JPS5826571A - Switching inverter circuit - Google Patents

Abstract

PURPOSE:To give stabilized self-starting capability to the titled circuit with a simple constitution by a method wherein the main transistor is turned off using an auxiliary transistor with a time constant circuit. CONSTITUTION:When ON position is given to the power source, no voltage is existed at both ends of coils L13 and L15, and the voltage which is obtained by dividing V1/2 (R11+R21) and R22 is given to the base of a transistor Q11. Accordingly, the transistor Q11 is turned into an active state, and voltage is induced at the coil L13. This voltage is positively fed back from the coil L15 to the base of the transistor Q11 through the intermediaries of the resistor R11 and a diode D11. At this time, a capacitor C11 is charged by a time constant circuit R12 and the capacitor C11, ON position is given to a transistor Q12 after the lapse of a prescribed period of time, the transistor Q11 is turned to OFF position, and a circuit S12 is turned to the ON mode. The above operation is repeated subsequently, and an oscillation mode is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a transistor having a time constant M't' to turn off a switching element.

The switching inverter (2) that constitutes the oscillation mode is connected to the circuit.

A switching inverter outputs an alternating current voltage (Kg) using DC input switching, etc. If this is further rectified and smoothed by a transformer and then returned to direct current, it becomes a DC-DC converter (
DC - DC Beloved Servant).

Conventional switching inverters can be divided into the following types depending on the driving mode.

(The AJ self-excited inverter uses the increased power of the switching element itself to oscillate, and is composed of passive elements except for the switching element. There are many types of self-excited inverters, but What they have in common is that they use the inertia and saturation characteristics of the output transformer or drive or transformer as an inductor to generate oscillation.

In this Banjo, there are the following 4 #s.

The advantages are that, in principle, both switching elements (with tight pull operation) are not turned on at the same time, so no so-called vertical current fi flows, and the operation is stable, and #II configuration is easy. The number of parts is small, and a power supply for the drive path is not required.

The disadvantages are that many require a starting circuit,
These include the need to use a saturated core (square hysteresis core), and the design being difficult unless a drive transformer is used independently when the power is high.

(BJ separately excited inverter) A clock is generated in a separate circuit, and the switching elements are operated by this clock.

This method has the following % sourness.

Advantages include that it can be constructed using only ordinary (saturable) transformers and that the frequency is stable.

The downside is that you have to get the timing right.

Switching elements with push-pull operation may turn on and off at the same time, causing electric current ff to flow, making it difficult to maintain safety (
(The efficiency may deteriorate, a drive voltage may be required, the circuit may be multi-mK or small, etc.).

The present invention aims to provide a switching inverter circuit that constitutes a new excavation mode that has the characteristics of both self-excited and separately-excited inverters, and achieves the effect of combining the advantages of each. . This invention is basically self-excited.

The oscillation mode is configured by turning off the switching element using an auxiliary transistor having a time constant circuit.

FIG. 1 is a diagram showing the principle of this invention. In Figure 1, Ql: Main switching element (bipolar transistor,
Field effect transistor, GTO (gat turn o)
ff::SCR), etc.) C2: Auxiliary switching element R1: Resistor R2 that provides a voltage or current that turns on Ql: A time constant circuit is configured with C1 and - Resistor CI that provides a voltage or current that turns on Q2: Capacitor Va that together with R2 constitutes a time constant (b) M: Voltage source vb having a voltage sufficient to turn on Ql through R1: Voltage source RL: Load.

When the switch armor 1 is turned on, path (b) in FIG. 1 operates as shown in FIG. 2. Namely.

■ A portion 1cVa indicated by Ma1 is given.

■ Positive bias is applied to main switching element QIK through R17J, and the power is 5 on.

■ The voltage k''X at the part indicated by M2 increases with time according to the time constant of R2 and C1.

■ If the voltage of M2 is different from the ON voltage of auxiliary switching element Q2, it turns on and the voltage at the part indicated by M3 falls to the saturation voltage of Ql (the saturation voltage of C2 is lower than the ON voltage of C2). ) 6 ■ The main switching element Q1 is turned off.

That's how it goes. Therefore, it is possible to configure an oscillation mode by combining the circuit shown in FIG. 1 and a fermentative load.

The third factor is to configure a push-pull inverter using the above principle and using a transformer having a negative feedback winding. This (b) path consists of the circuit shown by Sl and the circuit shown by S
The circuit shown in 2 turns on and off alternately, and the coil L +
A 13 K AC voltage is generated. In Fig. 3, coils Lll, L12 and L13 are wound on the same core of a transformer.

The coils i, 13 and L 11 and the coils L13 and L12 are each connected in a positive feedback direction.

In the circuit S1, a transistor Qll is a main switching transistor, C12 is an auxiliary switching transistor, and a capacitor ell constitutes a time constant circuit together with a resistor R12.

The diodes Dll and D12 are for operating the transistor Qll in a non-saturated state. 'f7j In other words, when a voltage is induced in the coil Lll, this causes the diode D
11 't' changes the pace of transistor Qll and turns it on. If the voltage drops of the diodes D1 and D12 are equal, the collector-emitter voltage vcE of the transistor Ql is equal to the base-emitter voltage v
When BEK becomes equal, diode D12 turns on and "CI-
An extra current flows between the collector and emitter of transistor Qll, leaving the current necessary to maintain vBli. As a result, gVcy is maintained at +X constant KVcyB≧vBE. Normal transistor saturation voltage Vcgt! Since it is smaller than the voltage between the transistors Qll and VBE, the transistor Qll
saturation is avoided. The circuit 82% has the same configuration as the circuit 81.

The circuit of FIG. 3 operates as follows.

When the circuit 81 is on, the coils L 12 and Li
Due to the positive feedback effect of 2, transistor Qll continues to be turned on. The voltage of the capacitor C1l rises by % with the time constant of R12・C1l, and after a predetermined time, the voltage of the transistor Q
12 is turned on, and transistor Qll is turned off. When the transistor Qll is turned off, the voltage applied to both ends of the coil L13 is reversed due to the induction of the coil L13, and the circuit 82411 is now turned on.

After transistor Qll turns off, transistor Q13
It takes a certain amount of time for Ql to turn on, but during this time transistor Ql] must remain off.
Fortunately, this is ensured for the following two reasons. One is the time from when transistor Q12 is turned on to when transistor Qll is turned on (on time of Q1). One is due to the sum of off-times of the transistor Q12 itself (transistor Q12 (transistor Q12 is completely saturated switching and requires a certain amount of time to turn off). Stable operation is possible by turning on Q13.Once transistor Q13 is turned on, transistor Qll becomes 0 bias and remains off.

After a certain period of time determined by time constant R14·CI2, transistor Q14 is turned on and transistor Q13 is turned off. In this way an oscillation mode is formed fl.

Operates as a switching inverter.

Next, some explanations will be given on how to make the embodiment shown in FIG. 3 oscillate. (Making the switching elements complementary) Transistors Qll and Q12 and transistors Q13 and Q14t in the embodiment shown in FIG. Score less (can).

In addition, the coil can be constructed as a one-piece coil without dividing it, and only need to be added in tandem from the middle. Fourth
The figure shows an example of such a configuration. In FIG. 4, t corresponding to the % portion in FIG. 3 is given the same reference numeral.

In Figure wi4, coil L15 is the coil Ll in Figure 3.
Common to l and LL2Y, resistor R15 is resistor R13
and R13 in common, resistor R16 has resistors R12 and R14 in common, and capacitor C15 has capacitors C1l and C12 in common.

Coil L16) X coil 1, 15. It is wound around the same core as Li2, and is for output (the corresponding coil is not shown in Figure 13).0 In Figure 4, when transistor Qll is turned on, coil L13 and Due to the positive feedback effect of Li2.

This transistor 911tX continues to be on. The voltage of the capacitor C15 gradually rises with a time constant R16·C15, and finally turns on the transistor Q12, and then turns off the transistor Qll. Then, the voltage applied across the coil L13 is reversed, a voltage is induced in the opposite direction by 15% in the coil L13, and the transistor Q13 is turned on.

At this time, capacitor C15 is also charged in the opposite direction, and the voltage across it gradually rises with time constant R16・C15.
After a predetermined time, transistor Q14 is turned on and transistor Q13 is turned off. Oscillation is performed in this manner.

(B) Self-starting I! Both the circuit in Figure 3 and the circuit in Figure 4 cannot self-start as they are, but the hold operation of transistors Q 12 and Q13 (continues to be on for a while even if the operation of the circuit is reversed, and the transistors Qll and Q13 (operation to hold the OFF state), it is possible to provide a safe self-starting capability.An example of a circuit that allows self-starting is shown in Fig. 5.In Fig. 5, the 3 @ and 4 Portions #IC that are common to each part in the figure are given the same reference numerals.

In diagram IIs, a series circuit of resistors R2] and R22 is connected to the diode 012 in parallel to the circuit 813, and
C reranoh resistor R2] * The voltage at the midpoint of Rη is applied to the base of transistor Qll. Once again @8
12 has resistors R23 and R24 in parallel with the diode D14.
The series circuit is 1i! These resistors R23, R2
4 is applied to the base of transistor Q13. As a result, even if the (2) paths 811 and 812 are in the off state, the resistors R2j, R21, R
13.

Since current flows through R14, R23, and R24, a base bias is applied to the transistors Qll and Q13, and self-activation is performed.

Note that when the circuit Jl] is in off mode, the transistor Ql
In order to prevent l from turning on, resistor R2] and Rη are
When the circuit Bll is in the off mode (at this time, the part indicated by ■ is drawn to -11), the values are determined so that the voltage between the base and the pins of the transistor QII is approximately OVK. Also, resistance R2].

R22 is chosen to supply enough current to its base to fill the active region of transistor Q 11 V and not to interfere with the non-saturated operation of transistor Qll.

Similarly, in the circuit 812C', resistors R23 and R2
Determine the value of 4.

In the circuit shown in Figure 5, when the power is turned on, the coil L15°Li
The voltage across 2 is 0 and it is a transistor. A voltage divided into 11 is given. KofL? Transistor Q from C
ll becomes active, and a voltage is induced in coil L13. This voltage is applied from the coil L15 to the resistor R11 and the transistor via the diode D114. l]'s base is returned to normal. At this time, the capacitor ell has a time constant R12.
After a predetermined period of time, the transistor Q12 is turned on and the transistor Q11 is turned off, setting the circuit 812 to the on mode. Thereafter, this is repeated and the oscillation mode is released. Note that self-starting may start from circuit 8121m, but in any case,
In reality, since there are slight differences in the elements of the circuits 811 and 812, one of them will always start up first.

In the mode in which the circuit 812@ is on, the above-mentioned resistor R23,
R24 settings 0. The voltage between the base of the transistor Qll and the output voltage is around θ, so no current flows through the transistor Qll.

Both switching elements (Q
13. Q13) is in the active region because :yilL15
．． This is true only when the voltage across Li2 is around 0.

This is the same as AB@ operation in an amplifier. This region allows for self-starting ability, but in Gusche pull switching, both switching elements ('Q11, Q13) are on at the same time! ! It is extremely dangerous if there is even a small amount of time. This is because when a large current is drawn, the turn-off time of the switching element is long (1) Before one switching element is completely turned off, the other one is turned on, causing a so-called vertical current to flow and deteriorating efficiency. However, in the 1115m circuit, this problem is also solved by the holding action of transistors Q12 and Q14. This is because when oscillation starts and the steady oscillation state is started, the transistor Q12% or Q14 is always on during the time when the transistors Q1 and Q13 are switched. Overcharge and Q12.Q14
(depending on the off-time of the eye and K), the off-state transistor is maintained in an off state (hold effect), so a positive bias is not simultaneously applied to the transistor Ql]IQ13. Therefore, in the l[5Fg circuit, even if the idling current is set in advance and self-starting capability is provided, once one oscillation starts, the idling current disappears and the idling current disappears. The current is 1
5! tl disappears, resulting in safe operation. Conversely,
The auxiliary transistors (transistors Q12 and Q14 in FIG. 5), which are the constituent elements of this invention, have a K hold effect.

It can be said that no problem will occur even if the device has a self-starting ability as shown in FIG.

(C) Constant oscillation frequency In each of the above embodiments, the oscillation frequency will shift depending on the power supply voltage. This is because, for example, in the embodiment shown in FIG. 4, the current charged to the capacitor C15 is determined by the resistor R12, and the voltage supplied thereto is proportional to the power supply voltage +BK. The tR6 diagram shows this state, and the solid line is the state of change in charging voltage when the power supply voltage is small, and the dot chain I! is the state of change in charging voltage when the power supply voltage is large. As you can see from this diagram.

When the power supply voltage is large, the time required to reach a constant value (here, the on-voltage of transistors Q 12 and Q 14) becomes shorter even with the same time constant, so the oscillation frequency becomes higher.

In order to solve this problem, a method for K as shown in diagram IN7 can be considered. The circuit in Fig. 117 is basically constructed from the circuit in Fig. 3 (circuit S2@ is omitted).
Parts common to those in the figures are given the same reference numerals.

ll! In Figure 7, resistors R12a and R12b are the third
The resistor R12 is divided into two parts. Resistor R12
a, the midpoint of R12b is the diode D25. It is connected to the emitter of transistor Q12 via D26. At this time, the instantaneous electromotive force V・1 of the coil Lll and the charging voltage Yell of the capacitor C1l are expressed as shown in FIG. (The figure is drawn with point X in the figure as a reference), diode D25. Due to the clamping effect of D26, Yell becomes an asymmetrical waveform, and the clamp works only on positive voltages (therefore, for negative voltages, the 1-degree fluctuation is ignored as is. Therefore, when the power supply voltage increases, Veil GW changes in the negative direction. In the positive direction, the time T1 from when the polarity is reversed to reach the clamp voltage is longer (becomes longer) until the voltage reaches the ON voltage of the transistor Q12.
As a result, the transistor Q12
It will take a long time for the on-voltage KVell to reach the oscillation frequency, and the oscillation frequency will become lower.The addition of the diodes D25 and D26 will change the relationship between the power supply voltage and the frequency, but the resistance R12a, R12
By varying the ratio of b, this relationship remains in the confession. The ratio of resistors R12a and R12b * is the clamp time TI
It has the meaning of Y adjustment. If the clamp time 〒1 is left too long, the oscillation pigeon wave number vk should be kept almost constant with respect to changes in the power supply voltage. FIG. 9 shows the change in v@11 at Koya.

(Suppression of fluctuations in duty ratio) Here, let us consider the duty ratio, which is one factor of a switching inverter. In an inverter, when output 1 is taken from the secondary side, it is generally rectified by a capacitor input. It is desirable that the ratio is 50 or better.Obviously, the oscillation mode is set with a duty ratio of 50, but in circuits such as those shown in Figures 3 and 4, if the duty ratio is changed for some reason. If the duty ratio is changed, the duty ratio does not have the ability to correct this.
l.

L12) and the voltage output from load winding II (also coil L13).

Figure l110 (The resistance is the voltage generated by the feedback winding and the load winding 1. Vd is the waveform when the duty ratio is 50, and V is the waveform when it is not. The transformer is designed so that the integral value of the output waveform with respect to time is 0. The positive voltage waveform (0
The area of the negative voltage waveform (the part shown with @) is equal to the area of the negative voltage waveform (the part shown with @). Therefore, the voltage of a narrow pulse is one tone higher per month than the voltage of a wide pulse. Figure 10 (bJ
(D Vd', Ve' +1 Vd.

These are waveforms obtained by rectifying V@. duty 50
- In the case of -, it becomes a complete direct current, but in other cases, the narrower waveform (the waveform of V and ■) jumps out, and in the case of a capacitor input type smoothing circuit, this narrower waveform Only pulses will flow to the load. Therefore, it can be said that it is desirable to operate according to the duty parameter.

In the circuits up to Figure 5, when the duty deviates from 50% for some reason and a voltage such as V in @10 ta) is fed back, the voltage at the part ■ is high, so the capacitor C11 (C15 in FIG. 4) is charged quickly, and the transistor Qll is quickly turned off, which makes the duty ratio further away from the negative.

In the circuit shown in Figure +7, the diode clamp solves this problem by m% and suppresses the variation in duty ratio.

FIG. 11 shows a DC-DC converter constructed by combining the above embodiments. The same reference numerals are given to the parts common to the previous embodiment.

In FIG. 11, VRI is the polynym for Death IIJI. The voltage generated by the coil L16Kffj is rectified, smoothed, and converted into a DC voltage.

The problem with this circuit is that the frequency fluctuates depending on the load current (as the load current increases, the frequency decreases (and as the load current decreases, the frequency increases). Possible changes include time and current busyness.The following method seems to be the solution for this busyness.

When the transistor Qll is used in a non-saturated state, as shown in FIG. 1Z, the base tm! B0. Only enough current flows to flow the required collector current V. As mentioned above, this operation is maintained by the diodes Dll and DI2. Therefore xBl)#/
c shows changes in load and current as they are (this only occurs in non-saturated switching. In proper switching mode, the drive current is constant regardless of the load current, so all the drive current flows through the transistor Ql).
(1B11 is constant regardless of the magnitude of the load current).

In Fig. 4, when the collector t"■C1] of the transistor Qll changes, I also changes VB!, 1.+vDF01(
vB, 1. □) Bll is the base-emitter voltage of transistor Qll.

vDFII (forward voltage of diode DH) also increases."When XC1110 becomes large, BEII+v
DFIIt is thick (becomes. Therefore, if you use this voltage to charge the capacitor C1l, you can compensate for the frequency drop when !c11 increases.Use this to charge the resistor R12 and the capacitor C11Q@13 It is conceivable to connect as shown in the figure. ・■Bl] is determined only by the sum of the load currents, and the current flowing through the resistor R11!R1] Since it is not affected by I5 (12 is affected by !8□1),
There is no change in frequency due to a change in power supply voltage WnK.

However, in the circuit shown in FIG. 13, the correction effect explained in FIG. 12 (correction for frequency fluctuations due to load current) is too large, resulting in negative IFr! If you remove it, the frequency will go up. Therefore, as shown in Figure 14, the volume VR12
All you have to do is press K to adjust.

As explained above, the present invention configures an oscillation mode by turning off a switching element using an auxiliary transistor having a single time constant circuit, and has various effects such as first-order effects.

■ Since the conventional single-excitation type inverter does not use the inertia and saturation characteristics of the transformer as an inductor to generate oscillation, the transformer core does not require a rectangular steresis core. Unlike conventional separately excited inverters, there is no need for a separate power supply for the drive.

(2) For example, as shown in the embodiment shown in FIG. 5, stable self-starting capability can be achieved with a simple configuration.

■ For example, as shown in the example shown in Figure 7, the circuit can be constructed with fewer components so that the oscillation frequency is not affected by fluctuations in the power supply voltage.■ For example, as shown in Figures 13 and 14
As shown in the embodiment shown in the figure, the circuit can be constructed with fewer components so that the oscillation frequency is not affected by fluctuations in the load current.

ω By combining the above, a stable switching inverter can be constructed with a small number of parts.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram for explaining the basic principle of this invention.
FIG. 2 shows tJl, the operating waveform diagram shown in FIG. 1, FIG. 3 is a circuit diagram showing an embodiment of the present invention, and FIG. 4 shows I! A circuit diagram showing an embodiment in which the switching element shown in Fig. 3 is made complementary, and Fig. 5 a circuit diagram showing an embodiment in which the switching element shown in Fig. 4 is further provided with self-starting capability. A diagram showing how the frequency changes depending on the power supply voltage in the waveform. Figure s7 is an example of a circuit in which the circuit in Figure 3 is summed to suppress fluctuations in the oscillation frequency due to fluctuations in the power supply voltage. Figure @S is a diagram showing how the frequency changes depending on the power supply voltage. The operating waveform diagram of the circuit in Figure N7, Figure 9, shows that the fluctuation of the oscillation frequency has been completely canceled by the adjustment of time 〒1 in Figure 8. The waveform diagram %fjR1O shows that the duty ratio is 504. Figure 1 is a waveform diagram to explain why it is desirable. Figure 1 is a circuit diagram that combines all of the above embodiments. Figure 12 is a circuit diagram that explains passive oscillation frequency due to load current. Figure 13 is a diagram showing the load current. FIG. 14 is a diagram illustrating an example of a circuit configured to suppress fluctuations in oscillation frequency caused by oscillation frequency, and FIG. 14 is a diagram illustrating an example of a circuit configured to adjust excessive correction effect JJ: in the circuit of FIG. Q・1, Qll, Q13...Main switching element %Q2゜Q12. Q14... Auxiliary switching element, [R2, C1], Qnx2. C1l'1. Back x
4. cxz”J= jpi6. cls: l・# constant circuit, [ho, 1, 12.1, 131. [L12
-, L151...Coil that could not be wound around the same core. Figure 2 157M 5W1. The

Claims (1)

[Claims] A main switching element connected to a DC power source via a load, a time constant circuit driven by the control power source of the main switching element, and an auxiliary switching device driven by the voltage of the time constant circuit to turn off the main switching element. A switched lag inverter circuit which is designed to confuse rooting head with elements.