JPH0320986B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a multi-output switching regulator type power supply device that utilizes cross regulation.

[Technical background of the invention]

A conventional multi-output switching mode power supply using cross regulation is constructed as shown in FIG. That is, one converter transformer 1
A plurality of output windings (here, two sets of secondary windings LB ₁ and LB ₂ are taken as an example) are wound around 1, and each winding has rectifier and smoothing circuits 12 ₁ and 12 ₂ . Then, a certain output (here, V ₁ output) among the plurality of outputs (V ₁ , V ₂ ) is compared with the reference voltage (V _REF ) by the differential amplifier 13, and the error amount is calculated. The signal is amplified and subjected to pulse width modulation by a pulse width modulation circuit 14, and is applied via a drive circuit 15 to a switching circuit 10 comprising switching power transistors Tr ₁ , Tr ₂ and the like. As a result, the DC voltage (Vdcin) obtained by directly rectifying the input AC
is applied to the converter transformer 11 after being changed into a high frequency voltage having a conduction time corresponding to the output voltage. A voltage corresponding to the turns ratio between the primary and each secondary is generated on the secondary side of the converter transformer 11, and predetermined output voltages (V ₁ , V ₂ ) are generated by the respective rectifying and smoothing circuits 12 ₁ and 12 ₂ . can get. At this time, the rectifier/smoothing circuit 12 sensed for stabilization control
The outputs (V ₁ ) of ₁ and 12 ₂ can be said to be stabilized, but the other outputs can be said to be quasi-stabilized outputs that are stabilized only by the cross regulation of the transformer.

[Problems with background technology]

The switching regulator power supply having the conventional configuration as described above has the following drawbacks. That is, the response to fluctuations in the quasi-stabilized output (V ₂ ) is very poor. This delay is due to the delay due to the smoothing filter included in the rectification and smoothing circuit 12 ₂ on the quasi-stabilized output side, the delay in the response of the converter transformer 11, and the rectification and smoothing circuit 12 ₁ on the stabilization output (V ₁ ) side. This is because there is a delay of the smoothing filter included in . Therefore, when a pulse load is applied to the quasi-stabilized output (V ₂ ), transient fluctuations in the output voltage become extremely large. In addition, in order to suppress the voltage fluctuation, a capacitor with a very large capacity is required. Furthermore, when trying to save the capacitance of the above capacitor by allowing a larger allowable output fluctuation, the collector current of the primary side power transistors (Tr ₁ , Tr ₂ ) has a very large transient peak, and heat generation also increases. Therefore, in order to maintain reliability, a transistor with a large current capacity is required, and a drive circuit that can supply a large base current to saturate the transistor in response to this large collector current is also required. . FIG. 2 shows the relationship between the output voltage fluctuation and the collector current of the transistor when the capacitance of the capacitor is relatively small. Here, ΔVd is the transient voltage fluctuation of the quasi-stabilized output when the load suddenly changes, ΔVs is the static load fluctuation caused by the internal resistance of the circuit, and τd is the response of the control circuit after the quasi-stable output starts to fluctuate. Indicates the time it takes for output to recover,
icpeak indicates the peak collector current value of the switching power transistors (Tr ₁ , Tr ₂ ).

Here, for example, the rated voltage of the quasi-stabilized output (V ₂ ) is 25V, the output capacitor (C ₀ ) is 10000μF,
If τd is 5ms and the load suddenly changes from 0A to 10A, the fluctuation (falling amount) in the output voltage will be ΔVd=Ipeak・τd/C...(1), so ΔVd=5V. To suppress this variation to 1V, an output capacitor (C ₀ ) of 50,000 μF is required.

As described above, conventional multi-output switching regulator type power supplies have poor dynamic characteristics with respect to quasi-stabilized outputs, and are considered unsuitable for pulse loads.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and it is possible to obtain a stable DC power supply with good responsiveness even to quasi-stabilized output due only to cross regulation of a transformer, with a simple and inexpensive configuration. The object of the present invention is to provide a multi-output switching regulator type power supply device.

[Summary of the invention]

The present invention provides a multi-output switching regulator type power supply device in which one end of the smoothing capacitor of each of the output circuits other than the output circuit to be subjected to stabilization control is connected to the corresponding output. In this configuration, the other end is connected to the output line of the output circuit to be subjected to the stabilization control, so that the stabilized output responds to sudden voltage fluctuations of the quasi-stabilized output. This makes it possible to obtain a stable DC power supply with good responsiveness even to quasi-stabilized output with a simple and inexpensive configuration.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows an embodiment of the present invention, and shows an example of application to a half-bridge type power source. In the figure, 31 and 32 are input DC voltage ( _Vdcio )
Dividing capacitors, 33 and 34 are switching power transistors, 35 is a converter transformer having a plurality of output windings (here, two sets of secondary windings LB ₁ and LB ₂ ), and 36 and 37 are converter transformers. This is a diode for regenerating the excitation energy of 35 to the primary side. 38 and 39 are rectifier and smoothing circuits provided corresponding to the output windings LB ₁ and LB ₂ of the converter transformer 35, and 40 and 41 are rectifier diodes that rectify the AC signal of the output winding LB ₁ of the converter transformer 35. , 42 and 43 are rectifier diodes for rectifying the AC signal of the output winding LB ₂ of the converter transformer 35, and 44 and 45 are smoothing coils. The above-mentioned components and circuit connections are the same as the conventional structure shown in FIG. 46 and 47 are smoothing capacitors, and among these capacitors 46 and 47, the capacitor 46 provided in the rectifying and smoothing circuit (hereinafter referred to as the stabilizing output circuit) 38 on the stabilizing output side (sense side) is an existing one. A rectifier and smoothing circuit (hereinafter referred to as a quasi-stable output circuit) 3 which forms a connection configuration and is on the quasi-stable output side
The capacitor 47 provided in the self-circuit 39
is connected between the positive output terminal (V ₂ plus line) of the stabilized output circuit 38 and the output terminal (V ₁ plus line) of the stabilized output circuit 38 . 48, 49 are dummy resistors, 5
0.51 is an external load (R _L ). 52 is a differential amplifier that amplifies the difference between the output voltage V ₁ and the reference voltage V _REF ; 53 is a pulse width modulation circuit that pulse width modulates the error signal obtained from the differential amplifier 52; 54
is a drive circuit that turns on and off the switching power transistors 33 and 34 using the signal period from the pulse width modulation circuit 53. Since each of these components 52 to 54 is an existing component, a detailed circuit explanation thereof will be omitted here.

Figures 4a and 4b are for explaining the operation of the embodiment shown in Figure ₃ above.
shows an equivalent circuit of the output section of the quasi-stabilized output (V ₂ ) when the load suddenly changes.

The operation of one embodiment will now be described with reference to FIG. 3 and FIGS. 4a and 4b. Assume that the load 51 connected to the quasi-stabilized output circuit 39 suddenly changes, and a load current as shown in FIG. 4a flows, for example. At this time, immediately after the load current increases from 0 to Ipeak, there is a smoothing circuit consisting of a smoothing coil 45, a smoothing capacitor 47, etc., so no current flows from the smoothing coil 45, and current is supplied from the smoothing capacitor 47. It turns out. By the way, since the smoothing capacitor 47 of the quasi-stabilized output circuit 39 is connected to the positive side line of the stabilized output circuit 38, the load current Ipeak at this time is
8 will also pass through, but the stabilizing output circuit 38
Since there is also a smoothing circuit consisting of a smoothing coil 45, a smoothing capacitor 46, etc., current is not supplied from the smoothing coil 44 but from the smoothing capacitor 46. Therefore, the control circuit consisting of the differential amplifier 52, the pulse width modulation circuit 53, the drive circuit 54, etc. responds to fluctuations in the output voltage (V ₁ ) of the stabilizing output circuit 38,
Until the output of the converter transformer 35 increases, the output voltages of both the stabilized output (V ₁ ) and the quasi-stabilized output (V ₂ ) continue to fall. In this way, fluctuations in the quasi-stabilized output (V ₂ ) are reflected in fluctuations in the stabilized output (V ₁ ) without time delay. Normally, the response time of a single output power supply is several tens of microseconds, so the response time is the same for fluctuations in the quasi-regulated output V ₂ , and the response time is several tens of microseconds for sudden load changes.
The output voltage (V ₂ ) will recover by simply waiting 10 μs. Figure 4b shows the equivalent circuit of the output circuit immediately after a sudden load change, and smoothing capacitor 4
6, 47 and the load resistor 51 form a series circuit. The case where the load suddenly increases has been described above, but the same applies to the case where the load suddenly decreases, so the explanation thereof will be omitted here.

By adopting the configuration of the embodiment described above, it is possible to obtain a stable DC power supply with good responsiveness even to a quasi-stabilized output due only to the cross regulation of the transformer. Also, as shown in Figure 2
Since icpeak (peak collector power supply of switching power transistor) no longer exists,
The reliability of the switching power transistor can be improved, and the transistor generates less heat, making it easier to design a heat sink. Furthermore, the capacity of the transistor can be reduced, and the drive circuit current capacity of the base of the transistor can be reduced. Also, the second
The transient voltage fluctuation ΔVd of the quasi-stabilized output (V ₂ ) shown in the figure can be suppressed by using a smoothing capacitor with a smaller capacity (approximately 1/100) than the conventional one.

Next, other embodiments will be described with reference to FIGS. 5 to 14. Figure 5, Figure 6, Figure 7, Figure 8,
11 and 14 respectively show other embodiments of the present invention. In the figures, the same parts as in FIG. 3 are denoted by the same reference numerals, and the explanation thereof will be omitted.

Fig. 5 shows an embodiment in which the present invention is applied to a forward type (single-stone type) switching regulator, and Fig. 6 shows an embodiment in which the present invention is applied to a ringing type switching regulator. This is an example. In the figure, 54s is a driver circuit, and _Tr1 is a switching power transistor.

FIG. 7 shows an embodiment in which there are a plurality of quasi-stabilized output circuits, and here, each smoothing capacitor _{47 ( 1 )} , ..., 47 _(o) are both connected to the positive output terminal (V ₁ plus line) of the stabilizing output circuit 38. In addition, in Figure 7, 35(A)
is the converter transformer, 54s is the drive circuit,
Tr ₁ is a switching power transistor.

FIG. 8 shows positive and negative quasi-stabilized output circuits 39 (+),
39 (-), and the load currents (I ₂ , I ₃ ) at each of its positive and negative output terminals (+V ₂ , -V ₂ ) flow symmetrically, as shown in Figure 9. An example in which the present invention is applied in a configuration is shown.

FIG. 11 shows an embodiment in which the present invention is applied to a configuration in which the smoothing coils of the stabilizing output circuit 38 and the quasi-stabilizing output circuit 39 are wound around a common core (same core). Fig. 10 shows an example of the conventional configuration, Fig. 12 shows the signal waveforms of each part of Fig. 10 (conventional example), and Fig. 13 shows the above-mentioned first example.
The signal waveforms of each part of FIG. 1 (example) are shown respectively. In the figure, reference numeral 100 indicates smoothing coils CH-1 and CH-2 having a common core. here,
In the conventional configuration shown in Fig. 10, the output terminal (V ₁ ) of the stabilizing output circuit PO ₁ and the quasi-stabilizing output circuit
When an imbalance with the output terminal (V ₂ ) current of PO ₂ occurs that exceeds a certain tolerance, the stabilizing output circuit PO ₁
The phases of the input voltage V _io 1 and the ripple voltage of the smoothing capacitor C ₁ may be reversed as shown in FIG. 12, which may cause oscillation. On the other hand, according to the embodiment shown in FIG. 11, the ripple current of the smoothing capacitor 46 of the stabilizing output circuit 38 is the sum of the ripple current of the check coil CH-1 and the ripple current of the check coil CH-2. The phases of the ripple voltage flowing into the smoothing capacitor 46 and the input voltage V _io 1 match as shown in FIG. 13.
Therefore, oscillation as in the conventional example described above does not occur.

FIG. 14 shows that a smoothing capacitor 200 is added to the output terminal (V ₂ ) of the quasi-stabilizing output circuit 39, and by sharing the current change at the time of sudden load change with the capacitor 200, stable addition is achieved at the time of sudden load change. The variation in the output (V ₁ ) can be adjusted, and this embodiment can be applied to each of the embodiments described above.

In each of the other embodiments described above, the third embodiment described above also applies.
It has the same effect as the embodiment shown in the figure, and it is possible to obtain a stable DC power supply with good response even to sudden voltage fluctuations in the quasi-stabilized output due to the cross regulation of the transformer. , and the configuration can be simplified.

〔Effect of the invention〕

As described in detail above, according to the multi-output switching regulator type power supply device of the present invention, the smoothing capacitor provided in the quasi-stable output side circuit is connected to the output line of that circuit and the stabilized output side circuit. By connecting it to the output line, it is possible to obtain a stable DC power supply with good responsiveness even to quasi-stabilized output due to transformer cross regulation only, with a simple and inexpensive configuration. Can be done.

[Brief explanation of the drawing]

Figure 1 is a circuit block diagram showing the configuration of a conventional multi-output switching regulator type power supply device.
This figure is a signal waveform diagram for explaining the operation shown in FIG. 1 above. FIG. 3 is a circuit block diagram showing an embodiment of the present invention, and FIGS. 4a and 4b are for explaining the operation of the above embodiment, where a is a signal waveform diagram and b is an output section. It is a figure showing an equivalent circuit of. Figure 5,
Figures 6, 7, 8, 11, and 14
The figures are circuit block diagrams showing other embodiments,
9 is a load current waveform diagram in the configuration shown in FIG. 8, FIG. 10 is a circuit block diagram showing a conventional configuration for comparison with the embodiment shown in FIG. 11, and FIG.
This figure is a signal waveform diagram for explaining the operation of FIG. 10, and FIG. 13 is a signal waveform diagram for explaining the operation of FIG. 11. 31, 32... Capacitor for input DC voltage division, 33, 34... Power transistor for switching, 35... Converter transformer, 36, 3
7... Diode (for regeneration), 38, 39... Rectification, smoothing circuit (38... Stabilization output circuit, 39...
...semi-stabilized output circuit), 40, 41, 42, 43
... Rectifier diode, 44, 45, 100 (C-
1, CH-2)...Chiyoke coil for smoothing, 4
6,47,200...Smoothing capacitor, 48,4
9...Dummy resistor, 50, 51...External load, 5
2...Differential amplifier, 53...Pulse width modulation circuit,
54, 54x, 54y...drive circuit, LB ₁ ,
LB ₂ ...Output winding.

Claims (1)

[Claims] 1. A multi-output switching regulator that has a single transformer with a plurality of secondary windings and a plurality of output circuits that obtain separately rectified and smoothed DC power from each secondary winding. In the power supply device, a smoothing capacitor of at least one second output circuit other than the first output circuit to be subjected to stabilization control among the plurality of output circuits is connected between the first and second output circuits. A multi-output switching regulator type power supply device that is characterized by: