JPH0511794U - Switching Regulator DC Power Supply - Google Patents

Abstract

(57) [Summary] [Objective] To provide a switching regulator DC power supply device that suppresses fluctuations of ± DC output voltage. [Configuration] PWM circuit P for controlling switching transistors Q1 and Q2 for switching a power supply DC voltage B ₀
w and a first feedback circuit for feeding back the + side DC output voltage + B1 to the first-stage comparator K of the PWM circuit Pw, and in the switching regulator DC power supply device forming a ± DC power source, the − side DC output voltage − A second feedback circuit Fb is provided for feeding back the voltage fluctuation of B1 to the first-stage comparator K.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a switching regulator DC power supply device that constitutes a ± DC power supply.

[0002]

[Prior Art]

The conventional switching regulator DC power supply device that constitutes a ± DC power supply includes diodes D1, D2, D3 and D4 for rectifying the secondary side output voltage of a transformer T having a center tap as shown in FIG. A rectifier circuit for bipolar output is configured by the choke coils L1 and L2 and capacitors C1 and C2, and the + side DC output voltage is fed back to the first-stage comparator K of the pulse width modulation circuit (referred to as PWM circuit) Pw. PWM control of the switching transistors Q1 and Q2 connected to the primary side of the transformer T by the output of the PWM circuit Pw by PWM control, so that one winding and the other winding of the primary side of the transformer T The direct current voltage + B ₀ was alternately applied to the wires to obtain ± DC output voltage. In FIG. 4, the + output DC voltage from the ± DC power supply device is applied to the SEPP amplifier whose output stage is composed of the transistors Q3 and Q4, Z is the load of the SEPP amplifier, and V ₀ is It shows the load voltage.

[0003]

[Problems to be solved by the device]

 However, according to the conventional switching regulator DC power supply device configured as described above, since only the + side DC output voltage + B1 is fed back to control the switching transistor on the primary side of the transformer, the − side It is not controlled by the DC output voltage -B1, and at the time of low frequency output of the amplifier as the load of the power supply device, the amplifier output voltage waveform vs. ± DC output voltage characteristic changes in the-side DC output voltage -B1 as shown in FIG. However, there was a problem that the amount of voltage drop was large, and there was a problem that the maximum output decreased.

An object of the present invention is to provide a switching regulator DC power supply device that can reduce the amount of voltage drop even at the time of low frequency output by feeding back the fluctuation amount of the − side DC output voltage. .

[0005]

[Means for Solving the Problems]

 The switching regulator DC power supply device of the present invention comprises a PWM circuit for controlling a switching element for switching the DC power supply, and a first feedback circuit for feeding back the + side DC output voltage to the first stage comparator of the PWM circuit. In the switching regulator DC power supply device constituting the ± DC power supply, a second feedback circuit is provided for feeding back the fluctuation of the − side DC output voltage to the first-stage comparator.

[0006]

[Action]

 In the switching regulator DC power supply device of the present invention, the + side DC output voltage is fed back to the first stage comparator of the PWM circuit by the first feedback circuit, and the fluctuation of the + side DC output voltage is suppressed. The fluctuation of the side DC output voltage is fed back to the first-stage comparator by the second feedback circuit, the fluctuation of the-side DC output voltage is suppressed, and the fluctuation of the ± DC DC output voltage is reduced.

[0007]

【Example】

 Hereinafter, the present invention will be described with reference to examples. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. The switching regulator DC power supply device of this embodiment has diodes D1, D2, D3, D4 for rectifying the secondary side output voltage of a transformer T having a center tap, choke coils L1, L2 and capacitors C1, C2. A bipolar rectifier circuit is configured with and, the voltage obtained by dividing the + side DC output voltage + B1 is fed back to the non-inverting input terminal of the first-stage comparator K of the PWM circuit Pw, and the − side DC output voltage −B1 is generated. The voltage of the sum of the fluctuation amount of the voltage applied to the resistor R2 of the feedback circuit Fb formed of the series circuit of the capacitor C3, the resistors R1 and R2 and the reference voltage power supply Vs and the voltage of the reference voltage power supply Vs is calculated as the first-stage comparator K. It returns to the inverting input terminal of. A diode D5 is connected to the connection point between the capacitor C3 and the resistor R1 to form a discharge path for the charges charged in the capacitor C3.

In this embodiment configured as described above, the voltage obtained by dividing the + side DC output voltage −B1 is supplied to the non-inverting input terminal of the first-stage comparator K of the PWM circuit Pw and fed back. Only the voltage fluctuation of the − side DC output voltage −B1 is supplied to the inverting input terminal of the first-stage comparator K of the PWM circuit Pw via the feedback circuit Fb and fed back.

Therefore, the voltage fluctuation of the − side DC output voltage −B1 is suppressed, the stability of the ± output power supply voltage is improved, and the amplifier output voltage waveform vs. ± DC output voltage characteristic becomes as shown in FIG. The fluctuation of the-side DC output voltage at the time of low frequency output is also reduced.

According to the present embodiment, the output power vs. frequency characteristic when an amplifier for amplifying left and right two-channel audio signals was used as a load was as shown by the solid line in FIG. On the other hand, in the case of the conventional example shown in FIG. 4, as shown by the broken line in FIG. 3, the output voltage vs. frequency characteristic is also clearly improved by comparing the two.

[0010]

[Effect of the device]

 As described above, according to the present invention, in addition to the feedback of the + side DC output voltage, only the fluctuation of the − side direct current output voltage is fed back, so that the ± DC output voltages are controlled to suppress the fluctuation. This has the effect of reducing fluctuations in each DC output voltage. Further, since the feedback is only for the fluctuation of the-side DC output voltage, there is also an effect that the DC output voltage becomes the same as in the case of the feedback system only for the + side DC output voltage.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a characteristic diagram of an amplifier output voltage waveform vs. ± DC output voltage characteristic for explaining the operation of one embodiment of the present invention.

FIG. 3 is an amplifier output power vs. frequency characteristic for explaining the operation of one embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional example.

FIG. 5 is a characteristic diagram of an amplifier output voltage waveform vs. ± DC output voltage for explaining the operation of the conventional example.

[Explanation of symbols]

T transformers D1 to D5 diodes L1 and L2 choke coils C1 to C3 capacitors Pw PWM circuit K comparators Q1 and Q2 switching transistors Q3 and Q4 transistors constituting an output stage of an amplifier as a load Fb feedback circuit

Claims (1)

[Claims for utility model registration] 1. A PWM circuit for controlling a switching element for switching a DC power supply, and a first feedback circuit for feeding back the + side DC output voltage to a first-stage comparator of the PWM circuit. In the switching regulator DC power supply device, which comprises ± DC power supply, the switching regulator is provided with a second feedback circuit that feeds back the variation of the − side DC output voltage to the first-stage comparator. DC power supply.