CN1487665A

CN1487665A - Class-D power amplifier with voltage controlled switching power supply

Info

Publication number: CN1487665A
Application number: CNA031541402A
Authority: CN
Inventors: 冯凯武
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-08-12
Filing date: 2003-08-12
Publication date: 2004-04-07

Abstract

The present invention relates to the topological structure of class-D audio power amplifier and may be used in voltage controlled switching power supply. The class-D audio power amplifier consists of primary rectifying filter, DC-AC converter, secondary rectifier, polarization change-over electronic switch, Buck conversion circuit, low-pass filter circuit, load, pulse width modulation circuit and polarization control circuit. By means of high frequency current varying technology, the topological structure converts industrial electric supply into output power supply modulated by the input signal to realize the audio power amplification. The present invention can reach the high efficiency similar to common class-D power amplification while eliminating its power supply voltage stabilizing link and lower cost and volume.

Description

Votage control switch power supply formula D (fourth) power-like amplifier

The present invention is mainly used in the audio power amplification sector of electrical type, also can be used for the votage control switch power supply that output voltage changes with input voltage.

Existing audio-frequency power amplifier according to the difference at current lead-through angle, generally all is operated in A (first) class, B (second) class, and 3 kinds of operating states of AB (first and second) class, there is inefficiency in the power amplifier of these types, and is bulky, the shortcoming that cost is higher.

In recent years, along with the fast development of high frequency power switching device and switch unsteady flow theory, D (fourth) genus audio power amplifier that makes electronic device be operated on off state has appearred, and it has experienced certain development, obtain very big progress, but also had a lot of problems to overcome.From existing data, D class power amplifier all is the pattern of " stabilized voltage power supply "+" switch power amplifier " mostly, is divided into power unit and power amplifier part, has two relatively independent feedback loops.Though the high efficiency problem that back level D class is amplified has obtained certain solution, the carrying load ability of stabilized voltage power supply is not well solved with the matching problem of back level power amplifier.Because feedback loop is relatively independent, back level power amplifier is greatly dynamically the time, and stabilized voltage power supply has little time in time to adjust output, causes the stabilized voltage power supply output voltage to fluctuate to some extent, can cause the distortion of output.Simultaneously,,, perhaps need complicated voltage stabilizing measure, caused the further reduction that is difficult to volume and cost because the stabilized voltage power supply part generally needs jumbo electric capacity no matter be linear stabilized voltage power supply or switching power supply.These have all limited the development of D class power amplifier.

The present invention proposes a kind of new benefit structure of opening up, use the HF switch Semiconductor Converting Technology, Switching Power Supply and the combination of D class A amplifier A are one, between power output, form a big feedback loop at the DC-AC circuit part, the middle voltage stabilizing link of power supply has omitted, dynamic characteristic also is improved, thereby has further reduced volume, has reduced cost.Be particularly suitable for powerful D class power amplifier, also can be used for the votage control switch power supply of other purposes, such as isolated frequency converter.

The present invention is achieved in that

In conjunction with the accompanying drawings, be described below.

This is opened up and mends structure is by a current rectifying and wave filtering circuit, DC-AC, and transformer, the secondary rectification, polarity is switched electronic switch, the Buck translation circuit, low-pass filter circuit, load, the pulse-width modulation circuit module, the polarity control circuit module is formed.

Rectifier bridge Rect and capacitor C 1 have constituted current rectifying and wave filtering circuit one time.Electric main is rectified into direct current, gives the DC-AC circuit supply.Capacitor C 1 plays filtering and storage power.

DC-AC partly finishes the inversion of direct current to high-frequency alternating current, and the direct current energy after the rectification is converted into the alternating current energy of high frequency, supplies with the high frequency transformer T1 that is attached thereto.This DC-AC is subjected to the control of pulse-width modulation (PWM) circuit module, and in a pulse period, it is big more to pass the pwm control signal duty ratio of coming from pulse-width modulation (PWM) circuit module, and the energy that sends high frequency transformer T1 to is also just many more.

High frequency transformer T1 elementary accepted the high-frequency ac electric flux that DC-AC supplies with, and is delivered to secondaryly, and finished the function of transformation and electrical isolation simultaneously.

D1, D2, D4, D5 have constituted the secondary rectifier, are the high-frequency ac electric rectification duplicate supply direct current that positive negative pressure is arranged.

SW1 and SW2 are electronic switches, have constituted polarity switching circuit.These two electronic switches are subjected to the polarity control circuit module controls, according to polarity control signal, select one of them switch opens, allow malleation or negative pressure be added on the inductance L 1.When the SW1 conducting, L1, C2 and D1, D2, D3, the positive polarity Buck translation circuit work that T1 forms; When the SW2 conducting, L1, C2 and D4, D5, D6, the negative polarity Buck translation circuit work that T1 forms.D1 wherein, D2, D4, D5 are that the Buck converter is with the public diode of secondary rectification.And D3, D6 is respectively the afterflow diode of positive-negative polarity Buck converter, gives the afterflow of Buck converter when high frequency transformer T1 is in nought state.Also can omit D3 and D6 under less demanding condition, if omitted D3 and D6, then the Buck converter passes through D1, D2 or D4, and half afterflow of D5 series connection T1 secondary coil, the internal resistance meeting of Buck converter at this moment increases to some extent, and efficient can descend to some extent.

LPF is a low pass filter, is responsible for radio-frequency component is filtered, and allows low-frequency component pass through, and gives load Rload.When load requires undemanding occasion or load itself to have filter function (as machinery inertial etc.) to ripple, also can omit this low pass filter.

Rload is the load of circuit, and when this circuit was used as audio-frequency power amplifier, Rload was generally loud speaker; When if this circuit is used for other votage control switch application of power, Rload is other loads.

PWM is the pulse-width modulation circuit module, and the input at that time of its basis and the situation of Buck converter output produce pwm control signal, are used for controlling the duty cycle of switching of DC-AC inverter switching tube, are delivered to the energy of load with adjustment.It mainly influences the absolute value that the voltage that outputs to load Rload changed with respect to the last pulse period.

POLCTRL is the polarity control circuit module of Buck converter, and the input at that time of its basis and the situation of Buck converter output are selected SW1 or one of them switch conduction of SW2.It mainly influences the polarity that the voltage that outputs to load Rload changed with respect to the last pulse period.

PWM module and the acting in conjunction of POLCTRL module just can polarizations, all variable random waveform voltage of amplitude given load.And the signal that PWM module and POLCTRL module produce is the result of input signal (INPUT) with the output signal feedback effect.If the design of feedback ring allows output with being entered as a functional relation, then output signal is exactly the power amplification after the input signal functional transformation.For example, the design of feedback ring allows output with being entered as a proportional relationship, and then output signal is exactly the power amplification of input signal.So, just realized the power amplification of D (fourth) class audio frequency, also can be used for the Switching Power Supply that output voltage changes with input voltage.

Claims

One kind be used in mainly that D (fourth) genus audio power amplifier also can be used for the votage control switch power supply open up the benefit structure.It is by a current rectifying and wave filtering circuit, DC-AC, and transformer, the secondary rectification, polarity is switched electronic switch, the Buck translation circuit, low-pass filter circuit, load, pulse-width modulation (PWM) circuit, polarity control circuit is formed.
2. circuit according to claim 1 is characterized by from civil power and is input to big feedback loop of formation between the power output.The loop of this feedback loop is: DC-AC → transformer T1 → secondary rectification → polarity is switched electronic switch → Buck translation circuit → polarity control circuit and pulse-width modulation (PWM) circuit → DC-AC.
3. circuit according to claim 1 is characterized in that being connected to the DC-AC circuit after a current rectifying and wave filtering circuit, and the DC-AC circuit outputs to high frequency transformer (T1) again.This DC-AC is subjected to the control of pulse-width modulation (PWM) circuit module.This DC-AC circuit can be a various ways, comprising: full-bridge type, semibridge system, pair transistor positive activation type, single-ended forward type, inverse-excitation type.
4. circuit according to claim 1 is characterized in that by D1, D2, and D4, D5 forms rectifier bridge, is connected on transformer T1 secondary, by this rectifier bridge secondary rectification, be the AC rectification of transformer output duplicate supply direct current with positive-negative polarity.The annexation of rectifier bridge and transformer is: the anode of D1 and D2 connect together (this tie point is designated as the P node); The negative electrode of D4 and D5 connect together (this tie point is designated as the N node); The negative electrode of D1, an end tap of the anode of D4 and one of them coil groups of transformer secondary output connect together (this tie point is designated as the A node); The negative electrode of D2, the other end tap of the anode of D5 and this coil groups of transformer secondary output connect together (this tie point is designated as the B node); The centre tap of this coil groups of transformer secondary output as this duplicate supply direct current " ".
5. according to claim 1 and 4 described circuit, it is characterized in that having two electronic switch SW1 and SW2 to be cascaded (this series connection node is designated as S), two ends link to each other with the N node with the P node respectively.This electronic switch is subjected to polarity control circuit control.This electronic switch can be the multiple electronic devices and components that can play on-off action, comprising: MOSFET, bipolar transistor, IGBT, MCT, controllable silicon.
6. according to the described circuit of claim 1,4 and 5, it is characterized in that having an inductance L 1 and a capacitor C 2 to be cascaded (this series connection node is designated as FB), the other end of L1 connects the S node, forms two groups of Buck translation circuits with D1～D6.Wherein the anode of D3 connects the P node, negative electrode connect " "; The anode of D6 connect " ", negative electrode connects the N node.When SW1 conducting SW2 ends, L1, C2 and D1, D2, D3, T1 form the Buck translation circuit work of positive polarity; When SW2 conducting SW1 ends, L1, C2 and D4, D5, D6, T1 form the Buck translation circuit work of negative polarity.D1 wherein, D2, D4, D5 are that the Buck converter is with the public diode of secondary rectification.And D3 and D6 are when the Buck converter needs afterflow, for the internal resistance that reduces the Buck converter increases, can omit D3 and D6 under certain condition.
7. according to claim 1 and 6 described circuit, the input that it is characterized by a low pass filter (LPF) is connected in the FB node, output and load connect together (this tie point is designated as the OUT node).When load has filter function (as machinery inertial etc.) to the less demanding occasion of ripple or load itself, also can omit this low pass filter.
8. according to the described circuit of claim 1,6 and 7, the feedback that it is characterized by pulse-width modulation circuit module and polarity control circuit module can be from the FB node sample, also can be from the OUT node sample.
9. according to claim 1 and 8 described circuit, it is characterized by pulse-width modulation (PWM) circuit module and participate in certain calculation, produce pulse-width signal, be used for adjusting the duty ratio of DC-AC circuit according to current input signal (INPUT) and feedback signal.
10. according to claim 1,5 and 8 described circuit, it is characterized by the polarity control circuit module and participate in certain calculation according to current input signal (INPUT) and feedback signal, the polarization control signal is used for controlling a conducting of selecting among two electronic switch SW1 and the SW2.
11. according to the described circuit of claim 1,9 and 10, pulse-width modulation (PWM) circuit module can merge inner separately identical or close circuit part with the polarity control circuit module, forms public modular unit mutually.