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WO2015120689A1 - 一种dc-dc转换电路及方法 - Google Patents

一种dc-dc转换电路及方法 Download PDF

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Publication number
WO2015120689A1
WO2015120689A1 PCT/CN2014/081720 CN2014081720W WO2015120689A1 WO 2015120689 A1 WO2015120689 A1 WO 2015120689A1 CN 2014081720 W CN2014081720 W CN 2014081720W WO 2015120689 A1 WO2015120689 A1 WO 2015120689A1
Authority
WO
WIPO (PCT)
Prior art keywords
voltage
conversion circuit
signal
reference voltage
switching tube
Prior art date
Application number
PCT/CN2014/081720
Other languages
English (en)
French (fr)
Inventor
樊晓东
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to US14/586,309 priority Critical patent/US9337741B2/en
Publication of WO2015120689A1 publication Critical patent/WO2015120689A1/zh

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Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/337Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration
    • H02M3/3376Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration with automatic control of output voltage or current
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00Details of apparatus for conversion
    • H02M1/0003Details of control, feedback or regulation circuits
    • H02M1/0016Control circuits providing compensation of output voltage deviations using feedforward of disturbance parameters
    • H02M1/0022Control circuits providing compensation of output voltage deviations using feedforward of disturbance parameters the disturbance parameters being input voltage fluctuations

Definitions

  • the present application relates to the field of circuit technologies, and in particular, to a DC-DC conversion circuit and method.
  • IB A Intermediate Bus Architecture
  • the IBA distributes the isolation, voltage regulation, and regulation functions of the DC-DC power supply module to two devices, the intermediate bus converter (IBC) and the non-isolated point-of-load converter (niPoL).
  • IBC intermediate bus converter
  • NiPoL non-isolated point-of-load converter
  • IBC has variable pressure and isolation functions.
  • niPoL provides voltage regulation.
  • the IBC converts the semi-regulated distribution bus into an unregulated and isolated transit bus voltage (typically 12V) that is supplied to a series of niPoLs.
  • the niPoL is close to the load and provides voltage and voltage regulation.
  • IBA The principle of IBA is to reduce the bus voltage to a voltage slightly higher than the load point, and then the lower price niPoL to complete the rest of the work.
  • IBA has the advantages of low cost and dynamic characteristics relative to DPA, which has become the mainstream architecture of power supply in communication systems.
  • FIG 1 is a schematic diagram of an IBA topology provided in the prior art.
  • the IBA topology is used in close to 50% fixed duty cycle mode of operation. That is, in the first half cycle of the input voltage Vin, the first switching transistor Q1 and the third switching transistor Q3 and the sixth switching transistor Q6 are simultaneously turned on at a fixed duty ratio of approximately 50%, and the second switching is performed in the second half of the cycle of Vin.
  • the tube Q2 and the fourth switching tube Q4 and the fifth switching tube Q5 are symmetrically turned on with a fixed duty ratio close to 50% and the first half period.
  • all switching transistors Q1-Q6) can achieve zero voltage switching (ZVS) turn-on, reduce switching losses, and reduce the copper loss and iron of the filter inductor because the output does not require an external filter inductor. Loss, the conversion efficiency of the entire topology can be optimized.
  • the duty cycle of the switching tube is not controlled by the loop, which is also called open loop control.
  • Embodiments of the present invention provide a DC-DC conversion circuit capable of achieving high conversion efficiency.
  • a DC-DC conversion circuit including: an output voltage detection module, an input voltage detection module, and a reference voltage generation Module, comparison module, control module and drive module;
  • the output voltage detecting module is configured to detect an output voltage of the DC-DC conversion circuit, and generate a feedback voltage signal linearly related to the output voltage;
  • the input voltage detecting module is configured to detect a voltage of a secondary winding end of the transformer in the DC-DC converting circuit, and generate an input voltage signal linearly related to a voltage of the secondary winding end; the reference voltage generating module, Generating a reference voltage from the input voltage signal; the reference voltage is linear with the input voltage signal;
  • the comparing module is configured to compare the feedback voltage signal with a reference voltage, and send the comparison result to the control module;
  • the control module is configured to generate a duty control signal according to the comparison result, and output the duty control signal to the driving module;
  • the driving module is configured to drive a switching tube in the DC-DC conversion circuit according to the duty control signal.
  • the reference voltage is linearly proportional to the input voltage signal and the feedback voltage signal, specifically:
  • V d Vin _ dec * K * D / N;
  • Vin _ dec is the input voltage signal
  • £ is the duty cycle of the switching tube in the DC-DC conversion circuit
  • N is the turns ratio of the primary winding and the secondary winding of the transformer in the DC-DC conversion circuit; it is a constant.
  • the method further includes: an output current detecting module and a reference voltage correcting module;
  • the output current detecting module is configured to detect an output current of the DC-DC converting circuit, generate a feedback current signal, and send the signal to the reference voltage correcting module;
  • the reference voltage correction module is configured to correct the reference voltage by using the feedback current signal.
  • the reference voltage correction module is configured to correct the reference voltage by using the feedback current signal /L i ⁇
  • the correction relationship is:
  • V d ' Kl * V d ;
  • Kl (l - M * Iout _ dec) ;
  • M is the line voltage drop coefficient is constant.
  • the duty ratio control signal controls an operating duty ratio of the switch tube to be 40%-49%.
  • the main circuit of the DC-DC conversion circuit includes: a first switch tube, a second switch tube, and a third switch tube a fourth switch tube, a fifth switch tube, a sixth switch tube and a transformer;
  • a first end of the first switch tube is connected to a positive end of the input voltage
  • a first end of the fourth switch tube is connected to a positive end of the input voltage
  • a second end of the first switch tube is connected to a primary side of the transformer a second end of the fourth switch tube connected to a different end of the primary winding of the transformer;
  • the first end of the second switch tube is connected to the same end of the primary winding of the transformer, the first end of the third switch tube is connected to the different end of the primary winding of the transformer; the second end of the second switch tube is The end is connected to the negative end of the input voltage, and the second end of the third switch tube is connected to the negative end of the input voltage;
  • the first end of the fifth switch tube is connected to the same end of the secondary winding of the transformer, the first end of the sixth switch tube is connected to the different end of the secondary winding of the transformer; the second end of the fifth switch tube is The end is connected to the negative end of the output voltage, and the second end of the sixth switch tube is connected to the negative end of the output voltage;
  • the tap of the secondary winding of the transformer is connected to the positive terminal of the output voltage.
  • the method further includes: a filter inductor;
  • a tap of the secondary winding of the transformer is connected to a positive end of the output voltage through the filter inductor; the input voltage detecting module is configured to detect the transformer from a common end of the filter inductor and the tap of the secondary winding The voltage at the secondary winding end.
  • the DC-DC conversion circuit is applied to a transit bus power supply architecture, and an output voltage of the DC-DC conversion circuit is a transit bus.
  • the power supply architecture is powered by the point of load.
  • a DC-DC conversion method for use in a DC-DC conversion circuit, including the following steps:
  • a switching transistor in the DC-DC conversion circuit is driven according to the duty ratio control signal.
  • the method before the comparing the feedback voltage signal and the reference voltage, the method further includes: detecting an output current of the DC-DC conversion circuit, and generating a linear relationship with the output current Feedback current signal;
  • the reference voltage is corrected using the feedback current signal.
  • the DC-DC conversion circuit provided by the above technical solution reflects the change of the input voltage by detecting the voltage in the secondary winding of the transformer, adjusts the reference voltage through the detected input voltage signal, compares the feedback voltage signal with the reference voltage, and compares As a result, the duty control signal is adjusted, and the switching control is turned on and off according to the duty control signal to adjust the output voltage of the DC-DC conversion circuit so that the output voltage changes in accordance with the input voltage. Therefore, the circuit provided by the present invention is closed loop control The circuit adjusts the output voltage by detecting the output voltage, and the reference voltage is not fixed. It varies with the input voltage, so that the duty ratio does not change over a wide range, but in a small range. Fine tuning, because the duty cycle adjustment range is too large, will reduce the conversion efficiency of the DC-DC converter circuit. In summary, the circuit provided in this embodiment can not only adjust the output voltage as the input voltage changes, but also achieve higher conversion efficiency.
  • FIG. 1 is a schematic diagram of an IBA topology provided in the prior art
  • Embodiment 1 of a DC-DC conversion circuit provided by the present invention
  • Figure 3 is a waveform diagram of main parameters corresponding to the embodiment of Figure 2;
  • Embodiment 4 is a schematic diagram of Embodiment 2 of a DC-DC conversion circuit provided by the present invention.
  • Figure 5 is a waveform diagram of main parameters corresponding to the embodiment of Figure 4.
  • Embodiment 6 is a flow chart of Embodiment 1 of a DC-DC conversion method provided by the present invention.
  • FIG. 7 is a flowchart of Embodiment 2 of a DC-DC conversion method provided by the present invention.
  • the embodiment of the present invention provides a DC-DC conversion circuit that reflects the input voltage Vin by detecting a voltage at the secondary winding end of the transformer, and adjusts the reference voltage by detecting the voltage at the secondary winding end.
  • the reference voltage is compared to the sensed output voltage to adjust the duty cycle control signal. That is, in the embodiment of the present invention, the duty ratio is adjusted by closed loop control, and the duty ratio is not fixed and remains unchanged. As Vin increases, the reference voltage increases, causing the output voltage to follow. Increased.
  • FIG. 2 the figure is a schematic diagram of a first embodiment of a DC-DC conversion circuit provided by the present invention.
  • the main circuit of the DC-DC conversion circuit is a bridge topology
  • the main circuit comprises: a first switch tube Ql, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, a fifth switch tube Q5, a sixth switch tube Q6 and a transformer T;
  • the first end of the first switch tube Q1 is connected to the positive end of the input voltage Vin
  • the first end of the fourth switch tube Q4 is connected to the positive end of the input voltage Vin
  • the second end of the first switch tube Q2 is The end is connected to the same name end of the primary winding of the transformer T, and the second end of the fourth switching tube Q4 is connected to the different end of the primary winding of the transformer T;
  • the first end of the second switch tube Q2 is connected to the same end of the primary winding of the transformer T, and the first end of the third switch tube Q3 is connected to the different end of the primary winding of the transformer T;
  • the second switch The second end of the tube Q2 is connected to the negative end of the input voltage Vin, and the second end of the third switch tube Q3 is connected to the negative end of the input voltage Vin;
  • the first end of the fifth switch tube Q5 is connected to the same end of the secondary winding of the transformer T, and the first end of the sixth switch tube Q6 is connected to the different end of the secondary winding of the transformer T;
  • the fifth switch The second end of the tube Q5 is connected to the negative end of the output voltage Vout, and the second end of the sixth switch tube Q6 is connected to the negative end of the output voltage Vout;
  • the tap of the secondary winding of the transformer T is connected to the positive terminal of the output voltage Vout.
  • Q1 and Q3 are simultaneously turned on at the same duty cycle; in the second half of Vin, Q2 and Q4 are symmetric with the first half cycle with the same duty cycle. Turn on.
  • all switching transistors Q1-Q6 can achieve zero voltage switching (ZVS) Open, reduce switching losses.
  • the duty ratio of each switch tube operation is not fixed.
  • the switch here includes Ql-Q4, and also includes Q5 and Q6.
  • Q5 and Q6 implement the function of a diode. Since the diode has a turn-on voltage drop, in order to reduce the conduction loss of the diode, switches Q5 and Q6 are used here instead of the diode.
  • the DC-DC conversion circuit includes: an output voltage detecting module 100, an input voltage detecting module 200, a reference voltage generating module 300, a comparing module 400, a control module 500, and a driving module 600;
  • the output voltage detecting module 100 is configured to detect an output voltage of the DC-DC conversion circuit, and generate a feedback voltage signal Vout_dec linearly related to the output voltage;
  • the output voltage detecting module 100 can be implemented by a voltage dividing circuit, for example, two resistors connected in parallel across the output voltage of the DC-DC converting circuit, and the two resistors realize the voltage division of the output voltage Vout.
  • the common terminal between the two resistors serves as the output of the feedback voltage signal Vout_dec. Since this technique is well known in the art, it will not be exemplified herein.
  • the input voltage detecting module 200 is configured to detect a voltage of a secondary winding end of the transformer in the DC-DC converting circuit, and generate an input voltage signal linearly related to a voltage of the secondary winding end;
  • the change in the input voltage Vin is reflected by detecting the voltage in the secondary winding of the transformer T.
  • the voltage is not directly detected on the primary side of the transformer T to reflect Vin.
  • the advantage of detecting the voltage on the secondary winding side of the transformer T in this embodiment is that the method of triggering the sample can be used, that is, only when the tap of the secondary winding is outputted at a high level, and the secondary winding can be avoided.
  • An expensive device such as a "linear optocoupler" that is required when the primary winding is sampled.
  • the tap of the secondary winding may be a center tap or may not be a center tap.
  • the reference voltage generating module 300 is configured to generate a reference voltage from the input voltage signal; the reference voltage is linearly related to the input voltage signal;
  • the reference voltage in this embodiment is not fixed, but is adjusted in real time by the detected input voltage signal. The purpose of this is to change the output voltage as the input voltage changes.
  • the comparison module 400 is configured to compare the feedback voltage signal with a reference voltage, and send the comparison result to the control module 500;
  • the control module 500 is configured to generate a duty control signal according to the comparison result, and output the duty ratio control signal to the driving module 600;
  • the duty cycle control signal is adjusted based on the comparison result and is not a fixed value.
  • the driving module 600 is configured to drive the switching tube in the DC-DC conversion circuit according to the duty control signal.
  • the signal that the driving module 600 finally outputs to the switching tube is a PWM signal, and the duty ratio of the PWM signal is determined by the duty ratio control signal.
  • the DC-DC conversion circuit provided in this embodiment reflects the change of the input voltage by detecting the voltage in the secondary winding of the transformer, adjusts the reference voltage through the detected input voltage signal, compares the feedback voltage signal with the reference voltage, and compares the reference voltage according to the comparison.
  • the duty control signal is adjusted, and the switching control is turned on and off according to the duty control signal to adjust the output voltage of the DC-DC converter circuit so that the output voltage changes in accordance with the input voltage.
  • the circuit provided by the present invention is a closed-loop control circuit, and the output voltage is adjusted by detecting the output voltage, and the reference voltage is not fixed, and varies with the input voltage, so that the duty ratio is not A large range of changes, but fine-tuning in a small range, because the duty cycle adjustment range is too large, will reduce the conversion efficiency of the DC-DC converter circuit.
  • the circuit provided in this embodiment can not only adjust the output voltage with the change of the input voltage, but also achieve higher conversion efficiency.
  • the reference voltage is linearly proportional to the input voltage signal and the feedback voltage signal, and is specifically:
  • V d Vin _ dec * K * D / N ( 1 )
  • Vin _ dec is the input voltage signal
  • N is the turns ratio of the primary winding and the secondary winding of the transformer in the DC-DC conversion circuit; it is a constant.
  • the duty cycle control signal controls the duty cycle of the switching transistor to be 40%-49%.
  • the waveform diagram of the main parameters of the circuit is analyzed in conjunction with FIG.
  • Figure 3 essentially combines two coordinate systems. The left side is the relationship between the input voltage Vin and the output voltage Vout, and the right side is the relationship between the output voltage Vout and the output current lout.
  • S2 is the output voltage Vout is a fixed output, in the steady-state operating mode, the relationship between the output voltage and the output current is a straight line parallel to the current axis.
  • the line of S3 refers to the relationship between output voltage and output current in the prior art when lout is between 0-A. When lout is greater than A, S3 coincides with the part of S1.
  • S 1 (solid line thicker than S3) is a polyline, including a line of lout that is parallel to the current axis between 0-A, and a line that lout is greater than A.
  • the present invention when lout is within A, it is light load, and lout is greater than A and is overloaded.
  • the present invention is a closed loop control, and at heavy loads, the circuit is saturated and becomes open loop control. That is, at light load, the DC-DC converter circuit operates in a closed-loop voltage regulator mode, and when out is changed, Vout is kept constant.
  • Circuit Embodiment 2 is the voltage of the primary winding detected from the secondary winding of the transformer.
  • FIG. 4 the figure is a schematic diagram of Embodiment 2 of a DC-DC conversion circuit provided by the present invention.
  • the reference voltage is adjusted only by the input voltage signal, so that the closed-loop control can be realized at light load.
  • the circuit may work in the open loop mode as the output current increases, because the adjustment range of the duty cycle is already limited, that is, the range of the duty cycle is narrow, so that The circuit is saturated and the circuit enters an uncontrolled open loop mode.
  • the present invention provides the second embodiment.
  • an output current is introduced, and the output current is used to correct the reference voltage, that is, when the heavy duty is opened. Pull the output voltage.
  • the DC-DC conversion circuit provided in this embodiment further includes: an output current detecting module 700 and a parameter Test voltage correction module 800;
  • the output current detecting module 700 is configured to detect an output current of the DC-DC converting circuit, generate a feedback current signal, and send the signal to the reference voltage correcting module 800;
  • the output current detecting module 700 may specifically detect the output current between the second end of the Q6 and the negative end of the output voltage.
  • a filter capacitor C may also be included, which is connected in parallel at both ends of the output voltage.
  • the reference voltage correction module 800 is configured to correct the reference voltage by using the feedback current signal.
  • the comparison module 400 compares the feedback voltage signal with the corrected reference voltage.
  • V d ' Kl * V d ;
  • M is the line voltage drop coefficient is constant.
  • the DC-DC converter circuit can realize closed-loop control in all load ranges, that is, closed-loop control can be realized at light load and heavy load, and the duty ratio is in a small range. Internal adjustment.
  • FIG. 5 the figure is a main parameter waveform diagram of the embodiment corresponding to Fig. 4.
  • FIG. 5 The difference between FIG. 5 and FIG. 3 is that in the relationship between the output voltage Vout on the right side and the output current lout, it can be seen that in the closed-loop control, the curve is pulled down and translated downward, so that the Vout in the closed-loop control is faster than the open loop. The Vout at the time of control is small.
  • the DC-DC conversion circuit provided by the above embodiment is introduced as an example in the application of the IBA, which supplies power to the load point in the IB A, thereby improving the working efficiency of the IB A. That is, the main circuit topology of the DC-DC conversion circuit can also be other forms. Since the technology of the main circuit topology is mature in the field, it is no longer exemplified.
  • the present invention also provides a The DC-DC conversion method is applied to a DC-DC conversion circuit, and the specific implementation steps thereof will be described below with reference to the accompanying drawings.
  • FIG. 6 is a flowchart of Embodiment 1 of a DC-DC conversion method provided by the present invention.
  • the DC-DC conversion method provided in this embodiment is applied to a DC-DC conversion circuit and includes the following steps:
  • the core of the DC-DC conversion method provided by the embodiment of the present invention is: reacting the input voltage Vin by detecting the voltage at the secondary winding end of the transformer, and adjusting the reference voltage by the voltage detected at the secondary winding end, the reference voltage is The detected output voltages are compared to adjust the duty cycle control signal. That is, in the embodiment of the present invention, the duty ratio is adjusted by closed loop control, and the duty ratio is not fixed and remains unchanged. As Vin increases, the reference voltage increases, causing the output voltage to increase.
  • S601 detecting an output voltage of the DC-DC conversion circuit, and generating a feedback voltage signal linearly related to the output voltage;
  • S602 detecting a voltage of a secondary winding end of the transformer in the DC-DC conversion circuit, and generating an input voltage signal linearly related to a voltage of the secondary winding end;
  • S603 generate a reference voltage from the input voltage signal, where the reference voltage is linear with the input voltage signal;
  • the reference voltage in this embodiment is not fixed, but is adjusted in real time by the detected input voltage signal.
  • the purpose of this is to change the output voltage as the input voltage changes.
  • the duty cycle control signal is adjusted based on the comparison result and is not a fixed value.
  • S606 Drive the switch tube in the DC-DC conversion circuit according to the duty ratio control signal.
  • the signal finally output to the switch is a PWM signal, and the duty ratio of the PWM signal is determined by the duty control signal.
  • the DC-DC conversion circuit reflects the change of the input voltage by detecting the voltage in the secondary winding of the transformer, adjusts the reference voltage through the detected input voltage signal, compares the feedback voltage signal with the reference voltage, and compares the reference voltage according to the comparison. Result to adjust the duty cycle control signal, according to the duty cycle control The signal is controlled to control the turn-on and turn-off of the switch to adjust the output voltage of the DC-DC converter circuit so that the output voltage changes in accordance with the input voltage.
  • the circuit provided by the present invention is a closed-loop control circuit, and the output voltage is adjusted by detecting the output voltage, and the reference voltage is not fixed, and varies with the input voltage, so that the duty ratio is not A large range of changes, but fine-tuning in a small range, because the duty cycle adjustment range is too large, will reduce the conversion efficiency of the DC-DC converter circuit.
  • the circuit provided in this embodiment can not only adjust the output voltage with the change of the input voltage, but also achieve higher conversion efficiency.
  • the duty cycle control signal controls the duty cycle of the switch tube to be 40% - 49%.
  • the reference voltage is adjusted only by the input voltage signal, so that the closed loop control can be realized at light load.
  • the circuit may work in the open loop mode as the output current increases, because the adjustment range of the duty cycle is already limited, that is, the range of the duty cycle is narrow, so that The circuit is saturated and the circuit enters an uncontrolled open loop mode.
  • the present invention provides the second embodiment.
  • the output current is introduced, and the output current is used to correct the reference voltage, that is, when the heavy duty is opened. Pull the output voltage.
  • S701-S703 in this embodiment are the same as S601-S603 in the first embodiment of the method.
  • the present invention adds step S704 before S604 of a method embodiment
  • S704 Detect an output current of the DC-DC conversion circuit, generate a feedback current signal linearly related to the output current, and correct the reference voltage by using the feedback current signal.
  • S705-S707 are the same as S604-S606 in the method embodiment, and are not described here.
  • the DC-DC converter circuit can realize closed-loop control in all load ranges, that is, closed-loop control can be realized at light load and heavy load, and the duty ratio is in a small range. Internal adjustment.
  • the DC-DC conversion circuit applied by the DC-DC conversion method provided by the above embodiment is introduced as an example in the application of the IB A, which supplies power to the load point in the IB A, which can improve IBA's work efficiency. That is, the main circuit topology of the DC-DC conversion circuit can also be His form, because the technology of the main circuit topology is mature in the field, is no longer - for example.
  • the above description is only a preferred embodiment of the present application, and is not intended to limit the scope of the application. Although the present application has been disclosed above in the preferred embodiments, it is not intended to limit the application.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

一种DC-DC转换电路及方法。在变压器的副边绕组检测电压来反应输入电压的变化,通过检测的该输入电压信号来调整参考电压,将反馈电压信号与参考电压比较,根据比较结果来调整占空比控制信号,根据占空比控制信号来控制开关管的导通和关断进而来调整DC-DC转换电路输出电压,使输出电压跟随输入电压来变化。该电路是闭环控制电路,通过检测输出电压来调整输出电压,并且参考电压也不是固定不变的,是随着输入电压来变化的,这样可以使占空比不会在大范围内变化,而是在小范围内微调,由于占空比调整范围太大,会降低DC-DC转换电路的转换效率。该电路不仅可以随着输入电压的变化来调整输出电压,而且可以实现较高的转换效率。

Description

一种 DC-DC转换电路及方法
本申请要求于 2014 年 2 月 17 日提交中国专利局、 申请号为 201410053294.4、 发明名称为"一种 DC-DC转换电路"的中国专利申请的优先 权, 其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电路技术领域, 特别涉及一种 DC-DC转换电路及方法。
背景技术
在目前的通信系统中, 电源大部分使用中转母线架构( IB A, Intermediate Bus Architecture )。 因为 IB A弥补了分布式电源架构 ( DPA, Distributed Power Architecture ) 的缺点。
IBA把 DC-DC电源模块的隔离、 变压及稳压功能分配到两个器件, 这两 个器件分别为中转母线转换器(IBC )和非隔离负载点转换器(niPoL )。
IBC具变压及隔离功能。 niPoL则提供稳压功能。
IBC 把半稳压的分布母线转为不稳压及隔离的中转母线电压(一般是 12V), 供电给一连串的 niPoL。
niPoL靠近负载, 提供变压及稳压功能。
IBA的原理是把母线电压降至一个稍稍高于负载点的电压,再由价格较低 的 niPoL来完成余下的工作。
因此, IBA相对于 DPA具有成本低和动态特性的优势成为目前通信系统 中电源的主流架构。
随着单板业务能力的增强, 基于负载点供电 (POL, Point-of-Load ) 的转 换模块越来越多, 功率越来越高, 而电路板的面积不变甚至在缩小, 这样就对 IB A电源效率的要求越来越高。
参见图 1, 该图为现有技术中提供的一种 IBA拓朴示意图。
该 IBA拓朴釆用以接近 50%的固定占空比的工作模式。即在输入电压 Vin 的上半个周期第一开关管 Q1和第三开关管 Q3与第六开关管 Q6同时以接近 50%的固定占空比导通,在 Vin的下半个周期第二开关管 Q2和第四开关管 Q4 与第五开关管 Q5以接近 50%固定占空比与上半个周期对称导通。 在这种工作模式下,所有的开关管(Q1-Q6 )均可以实现零电压开关(ZVS ) 开通, 减少开关损耗, 同时由于输出不需要外加滤波电感, 也可以减少滤波电 感的铜损和铁损, 整个拓朴的转换效率可以达到最佳。这种工作方式下开关管 的占空比不受环路控制, 又称为开环控制。
虽然固定占空比的这种开环控制可以实现高效功率转换,但由于开环控制 对输出电压的不可控性, 不可避免地将导致输出电压调节变差。
发明内容
本发明实施例提供一种 DC-DC转换电路, 既能够实现较高的转换效率, 第一方面, 提供一种 DC-DC转换电路, 包括: 输出电压检测模块、 输入 电压检测模块、 参考电压生成模块、 比较模块、 控制模块和驱动模块;
所述输出电压检测模块, 用于检测 DC-DC转换电路的输出电压, 生成与 所述输出电压成线性关系的反馈电压信号;
所述输入电压检测模块, 用于检测所述 DC-DC转换电路中变压器的副边 绕组端的电压, 生成与所述副边绕组端的电压成线性关系的输入电压信号; 所述参考电压生成模块, 用于由所述输入电压信号生成参考电压; 所述参 考电压与所述输入电压信号成线性关系;
所述比较模块, 用于将所述反馈电压信号和参考电压进行比较,将比较结 果发送给所述控制模块;
所述控制模块, 用于根据比较结果生成占空比控制信号,将所述占空比控 制信号输出给所述驱动模块;
所述驱动模块, 用于根据所述占空比控制信号驱动所述 DC-DC转换电路 中的开关管。
在第一方面的第一种可能的实现方式中,所述参考电压与所述输入电压信 号和所述反馈电压信号成线性比例关系, 具体为:
Vd = Vin _ dec * K * D / N;
其中, 为所述参考电压;
Vin _ dec为所述输入电压信号;
£»为所述 DC-DC转换电路中开关管的工作占空比; N为所述 DC-DC转换电路中变压器的原边绕组和副边绕组的匝比; 为常数。
结合第一方面及上述任一种可能的实现方式中,在第二种可能的实现方式 中, 还包括: 输出电流检测模块和参考电压修正模块;
所述输出电流检测模块, 用于检测 DC-DC转换电路的输出电流, 生成反 馈电流信号并发送给所述参考电压修正模块;
所述参考电压修正模块, 用于使用所述反馈电流信号修正所述参考电压。 结合第一方面及上述任一种可能的实现方式中,在第三种可能的实现方式 中, 所述参考电压修正模块, 用于使用所述反馈电流信号 / L i ^修正所述参 考电压 的修正关系为:
Vd' = Kl * Vd ;
Kl = (l - M * Iout _ dec) ;
为修正系数;
为修正后的参考电压;
M为线路压降系数为常数。
结合第一方面及上述任一种可能的实现方式中,在第四种可能的实现方式 中, 所述占空比控制信号控制所述开关管的工作占空比为 40%-49%。
结合第一方面及上述任一种可能的实现方式中,在第五种可能的实现方式 中, 该 DC-DC转换电路的主电路包括: 第一开关管、 第二开关管、 第三开关 管、 第四开关管、 第五开关管、 第六开关管和变压器;
所述第一开关管的第一端连接输入电压的正端,所述第四开关管的第一端 连接所述输入电压的正端;所述第一开关管的第二端连接变压器原边绕组的同 名端, 所述第四开关管的第二端连接变压器的原边绕组的异名端;
所述第二开关管的第一端连接变压器的原边绕组的同名端,所述第三开关 管的第一端连接变压器的原边绕组的异名端;所述第二开关管的第二端连接输 入电压的负端, 所述第三开关管的第二端连接输入电压的负端;
所述第五开关管的第一端连接变压器的副边绕组的同名端,所述第六开关 管的第一端连接变压器的副边绕组的异名端;所述第五开关管的第二端连接输 出电压的负端, 所述第六开关管的第二端连接输出电压的负端; 所述变压器副边绕组的抽头连接输出电压的正端。
结合第一方面及上述任一种可能的实现方式中,在第六种可能的实现方式 中, 还包括: 滤波电感;
所述变压器副边绕组的抽头通过所述滤波电感连接输出电压的正端; 所述输入电压检测模块,用于从所述滤波电感和所述副边绕组的抽头的公 共端检测所述变压器的副边绕组端的电压。
结合第一方面及上述任一种可能的实现方式中,在第七种可能的实现方式 中, 该 DC-DC转换电路应用于中转母线供电架构中, DC-DC转换电路的输出 电压为中转母线供电架构的负载点供电。
第二方面, 提供一种 DC-DC转换方法, 应用于 DC-DC转换电路中, 包 括以下步骤:
检测 DC-DC转换电路的输出电压, 生成与所述输出电压成线性关系的反 馈电压信号;
检测 DC-DC转换电路中变压器的副边绕组端的电压, 生成与副边绕组端 的电压成线性关系的输入电压信号;
由所述输入电压信号生成参考电压,所述参考电压与所述输入电压信号成 线性关系;
将所述反馈电压信号和参考电压进行比较, 产生比较结果;
由所述比较结果调整占空比控制信号;
根据所述占空比控制信号驱动 DC-DC转换电路中的开关管。
在第二方面的第一种可能的实现方式中,将所述反馈电压信号和参考电压 进行比较之前, 还包括: 检测 DC-DC转换电路的输出电流, 生成与所述输出 电流成线性关系的反馈电流信号;
运用所述反馈电流信号修正所述参考电压。
以上技术方案提供的 DC-DC转换电路, 通过在变压器的副边绕组检测电 压来反应输入电压的变化,通过检测的该输入电压信号来调整参考电压,将反 馈电压信号与参考电压比较,根据比较结果来调整占空比控制信号,根据占空 比控制信号来控制开关管的导通和关断进而来调整 DC-DC 转换电路输出电 压, 使输出电压跟随输入电压来变化。 因此, 本发明提供的该电路是闭环控制 电路, 通过检测输出电压来调整输出电压, 并且参考电压也不是固定不变的, 是随着输入电压来变化的, 这样可以使占空比不会在大范围内变化, 而是在小 范围内微调, 由于占空比调整范围太大,会降低 DC-DC转换电路的转换效率。 综上, 本实施例提供的电路不仅可以随着输入电压的变化来调整输出电压, 而 且可以实现较高的转换效率。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案,下面将对实施 例或现有技术描述中所需要使用的附图作简单地介绍,显而易见地, 下面描述 中的附图仅仅是本发明的一些实施例, 对于本领域普通技术人员来讲,在不付 出创造性劳动的前提下, 还可以根据这些附图获得其他的附图。
图 1是现有技术中提供的一种 IBA拓朴示意图;
图 2是本发明提供的 DC-DC转换电路实施例一示意图;
图 3是图 2实施例对应的主要参数波形图;
图 4是本发明提供的 DC-DC转换电路实施例二示意图;
图 5是图 4实施例对应的主要参数波形图;
图 6是本发明提供的 DC-DC转换方法实施例一流程图;
图 7是本发明提供的 DC-DC转换方法实施例二流程图。
具体实施方式
下面将结合本发明实施例中的附图,对本发明实施例中的技术方案进行清 楚、 完整地描述, 显然, 所描述的实施例仅仅是本发明一部分实施例, 而不是 全部的实施例。基于本发明中的实施例, 本领域普通技术人员在没有做出创造 性劳动前提下所获得的所有其他实施例, 都属于本发明保护的范围。
为使本发明的上述目的、 特征和优点能够更加明显易懂, 下面结合附图对 本发明的具体实施方式做详细的说明。
需要说明的是, 本发明实施例提供一种 DC-DC转换电路, 通过在变压器 的副边绕组端检测电压来反应输入电压 Vin, 并且通过在副边绕组端检测的电 压来调整参考电压,将参考电压与检测的输出电压进行比较,从而调整占空比 控制信号。 即, 本发明实施例是通过闭环控制来实现占空比的调节, 占空比不 是固定保持不变的。 当 Vin增大时, 参考电压随着增大, 从而使输出电压也随 之增大。
可以理解的是, 本发明实施例提供的 DC-DC转换电路的工作原理可以应 用于任何使用 DC-DC供电的场合, 下面实施例中仅以 DC-DC转换电路应用 于 IB A中为例来进行介绍。 电路实施例一:
参见图 2, 该图为本发明提供的 DC-DC转换电路实施例一示意图。
为了更好地理解和实施本发明的技术方案, 下面首先介绍一下 IBA 中的 DC-DC转换主电路的拓朴;
如图 2所示, DC-DC转换电路的主电路为桥式拓朴;
主电路包括: 第一开关管 Ql、 第二开关管 Q2、 第三开关管 Q3、 第四开 关管 Q4、 第五开关管 Q5、 第六开关管 Q6和变压器 T;
所述第一开关管 Q1的第一端连接输入电压 Vin的正端, 所述第四开关管 Q4的第一端连接所述输入电压 Vin的正端; 所述第一开关管 Q2的第二端连 接变压器 T原边绕组的同名端,所述第四开关管 Q4的第二端连接变压器 T的 原边绕组的异名端;
所述第二开关管 Q2的第一端连接变压器 T的原边绕组的同名端,所述第 三开关管 Q3 的第一端连接变压器 T 的原边绕组的异名端; 所述第二开关管 Q2的第二端连接输入电压 Vin的负端, 所述第三开关管 Q3的第二端连接输 入电压 Vin的负端;
所述第五开关管 Q5的第一端连接变压器 T的副边绕组的同名端,所述第 六开关管 Q6 的第一端连接变压器 T 的副边绕组的异名端; 所述第五开关管 Q5的第二端连接输出电压 Vout的负端, 所述第六开关管 Q6的第二端连接输 出电压 Vout的负端;
所述变压器 T副边绕组的抽头连接输出电压 Vout的正端。
在输入电压 Vin的上半个周期, Q1和 Q3与 Q6同时以相同的占空比导通; 在 Vin的下半个周期, Q2和 Q4与 Q5以相同的占空比与上半个周期对称 导通。
在这种工作模式下,所有的开关管(Q1-Q6 )均可以实现零电压开关(ZVS ) 开通, 减少开关损耗。
需要说明的是, 本发明实施例中的这种导通模式, 各个开关管工作的占空 比并不是固定不变的。 此处的开关管包括 Ql-Q4, 还包括 Q5和 Q6。 Q5和 Q6实现的是二极管的作用, 由于二极管存在导通压降, 为了降低二极管的导 通损耗, 此处使用开关管 Q5和 Q6来代替二极管。
本实施例提供的 DC-DC转换电路, 包括: 输出电压检测模块 100、 输入 电压检测模块 200、 参考电压生成模块 300、 比较模块 400、 控制模块 500和 驱动模块 600;
所述输出电压检测模块 100, 用于检测 DC-DC转换电路的输出电压, 生 成与所述输出电压成线性关系的反馈电压信号 Vout_dec;
需要说明的是, 输出电压检测模块 100 可以由分压电路来实现, 例如在 DC-DC 转换电路的输出电压两端并联串联的两个电阻, 这两个电阻实现对输 出电压 Vout的分压, 两个电阻之间的公共端作为该反馈电压信号 Vout_dec的 输出端。 由于该技术属于本领域的公知技术, 在此不再举例说明。
所述输入电压检测模块 200, 用于检测所述 DC-DC转换电路中变压器的 副边绕组端的电压, 生成与所述副边绕组端的电压成线性关系的输入电压信 号;
本实施例中是通过在变压器 T的副边绕组检测电压,从而来反应输入电压 Vin的变化情况。本实施例中并不是直接在变压器 T的原边进行电压的检测来 反应 Vin。
本实施例中在变压器 T的副边绕组侧检测电压的优点是:可以釆用触发釆 样的方式, 即只在副边绕组的抽头输出高电平时釆样,通过副边绕组釆样可以 避免在原边绕组釆样时需要使用的 "线性光耦" 这样价格昂贵的器件。
可以理解的是, 所述副边绕组的抽头可以为中心抽头,也可以不为中心抽 头。
所述参考电压生成模块 300, 用于由所述输入电压信号生成参考电压; 所 述参考电压与所述输入电压信号成线性关系;
本实施例中的参考电压不是固定不变的,而是通过检测的输入电压信号来 实时调整的, 这样做的目的是为了在输入电压变化时, 使输出电压随之变化。 所述比较模块 400, 用于将所述反馈电压信号和参考电压进行比较, 将比 较结果发送给所述控制模块 500;
所述控制模块 500, 用于根据比较结果生成占空比控制信号, 将所述占空 比控制信号输出给所述驱动模块 600;
占空比控制信号是根据比较结果调整的, 并不是一个固定不变的值。
所述驱动模块 600, 用于根据所述占空比控制信号驱动所述 DC-DC转换 电路中的开关管。
需要说明的是, 驱动模块 600最终输出给开关管的信号为 PWM信号, PWM信号的占空比由占空比控制信号来确定。
本实施例提供的 DC-DC转换电路, 通过在变压器的副边绕组检测电压来 反应输入电压的变化,通过检测的该输入电压信号来调整参考电压,将反馈电 压信号与参考电压比较,根据比较结果来调整占空比控制信号,根据占空比控 制信号来控制开关管的导通和关断进而来调整 DC-DC转换电路输出电压, 使 输出电压跟随输入电压来变化。 因此, 本发明提供的该电路是闭环控制电路, 通过检测输出电压来调整输出电压, 并且参考电压也不是固定不变的,是随着 输入电压来变化的, 这样可以使占空比不会在大范围内变化, 而是在小范围内 微调, 由于占空比调整范围太大,会降低 DC-DC转换电路的转换效率。 综上, 本实施例提供的电路不仅可以随着输入电压的变化来调整输出电压,而且可以 实现较高的转换效率。
需要说明的是,所述参考电压与所述输入电压信号和所述反馈电压信号成 线性比例关系, 具体为:
Vd = Vin _ dec * K * D / N ( 1 )
其中, 为所述参考电压;
Vin _ dec为所述输入电压信号;
£»为所述 DC-DC转换电路中开关管的工作占空比;
N为所述 DC-DC转换电路中变压器的原边绕组和副边绕组的匝比; 为常数。
为了使电路的转换效率较高,所述占空比控制信号控制所述开关管的工作 占空比为 40%-49%。 为了更好地体现本发明电路实施例一的优点,下面结合图 3来分析该电路 的主要参数的波形图。
图 3实质是两个坐标系拼在一起的,左边是输入电压 Vin与输出电压 Vout 的关系曲线, 右边是输出电压 Vout与输出电流 lout的关系曲线。
在图 3中, 横坐标为输出电流 Iout, 纵坐标为输出电压 Vout。
其中, S2是输出电压 Vout为固定输出, 稳压工作模式时, 输出电压与输 出电流的关系曲线, 就是与电流轴平行的一条直线。
而 S3的直线指的是 lout在 0-A之间时, 现有技术中输出电压与输出电流 的关系曲线。 当 lout大于 A时, S3与 S1的部分重合。
而 S 1 (比 S3粗的实线)是一条折线, 包括 lout在 0-A之间与电流轴平行 的一段直线, 还包括 lout大于 A以后的一段直线。
从该图中可以看出, lout在 A以内时, 属于轻载, lout大于 A以后属于重 载。在轻载时, 本发明属于闭环控制, 在重载时, 电路饱和, 变为了开环控制。 即, 在轻载时, 该 DC-DC转换电路工作在闭环稳压模式, lout变化时, Vout 是保持稳压不变的。
从左边的输入电压 Vin与输出电压 Vout之间的关系曲线 S4可以看出, 输 出电压 Vout是跟随输入电压 Vin进行变化的。
其中, S5是从变压器的副边绕组检测的原边绕组的电压。 电路实施例二:
参见图 4, 该图为本发明提供的 DC-DC转换电路实施例二示意图。
电路实施例一中仅是通过输入电压信号来调整参考电压,这样可以在轻载 时实现闭环控制。 但是在重载时, 随着输出电流的增大, 该电路有可能工作于 开环模式, 因为, 此时占空比的调节范围已经很有限, 即占空比的变化范围很 窄, 从而使电路处于饱和状态, 电路进入了不可控的开环模式。 为了解决电路 在重载时继续工作在闭合模式, 本发明提供了实施例二,在电路实施例二中引 入了输出电流, 利用输出电流来修正参考电压, 即在重载开环时有目的地将输 出电压拉氐。
本实施例提供的 DC-DC转换电路, 还包括: 输出电流检测模块 700和参 考电压修正模块 800;
所述输出电流检测模块 700, 用于检测 DC-DC转换电路的输出电流, 生 成反馈电流信号并发送给所述参考电压修正模块 800;
需要说明的是, 所述输出电流检测模块 700具体可以在 Q6的第二端与输 出电压的负端之间进行输出电流的检测。
在图 4中,还可以包括滤波电容 C,所述滤波电容 C并联在输出电压的两 端。
所述参考电压修正模块 800, 用于使用所述反馈电流信号修正所述参考电 压。 比较模块 400利用修正后的参考电压与所述反馈电压信号进行比较。
使用所述反馈电流信号 /OMt _ ^c修正所述参考电压 ^的修正关系为:
Vd' = Kl * Vd ;
Kl = (l - M * lout _ dec);
为修正系数;
为修正后的参考电压。
M为线路压降系数为常数。
通过输出电流对参考电压进行补偿以后, 可以使 DC-DC转换电路在所有 负载范围内均实现闭环控制, 即在轻载和重载时均可以实现闭环控制, 并且使 占空比在微小的范围内调整。
下面结合图 5分析加入电流修正后的波形。
参见图 5, 该图为图 4对应的实施例的主要参数波形图。
图 5与图 3的区别是, 在右边的输出电压 Vout与输出电流 lout的关系曲 线中可以看出, 闭环控制时, 该曲线被拉低, 向下平移, 这样闭环控制中的 Vout比开环控制时的 Vout要小。
可以理解的是, 以上实施例提供的 DC-DC转换电路是以应用在 IBA中为 例进行介绍的, 该电路为 IB A中的负载点进行供电, 这样可以提高 IB A的工 作效率。 即 DC-DC转换电路的主电路拓朴也可以为其他形式, 由于主电路拓 朴的技术在本领域比较成熟, 在此不再——举例说明。 基于以上实施例提供的一种 DC-DC 转换电路, 本发明还提供了一种 DC-DC转换方法, 该方法应用于 DC-DC转换电路中, 下面结合附图来介绍其 具体实现步骤。
方法实施例一:
参见图 6, 该图为本发明提供的一种 DC-DC转换方法实施例一流程图。 本实施例提供的 DC-DC转换方法, 应用于 DC-DC转换电路中, 包括以 下步骤:
需要说明的是, 所述 DC-DC转换电路的拓朴具体可以参见图 2所示。 本发明实施例提供的 DC-DC转换方法的核心是: 通过在变压器的副边绕 组端检测电压来反应输入电压 Vin, 并且通过在副边绕组端检测的电压来调整 参考电压,将参考电压与检测的输出电压进行比较,从而调整占空比控制信号。 即, 本发明实施例是通过闭环控制来实现占空比的调节, 占空比不是固定保持 不变的。 当 Vin增大时, 参考电压随着增大, 从而使输出电压也随之增大。
S601 : 检测 DC-DC转换电路的输出电压, 生成与所述输出电压成线性关 系的反馈电压信号;
S602: 检测 DC-DC转换电路中变压器的副边绕组端的电压, 生成与副边 绕组端的电压成线性关系的输入电压信号;
S603: 由所述输入电压信号生成参考电压,所述参考电压与所述输入电压 信号成线性关系;
本实施例中的参考电压不是固定不变的,而是通过检测的输入电压信号来 实时调整的, 这样做的目的是为了在输入电压变化时, 使输出电压随之变化。
S604: 将所述反馈电压信号和参考电压进行比较, 产生比较结果;
S605: 由所述比较结果调整占空比控制信号;
占空比控制信号是根据比较结果调整的, 并不是一个固定不变的值。
S606: 根据所述占空比控制信号驱动 DC-DC转换电路中的开关管。
需要说明的是, 最终输出给开关管的信号为 PWM信号, PWM信号的占 空比由占空比控制信号来确定。
本实施例提供的 DC-DC转换电路, 通过在变压器的副边绕组检测电压来 反应输入电压的变化,通过检测的该输入电压信号来调整参考电压,将反馈电 压信号与参考电压比较,根据比较结果来调整占空比控制信号,根据占空比控 制信号来控制开关管的导通和关断进而来调整 DC-DC转换电路输出电压, 使 输出电压跟随输入电压来变化。 因此, 本发明提供的该电路是闭环控制电路, 通过检测输出电压来调整输出电压, 并且参考电压也不是固定不变的,是随着 输入电压来变化的, 这样可以使占空比不会在大范围内变化, 而是在小范围内 微调, 由于占空比调整范围太大,会降低 DC-DC转换电路的转换效率。 综上, 本实施例提供的电路不仅可以随着输入电压的变化来调整输出电压,而且可以 实现较高的转换效率。
为了使电路的转换效率较高,所述占空比控制信号控制开关管的工作占空 比为 40%-49%。 方法实施例二:
方法实施例一中仅是通过输入电压信号来调整参考电压,这样可以在轻载 时实现闭环控制。 但是在重载时, 随着输出电流的增大, 该电路有可能工作于 开环模式, 因为, 此时占空比的调节范围已经很有限, 即占空比的变化范围很 窄, 从而使电路处于饱和状态, 电路进入了不可控的开环模式。 为了解决电路 在重载时继续工作在闭合模式, 本发明提供了实施例二,在方法实施例二中引 入了输出电流, 利用输出电流来修正参考电压, 即在重载开环时有目的地将输 出电压拉氐。
本实施例中的 S701-S703分别与方法实施例一中的 S601-S603相同。
本发明在方法实施例一种的 S604之前增加了步骤 S704;
S704: 检测 DC-DC转换电路的输出电流, 生成与所述输出电流成线性关 系的反馈电流信号; 运用所述反馈电流信号修正所述参考电压。
S705-S707分别与方法实施例中的 S604-S606相同, 在此不再赘述。
通过输出电流对参考电压进行补偿以后, 可以使 DC-DC转换电路在所有 负载范围内均实现闭环控制, 即在轻载和重载时均可以实现闭环控制, 并且使 占空比在微小的范围内调整。
可以理解的是, 以上实施例提供的 DC-DC转换方法应用的 DC-DC转换 电路是以应用在 IB A中为例进行介绍的,该电路为 IB A中的负载点进行供电, 这样可以提高 IBA的工作效率。 即 DC-DC转换电路的主电路拓朴也可以为其 他形式, 由于主电路拓朴的技术在本领域比较成熟, 在此不再——举例说明。 以上所述,仅是本申请的较佳实施例而已, 并非对本申请作任何形式上的 限制。 虽然本申请已以较佳实施例揭露如上, 然而并非用以限定本申请。 任何 熟悉本领域的技术人员,在不脱离本申请技术方案范围情况下,都可利用上述 揭示的方法和技术内容对本申请技术方案做出许多可能的变动和修饰,或修改 为等同变化的等效实施例。 因此, 凡是未脱离本申请技术方案的内容, 依据本 申请的技术实质对以上实施例所做的任何简单修改、等同变化及修饰, 均仍属 于本申请技术方案保护的范围内。

Claims

权 利 要 求
1、 一种 DC-DC转换电路, 其特征在于, 包括: 输出电压检测模块、 输入 电压检测模块、 参考电压生成模块、 比较模块、 控制模块和驱动模块;
所述输出电压检测模块, 用于检测 DC-DC转换电路的输出电压, 生成与 所述输出电压成线性关系的反馈电压信号;
所述输入电压检测模块, 用于检测所述 DC-DC转换电路中变压器的副边 绕组端的电压, 生成与所述副边绕组端的电压成线性关系的输入电压信号; 所述参考电压生成模块, 用于由所述输入电压信号生成参考电压; 所述参 考电压与所述输入电压信号成线性关系;
所述比较模块, 用于将所述反馈电压信号和参考电压进行比较,将比较结 果发送给所述控制模块;
所述控制模块, 用于根据比较结果生成占空比控制信号,将所述占空比控 制信号输出给所述驱动模块;
所述驱动模块, 用于根据所述占空比控制信号驱动所述 DC-DC转换电路 中的开关管。
2、根据权利要求 1所述的 DC-DC转换电路, 其特征在于, 所述参考电压 与所述输入电压信号和所述反馈电压信号成线性比例关系, 具体为:
Vd = Vin _ dec * K * D / N
其中, 为所述参考电压;
¼'M _ ifec为所述输入电压信号;
£»为所述 DC-DC转换电路中开关管的工作占空比;
N为所述 DC-DC转换电路中变压器的原边绕组和副边绕组的匝比; 为常数。
3、 根据权利要求 1或 2所述的 DC-DC转换电路, 其特征在于, 还包括: 输出电流检测模块和参考电压修正模块;
所述输出电流检测模块, 用于检测 DC-DC转换电路的输出电流, 生成反 馈电流信号并发送给所述参考电压修正模块;
所述参考电压修正模块, 用于使用所述反馈电流信号修正所述参考电压。
4、根据权利要求 3所述的 DC-DC转换电路, 其特征在于, 所述参考电压 修正模块, 用于使用所述反馈电流信号 /OMt _ c修正所述参考电压 ^的修正关 系为:
Vd' = Kl *Vd ;
Kl = (l - M * lout _ dec);
n为修正系数;
V<;为修正后的参考电压;
Μ为线路压降系数为常数。
5、 根据权利要求 1-4任一项所述的 DC-DC转换电路, 其特征在于, 所述 占空比控制信号控制所述开关管的工作占空比为 40%-49%。
6、 根据权利要求 1所述的 DC-DC转换电路, 其特征在于, 该 DC-DC转 换电路的主电路包括: 第一开关管、 第二开关管、 第三开关管、 第四开关管、 第五开关管、 第六开关管和变压器;
所述第一开关管的第一端连接输入电压的正端,所述第四开关管的第一端 连接所述输入电压的正端;所述第一开关管的第二端连接变压器原边绕组的同 名端, 所述第四开关管的第二端连接变压器的原边绕组的异名端;
所述第二开关管的第一端连接变压器的原边绕组的同名端,所述第三开关 管的第一端连接变压器的原边绕组的异名端;所述第二开关管的第二端连接输 入电压的负端, 所述第三开关管的第二端连接输入电压的负端;
所述第五开关管的第一端连接变压器的副边绕组的同名端,所述第六开关 管的第一端连接变压器的副边绕组的异名端;所述第五开关管的第二端连接输 出电压的负端, 所述第六开关管的第二端连接输出电压的负端;
所述变压器副边绕组的抽头连接输出电压的正端。
7、 根据权利要求 6所述的 DC-DC转换电路, 其特征在于, 还包括: 滤波 电感;
所述变压器副边绕组的抽头通过所述滤波电感连接输出电压的正端; 所述输入电压检测模块,用于从所述滤波电感和所述副边绕组的抽头的公 共端检测所述变压器的副边绕组端的电压。
8、 根据权利要求 1所述的 DC-DC转换电路, 其特征在于, 该 DC-DC转 换电路应用于中转母线供电架构中, DC-DC转换电路的输出电压为中转母线 供电架构的负载点供电。
9、 一种 DC-DC转换方法, 其特征在于, 应用于 DC-DC转换电路中, 包 括以下步骤:
检测 DC-DC转换电路的输出电压, 生成与所述输出电压成线性关系的反 馈电压信号;
检测 DC-DC转换电路中变压器的副边绕组端的电压, 生成与副边绕组端 的电压成线性关系的输入电压信号;
由所述输入电压信号生成参考电压,所述参考电压与所述输入电压信号成 线性关系;
将所述反馈电压信号和参考电压进行比较, 产生比较结果;
由所述比较结果调整占空比控制信号;
根据所述占空比控制信号驱动 DC-DC转换电路中的开关管。
10、 根据权利要求 9所述的 DC-DC转换方法, 其特征在于, 将所述反馈 电压信号和参考电压进行比较之前, 还包括: 检测 DC-DC转换电路的输出电 流, 生成与所述输出电流成线性关系的反馈电流信号;
运用所述反馈电流信号修正所述参考电压。
PCT/CN2014/081720 2014-02-17 2014-07-07 一种dc-dc转换电路及方法 WO2015120689A1 (zh)

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