JPH041586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a chopper type DC power supply device for supplying a regulated voltage to a load by turning on/off a switch element.

[Conventional technology and its problems]

A typical conventional chopper type power supply device includes a switching transistor connected between a DC power source and a load, a smoothing circuit connected between the switching transistor and the load, an output voltage detection circuit, An error amplifier that compares the output detection voltage and the reference voltage, a triangular wave generator, a comparator that compares the triangular wave and the error output to form a PWM pulse, and a drive connected between the comparator and the switching transistor. It consists of a circuit. this
A PWM type power supply device stably turns on and off a switching transistor at a constant frequency.
Although it has the advantage of being able to be turned off, it has the disadvantage of increasing cost because it requires a triangular wave generator, a comparator, and a driving circuit.

Another typical chopper type power supply device, as disclosed in Japanese Patent Laid-Open No. 48-2016, connects a switching transistor and a reactor between a DC power supply and a load, and provides positive feedback to the reactor. The driving windings for the transistors are electromagnetically coupled, and the switching transistors are controlled to be turned on and off by the driving windings. In this positive feedback type chopper type power supply device, when the collector current of the switching transistor is I _C , the base current is I _B , and the current amplification factor is h _FE , the collector current I _C gradually increases from zero, and I When _C = I _B × h _FE , the switching transistor turns off. The output voltage is adjusted by changing the magnitude of the base current I _B . For example, when the base current is reduced, the on-time width of the switching transistor becomes smaller, and the output voltage decreases.

Incidentally, the base current is adjusted by bypassing a portion of the base current supplied from the drive winding to the switching transistor. Therefore, the bypassed current caused power loss. Furthermore, in a positive feedback type chopper type power supply device, when the required power of the load is small (during light load), both the on time width and the off time width of the switching transistor become small, and the on/off time of the switching transistor decreases. Off-repetition frequency increases. As a result, the number of times the switching transistor is turned on and off per unit time increases, and the ratio of power loss due to switching to the total power loss increases. Also,
In conventional positive feedback chopper circuits, the waveform of the current flowing through the switching transistor is a triangular wave that gradually rises from zero, resulting in a large ripple in the output voltage and a large amount of power being supplied by a single switching transistor. I can't.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a chopper type DC power supply device that has a simple circuit configuration and can supply a relatively large amount of power.

[Means for solving problems]

In order to solve the above problems and achieve the above objects, the present invention includes a DC power supply, a switch element connected between one end and the other end of the DC power supply with or without a load; a reactor connected in series to the switch element; a control circuit for controlling on/off of the switch element; and a control circuit for smoothing the output obtained based on the series circuit of the switch element and the reactor and supplying the smoothed output to the load. In the chopper type DC power supply device comprising a smoothing means, the control circuit includes a drive winding that is electromagnetically coupled to the reactor and connected to the switch element so as to drive the switch element by positive feedback, and a charging voltage. a capacitor connected in series with the drive winding so as to be able to turn on the switch element; and a capacitor connected between the DC power supply and the capacitor, and to turn on the switch element. a charging circuit having a resistor for charging the capacitor with a time constant to a voltage level that allows the switching element to switch from an on state to an off state;
a voltage detection means for detecting the voltage supplied to the load; a reference voltage source; and a voltage detection means connected to the voltage detection means and the reference voltage source; A signal corresponding to the difference from the obtained reference voltage is output, and this output controls the charging current of the capacitor or the point at which the switch element is switched from the on state to the off state by the off control circuit. The present invention relates to a chopper type DC power supply device characterized by comprising a circuit.

[Effect]

When the capacitor of the above invention is charged to a predetermined voltage level, the switch element is forced to quickly switch from the OFF state to the ON state, and the switch element is driven by the sum of the voltage of the capacitor and the voltage of the drive winding,
A relatively large current flows into the reactor immediately after the switch element starts to turn on. Therefore, the circuit of the present invention has a large ability to supply power to a load.

[First Embodiment] FIG. 1 shows a chopper type DC stabilized power supply device according to a first embodiment of the present invention. A current detection resistor 3 and a P-channel MOS field effect transistor (FET) are connected between one end of the DC power supply 1 and one end of the load 2.
4 and reactor 5 are sequentially connected in series. The other end of the DC power supply 1 and the other end of the load 2 are connected by a common line 6. The DC power supply 1 consists of a rectifying and smoothing circuit connected to a commercial AC power supply,
Supply voltage that can fluctuate.

FET4 has source S, drain D, gate G
The source S is connected to the current detection resistor 3 and the drain D is connected to the reactor 5. This FET
4 is configured as a P-channel enhancement type that turns on when a negative voltage exceeding a threshold voltage is applied to the gate G.

A rectifying diode 7 is connected between the input side terminal of the reactor 5 and the common line 6, and a smoothing capacitor 8 is connected between the output side terminal of the reactor 5 and the common line 6.

A drive winding 9 connected between the source and gate of the FET 4 to constitute an on/off control circuit for the FET 4 is electromagnetically coupled to the reactor 5 . This drive winding 9 is provided to drive the FET 4 by positive feedback, and is electromagnetically coupled to the reactor 5 as shown by the broken line.

A first capacitor 10 connected in series to the winding 9 between the gate and source of the FET 4.
is for determining the point at which the FET 4 changes from the OFF state to the ON state. A resistor 11 for charging the first capacitor 10 with a predetermined charging time constant is connected between the first capacitor 10 and the common line 6.

A transistor 13 is connected between the power supply side terminal of the current detection resistor 3 and the gate G via a reverse current blocking diode 12 in order to control the switching of the FET 4 from the on state to the off state. A resistor 14 that provides a bias voltage to the base of the transistor 13
is connected between the FET side terminal of the current detection resistor 3 and the base of the transistor 13. A second capacitor 15 for removing rip voltage is connected in parallel to this bias resistor 14.

In order to control the voltage V ₃ across the bias resistor 14 based on the load voltage (output voltage), voltage detection resistors 16 and 17, a reference voltage source 18, and an error amplifier 19 are provided. Two voltage detection resistors 1
6 and 17 are connected between the output line 20 and the common line 6 in order to divide and detect the load voltage. One input terminal of the error amplifier 19 is connected to the voltage dividing point of the two resistors 16 and 17,
The other input terminal is connected to a reference voltage source 18, and the output terminal is connected to one end of the resistor 14. As a result, the resistor 14 is connected between one end of the DC power supply 1 and the output terminal of the error amplifier 18 via the current detection resistor 3.

(Operation) When the DC power supply 1 starts supplying power, the first capacitor 10 is charged in a closed circuit consisting of the DC power supply 1, the current detection resistor 3, the winding 9, the first capacitor 10, and the resistor 11. starts. Charging of the first capacitor 10 proceeds according to a predetermined time constant,
This voltage V ₁ is the threshold voltage V _th of FET4
When it reaches , FET 4 changes from the off state to the on state. Figure 2 shows the state in which FET 4 is in on-off operation after startup, but the operation at startup is virtually the same, and the FET 4 changes from the OFF state to the ON state at startup. The transformation of
Gate-source voltage at time t ₁ in Figure 2 C
This is done based on the same principle as the relationship between V _GS and threshold voltage V _th . When FET4 is turned on at, for example, time _t1 in FIG. 2, FET4 is driven by the sum of the voltage of capacitor 10 and the voltage of drive winding 9, so that the drain current I _D of FET4 increases as shown in FIG. As shown in the figure, it started flowing at a relatively large level from the beginning,
It increases with a slope. This drain current _ID flows through the reactor 5 to the smoothing capacitor 8 and the load 2. During the ON period of FET4, the power supply voltage V _a
A voltage approximately equal to the difference between the voltage of the output line 20 and the voltage of the output line 20 is applied to the reactor 5. Since the drive winding 9 is electromagnetically coupled to the reactor 5, a voltage corresponding to the turns ratio between the two is obtained in the drive winding 9. FET4
The direction of the voltage _V2 obtained in the drive winding 9 during the on-period of is determined so that it is high on the source S side and low on the gate G side, so the P channel MOS-
This direction is for turning on FET4. Therefore,
The ON state of the FET 4 is maintained by the positive feedback voltage V ₂ obtained in the drive winding 9. During the ON period _t1 to _t2 of the FET 4, the source-drain voltage _VDS becomes almost zero as shown in FIG. 2A. FET
Since a reactor 5 including an inductance is connected in series with 4, the drain current I _D is as shown in Fig. 2B.
As shown in Figure 2, it increases with time. As a result, the voltage V ₄ across the current detection resistor 3 also increases with time during the on period (t ₁ to t ₂ ) compared to the drain current _ID in FIG. 2B.

On the other hand, the voltage V ₃ across the bias resistor 14 is
Voltage Va of power supply 1 and output voltage Vb of error amplifier 19
This is the value obtained by dividing the value of the difference (Va−Vb) between the current detection resistor 3 and the bias resistor 14. Since the output voltage supplied to the load 2 usually does not change rapidly, the voltage V ₃ across the resistor 14 is a direct current (flat) value. Since a series circuit consisting of a bias resistor 14 and a current detection resistor 3 is connected between the base and emitter of the transistor 13, the bias voltage V ₃ and current detection voltage V ₄ shown in FIG. The sum (V ₃ +V ₄ ) is applied between the base and emitter of the transistor 13. Base of transistor 13
The emitter voltage V _BE gradually increases in response to the increase in the drain current _ID , and when it reaches this threshold voltage (approximately 0.6 V) at t ₂ as shown in FIG. 2H, the transistor 13 turns on. become. As a result, the source and gate of FET4 are short-circuited through a circuit consisting of current detection resistor 3, transistor 13, and diode 12, making it impossible to maintain FET4 in the on state, and FET4 changes from on state to off state. Convert to

During the off period ( _t2 to _t4 ) of the FET 4, the energy stored in the reactor 5 is released in a closed circuit consisting of the reactor 5, the load 2 and/or the capacitor 8, and the diode 7. At this time, the diode 7 is turned on, and a current I _F flows therein as shown in FIG. 2D. Output current I _L of reactor 5
is the ON period (t ₁ to t ₂ ) of FET 4 shown in Figure 2B.
The current I _D is combined with the current I _F during the off period (t ₂ to t ₄ ) shown in FIG. 2D, and flows in a smoothed state as shown in FIG. 2E.

When FET4 turns off at time _t2 , the drain current I _D becomes substantially zero, so it becomes impossible to keep transistor 13 on with current detection voltage _V4 , and transistor 13 turns off FET4. It becomes impossible to maintain control. but,
Since the direction of the voltage V ₂ of the drive winding 9 is opposite to that during the on period, the FET 4 does not turn on immediately, and the off state of the FET 4 is maintained.

During the off period (t ₂ to t ₄ ) of FET4, the first
The capacitor 10 is charged based on the sum of the voltage Va of the power supply 1 and the voltage V ₂ of the drive winding 9. 1st
Since the charging resistor 11 and the current detection resistor 3 are connected in series to the capacitor 10, the capacitor 10 is charged as shown in FIG. Proceed as shown. Charging of the capacitor 10 progresses, and V ₁ +V ₂
(opposite polarity to V ₁ ) is the threshold voltage of FET4
When V _th is crossed, FET 4 is turned on again.
As a result, the FET 4 automatically operates intermittently.

A more detailed explanation of the change in the voltage V ₁ of the capacitor 10 is as follows. In the interval from t ₂ to _{t 3} ,
The capacitor 10 is charged based on the sum of the voltage Va of the power supply 1 and the winding voltage V ₂ shown in FIG. 2G. During this t ₂ to _{t 3} period, the voltage of the capacitor 10 V ₁
The polarity of is negative on the source side and positive on the gate side. t ₃
At that point, the voltage V ₁ across capacitor 10 is zero volts. During the period _t3 to _t4 , the capacitor 10 is charged to the positive polarity, the source side becomes positive, the gate side becomes negative, and the voltage becomes such that the FET 4 can be turned on. Since the winding voltage V ₂ during the period t ₃ to _{t 4} has a positive polarity on the gate side, the threshold voltage is reached after the positive capacitor voltage V ₁ cancels the opposite winding voltage V ₂ . Reach V _th . V ₁ +V ₂
When the gate-source voltage V _{GS consisting of V GS} reaches the threshold voltage V _th at time t ₄ and FET 4 turns on, the winding voltage increases as shown in
The direction of V ₂ is reversed, and FET 4 is driven by positive feedback.

When a positive voltage is generated in the winding 9 at time t ₄ , the capacitor 10 is charged in the reverse direction in the closed circuit consisting of the winding 9, the source-gate capacitance of the FET 4, and the capacitor 10, and the voltage shown in FIG. As shown, the voltage becomes reverse polarity. Since the resistance in the reverse charging closed circuit of the capacitor 10 is extremely small, the reverse charging operation is performed quickly. Therefore, in FIG. 2F, the voltage change during the transient periods t ₁ and t ₄ is approximately shown by a single line extending in the vertical direction.

When FET4 switches from on to off at t ₅ ,
A reverse voltage (a voltage that charges the capacitor 10 in the positive direction) is generated in the winding 9 as shown in FIG. 2G. Also, at this time, a closed circuit is formed in which the transistor 13 and the capacitor 10 are formed, and the capacitor 10 is rapidly charged by the voltage of the winding 9, and this voltage increases rapidly. Since the transistor 13 is only in the ON state for a short time, this time width is omitted in FIG.

During the period _t5 to _t6 after the transistor 13 is turned off, the capacitor 10 is charged by the power supply voltage Va and the winding voltage _V2 . Charging during this period t ₅ to t ₆ can be performed in a closed circuit including the resistor 11, so the capacitor voltage V ₁ increases with a slope.

(Constant Voltage Control Operation) The voltage between the output line 20 and the common line 6 is divided by the resistors 16 and 17 and becomes an input to the error amplifier 19. Error amplifier 19 generates an output corresponding to the difference between the output detection voltage and the voltage of reference voltage source 18. In this example, the reference voltage source 18 is connected to the error amplifier 19.
Since it is connected to the non-inverting input terminal of the error amplifier 19, when the output detection voltage increases, the output voltage of the error amplifier 19 increases.
Vb also becomes lower. Since the voltage V ₃ across the resistor 14 is obtained by dividing the difference Va - Vb between the output voltage Vb of the error amplifier 19 and the power supply voltage Va by the resistors 13 and 14, it changes in accordance with the error output voltage Vb. do.
Therefore, resistor 14 functions as a variable bias voltage source.

The point at which the FET 4 turns from on to off changes depending on the current detection voltage V ₄ of the resistor 3 and the bias voltage V ₃ of the resistor 14 . In the period t ₁ to _{t 2} in Fig. 3, when the input voltage (power supply voltage Va) is low, the period t ₂ to _{t 3}
The period shows the waveforms of each part when the input voltage is high, the period from t ₃ to _{t 4} when the drain current (load current) is large, and the period from t ₄ to _{t 5} when the drain current is small.
If the input voltage between t ₁ and _{t 2} is low, the drain current _ID and current detection voltage V ₄ at the time of turning on will also be small, so that by the time V _BE reaches 0.6V as shown in Figure 3D, It takes a relatively long time and the on-time width becomes long.

When the input voltage between t ₂ and _{t 3} is high, the current detection voltage V ₄ at the time of turning on increases by △V, so V _BE
The time it takes for the voltage to reach 0.6V becomes shorter, and the on-time width becomes shorter.

When the drain current _ID between _t3 and _t4 is large, the voltage of the output line 20 tends to decrease, and the error output voltage Vb conversely increases. For this reason, the resistor 14
The voltage _V3 becomes lower. Therefore, even if the drain current I _D is large, it takes a long time for V _BE of the transistor 13 to reach 0.6V, and the necessary on-time width is obtained and the output voltage is returned to the desired value.

When the drain current between _t4 and _t5 is small, the output voltage tends to increase, the error output voltage Vb decreases, and the voltage _V3 across the resistor 14 increases. Therefore, even if the amplitude of the drain current _ID is small, V _BE reaches 0.6V relatively quickly as shown in FIG. 3D, and the output voltage returns to the desired value.

As is clear from the above description, the chopper type DC power supply device shown in FIG. 1 has the following advantages.

(1) The point at which the FET 4 changes from the off state to the on state is determined by the charging voltage V ₁ of the first capacitor 10, and the point at which the FET 4 changes from the on state to the off state is determined by the bias voltage V ₃ and the current detection voltage V Determined by the sum with ₄ . Therefore, the on/off period of the FET 4 does not change significantly in response to input voltage fluctuations and load current fluctuations. When the load current is small, when the number of times FET 4 is switched per unit time is reduced, the ratio of power loss due to switching of FET 4 to the total power loss of the chopper type power supply circuit becomes smaller.

(2) The transistor 14 momentarily turns on when the FET 4 changes from the on state to the off state, and remains off during the rest of the period.
Power loss in transistor 14 is small.

(3) The circuit configuration is simple because a triangular wave oscillator and voltage comparator are not used.

(4) Overcurrent protection for FET 4 can also be performed with a circuit including resistor 3 for controlling FET 4 from on to off.

(5) Since a relatively large drain current _ID flows from the time when the FET 4 starts to turn on, a large amount of power can be supplied, and the ripple component becomes small.

[Second Embodiment] Next, a chopper type power supply device according to a second embodiment shown in FIG. 4 will be described. However, in FIG. 4 and FIGS. 5 to 18, which will be explained later, parts common to those in FIG.

The charging resistor 11 of the chopper circuit shown in FIG. 4 is connected between one end of the capacitor 10 and the output line 20 of the reactor 5. Therefore, charging of the capacitor 10 is performed by a circuit including the power supply 1, the current detection resistor 3, the winding 9, the capacitor 10, the resistor 11, and the load 2. Other details are the same as in Figure 1.

[Third Embodiment] The circuit of the third embodiment shown in FIG. 5 is obtained by adding a capacitor 21, diodes 22 and 23, and a resistor 24 to the circuit of FIG. capacitor 2
1 is connected in parallel to the winding 9 via the diode 22, and is the voltage of the winding 9 obtained when FET 4 is turned on.
Charged by V ₂ . first capacitor 10
Since a resistor 24 is connected via a diode 22 between the power supply capacitor 21 and the newly installed power supply capacitor 21, the power supply capacitor 21, the winding 9, the first capacitor 10, and the diode 23 are connected during the off period of the FET 4. , a resistor 24 is formed, and the capacitor 10 is charged with the help of the voltage of the power supply capacitor 21. Others are the same as in FIG.

[Fourth Example] In the fourth example shown in FIG.
The transistor 13 is changed to a channel type, and the transistor 13 is changed to an npn type. Further, since the drain D of the FET 4 is connected to the power supply 1 side, the current detection resistor 3 is connected between the source and the load 2, and the reactor 5 is connected between the power supply 1 and the drain.
The connections of the transistor 13, capacitor 10, winding 9, etc. to the source and gate of the FET 4 are essentially the same as in FIG. In addition, charging resistor 1
1 is connected between the positive terminal of power supply 1 and one end of capacitor 10 .

Since the reactor 5 is connected between the FET 4 and the power supply 1, the energy of the reactor 5 cannot be directly released to the load 2 during the off period of the FET 4. For this reason, an energy emitting winding 25 that is electromagnetically coupled to the reactor 5 is connected in parallel to the load 2 via the diode 7. This makes it possible to smooth the chopper output similarly to the circuit shown in FIG. In FIG. 6, since the FET 4 is of an n-channel type, the FET 4 is turned on when the capacitor 10 is charged to a predetermined value or more so that the gate side is positive. Other operations are essentially the same as in FIG.

[Fifth Embodiment] The circuit of the fifth embodiment shown in FIG. 7 is a partial modification of the circuit shown in FIG. has been moved to. Other points are substantially the same as FIG. 6.

[Sixth Embodiment] In the circuit of the sixth embodiment shown in FIG. 8, the reactor 5 is connected between the FET 4 and the load 2 as in FIG. It is a channel type. In FIG. 8, a charging resistor 11 is connected between the auxiliary power source 26 connected in series to the main power source 1 and the capacitor 10.

[Seventh Embodiment] In the circuit of the seventh embodiment shown in FIG. 9, a capacitor 14a is connected in place of the bias resistor 14 in FIG. 1, and a diode 15a is connected in place of the capacitor 15 in FIG. It is connected. The other circuit configuration is the same as that in FIG.

As is clear from FIG. 10, which shows the state of each part in FIG. 9, the ON switching operation of the FET 4 depending on the charging voltage V ₁ of the first capacitor 10 is the same as the circuit shown in FIG. 1. On the other hand, the off-conversion operation of the FET 4 is performed depending on the charging voltage of the second capacitor 14a. Since the second capacitor 14a is connected in parallel to the winding 9 via the resistor 27, it is charged by the positive voltage of the winding 9 during the ON period t1 _{to t2 of} the FET 4. Also, the power supply voltage
A voltage Va-Vb, which is the difference between Va and the error voltage Vb, is applied to the second capacitor 14a via the current detection resistor 3, and this also charges the second capacitor 14a. During the period t ₂ to _{t 4} (off period) in FIG. 2, a reverse voltage is generated in the winding 9, so the second
The capacitor 14a is charged in the opposite direction via the resistor 27. The diode 15a connected in parallel to the second capacitor 14a is connected to the capacitor 14.
When it is reverse charged to about -0.6V, it turns on and a forward voltage drop of about 0.6V is obtained. Therefore, the reverse charging voltage level of the second capacitor 14a is fixed at approximately -0.6V. When the FET 4 is turned on and a positive feedback voltage is generated in the winding 9, charging of the capacitor 14a starts and the charging voltage _V3 gradually increases. When the sum of the voltage V ₃ of the capacitor 14a and the current detection voltage V ₄ reaches approximately 0.6V, the transistor 13 is turned on and the FET 4 is turned off.

When the voltage of the output line 20 becomes lower than a predetermined value, the output voltage Vb of the error amplifier 19 increases, and the charging current of the second capacitor 14a, which depends on the power supply voltage Va and the error voltage Vb, decreases. The sum of the charging current based on the line voltage V ₂ and the charging current based on the power supply voltage Va also becomes lower, and the slope of the capacitor voltage V ₃ becomes gentler as shown by the dotted line in FIG. 10H. Therefore, V ₃ +V ₄ becomes the transistor 13
The time it takes to reach the value that turns on (approximately 0.6V) becomes longer, and the time that FET4 is turned on also becomes longer.
The output voltage is returned to the desired value.

This seventh embodiment also has the same advantages as the first embodiment.

[Eighth Embodiment] The circuit of the eighth embodiment shown in FIG. 11 is obtained by removing the current detection resistor 3 from the circuit of FIG. 9.
In this case, the switching of transistor 13 into the on-state depends only on the voltage of second capacitor 14. The rest is the same as FIG. 9.

[Ninth Embodiment] The circuit of the ninth embodiment shown in FIG. 12 is a partial modification of the circuit of FIG. 9. In this example, in order to change the charging time constant of the first capacitor 10, a transistor 29 is connected in parallel to the first capacitor 10 via a resistor 28, and the output of the error amplifier 19 is connected to the base of this transistor 29. ing. Therefore, when the output voltage increases, for example, the output voltage Vb of the error amplifier 19 decreases,
The base current of the transistor 29 increases, the emitter-collector resistance of the transistor 29 decreases, and the amount of charging current flowing into the first capacitor 10 via the winding 9 bypasses to the transistor 29, increasing the amount of charging current flowing into the first capacitor 10 via the winding 9. The charging speed of the capacitor 10 becomes slower, the slope of the off period _t2 to _t4 of the capacitor voltage _V1 shown in FIG. 2F or FIG. 10F becomes gentler, the off period of the FET 4 becomes longer, and the output voltage becomes It is returned to the desired value. When the output voltage becomes high, the operation is opposite to that when the output voltage is low. like this
Even if you control the off time width of FET4,
The same advantages as in the embodiment are obtained.

[Tenth embodiment] The circuit of the tenth embodiment shown in FIG. 13 is a modification of the circuit shown in FIG. 1, in which the reactor 5 is connected in parallel to the load 2, and the diode 7 is
and the load 2 in series with the output line 20 between the load 2 and the load 2 . The connection polarity of the diode 7 is such that the anode is on the load 2 side and the cathode is on the FET 4 side. Therefore, the diode 7 is turned off during the on period of the FET 4, a downward voltage is generated in the reactor 5 during the off period of the FET 4, and the diode 7 is turned off.
is turned on. Therefore, the capacitor 8 is charged so that the lower side becomes positive. Since the direction of the voltage of the reactor 5 during the off period of the FET 4 is opposite to that in FIG. 1, the polarity of the reference voltage source 18 is also opposite to that in FIG. 1. Note that in the circuit shown in Figure 13, the FET
The energy stored in the reactor 5 during the ON period of FET 4 is released toward the capacitor 8 and the load 2 during the OFF period of FET 4.

[Eleventh Embodiment] Although the chopper type DC power supply device of the eleventh embodiment shown in FIG. 14 is different from that in FIG. 1 in connection, the principle is essentially the same. This figure 14
The FET 4 is of n-channel type and is connected in parallel to the load 2. That is, for power supply 1,
A series circuit consisting of a reactor 5, a FET 4, and a current detection resistor 3 is connected in parallel, but the load 2 is not connected in this series circuit. A reactor 5 is connected between the power supply 1 and the FET 4.
In order to release the energy of this reactor 5 to the load 2 side during the off period of FET 4, the reactor 5
A diode 7 is connected between the load 2 and the load 2. Current detection resistor 3, drive winding 9, capacitor 10, charging resistor 11, diode 12, transistor 13, for driving FET 4 on and off,
A variable bias resistor 14 and a ripple removal capacitor 15 are connected to the FET 4 in the same relationship as shown in FIG.
2. The polarity of the transistor 13 is reversed from that in FIG.

In the circuit of FIG. 14, when capacitor 10 is charged to a predetermined level through resistor 11,
FET4 turns on. During the ON period of the FET 4, the diode 7 is maintained in an OFF state with a reverse bias, so power is supplied from the smoothing capacitor 8 to the load 2. During the ON period of the FET 4, almost the entire voltage Va of the power supply 1 is applied to the reactor 5, energy is accumulated in the reactor 5, and a positive feedback voltage V ₂ is obtained in the drive winding 9, and the FET
4 is maintained in the on state. When FET 4 turns on, the drain current gradually increases, so the voltage V ₄ across current detection resistor 3 also gradually increases.
When V ₃ +V ₄ becomes approximately 0.6V, transistor 13
turns on and FET4 turns off. FET
4 is turned off, the diode 7 becomes forward biased and conducts, and the reactor 5 is connected to the voltage Va of the power supply 1.
The voltages are added and supplied to the capacitor 8 and the load 2. Therefore, a voltage higher than the voltage Va of the power supply 1 can be supplied to the load 2.

Since the on/off control operation of the FET 4 occurs on exactly the same principle as in FIG. 1, the same effects as in FIG. 1 can be obtained.

[Twelfth Embodiment] The circuit of the twelfth embodiment shown in FIG.
The position of the current detection resistor 3 in the figure is changed,
A current detection resistor 3 is connected in series to the common line 6.

[13th Embodiment] The circuit of the 13th embodiment shown in FIG.
The resistor 14 in the figure is replaced with a capacitor 14a, the capacitor 15 is replaced with a diode 15a, and a resistor 27 is installed between the capacitor 14a and the winding 9.
is connected. In short, the off control circuit portion of FIG. 14 is the same as that of FIG.

[Fourteenth embodiment] The circuit of the fourteenth embodiment shown in FIG.
This is a partial modification of the circuit shown in the figure, in which a transistor 29 is connected in parallel to the first capacitor 10 via a resistor 28, and the output of the error amplifier 19 is connected to the base of the transistor 29.
That is, the circuit shown in FIG. 17 is obtained by applying the voltage control method shown in FIG. 12 to the chopper circuit shown in FIG. 16.

[Fifteenth Embodiment] The circuit of the 15th embodiment shown in FIG. 18 is obtained by replacing the FET 4 in FIG. 1 with a transistor 4a. The emitter, collector, and base of this transistor 4a are connected to correspond to the source, drain, and gate of the FET 4 shown in FIG.
Note that in order to continue the base current when the transistor 4a is turned on by the winding 9, the capacitor 1
A resistor 32 is connected in parallel to 0 through a diode 31. Therefore, the base current based on the positive feedback voltage obtained in the winding 9 flows in a closed circuit between the winding 9, the emitter and base of the transistor 4a, the resistor 32, and the diode 31.

[Modified example]

The present invention is not limited to the above-described embodiments, but can be modified, for example, as follows.

(1) The resistor 14 and capacitor 15 in FIGS. 4, 5, 6, 7, and 8 may be replaced with the capacitor 14a and diode 15a in FIG. 9.

(2) Resistor 28 and transistor 29 shown in Figure 12
Accordingly, the charging time constant control method for the first capacitor 10 can also be applied to the circuit shown in FIG.

(3) FET4 may be a plurality of FETs connected in parallel and/or in series.

(4) The transistor 13 may be a FET.

(5) Figures 4 to 9 and 11 to 17
The FET may be replaced with a transistor, and a diode may be connected in parallel to the first capacitor 10 via a resistor as in FIG. 18.

〔Effect of the invention〕

As is clear from the above, according to the present invention, the switch element is turned from off to on based on the voltage of the capacitor, and a relatively large current can be passed through the reactor immediately after the switch is turned on, thereby improving the power supply capability. be able to.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the DC power supply device of the first embodiment according to the present invention, FIG. 2 is a waveform diagram showing the states of each part in FIG. 1, and FIG. I _D , V ₄ , V ₃ , with respect to changes in drain current
Waveform diagrams showing changes in V _BE , Figures 4, 5, and 6
7, 8, and 9 are circuit diagrams showing the DC power supply devices of the second, third, fourth, fifth, sixth, and seventh embodiments, respectively, and FIG. Waveform diagrams showing the states of each part in the figure, Figures 11, 12, 1
3, 14, 15, 16, 17, and 18 are the 8th, 9th, 10th, 11th, and
FIG. 7 is a circuit diagram showing DC power supply devices of twelfth, thirteenth, fourteenth and fifteenth embodiments, respectively. DESCRIPTION OF SYMBOLS 1... DC power supply, 2... Load, 3... Current detection resistor, 4... Field effect transistor, 5... Reactor, 6... Common line, 9... Winding wire, 10...
...First capacitor, 11...Resistor, 12...Diode, 13...Transistor, 14...Resistor, 15...Capacitor.

Claims (1)

[Claims] 1. A DC power source, a switch element connected with or without a load between one end and the other end of the DC power source, and a reactor connected in series to the switch element. A chopper type DC power supply device comprising a control circuit for controlling on/off of the switch element, and a smoothing means for smoothing an output obtained based on a series circuit of the switch element and the reactor and supplying the smoothed output to a load. , the control circuit includes: a drive winding that is electromagnetically coupled to the reactor and connected to the switch element so as to drive the switch element in positive feedback; and the switch element can be turned on by a charging voltage. a capacitor connected in series with the drive winding; and a capacitor connected between the DC power supply and the capacitor, and increasing the time constant of the capacitor to a voltage level capable of turning on the switch element. a charging circuit having a resistor for charging the switch element; an off control circuit for switching the switch element from an on state to an off state; and a voltage detection means for detecting a voltage supplied to the load. and a reference voltage source, which is connected to the voltage detection means and the reference voltage source and outputs a signal corresponding to the difference between the detected voltage obtained from the voltage detection means and the reference voltage obtained from the reference voltage source. , and a circuit that controls the charging current of the capacitor by this output or controls the point in time when the switch element is switched from the on state to the off state by the off control circuit. Chiyotsupa type DC power supply.