JPS58190277A - Drive circuit for switching type dc converter - Google Patents

Abstract

PURPOSE:To stabilize the operation of a converter by composing to automatically limit the current when a load is shortcircuited to a small value. CONSTITUTION:The terminal voltage of a condenser C4 becomes much smaller than the normal value in the state that a load is shortcircuited or in the near state, and the amplitude of a jumping voltage which is presented at a coil 12 can be suppressed by the voltage of a condenser C4 to a small amplitude. Accordingly, the voltage of the coil 13 can be reduced, and the slope of the waveform in the vicinity of zero crossing point can be very smooth. Thus, the voltage waveform at the point c, at which the waveform is differentiated, can be reduced in negative amplitude. In this manner, even if a pulse is applied to the point c since the voltage Vd from the point d is considerably larger than the voltage Ve at the initial zero crossing point of the jumping voltage, a comparator 6 does not operate. Therefore, the comparator 6 does not operate until the voltage Vd is reduced to the value near the Ve, with the result that the opening period of the switch 14 becomes much longer than the normal operation.

Description

[Detailed description of the invention] A repetitive force of an appropriate time width is applied to the excitation winding from a DC power supply.
In a separately excited switch lug DC converter that utilizes the entire VC-induced rebound voltage, the above output 1m or the same waveform voltage 1 is applied to the detection winding 1 to ensure operational stability.
Conventionally, a method has been used in which the zero loss point of the rebound 9 pressure waveform appearing at 171 is detected, the closed side of the main switch is determined based on the signal, and the vibration waveform and switch operation are synchronized.

The present invention is a switch driving signal generating circuit K11 which is necessary for this type of device.The purpose of the present invention is to enable extremely heavy-duty circuit assembly using commercially available timer ICs, and to short-circuit one load. To automatically limit excessive current at a time to a sufficiently small value below a specified value without providing a separate current limiting circuit.

To explain Figure Wi in A-physical terms, in Figure 1, 1
The portion to the left of the dotted chain line MuA' corresponds to an example of a drive signal generation circuit embodying the present invention. The output transformer l located on the upper right side of the @fastening has a primary excitation winding of 11%, a secondary output winding 12 and a voltage waveform detection winding 13, and the primary winding 11 is in series with the main switch element 14. and is connected to the main current 11Vl. The secondary winding 12 is connected to a series circuit of a rectifier diode Ds and a smoothing capacitor C4, and a series circuit of a load resistor RA and a current winding 21 of the output control signal voltage generation circuit j12 is connected in parallel with C4. 2Fi output current i.e. R7
Detects the difference between the current of A series charging resistor gt, a capacitor C1, and a discharging switch element 17f connected in parallel with the series charging resistor gt and the capacitor C1 are connected between the terminals of the DC power supply for commercial use. This is the standard to be set.

4 wires 1 to synchronous pulse shaping connected to the above detection winding 13
5 is a resistor R4 and a rectifier diode D! series circuit and 1
t4 and D! The junction of Cm and R8 (oc is the output point of circuit 15) is branched from the junction of Cm and R8 and connected in parallel with D from the series circuit of capacitor Ca and low resistance Rs.
The sRil path constitutes a dividing circuit, and therefore the number of input points is
The primary pressure that is generated is rectified by Dt, and the tentatively divided 100 points are λ1. 63゜Above capacitor CI
g) Capacitor charging/discharging circuit 1 branching from the positive terminal point P
6 is connected in parallel with CI! It consists of a series circuit of a diode Di and a high resistance R2, and a capacitor C2 connected between the junction point d of Dl and R1 and the output point C, and the point d becomes the output point. The circuit Dt-C2 has the above-mentioned t resistor Rs connected in series to form an interlocking charging circuit tube in which Ct is charged in conjunction with the charging of cl during the charging period, and the circuit R-Cm is R1 is also included to form a slow discharge circuit in which when Ct is discharged at once, Ct is slowly discharged due to the high resistance R-.

The general circuit 4 connects the output point P of the timing circuit 3 and the circuit l-
The control voltage (2) from the output control signal voltage generation circuit 2 receives each output voltage from the output point d. This is a circuit that generates drive No. 1 for opening and closing the switch element 14 in response to the following. This circuit is usually implemented as an IC, but in Figure tii
presents its functions in the form of a popular book diagram. The voltage ■p from point P and the control voltage Vat are given as inputs to the first voltage comparator circuit 5ue-) and (a), respectively, and the output passes through the differentiating circuit 8 to the input terminal of the flip-flop circuit 7. Given. The second voltage comparator circuit 6 receives a control voltage V as an H and output input. The voltage dividing circuit R, -R divides the voltage to an appropriate ratio and the voltage VaVt from the dots is given, and its output is as shown in the above day 11.
7e*t output Q of 0 circuit 7 given to input S
is applied to the control point of the switch element 14, while the reset output Q is applied to the control point of the short-circuit switch element 170 of 01.

What about the device shown in Figure 1? Volume 0 $1i explaining about ¥m
The voltage at point 1 induced at point 113 has a waveform as shown in curve a in FIG. 2, from time tl to t! At this point, a large rebound stain pressure of positive polarity appears during the open period of the switch 14. T! From t
During the period of 0, the voltage waveform at the point 0 in FIG.
Because of the diode Da and the diode Da, the positive part of the curve 1 in FIG. 2 has a waveform like a broken line with limited amplitude, as shown by the curve Ml)K in FIG. When this waveform is differentiated by the H path Cs Ra, the second
As shown by curve G in the figure, a pulse waveform generated at the zero-crossing point of the waveform is generated at output point C in FIG. Among these, only the negative polarity is used as a synchronization pulse.

In the general circuit 4, the flip 7a tube circuit 0 When γ is in the reset state, its Q output is Q.

Since the Q output is l (positive output), the switch 14 is open and the switch 17 is closed, so the capacitor C1
The voltage is almost zero. Therefore, if the circuit 7 is now reset to the energization of the input S, the Q output Fil and the Q output become 0, so the switch f14 is closed and the excitation current starts flowing to the winding 11, and at the same time, the switch 17Fi is opened and the capacitor Cs#i is charged by the current flowing from IGi Vg through resistor Rxff1 and begins to rise to a terminal voltage of %C1 as shown in FIG.

At this time, the voltage Va at point d in Figure 1 also rises as shown by the broken line in Figure 4 in accordance with 1.

Voltage comparator circuit 50 For both inputs, V, <V. The output of the function is a constant positive value, but ■1 is ■. The moment the aperture becomes sharp, the aperture output suddenly changes to a negative value. This output is differentiated by circuit 8 and applied to the input of flip-flop circuit 70B to reset this circuit. Therefore, switch 14tl-
Then, the switch 17 closes. Therefore, the voltage of C1 is rapidly discharged, and Vp1 suddenly drops to a value close to zero as shown in FIG.

However, as soon as the charge FiDt charged in Ct is in a reverse bias state, K does not discharge ■cL is RxCg
With a time constant of (Rs < R), it slowly descends like the 4th wAM line.

The synchronized pulse from Kokeshi 11 and 15 is C! via point al
(If t is not added, vd is the H input voltage V of the comparator circuit 6
Continue descending until you feel at home. When V, 1 becomes equal to Vz, the output of comparator circuit 6 suddenly changes from positive to negative and is applied to circuit 7 through differential circuit 9, so circuit 7 is set and everything returns to its initial state. , the above operation will be repeated again.

However, in the operating state of the camp, when the switch 14 opens at time t1 in FIG. 113, a rebound voltage as shown in the second figure is generated, and at the zero cross point, the curve lac in the same figure is generated.
A relatively large synchronous pulse appears with an amplitude such as n, which is transmitted to point a via capacitor Ctt, and voltage Vd is
As shown in the figure, at time tl, the voltage temporarily becomes lower than Vz, so the comparator circuit 6 is activated and the flip-flop circuit 7 is set, and at this point the voltage returns to the initial state. The period between tQ and tl is the closed period To of the switch 14, and the period between tl and t2 is the open period Tf.

Control voltage■. Tn changes when the size of changes, but T
t4n always matches the rebound voltage waveform width), the system operates stably.

The feature of this device is that the current is automatically limited to a safe small value when the load is short-circuited, and normal operation resumes as soon as the short-circuit is removed. Next, the reason will be explained. If the load is short-circuited or close to it, the output current will be much larger than the normal value, so the output of circuit 2 will be becomes almost zero,
It operates to minimize the closing time of the switch 14, thereby reducing the output voltage and therefore the short circuit current. However, there is a limit to the minimum value of c for which the circuit 4 normally operates, and therefore the closing time width of the switch 14 cannot be brought close to zero K. Therefore, it is difficult to sufficiently reduce the short-circuit current using only the above-mentioned normal current control function. In the circuit of this device, when the load is short-circuited or in a state close to it, the terminal voltage of C4 becomes much smaller than the normal value, so the amplitude of the rebound voltage appearing in windings 1 and 12 is also suppressed to a small amplitude by the voltage of C4. be done. Therefore, the voltage of winding 1113 also becomes small, as shown by curve a in FIG. Therefore, the slope of the waveform near the four-way loss point is very uncertain as shown in the figure.Therefore, the voltage waveform at point C in Figure 1 obtained by differentiating this waveform also becomes curve laC in Figure 3. The negative amplitude becomes small.Therefore, at the first zero-crossing point t8 of the rebound voltage, it is considerably larger than Va h V7, so even if a pulse is applied to point C, the comparison circuit 6Fi does not operate. Since the bounce and voltage form a damped oscillatory waveform, the pulse generated in the bale has an even smaller amplitude. Therefore, Vd is ■
The comparator circuit 6 is not activated until the value of 0 is reduced to a value close to 0, and the open period of the switch 14 is much longer than in normal operation. If the human resistance of circuit 60 is high, the value of resistor R1 can be increased, so it is possible to select a large VdO extinction time constant CtRxk. Turn on the switch and hit the switch every second.
By reducing the number of closures, it is possible to limit the output voltage ttIL to a sufficiently small value. It is clear that normal operation will be automatically restored when the short circuit is removed.

The above is the control word turtle pressure■. A friend mentioned the case where the voltage changes automatically in response to the load current, but as a variation of the voltage ■. It is clear that there is no problem with the short-circuit current limiting function of this device even if the voltage is applied from the outside independently of the output detection circuit 2.

Next, the 14P4 session will discuss the short-circuit current limiting effect of this device. In this type of power supply device with an output rated current of 05 mm and a voltage of about 5000 V, the open period of the switch 14 hardly changes even if the present invention does not apply, that is, a short circuit occurs, and only the closed period becomes the minimum value. If no other special current limiting means are taken, it is difficult to limit the short circuit current to a few mA or less. However, in the device of the present invention with the same rating, the short circuit current could be limited to t1 mA or less.

As is clear from the above description, the drive circuit of the present invention can be manufactured easily and inexpensively using commercially available ICs and other components, stabilizes the operating sound of the converter, and prevents the drive circuit from causing a load short-circuit. The short-circuit current can be limited automatically without a separate current-limiting circuit.
K has the characteristic of automatically returning to the original 'ItwJ' work.

[Brief explanation of the drawing]

The voltage waveform diagram at each point during full-time bursting, Figure 3 is a similar waveform diagram when the load is short-circuited, Figure 4 is the voltage waveform diagram at each point when there is no synchronized pulse, and Figure 5 is the voltage waveform diagram at each point when there is no synchronous pulse. FIG. 6 is a similar voltage hourglass diagram for the case of FIG. l: tB force transformer 13: Voltage waveform detection winding 2
: Output control signal voltage starting circuit 3: Timing circuit 5.6 = Voltage comparison circuit 7: 7 lip 70 tube circuit 14.17: Switch element 15: Synchronous pulse shaping circuit 16: Condenser charging/discharging circuit Agent Patent attorney Kamiyama Miscellaneous

Claims (1)

[Claims] A tall voltage wave tlR in which a parallel circuit of a capacitor and a discharging switch element is connected in series with a charging resistor between DC power supply terminals.
A synchronous pulse shaping circuit configured to generate a pulse at its zero-cruise point by differentiating the shape, and a series circuit of the capacitor of the timing circuit, a parallel Kl flow diode, and a resistor.
ii) A capacitor charge/discharge H path that connects a capacitor between the junction of these two and the output point of the synchronous pulse shaping circuit and uses the junction as the output point; and an output voltage and output control signal of the timing circuit. a first voltage comparator circuit having one voltage input; a g-snow voltage comparator circuit having both inputs the voltage obtained by dividing the output control signal voltage JfiK and the output voltage of the capacitor charging/discharging H path; A flip-flop circuit is provided which operates alternately in response to each output of the second voltage comparator circuit, and a set and reset circuit of the flip-flop circuit is provided with a switch element in series with the primary winding of the output transformer and the above-mentioned timing. A drive circuit for a switching type DC converter that is connected to each control point of a discharge switch element in the circuit.