JPS6192169A - Multioutput dc/dc converter - Google Patents

Abstract

PURPOSE:To reduce the turning OFF loss of a main transistor by providing an oscillator which outputs a triangular wave signal or a reverse sawtooth wave signal in a pulse width modulator for stabilizing the DC output. CONSTITUTION:A main transistor 4 is driven by a pulse width modulation signal of a comparator 16 to stabilize the DC voltage to be supplied to a load 12. On the other hand, a sub transistor 20 is driven by the pulse width modulation signal of a comparator 26 to stabilize the DC voltage supplied to a load 23. The output signal of an oscillator 27 is a reverse sawtooth wave, and the turning ON periods of the transistors 4, 20 coincide, and the turning OFF time of the transistor 20 is earlier than the turning OFF period of the transistor 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention uses pulse width control to stabilize the entire output of the main output, and in synchronization with this main output, the sub output also has a pulse width itt.
The present invention relates to a multi-output DC-DC converter that stabilizes C for control purposes.

[Conventional technology]

Conventionally, there was a circuit for this glaze as shown in FIG. In Figure 7, the human power source (1) is the Tunli Transformer (2).
) is connected to the second winding (8) and to the main transistor (4). ′! In addition, a transformer (
2) Reset winding i (Ill') is connected to diode (13) Vc4 ffl.Transformer (2)
) is connected to the distorted current diodes (8) and (9) to the secondary winding (7), and a smoothing choke coil and a capacitor l,
1 is connected to the negative direction scream through the force. Both ends of the load (121) are connected to the input of the error amplifier (14) together with the differential pressure (131). ), and the output of the comparator (1) is connected to the base of the transistor (4). Meanwhile, the other secondary winding of the transformer (2) η is connected to the rectifier diode (1) and ( 194b - Connected to the sub-transistor block, Chiho's terminal block 4
load (1231Kff via 211 and capacitor)
It is connected. Both ends of load-1 are connected to the input of error amplification circuit j along with a reference voltage example. Error amplifier (
The output of the oscillator (b) is sent to the comparator t26
The output of the n1 comparator tS+ is connected to the base of the sub-transistor (1) with the input vc connected to the n1 (10) base.

Next, the operation of the above configuration will be explained. First, input power (
1) is applied to the secondary winding i (81) of the lance (2), and when the main transistor (4) is opened and closed in all cycles, the secondary winding (7) and 57) A rectangular wave voltage is induced depending on the turns ratio between the negative winding and the secondary winding of the transformer (2). In addition, by using the reverse induced voltage generated when the main transistor (4) opens in the winding (6), the magnetic flux of the transformer (2) is returned to the initial state by causing the diode (6) to escape. It has a function to return or reset.

When the main transistor (4) is closed, the secondary winding &
(7) [For the induced voltage, diodes (8) and (9)
The F system was swept away, and the choke coil σq and Cano (Sita J
The smoothed fC DC voltage is supplied to the load (chest).The DC voltage supplied to the load (chest) is equal to the reference voltage (
13) and the error amplifier (141), and the constant frequency sawtooth wave signal which is output by converting the output of the difference amplifier a to the oscillator μsJ, and the constant frequency sawtooth wave signal which is compared in the ratio amplifier (161). When this pulse width modulator is driven by the transistor (4), the flow pressure supplied to the load is stabilized.

On the other hand, when the main transistor (4) is open, the voltage induced in the secondary winding (lv) flows through the diode (i8) and [19J vc f] when the sub-transistor tray is closed. The nine current pressure is smoothed by the choke coil +Zll and the capacitor and is supplied to the load (-). The voltage supplied to the load 1 in the enclosure is compared with the reference voltage in an error amplifier 2, and the output k of this error amplifier is
@71 Oscillator (with 157 single-cycle wave signals).

When comparing i 7n+ with 2, it is converted into a pulse width modulated signal J@ with a constant period. When the sub-transistor group is driven by this pulse width modulation, the current pressure supplied in the negative direction is stabilized.

Here, the opening/closing of the sub-transistor (2) is synchronized with the opening/closing operation of the main transistor (4), and the opening/closing of the sub-transistor (4) is
) The number of turns of the winding (3) is set so that the conduction time width of the raw transistor (4) is smaller than the conduction time width of the raw transistor (4). Furthermore, the turn-off timings of the main transistor (4) and the sub-transistor (4) coincide.

The operating waveform t at the trough in FIG. 7 is shown in FIG.

In taJ, ose is the output waveform of the generator), A
MPI is the output signal between the error amplifiers. work) VCS
;-, v[]□Ha v of winding (7) of transformer (2)
j generated pressure, (cl Ic &, 18□ is the winding (7)
The output 'current of is 2 in the company j, and the v82Ic winding (17
) ノL'5 W jjL pressure, (el Ic 2Vr, output signal of AMP 2 U error amplifier In+, (fJ
K9, v08□ is the collector of the sub-transistor.
In the emitter separation pressure, (g), 182 is the winding rX''
In (h), the collector j1@emitter pressure of the transistor (4), and in (1), ip is the collector current of the transistor (4).

And the king transistor (4) and the sub transistor 1.20
If we look closely at the + m, we get the waveform shown in Figure 9. Q.
If (% l high n ?N n n
Each volume of ik Lance (9,) at(al t (5
) + (7) + Qq) tv winding fi'T', ng, is the load (current supplied to the chest, and ng 2 is the load μ
This is the current supplied to s1. tr is the turn-on time of the transistor, and tv is 2 when the transistor is turned-off.
The rising time s tt of the collector-emitter voltage is the falling time ``'C of the collector current.
The period of the l-DC converter is ``c''.

In the DC-DC converter Ics', most of the loss in the transistor is transient loss when the transistor is turned on and turned off. Here, the transient loss P of the transistor (4) can be expressed by the following equation.

17c1 Transient loss of sub-transistor ■ P2 can be expressed by the following formula.

This is because the inductance load is fully opened and closed even though the collector current does not decrease until the collector-emitter voltage rises when the main transistor (4) turns off in Figure 9 1c. , most of the transient loss of a transistor is the loss at turn-off.

[Problem that the invention seeks to solve]

The conventional multi-output DC-DCC set has the advantage that the turn-off loss of the sub-transistor (1.201) does not occur, but the turn-off loss of the main transistor (4) is generated by Futada's force, and the -sub-sleep pressure V If □ is a high voltage,
There was a problem in that the turn-off loss of the transistor (4) became large.

This invention was made to solve all of these problems, and is a multi-output D that reduces the turn-off loss of the main transistor (4) and increases the conversion efficiency of the converter as a whole.
The overall objective is to obtain a complete set of C-DCC data.

[Means for solving problems]

This is an fC type in which an oscillator for outputting a triangular wave signal or an inverse sawtooth wave signal is provided in a pulse width modulation circuit for stabilizing the DC output.

[Effect]

In the above energizer, the turn-on timing of the main transistor and the turn-off time of the sub-transistor match, or the sub-transistor is turned on after the raw transistor is turned on LJc, and the sub-transistor is turned off before the main transistor is turned off.

〔Example〕

FIG. 1 shows a circuit 1'''C showing a first embodiment of the present invention.
be. 2 in the same figure, (a) is an optical sensor, and this oscillator () is an oscillator that can output an inverted sawtooth wave.fxh
, and other constituent elements are the same as those in FIG. 7 showing the conventional example, so the same reference numerals are given and detailed description thereof will be omitted.

Next, let's read about the operation of the above 3C configuration. First, the primary transistor (4) is driven by the pulse width modulation circuit of the comparator (16) so as to fully stabilize the DC voltage across the load (9).Meanwhile, the secondary transistor (4) is also driven by the pulse width modulation circuit of the comparator (16).
comparator array 1 to stabilize the DC voltage supplied to comparator array 1.
It is driven by a pulse width modulated signal VC.

Here, since the output signal of the oscillator is an inverse sawtooth wave, the turn-on timing of the main transistor (4) and the sub-transistor (4) coincide.The turn-off timing of the sub-transistor (4) is the turn-off timing of the main transistor (4). It's early in the season.

FIG. 2 shows operating waveforms of each part in FIG. 1.

2, the same reference numerals as in FIG. 8 indicate the same parts.

Next, the detailed operation of the main transistor (4) and the sub-transistor is shown in Fig. 3. In the figure, the same parts are indicated by the same reference numerals as in FIG. 9. In Figure 3, no turn-on loss occurs in the sub-transistor.

Conversely, turn-off loss occurs. First, the transient loss P of the transistor (4) can be expressed by the following equation.

In addition, the transient loss P4 of )) in the sub transistor can be expressed by the following equation.

The circuit of Figure 7 and the circuit of Figure 1 have two main transistors (
Comparing the sum of the transient losses of 4) and auxiliary transistor), it can be expressed by the following formula. However, 1r=1v=1. Assume that =1.

That is, (Pyo+P2)>(P3+P4).

Therefore, the lower transient loss of the transistor in the circuit of FIG. 1 is smaller than the sum of the transient loss of the transistor in the circuit of the seventh factor. That is, the multi-output DC-DCC set according to this embodiment has a higher conversion efficiency than the conventional one.

Next, FIG. 4 is a circuit diagram showing a second embodiment of the present invention.

Same figure VC'J? The decoy 1 is an oscillator, and this oscillator is an oscillator that can output a general triangular wave.

3. Other components are given the same reference numerals as those in FIG. 7 showing the conventional reli, and detailed explanation thereof will be omitted.

Next, the operation of the upper SP configuration will be explained. First, the main transistor (4) is operated in conjunction with the pulse width modulated signal of the load (comparator α6) so as to stabilize the DC voltage supplied to the load (comparator α6). On the other hand, the sub-transistor also has a load of 12!
C9 is driven by the pulse width modulation signal of comparator 1 so as to stabilize the DC voltage supplied to 3+. Here, since the output signal of the output signal β) is a triangular wave, there is no difference in the turn-on and turn-off times of the main transistor (4) and the sub-transistor (4). And King Toranozj'
(The sub-transistor (20) is turned on after 47 is turned on, while the sub-transistor is turned on before the main transistor (4) is turned off). The complete waveform is shown in Figure 5.

Is it strange that the same numbers and parts are the same as in Figure 8? show.

Next, Figure 6 shows the detailed tIJJ construction of the main transistor (4) and the sub-transistor tray. 2, the same reference numerals as in FIG. 9 indicate the same parts. In FIG. 6, a turn-on loss and a turn-off loss occur in the sub-transistor (a) i Ic n s.

First, the transient loss P3 of the transistor (4) is expressed by the following formula %
Formula %'' Also, the transient loss P4 of the sub-transistor (4) can be expressed by the following formula.

e2 X()V,
Comparing the sum of the transient losses of 4) and the sub-transistor (2), it can be expressed by the following formula. However, tr=j, v=t, ,=j,
Assume that

That is, (P + P2) P3 + P4).

Therefore, the sum of the transient losses of the transistors in the circuit of FIG.
It is smaller than the sum of hypercough loss in path (b) of the figure. That is, the multi-output DC-])C converter according to this embodiment has higher conversion efficiency than the conventional one.

2 In the above implementation, the DC-DC converter conversion method is a forward fist converter that excites the magnetic flux of the transformer in one direction, but it is also suitable for a push-pull converter that excites the magnetic flux of the transformer in both positive and negative directions. There is an effect.

In addition, when the element that opens and closes is a transistor, only VC is shown, but other switching elements such as MOS FET or thyristor can also be used.

Further, in the above embodiment, a two-output DC-DCC converter mill was described, but the effects of the above MC embodiment and colleagues are also excellent in a DC-DC converter with three or more outputs, that is, a decimal output.

The circuit of the 3-oscillator shown in the above embodiment can obtain a nine-inverted sawtooth signal or a one-inverted triangular wave IN signal, and may also be a one-way circuit of A(I) and HIF. The output can be stabilized not only by voltage but also by direct current or single power.

〔Effect of the invention〕

As described above, according to the present invention, the reverse sawtooth pattern 121 is formed in the circuit.
! Since an oscillator capable of outputting a No. II or general triangular wave signal is provided, the turn-on timing of the main switch element such as a transistor and the sub-switch element can be synchronized, or the turn-on timing of the main switch element such as a transistor can be synchronized with that of the sub-switch element. At the time of turn, pA is delayed and the turn-off time of the sub-switch element is set before the turn-off time of the main switch element.
As a result of setting T:@s7, the collector 1 current at turn-off of the main switch system is lowered, the turn-off loss is reduced, and the conversion efficiency as a whole is increased. Things will happen.

[Brief explanation of drawings]

Figure 1 shows the first implementation of this invention? FIG. 2 is an hourglass diagram showing the operation of the trough of the circuit shown in FIG. Fig. 4 is a circuit diagram showing the entire second embodiment of this light, Fig. 5 is a waveform diagram showing the operation of each part of the circuit shown in Fig. 4, and Fig. 6 is the circuit shown in the above second embodiment. VC
Figure 7 is a circuit diagram showing a conventional multi-output DC-DC converter, Figure 8 is a waveform diagram showing the operation of the trough of the circuit shown in Figure 7, and Figure 9 is a circuit diagram showing the conventional multi-output DC-DC converter. FIG. 2 is an operation hourglass diagram of transistors in the circuit of FIG.
. Figure VC, 9, (1) U human power source Th (21U
) Lance, (81° (5) is the -secondary winding of transformer (2) % (7) t 117) is the secondary winding of transformer (2), (4) is the main transistor, and ) is the sub-transistor. , (61, tel, (93, (B), t19)
is evening iode, +JO). 121) is a choke coil, (b) is a capacitor,
(E, n+ is the load, (187, example is the positive pressure, 9
phrase, μs] is an error-run trivializer, (16I is the adjacent 1 is a comparator,
Curse 1. 41 is an oscillator. In addition, the same symbol in the valley diagram indicates the same or equivalent item.

Claims (1)

[Claims] A main switch element connected to the primary winding side of the transformer,
A plurality of output circuits including a sub-switch element connected to the secondary winding side of the transformer, a rectifier diode, a smoothing choke coil, and a capacitor connected to the secondary winding side of the transformer, and these output circuits. a multi-output DC with multiple pulse width modulation circuits to stabilize the output of the
- in the DC converter, the pulse width modulation circuit;
an oscillator that outputs a triangular wave signal or an inverse sawtooth wave signal to make the sub switch conductive at the same time as or after the main switch element is made conductive, and to cut off the sub switch element before the main switch element is cut off; A multi-output DC-DC converter characterized by being provided with.