage so that the _RMS is constant is calculated (see FIG. 4).

Further, when the first detection circuit II detects the duty ratio D of the pulse voltage and the second detection circuit III detects the average value V _AVE of the pulse voltage, the operation circuit V performs the operation of the equation. Thus, the target value of the duty ratio D of the pulse voltage is calculated such that the effective value V _RMS becomes constant with respect to the current average value V _AVE .

Note that when the first detection circuit II detects the voltage V _ON and the second detection circuit III detects the duty ratio D, the arithmetic circuit V performs the inverse operation of the equation. Also, the first
When the detection circuit II detects the voltage V _ON and the second detection circuit III detects the average value V _AVE , the arithmetic circuit V performs the inverse operation of the equation. Further, when the first arithmetic circuit II detects the average value V _AVE and the second detection circuit III detects the duty ratio D, the arithmetic circuit V performs the inverse operation of the equation.

The voltage control device determines different first and second detection items among the detection items of the peak value, the average value, and the duty ratio of the pulse voltage applied to the load L to the first and second detection items.
Detection circuits II and III
By changing the ratio between the on-time and off-time of the switching element I according to the difference between the detection output of the first detection circuit II and the target value by the IV, the detection output of the first detection circuit II is changed to the target value. And the arithmetic circuit V controls the first detection item corresponding to the detection output of the second detection circuit III in accordance with the relationship between the first and second detection items under the condition that the effective value is constant. Since the value is calculated and given as the target value from the arithmetic circuit V to the switching control circuit IV, the power supplied to the load L can be controlled to be constant.

Next, a specific circuit configuration of the voltage control device will be described with reference to FIGS. In the voltage controller shown in Fig. 5, the switching element I is composed of a switching transistor TR _1.

The first detection circuit II is configured to detect a value obtained by dividing a pulse voltage applied to both ends of the load L and averaging the divided voltage.
It is composed of R ₈ , R ₉ , R ₁₀ and a capacitor C _4, and the time constant of the resistor R ₈ and the capacitor C ₄ is set sufficiently large with respect to the frequency of a triangular wave generating circuit described later.

The second detection circuit III is configured to detect the peak value of the battery B, that is, the voltage at both ends of the battery B, and includes resistors R ₁₈ , R
It consists of _nineteen .

The arithmetic circuit V is for performing approximate calculation of equation (linear approximation), is composed of an operational amplifier OP ₃ and resistor R ₁₃ to R ₁₇ and zener diode ZD _1, a resistor R ₁₃ and the resistor R ₁₆ is The resistance values are set equal, and the resistance values of the resistors ₁₄ and ₁₅ are set equal.

The switching control circuit IV includes a differential amplifier IVA for detecting a difference between an output voltage of the arithmetic circuit V and an output voltage of the first detection circuit II, and a triangular wave generating circuit for generating a triangular wave voltage.
IVB, output voltage of differential amplifier IVA and triangular wave generation circuit IV
And a comparison circuit IV C turning on and off the switching transistor TR ₁ and the pulse signal generated by comparing the output voltage of the B.

The differential amplifier IV A, operational amplifier is composed of OP ₂ and the resistor R ₃ to R ₇ and the capacitor C ₁ Tokyo, and the resistor R ₄ and the resistor R ₇ to set the resistance value equal, also resistors R ₅ and the resistor R _{6 has the same} resistance value. Further, the triangular wave generating circuit IV B is composed of the inverting amplifier I ₁ ~I ₃ resistors R _11, R ₁₂ and capacitor C _2, C ₃ Prefecture. Further, the comparison circuit IV C includes an operational amplifier OP ₁ and a resistor R ₁ ,
Consisting of R ₂ and the transistor TR ₂ Metropolitan.

 Here, the operation of the switching control circuit IV will be described.

Differential amplifier IV A includes an operational amplifier output voltage V _A of the arithmetic circuit V to the inverting input of the OP ₂ is input, the output voltage V _B of the first detection circuit II is inputted to the non-inverting input terminal, operation Amplifier OP
From _second output terminal for outputting the voltage V _X, which is expressed by the following equation.

V _X = (R ₄ / R ₅ ) (V _B −V _A )... The comparison circuit IV C calculates the triangular wave voltage applied to the non-inverting input terminal of the operational amplifier OP _{1 and} the voltage V _X applied to the inverting input terminal. , And during the period when the triangular wave voltage is higher, the operational amplifier OP ₁
The output voltage to a high level to turn on the transistors TR ₂ and, therefore by turning on the switching transistor TR _1, to the voltage applied from the battery B to the load L. On the other hand, the voltage V _X
High period towards the output voltage of the operational amplifier OP ₁ in a manner to shut off the transistors TR ₂ low level (zero) to stop the application of voltage from the battery B to the load L. As a result, the load L
Is applied with a pulse voltage.

By so operating that it, when the first output voltage of the differential amplifier IV A by the change in the voltage V _B based on the drop in the voltage of the battery B output from the detection circuit II, i.e. V _X changes, the switching transistor TR ₁ is the time and the switching transistor TR ₁ which is energized from the battery B to the load L becomes oN is the ratio change between the time of voltage application to the load L turned off is stopped, the ratio calculation Amplifier OP ₂
Will be stabilized in a state where both input voltages are equal. In this case, when the voltage V _X decreases the voltage of the battery B is reduced, the switching transistor TR ₁ with on-time switching transistor TR ₁ is turned on is longer
The off time during which is turned off is shortened.

With such a control operation, the average value of the pulse voltage detected by the first detection circuit II follows the output (target value) of the arithmetic circuit V.

On the other hand, the output voltage V _{C of} the second detection circuit III and the voltage V _{D at} the connection point of the Zener diode ZD ₁ and the resistor R ₁₇ are equal to the inverting input terminal and the non-inverting input terminal of the operational amplifier OP ₃ constituting the differential amplifier. in are input, operational amplifier output from (R ₁₃ / R ₁₄₎ of the OP ₃ (V _D -V _C) voltage V _Y represented by will be is output, and now V _D> V _C since the V _D is set to a constant, when the voltage of the battery B is high becomes low voltage V _Y, the arithmetic circuit V becomes to have the input-output characteristic obtained by linear approximation characteristic of FIG. 3 for example, a battery The target value of the average value of the pulse voltage corresponding to the voltage B, that is, the peak value, is output. Then, this target value is supplied from the arithmetic circuit V to the operational amplifier.
It will be applied to the inverting input of the OP _2, so that the effective value of the pulse voltage is controlled to be constant.

In the voltage controller shown in FIG. 6, the switching element I is composed of a switching transistor TR _3.

The first detection circuit II is configured to detect the duty ratio of the pulse voltage applied to both ends of the load L, and to connect the resistors R ₂₆ , R
It is composed of ₂₇ and a capacitor C ₆ and a Zener diode ZD _2.

Second detection circuit III is the peak value of the battery B, ie a structure for detecting the voltage across the battery B, the resistor R _34, R
It consists of ₃₅ and.

The arithmetic circuit V performs an approximate operation of the equation,
Operational amplifier OP ₆ and resistors R ₂₈ to R ₃₃ and a Zener diode ZD ₃
And consists of the resistor and the R ₂₉ and the resistor R ₃₂ have set the resistance value equal, also has set the resistor R ₃₀ resistors R ₃₁ both resistance equal.

The switching control circuit IV includes operational amplifiers OP ₄ and OP
It is composed of ₅ and the resistance R ₂₁ to R ₂₅ and capacitor C _5.

 Next, the operation of the voltage control device will be described.

The first detection circuit II outputs a voltage corresponding to the duty ratio of the pulse voltage applied to the load L. On the other hand, the second detection circuit III detects the voltage of the battery B, that is, the peak value of the pulse voltage, and the arithmetic circuit V performs the approximate calculation of the equation (linear approximation of the curve in FIG. 4) to obtain the voltage of the battery B. The target value of the duty ratio of the corresponding pulse voltage is output.

The switching control circuit IV, when the transistors TR ₄ and the switching transistor TR ₃ is on, resistor-capacitor C ₆ is Zener diode ZD ₂ Zener voltage V _ZD
It is charged through R _26. The voltage of the capacitor C ₆ is amplified by the operational amplifier OP _5, resistors R ₂₃ and capacitor
Is smoothed by C _5, applied to the inverting input of the operational amplifier OP _4. When the voltage at the inverting input of the operational amplifier OP ₄ is greater than the voltage at the non-inverting input terminal, the transistor TR ₄ and the switching transistor TR ₃ is turned off the output of the operational amplifier OP ₄ is a zero V. Then, the capacitor C ₆
A voltage of falling, thus calculating the voltage at the output terminal of the amplifier OP ₅ also lowered, the voltage at the inverting input terminal of the resistance R ₂₂ and the operational amplifier OP ₄ are smoothed by the capacitor C ₅ also descends. Then, the operational amplifier OP ₄ of the inverting input terminal of the voltage operational amplifier OP ₄ of the non-inverting operation at the moment becomes lower than the voltage of the input amplifier OP ₄ of the voltage at the output terminal the power supply voltage (voltage of the battery B) is the transistor TR ₃ and the switching transistor TR ₄ is turned on, thereby a voltage applied to the incandescent lamp as a load L.

Hereinafter, by repeating the above operation, the capacitor
Will be the voltage of C ₅ to follow the output voltage of the operational circuit V, thus the voltage of the capacitor C _6, that is, the duty ratio of the pulse voltage to follow the output voltage of the operational circuit V (target value).

On the other hand, the output voltage of the arithmetic circuit V changes the target value of the duty ratio in accordance with the change of the average value of the pulse voltage so that the effective value of the pulse voltage becomes constant. The power is controlled to be constant.

〔The invention's effect〕

According to the voltage control apparatus of the present invention, different first and second detection items among the detection items of the peak value, the average value, and the duty ratio of the pulse voltage applied to the load are set to the first.
And a second detection circuit, and the switching control circuit changes the ratio between the on time and the off time of the switching element according to the difference between the detection output of the first detection circuit and the target value. The detection output of the first detection circuit is controlled so as to follow the target value, and the calculation circuit outputs the detection output of the second detection circuit in accordance with the relationship between the first and second detection items under the condition that the effective value is constant. Since the value of the corresponding first detection item is calculated and given as a target value from the arithmetic circuit to the switching control circuit, the power supplied to the load can be controlled to be constant.

Further, the first and second detection circuits only need to detect different first and second detection items among the detection items of the peak value, the average value, and the duty ratio of the pulse voltage applied to the load, It is possible to perform constant control of the power supplied to the load, and it is simple in construction and can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention,
FIG. 2 is a circuit diagram showing a specific configuration of the detection circuit, FIG. 3 is a characteristic diagram showing a relationship between the voltage V _ON and the voltage V _AVE when the effective value is fixed, and FIG. Voltage V
Characteristic diagram showing the relationship between the _ON and the duty ratio D, Figure 5 and FIG. 6 is a circuit diagram showing a specific configuration example of each voltage controller, FIG. 7 is a circuit diagram showing a configuration of a conventional emergency lamp lighting device FIG. 8 is an explanatory diagram of the duty ratio. I: switching element, II: first detection circuit, III
... Second detection circuit IV. Switching control circuit V
…… Calculation circuit, B …… Battery, L …… Load

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-56-54791 (JP, A) JP-A-60-97595 (JP, A) JP-A-53-139495 (JP, A)

Claims (1)

(57) [Claims] 1. A switching element interposed between a load driven by a battery and the battery to supply power from the battery to the load in a pulsed manner, and a peak value and an average value of a pulse voltage applied to the load. And first and second detection circuits respectively detecting different first and second detection items among the respective detection items of the duty ratio, turning on / off the switching element, and detecting the output of the first detection circuit. A switching control circuit that controls a detection output of the first detection circuit to follow the target value by changing a ratio between an on time and an off time of the switching element according to a difference from a target value; The value of the first detection item corresponding to the detection output of the second detection circuit is calculated according to the relationship between the first and second detection items under the condition that the effective value is constant, and the scan is performed. Voltage control apparatus and an arithmetic circuit for providing as the target value to the etching control circuit.