JP3093893B2 - Power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for performing DC voltage conversion using a chopper circuit.

[0002]

2. Description of the Related Art Conventionally, there has been provided a power supply device which obtains a DC output voltage obtained by stepping down or stepping up an input voltage by controlling ON / OFF of a switching element connected in series or parallel to an input. For example, a step-up power supply device has a configuration as shown in FIG. In the example of FIG. 6, a pulsating voltage which is the output of the rectifier RE of the AC power source AC such as a diode bridge for full-wave rectifying an input voltage Vi, a primary winding L ₁ of the inductor CH between the output terminals of the rectifier RE a series circuit of the switching element Q ₁ and the resistor R ₅ made of MOSFET, the main circuit a series circuit of a diode D ₁ of the reverse-current blocking switching element Q ₁ and the capacitor C ₁ for smoothing connected in parallel 1
Is provided. The switching element Q ₁ is are on-off controlled by a control circuit 2 to be described later.

When only the main circuit 1 is extracted from the circuit of FIG. 6, the result is as shown in FIG. The period switching device Q ₁ is turned on, the input voltage Vi to the primary winding L ₁ of the inductor CH is applied, the current i _L1 that flows through the primary winding L ₁ of the inductor CH is the switching element Q ₁ If the elapsed time after turning on is t, i _L1 = (Vi / L ₁ ) t (where L ₁ is the inductance of the primary winding L ₁ ). That is, when the ON period of the switching element Q ₁ and T _ON,
Peak value I _P of the current i _L1 that flows through the primary winding L ₁ of the inductor CH becomes _{I P = (Vi / L 1} ) T ON. On the other hand, when the switching element Q ₁ is turned off, 1 the voltage across the primary winding L ₁ of the inductor CH is neglecting the forward voltage drop of the diode D ₁ and the output voltage is a voltage across the capacitor C ₁ and Vo, − (Vo−Vi). That is, the voltage of opposite polarity is applied between the primary winding of the L ₁ across the inductor CH and when on the switching element Q ₁ is turned off. Energy switching element Q ₁ is stored in the inductor L ₁ while is on, the switching element Q ₁
Is released when the power supply is turned off.
The current i _L1 flowing through the next winding L ₁ is determined by the switching element Q ₁
Assuming that the elapsed time after turning off is t, i _L1 = I _P − ｛(V
o−Vi) / L ₁ ｝ t. Thus, current i _L1 that flows through the primary winding L ₁ of the inductor CH is as shown in FIG. 8 (a). In FIG. 8, switching element Q ₁ is at time t
On _1, showing a state in which turned off at time t _2.

The inductor CH is connected to the secondary winding L ₂
Assuming that the turns ratio between the primary winding L ₁ and the secondary winding L ₂ is n ₁ : n ₂ , the voltage e ₂ induced in the secondary winding L ₂ of the inductor CH is , the oN period of the switching element Q ₁ becomes _{e 2 = (n 2 / n} 1) Vi, is in the oFF period of the switching element _{Q 1 e 2 = - (n} 2 / n 1) (Vo
−Vi). Further, in the OFF period of the switching element Q _1, the stored energy of the inductor L ₁ is all discharged, the voltage will not be induced in the secondary winding L _2. Thus, if the input voltage Vi is constant voltage of the DC induced voltage e ₂ to the secondary winding L ₂ is 8
As in (b), it becomes a rectangular wave whose polarity is reversed with the on-off switching element Q _1.

The ON / OFF timing of the switching element Q ₁ is controlled by a control circuit 2. Control circuit 2
Are the input voltage Vi, the output voltage Vo, the switching element Q
Current flowing to _1, a voltage e ₂ induced in the secondary winding L ₂ of the inductor CH comprehensively, to determine the timing of the on-off switching element Q _1. That is, the input voltage Vi is divided by the two resistors R ₁ and R ₂ as the first detection unit connected between the output terminals of the rectifier RE, and is input to the control circuit 2 as the first detection voltage V _1. , Output voltage Vo
Is divided by two resistors R ₆ and R ₇ as a second detection unit connected between both ends of the capacitor C ₁ and is input to the control circuit 2 as a _second detection voltage V ₂ . The current flowing through the switching element Q ₁ is detected as a voltage across the resistor R ₅ as a third detector connected in series to the switching element Q _1, this voltage control circuit 2 as a third detection voltage V ₃ Is entered. Secondary winding L of inductor CH
Voltage across e ₂ of ₂ is inputted to the control circuit 2 via the resistor R _4. Here, a main part of the control circuit 2 (a part surrounded by a broken line in FIG. 6) is provided as an integrated circuit (for example, MC34261 manufactured by Motorola), and the control circuit 2 can be configured by externally attaching some components. I can do it.

[0006] The control circuit 2, a second detection voltage V ₂ is compared with a reference voltage Vref set by reference voltage generator 29, an output proportional to the difference between the second detection voltage V ₂ and the reference voltage Vref An error amplifier 21 is provided as an error detector that generates the error. The error voltage V ₂ ′ output from the error amplifier 21 is
Is input to the first detection voltages V ₁ with the multiplier 22, the output value QM proportional to the result obtained by multiplying the first detection voltage V ₁ and the error voltage V ₂ 'is obtained from the multiplier 22. Therefore, the output value QM of the multiplier 22 is QM = κV
₁ V ₂ ′ (κ is a constant). Multiplier 22
The output value QM of the third detection voltage V ₃
And the output of the comparator 23 is the third detection voltage V ₃
Is at the H level during a period during which the output voltage is equal to or higher than the output value QM of the multiplier 22 (V ₃ ≧ QM). When the output of the comparator 23 rises to the H level, the RS latch 24 is reset, and when the output of the RS latch 24 goes to the L level, the output of the output circuit 25 becomes L.
The switching element Q ₁ is turned off becomes level. In short, during a period the switching element Q ₁ is on,
Since current i _L1 that flows through the primary winding L ₁ of the inductor CH as shown in FIG. 8 (a) is also a current flowing through the switching element Q ₁ increases with increasing, by the third detection voltage V ₃ to the switching element Q ₁ the current flowing is monitored, it is to turn off the switching element Q ₁ at the time when the desired energy is accumulated in inductor CH. Thus, the first detection voltage V ₁ , the second detection voltage V ₂ , and the third detection voltage V
₃ determines the timing of turning off the switching element Q _1. In other words, the primary winding L of the inductor CH
Since the peak value I _P of the current i _L1 that flows _through the equivalent to the peak value of the current flowing through the resistor _{R 5, I P R 5 =} V 3 = κV 1
Will be to satisfy V ₂ ', as shown in FIG. 9, the current i _L1
Envelope of the peak value I _P is the same shape as the pulsating voltage is the input voltage Vi.

On the other hand, the timing for turning on the switching element Q ₁ is, is determined by the voltage e ₂ induced in the secondary winding L ₂ of the inductor CH a fourth detector as a fourth detection voltage. That is, the switching element Q ₁ is if off, the voltage e ₂ having a polarity of the arrow in FIG. 6 is induced in the secondary winding L ₂ of the inductor CH, inductor C
Since the energy stored in H is the induced voltage e ₂ according emitted decreases, the zero point induced voltage e ₂ detector 2
6 by detecting when made of the induced voltage e ₂ is almost 0V compared to the predetermined voltage. When the zero point detector 26 detects a point in time when the induced voltage e ₂ becomes almost 0 V (that is, when
The stored energy of the duster CH falls below the specified value
) , The RS latch 24 is set. When the output of the RS latch 24 becomes H level, the output of the output circuit 25 becomes H level, the switching element Q ₁ is turned on. That is, the voltage e induced in the secondary winding L ₂ of the inductor CH
By monitoring ₂ is to determine the timing to turn on the switching element Q _1. Here, the delay circuit 27 and the timer circuit 28 are provided to ensure the operation of the RS latch 24.

As described above, the multiplier 22 and the comparator 2
3, RS latch 24, a than the judgment control unit by the output circuit 25 is constituted, by determining the timing of the on-off switching element Q ₁ on the basis of the respective portions of the voltage and current of the main circuit 1, the main The output voltage Vo of the circuit 1 is controlled so as to be maintained at a constant voltage corresponding to the reference voltage Vref set by the control circuit 2. Further, the input current waveform becomes a waveform close to a sine wave.

[0009]

By the way, between the first detection voltage V ₁ and the input voltage Vi, as described above,
V ₁ = κ ₁ Vi (κ ₁ is a voltage dividing ratio of the resistors R ₁ and R ₂ ). On the other hand, the input current Ii to the main circuit 1 is proportional to the peak value I _P of the current i _L1 that flows through the primary winding L ₁ of the inductor CH, the waveform of the input current Ii, the peak value I _P as shown in FIG. 10 Is a curve obtained by doubling the envelope of.
Here, when the input power is W, the input current Ii is I
Because it can be expressed as i = W / Vi, the peak value I _P is inversely proportional to the input voltage Vi. Also, the third detection voltage V ₃
Peak value of, since it is V ₃ = I _P R _5, if the proportional constant and kappa _3, so that can be expressed as _{V 3 = κ 3 (1 /} Vi).

On the other hand, when the current i _L1 flowing through the primary winding L ₁ of the inductor CH reaches the peak value I _P , the first detection voltage V ₁ , the third detection voltage V _3, and the error voltage V ₂ ′ V ₃ = κV ₁ V ₂ ′ is established during this period, so that the error voltage V ₂ ′ with respect to the input voltage Vi is V ₂ ′ = κ ₂ (1/1) if κ ₃ / κκ ₁ = κ ₂ Vi ² ), and the error voltage V ₂ ′ output from the error amplifier 21 is equal to the input voltage 2
It is inversely proportional to the power.

This means that the output voltage Vo of the power supply having the above-mentioned configuration is kept constant without changing the load, and when only the input voltage Vi changes, the error voltage V ₂ ′ is changed by the change of the input voltage Vi. This means that a change width of the square of the magnification is required. For example, when the input voltage Vi is 100 to
Assuming that the input voltage changes between 300 V and the other conditions are not changed, when the input voltage is 300 V as compared with the case where the input voltage Vi is 100 V, the change magnification of the input voltage Vi is three times. Therefore, the error voltage V ₂ ′ must be controlled to 1/9.

That is, if the upper limit value of the allowable range of the input voltage V ₂ ′ of the multiplier 22 is V _2H ′, the lower limit value is V _2L ′, the upper limit value of the input voltage is V _H , and the lower limit value is _VL. , V _2H ′ ≧
κ ₂ (1 / V _L ² ) and V _2L ′ ≦ κ ₂ (1 /
_VH ² ) = κ ₂ (V _L / V _H ) ² (1 / V _L ² ), so that (V _H / V _L ) ² V _2L ≦ κ
Relationship ^{_{2 (1 / V L 2)}} ≦ V 2H ' is obtained. Therefore, V _2H ′ / V _2L ′ ≧ (V _H / V _L ) ² holds, and the error voltage V ₂ ′ is equal to 2 times the change magnification of the input voltage Vi.
It changes at a magnification inversely proportional to the power.

However, the output voltage of the error amplifier 21 and the multiplier 22 connected to the output of the error amplifier 21
There is a problem that normal control cannot be performed if the rate of change of the error voltage V ₂ ′ is large. For example, if the error voltage V ₂ ′ attempts to exceed the upper limit of the allowable range, the output voltage Vo will drop below a predetermined voltage, and conversely, if the error voltage V ₂ ′ attempts to drop below the lower limit of the allowable range. The output voltage Vo exceeds a predetermined voltage, and in some cases, there is a problem that the main circuit 1 is broken. In particular, when an off-the-shelf integrated circuit is used for the control circuit 2 as described above, the allowable operating range of the error amplifier 21 and the multiplier 22 is specified as a specification, so that the change range of the input voltage Vi is There is a problem that it is limited to a narrow range by specifications.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply device capable of maintaining a constant output voltage even when an input voltage changes over a wide range. Things.

[0015]

Means for Solving the Problems] In the present invention of claim 1, the switching element includes a switching element and an inductor
The energy stored in the inductor during the
A main circuit consisting of a chopper circuit for performing DC voltage conversion by discharging to the output side during the off period of the switching element, and a control circuit for controlling ON / OFF of the switching element. A first detection unit for generating a first detection voltage proportional to an input voltage to the switching circuit, a second detection unit for generating a second detection voltage proportional to the output voltage of the main circuit, A third detector that generates a third proportional detection voltage, a fourth detector that generates a fourth detection voltage proportional to the current flowing through the inductor, and a difference between the second detection voltage and the set voltage. An error detection unit that outputs a voltage, and when the third detection voltage reaches a voltage value obtained by multiplying a product of the first detection voltage and the error voltage by a specified magnification, the switching element is turned off, and the stored energy of the inductor is set to a specified value.
A determination control unit that turns on the switching element when the release to the following is detected based on the fourth detection voltage ;
Keep the second detection voltage constant against input voltage fluctuations.
Detection of input voltage when input voltage rises
A voltage adjuster for adjusting the voltage ratio in a direction to decrease the ratio.
It is characterized by having .

According to the second aspect of the present invention, the switching element and
And the inductor during the ON period of the switching element.
The energy stored in the inductor turns off the switching element.
DC voltage conversion by discharging to the output side during the period
The main circuit consisting of a chopper circuit and the switching element
A control circuit for performing on / off control.
Generating a first detection voltage proportional to the input voltage to the circuit;
A first detection unit and a second detection proportional to an output voltage of the main circuit
A second detector for generating a voltage,
A third detection unit for generating a third detection voltage proportional to the electric current
And a fourth detection voltage proportional to the current flowing through the inductor
And a second detection voltage, a set voltage,
Error detection that outputs a voltage proportional to the difference
And the third detection voltage is equal to the first detection voltage and the error voltage.
When the voltage multiplied by the specified magnification is multiplied by the product of
Turn off the inductor and the stored energy of the inductor is below the specified value
Is detected based on the fourth detection voltage.
And a judgment control unit that turns on the switching element
To keep the second detection voltage constant with respect to voltage fluctuation
When the input voltage rises, the difference between the second detection voltage and the set voltage
Voltage to reduce the ratio of error voltage to
And a pressure adjusting unit .

According to the third aspect of the present invention, the switching element and
And the inductor during the ON period of the switching element.
The energy stored in the inductor turns off the switching element.
DC voltage conversion by discharging to the output side during the period
The main circuit consisting of a chopper circuit and the switching element
A control circuit for performing on / off control.
Generating a first detection voltage proportional to the input voltage to the circuit;
A first detection unit and a second detection proportional to an output voltage of the main circuit
A second detection unit for generating a voltage, and a communication between the second detection unit and the switching element.
A third detection unit for generating a third detection voltage proportional to the electric current
And a fourth detection voltage proportional to the current flowing through the inductor
And a second detection voltage, a set voltage,
An error detection unit that outputs the difference of
The detection voltage is a specified magnification to the product of the first detection voltage and the error voltage.
When the voltage value multiplied by
The stored energy of the nectar has been released below the specified value
Is detected based on the fourth detection voltage.
The judgment control unit that turns on the switching element and the
Input voltage rises to keep the second detection voltage constant
Then, the third detection of the current flowing through the switching element is performed.
A voltage adjustment unit that adjusts the output voltage ratio in a direction to increase it
It is characterized by having.

[0018]

According to the above construction, by providing the voltage adjusting section, any one of the first detection voltage, the error voltage and the third detection voltage is adjusted according to the level of the input voltage, and the second detection voltage is adjusted. Is kept substantially constant, so that the output voltage can be kept substantially constant even when the input voltage fluctuates greatly. That is, the output voltage can be stabilized while the difference between the upper and lower limits of the voltage range allowed as the input voltage is made large.

[0019]

【Example】

(Example 1) This example adds a voltage regulating circuit 3 as a voltage adjusting unit to the conventional configuration shown in FIG. 6, the first detection voltages V ₁ to be input to the multiplier 22 in response to the input voltage Vi It is designed to be switched. That is, the voltage adjustment circuit 3 includes two resistors R ₁₀ and R _{10 for} dividing the input voltage Vi.
_11, a capacitor C ₂ of the parallel-connected smoothing via the diode D ₂ to the resistor R _11, had an output of open collector type for comparing the voltage across the capacitor C ₂ and a predetermined reference voltage Vref2 comparator and CP _1, an anode connected to the output terminal of the comparator CP ₁ resistor R _1, R ₂
A diode D ₃ whose cathode is connected to the connection point of the series-connected to the anode side of the diode D ₃ diode D
₃ resistor series circuit is connected in parallel with the resistor R ₁ with R ₁₂
And

The operation of the voltage adjustment circuit 3 will be described.
Input voltage Vi is the voltage across the resistor R _10, is divided by R ₁₁ is smoothed by the capacitor C ₂ capacitor C ₂ is input to the comparator CP ₁ as a comparison voltage Vc. Therefore, the comparison voltage Vc reflects not the short-term fluctuation of the input voltage Vi but the time-average fluctuation of the input voltage Vi. In the comparator CP _1, the comparison voltage V
c is compared with the reference voltage Vref2, and the output is opened during a period when Vc <Vref2, that is, during a period when the input voltage Vi is relatively low. Once the open output of the comparator CP ₁ is diode D ₃ resistance R ₁₂ because turned on is connected in parallel to the resistor R _1, resistor R _1, the first detection voltage V which is the potential of the connection point R _{2 1} is the resistance R ₁ and the resistance R
It becomes divided voltage of the input voltage Vi by ₁₂ parallel resistance between the resistor R _2. If this partial pressure ratio is A _L , A _L = R ₂
/ Becomes _{{R 1 / (1 + R} 1 / R 12) + R 2}.

On the other hand, the input voltage Vi is relatively high and Vc ≧ V
The period in which the ref2, the output of the comparator CP ₁ becomes short, resistance diode D ₃ is turned off R
Will _{be 12} is disconnected from the resistor R _1, becomes the first detection voltage V ₁ was resistors R _1, R ₂ only by the voltage dividing the input voltage Vi minute. If the partial pressure ratio at this time is A _H ,
A _H = R ₂ / (R ₁ + R ₂ ). That is, the voltage dividing ratio A _L during the period when the input voltage Vi is relatively low is changed to the input voltage Vi.
By but the larger than the partial pressure ratio A _H a relatively high period, is to reduce the first variation width of the detection voltages V ₁ as compared to the variation range of the input voltage Vi. As described in the background art, V ₃ = κV ₁ V ₂ ′, and the peak value of the third detection voltage has relatively small fluctuation. Therefore, if the fluctuation width of the _first detection voltage V ₁ becomes small, , The second detection voltage V ₂
Becomes smaller. Thus, the input voltage Vi
There also vary over a relatively wide range, the second variation width of the detection voltage V ₂ is input to the control circuit 2 can be suppressed, than it can be kept substantially constant output voltage Vo .

Next, a method of setting the values of the resistors R ₁ , R ₂ and R ₁₂ will be described. Here, regarding the input voltage Vi,
Upper limit value and the lower limit value respectively V _H, and V _L, the input voltage Vi when switching the division ratio and V _M. Also,
Regarding the error voltage V ₂ ′, the upper limit value and the lower limit value are V _2H ′ and V _2L ′, respectively. Here, V ₃ = κV ₁ V ₂ ′ and A _L V _L ≦ V ₁ ≦ A during the period when the voltage division ratio is A _L.
Is an _L V _M. When V ₁ = _AL V _L , V ₂ ′ ≦
Since the condition of V _2H ′ must be satisfied, the following equation is established. _{V 3 ≦ κA L V L V} 2H '(1) Further, when V ₂ = A _L V _M is, V _2' do not have to meet the condition of ≧ V _2L ', the following equation is established. _{V 3 ≧ κA L V M V} 2L '(2) In the same manner, the period division ratio is A _H, the following equation is established. _{V 3 ≦ κA H V M V} 2H '(3) V 3 ≧ κA H V H V 2L' (4) By the way, the input current Ii is about 1 current i _L1 that flows through the primary winding L ₁ of the inductor CH Since the current i _L1 is equal to the current flowing through the resistor R ₅ during the ON period of the switching element Q ₁ , if the input power is W, V ₃ = 2WR
₅ / Vi, and according to equation (4), A _H ≦ V ₃ / κV
An _{H V 2L '= 2WR 5 /} κV H 2 V 2L', because it is _{A H = R 2 / (R} 1 + R 2) as described above, after all, the resistance R _1, R ₂ satisfies the following equation It is necessary. _{R 2 / (R 1 + R} 2) ≦ 2WR 5 / κV H 2 V 2L '... Meanwhile, (1) According to the formula _{A L ≧ V 3 / κV L} V 2H' it is, as described above A _L = _{R 2 / {R 1 / (} 1 + R 1 / R
₁₂ ) + R ₂ }, the resistors R ₁ , R ₂ and R ₁₂ need to satisfy the following equation. R ₂ / {R ₁ / (1 + R ₁ / R ₁₂ ) + R ₂ } ≧ 2WR ₅ / κV _L ² V _2H ′ Further, as described in the section of the problem to be solved by the invention, V _2H ′ / V _{2L '≧ (V M / V} L) 2 _{and, V 2H' / V 2L '} ≧ (V H / V M) 2 must be established. If deformed both ^{_{equations, V M 2 ≦ (V 2H}} '/ V 2L') V
_L ^2, and ^{_{V M 2 ≧ (V 2L '}} / V 2H') a V _H ^2,
_{(V 2H '/ V 2L'} ) V L 2 = V M1 2, (V 2L '/
If put a ^{_{V 2H ') V H 2 =}} V M2 2, V M1 2 ≧ V M 2 ≧ V
Since _M2 ² must be established, it may be consequently satisfy the following equation. V _M1 > V _M2 ... According to the specifications of the main circuit 1 and the control circuit 2, the constant values of the resistors R ₁ , R ₂ , and R ₁₂ , the upper limit value V _H and the lower limit of the input voltage Vi are satisfied so as to satisfy the above-mentioned conditions. When the value _VL is set, the variable range of the input voltage Vi can be significantly widened as compared with the case where the voltage adjustment circuit 3 is not provided. Here, with respect to the specifications of the control circuit 2, simply switching the _first detection voltage V1 in two stages requires the input voltage Vi.
When the variation width of the upper limit value _VH and the lower limit value _VL cannot be handled, the number of switching stages of the _first detection voltage V1 may be further increased.

(Embodiment 2) In Embodiment 1, the input voltage Vi
First detecting the voltage had to switch the V ₁ in response to, in this embodiment, as shown in FIG. 2, the point was to switch the third detection voltage V ₃ are different. That is, as in the first embodiment, the voltage adjustment circuit 3
It comprises two resistors R ₁₀ , R _{11 for} dividing i and a smoothing capacitor C ₂ connected in parallel to the resistor R ₁₁ , and the voltage across the capacitor C ₂ is used as a comparison voltage Vc as a reference voltage Vref _{2 by} the comparator CP _1. Is to be compared with.
Resistance R for pull up to the output terminal of the comparator CP _1
14 is connected, it is adapted to turn on and off the transistor Q ₂ as a switching element by the output of the comparator CP _1. The emitter of the transistor Q ₂ - the collector resistor R ₁₃ are connected in series, the series circuit is connected in parallel to the resistor R ₅ connected in series to the switching element Q _1.

The comparator CP _1, the lower period than the reference voltage Vref2 comparison voltage Vc low input voltage Vi (Vc <Vref2), connected in parallel to resistor R ₁₃ to turn on transistor Q ₂ to the resistor R ₅ By doing so, the third detection voltage V ₃ is reduced, and the input voltage Vi is high and the comparison voltage V ₃ is high.
During the period when c is equal to or higher than the reference voltage Vref2, (Vc ≧ Vref
2), to turn off the transistor Q ₂ resistor resistance R ₁₃ R
Separately from the ₅ pulls the third detection voltage V _3.

In this embodiment, the third detection voltage V ₃ is switched in accordance with the input voltage Vi.
Since the first detection voltage V ₁ , the error voltage V ₂ ′, and the third detection voltage V ₃ have a relationship of V ₃ = κV ₁ V ₂ ′, the second detection with respect to the variation width of the input voltage Vi. Voltage V ₂ (= V
The change width of ₂ '+ Vref) can be reduced. That is, even if the input voltage Vi fluctuates significantly, the output voltage Vo can be kept substantially constant. Other configurations and operations are the same as those of the first embodiment.

[0026] (Embodiment 3) In this embodiment, as shown in FIG. 3, there is that to regulate the first detection voltages V ₁ in response to the input voltage Vi, Example 1 the voltage whereas with the comparator CP ₁ in the regulation circuit 3, in this embodiment there is a difference that it uses a current mirror CM.

That is, a diode D ₄ for preventing backflow is added between the output terminal of the rectifier RE and the primary winding L ₁ of the inductor CH, and the voltage adjusting circuit 3 connects the cathode of the diode D ₄ and the primary winding. input voltage Vi at the connection point between the line L ₁
Is configured to be detected. The input voltage Vi is divided by _two resistors R ₁₀ and R _{11 and} smoothed by a capacitor C ₂ connected in parallel with the resistor R ₁₁ . Current mirror C composed of two transistors Q ₃ and Q ₄
Since the M current corresponding to the voltage across the capacitor C ₂ through the resistor R ₁₅ flows, the output current of the current mirror CM will be increased or decreased in accordance with the voltage across the capacitor C _2. The emitter of the transistor Q ₄ which is an output side of the current mirror CM - since its collector is connected in parallel to the resistor R _2, if increasing the output current of the current mirror CM is, the first detection voltages V ₁ is lowered equivalently Will be. That is, in the first embodiment, the first detection voltage V ₁ is switched in two steps according to the input voltage Vi. However, in the present embodiment, the first detection voltage V _{1 is} continuously and steplessly controlled by the current mirror CM. Is increased or decreased.

[0028] In this embodiment, between the connection point of the resistors R _10, R ₁₁ and the connection point of the resistors R _1, R _2, be connected to one serial circuit of the diode D ₅ and the resistor R _16, the input When the diode D ₅ in a valley portion in the pulsating waveform of the voltage Vi turned off, the first detection voltage a than increasing its V ₁ to disconnect the resistor R _16, a diode D ₅ and the resistor R ₁₆ is
Has a function to increase the on period of the switching element Q ₁ in the valleys of the input voltage Vi. The diode D ₄ is by blocking regenerative current in the inductor CH, it has a function to reduce harmonic components of the input current. Other configurations are the same as in the first embodiment.

(Embodiment 4) As shown in FIG. 4, the voltage adjusting circuit 3 in this embodiment switches the error voltage V ₂ ′ according to the input voltage Vi. In the present embodiment, the entire control circuit 2 is not formed by one integrated circuit, but is formed by using an integrated circuit for each function of the control circuit 2. The functions of the control circuit 2 are described above. This is the same as that shown in each embodiment.

In the voltage adjusting circuit 3, as in the first embodiment,
The input voltage Vi is divided by the resistors R ₁₀ and R ₁₁ , and a series circuit of a diode D ₂ and a capacitor C ₂ is connected in parallel to the resistor R ₁₁ , so that the voltage smoothed by the capacitor C ₂ is used as a comparison voltage Vc. input to CP _1. Further, in the comparator CP _1, compared with reference voltage Vref2 of the comparison voltage Vc, the output circuit is opened when the comparison voltage Vc is lower than the reference voltage Vref2. On the other hand, the series circuit of the control circuit 2 of the error amplifier 21 of the output end of two resistors R _17, which is connected to one end to the circuit ground in, R ₁₈ is connected, further connection point of the resistors R _17, R ₁₈ resistor R ₁₉ is connected between the output terminal of the comparator CP ₁ and.

The error voltage V ₂ 'input to the multiplier 22
Is obtained from the connection point of the resistors R ₁₇ and R ₁₈ . Therefore, when the comparator CP ₁ is the output circuit is open, the output voltage of the error amplifier 21 is divided by the voltage dividing ratio of only the resistor R _17, R _18, when the output circuit of the comparator CP ₁ is short, the resistance R ₁₈ and resistance R
The output voltage of the error amplifier 21 is divided by the voltage dividing ratio by ₁₉ parallel resistance of the resistor R _17. That is, the input voltage V
The i is smaller period than the reference voltage Vref2 comparison voltage Vc is low, the output circuit of the comparator CP ₁ is an error voltage V ₂ 'obtained by dividing the output voltage of the resistor R _17, R ₁₈ of the error amplifier 21 becomes open can get. During the period when the input voltage Vi is high and the comparison voltage Vc is equal to or higher than the reference voltage Vref2,
The output circuit of the comparator CP ₁ is the error voltage V ₂ 'obtained by dividing the output voltage of the resistor R _17, R _18, R ₁₉ of the error amplifier 21 becomes short is obtained. In this manner, the variation width of the error voltage V ₂ ′ with respect to the change of the input voltage Vi can be reduced, and as a result, the output voltage V ₀ can be kept constant even if the input voltage Vi changes greatly. is there. Other configurations are the same as in the first embodiment.

(Embodiment 5) As shown in FIG. 5, the voltage adjusting circuit 3 in this embodiment switches the output of the multiplier 22 according to the level of the input voltage Vi. Detection of the level of the input voltage Vi is the same as in Example 4, divided by the resistors R _10, R ₁₁ an input voltage Vi, the voltage smoothed by the capacitor C ₂ through the diode D ₂ of the comparator CP ₁ The reference voltage Vref2 is compared with the reference voltage Vref2. A series circuit of resistors R ₂₀ and R ₂₁ is connected between the output terminal of the multiplier 22 and the circuit ground.
The voltage at the connection point between the two resistors R ₂₀ and R ₂₁ is input to the comparator 23. The resistor R ₂₂ is connected between the two resistors R _20, connection point of the R ₂₁ and the output terminal of the comparator CP _1.

[0033] Thus, the output voltage of the input voltage Vi is lower comparison voltage Vc is the reference voltage Vref2 is less than the period becomes an open output circuit of the comparator CP ₁ is multiplier 22 is divided by only the resistor R _20, R ₂₁ Will be. On the other hand, the output voltage of the input voltage Vi is high and the output circuit of the comparator CP ₁ to period comparison voltage Vc is the reference voltage Vref2 or more becomes short multiplier 22 resistors R _20,
The voltage is divided by R ₂₁ and R ₂₂ . In this manner, when the input voltage Vi increases, the voltage division ratio of the output voltage of the multiplier 22 is reduced to reduce the voltage input to the comparator 23. As a result, even if the input voltage Vi changes greatly, the output voltage Vo Can be kept constant. Other configurations are the same as in the fourth embodiment.

In each of the above embodiments, the main circuit 1 is a step-up type chopper circuit. However, other types of chopper circuits (step-up type, inverting type (step-up / step-down type), etc.) are also applicable to the technical idea of the present invention. It goes without saying that it can be applied.

[0035]

According to the present invention, as described above, by providing the voltage adjusting unit, any one of the first detection voltage, the error voltage, and the third detection voltage is adjusted according to the level of the input voltage.
Since the second detection voltage is kept almost constant,
This has the advantage that the output voltage can be kept substantially constant even if the input voltage fluctuates significantly. That is, it is possible to output a stable DC voltage in which the harmonic distortion of the input current is improved and the difference between the upper and lower limits of the voltage range allowed as the input voltage is large.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is a circuit diagram showing a second embodiment.

FIG. 3 is a circuit diagram showing a third embodiment.

FIG. 4 is a circuit diagram showing a fourth embodiment;

FIG. 5 is a circuit diagram showing a fifth embodiment.

FIG. 6 is a circuit diagram showing a conventional example.

FIG. 7 is a circuit diagram showing a main circuit in a conventional example.

FIG. 8 is an operation explanatory diagram of a main circuit in a conventional example.

FIG. 9 is an operation explanatory diagram showing a relationship between an input voltage waveform and a current flowing through an inductor in a conventional example.

FIG. 10 is an operation explanatory diagram showing a relationship between an input current and a current flowing through an inductor in a conventional example.

[Explanation of symbols]

1 main circuit 2 control circuit 3 voltage switching circuit 21 the error amplifier 22 the multiplier 23 comparator 24 RS latch 25 output circuits CH inductor L ₁ 1 winding L ₂ 2 winding Q ₁ switching element R ₁ resistor R ₂ resistor R ₅ resistor R ₆ resistor R ₇ resistor

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Nishino 1048 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Works, Ltd. Inventor Katsunobu Hamamoto 1048 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd. (56) Reference JP-A-3-22865 (JP, A) JP-A-5-184159 (JP, A) JP-A-4-168975 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02M 3/155

Claims (3)

(57) [Claims] A switching element and an inductor are stored in an inductor during an ON period of the switching element.
Energy is released to the output side during the off period of the switching element
A main circuit comprising a chopper circuit for performing DC voltage conversion and a control circuit for controlling ON / OFF of a switching element, wherein the control circuit generates a first detection voltage proportional to an input voltage to the main circuit. A first detection unit that generates a second detection voltage proportional to the output voltage of the main circuit.
A detection unit, a third detection unit that generates a third detection voltage proportional to a current supplied to the switching element, a fourth detection unit that generates a fourth detection voltage proportional to a current flowing through the inductor, and a second detection unit. An error detection unit that outputs a difference between the detection voltage and the set voltage as an error voltage, and a switching element when the third detection voltage becomes a voltage value obtained by multiplying a product of the first detection voltage and the error voltage by a specified magnification. A determination control unit that turns off the switching element when it is turned off and detects that the accumulated energy of the inductor has been discharged to a specified value or less based on the fourth detection voltage;
Pair, and an input voltage input voltage rises to maintain the a constant to
And a voltage adjusting unit for adjusting the ratio of the first detection voltage to be reduced . 2. The method according to claim 1, wherein the switching element and the inductor are stored in the inductor during an ON period of the switching element.
Energy is released to the output side during the off period of the switching element
A main circuit comprising a chopper circuit for performing DC voltage conversion and a control circuit for controlling ON / OFF of a switching element, wherein the control circuit generates a first detection voltage proportional to an input voltage to the main circuit. A first detection unit that generates a second detection voltage proportional to the output voltage of the main circuit.
A detection unit, a third detection unit that generates a third detection voltage proportional to a current supplied to the switching element, a fourth detection unit that generates a fourth detection voltage proportional to a current flowing through the inductor, and a second detection unit. Voltage proportional to the difference between the
An error detecting section for outputting a pressure of error voltage, a third detection voltage is first detected voltage and becomes a voltage value obtained by multiplying the specified ratio to the product of the error voltage to turn off the switching element stored energy of the inductor is defined the that the value released to below 4 of a determination control unit to turn on the switching element when detecting based on the detection voltage, a second detection voltage input voltage to maintain the a constant against fluctuation of input voltage Rise
Error voltage with respect to the difference between the second detection voltage and the set voltage
And a voltage adjuster for adjusting the ratio of the power supply to decrease . 3. A switching element and an inductor are stored in the inductor during an ON period of the switching element.
Energy is released to the output side during the off period of the switching element
A main circuit comprising a chopper circuit for performing DC voltage conversion and a control circuit for controlling ON / OFF of a switching element, wherein the control circuit generates a first detection voltage proportional to an input voltage to the main circuit. A first detection unit that generates a second detection voltage proportional to the output voltage of the main circuit.
A detection unit, a third detection unit that generates a third detection voltage proportional to a current supplied to the switching element, a fourth detection unit that generates a fourth detection voltage proportional to a current flowing through the inductor, and a second detection unit. An error detection unit that outputs a difference between the detection voltage and the set voltage as an error voltage, and a switching element when the third detection voltage becomes a voltage value obtained by multiplying a product of the first detection voltage and the error voltage by a specified magnification. A determination control unit that turns off the switching element when it is turned off and detects that the accumulated energy of the inductor has been discharged to a specified value or less based on the fourth detection voltage;
The input voltage increases so as to maintain at a constant when the switching
Increase the ratio of the third detection voltage to the current flowing through the element
A power supply device, comprising: