CN116054592A - DC converter with secondary control mode and control method thereof - Google Patents
DC converter with secondary control mode and control method thereof Download PDFInfo
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Abstract
The invention provides a direct current converter in a secondary control mode and a control method thereof, wherein the direct current converter comprises a power input port, a main power module, a power output port, an auxiliary power supply module, a driving isolation module, a primary driving control module, a secondary driving control module, a pulse width modulation module, a voltage feedforward module and an output sampling module; in the invention, the structure that the voltage feedforward module is used for feedforward to the pulse width modulation module is combined, the voltage feedforward module is used for sampling the input voltage in real time to obtain the input feedback voltage, the output feedback voltage and the input feedback voltage are combined, the pulse width modulation module is used for pulse width modulation control, when the input feedback voltage fluctuates, the pulse width modulation signal of the pulse width modulation module is quickly regulated to stabilize the output voltage before the output sampling module acts, the phenomenon that the output voltage can overshoot or sag greatly when the input voltage transient jump occurs can be effectively avoided, and the input voltage step response speed of the direct current converter is improved.
Description
Technical Field
The present invention relates to the field of electronic circuits, and in particular, to a secondary control mode dc converter and a control method thereof.
Background
The direct current converter (namely DC-DC) of the secondary control mode places the pulse width modulator on the secondary side, the power MOS tube on the secondary side can be directly driven by the secondary pulse width modulator, and the driving signal of the MOS tube on the primary side is transmitted by the digital isolator. The output voltage error signal of the DC converter in the secondary control mode can be directly transmitted to the secondary pulse width modulator after being sampled, so that delay caused by optocoupler isolation in the DC converter in the primary control mode is avoided, and the load dynamic performance is superior.
However, one disadvantage of the secondary control mode dc converter is that the pulse width modulator on the secondary side cannot directly sample the input voltage signal, and when the input voltage transitions, an output voltage jump is first caused, and then the output voltage error signal is sampled into the pulse width modulator by the output voltage sampling network. The input step response of a secondary control mode dc converter is limited because the pulse width modulator cannot respond immediately due to the delay of the output voltage feedback loop, and when there is a transient transition in the input voltage, the converter output voltage may appear to overshoot or drop significantly, affecting system stability.
Therefore, an input step dynamic response boost scheme of the dc converter in the secondary control mode is urgently needed.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present invention provides a technical solution of a secondary control mode dc converter with a voltage feedforward function, based on feedforward of an input voltage, when there is a transient transition in the input voltage, a pulse width modulation signal output by a pulse width modulation module is adjusted to stabilize the output voltage before an output sampling module acts, so as to increase the step response speed of the input voltage of the dc converter.
In order to achieve the above object and other related objects, the present invention provides the following technical solutions.
The DC converter comprises a power input port, a main power module, a power output port, an auxiliary power supply module, a driving isolation module, a primary driving control module, a secondary driving control module, a pulse width modulation module, a voltage feedforward module and an output sampling module, wherein the power input port, the main power module and the power output port are sequentially connected in series, the power input port is connected with an input voltage, the main power module performs power conversion on the input voltage to obtain an output voltage, the output voltage is output after passing through the power output port, the output sampling module is connected with the power output port, the output sampling module samples the output voltage to obtain an output feedback voltage and feeds the output feedback voltage back to the pulse width modulation module, the pulse width modulation module is connected with the voltage feedforward module and the secondary driving control module respectively, the pulse width modulation module is connected with the primary driving control module after passing through the driving isolation module, the input end of the auxiliary power supply module is connected with the power input port, the output end of the auxiliary power module is connected with the primary driving control module, the output voltage is changed, and the output feedback voltage is fed back to the auxiliary power module;
the voltage feedforward module samples and converts the auxiliary power supply voltage in real time to obtain an input feedback voltage, the input feedback voltage follows the input voltage in real time, and the pulse width modulation module receives the output feedback voltage and the input feedback voltage and performs pulse width modulation control based on the output feedback voltage and the input feedback voltage: when the input feedback voltage fluctuates, before the output sampling module acts, the pulse width modulation signal of the pulse width modulation module is adjusted to stabilize the output voltage, and the step response speed of the input voltage of the direct current converter is improved.
Optionally, the auxiliary power supply module includes a flyback topology auxiliary power supply module, where the flyback topology auxiliary power supply module includes a primary winding and at least two secondary windings, and converts to obtain at least two auxiliary power supply voltages with different magnitudes, so as to supply power to the primary drive control module, the secondary drive control module, and the pulse width modulation module, and supply input samples to the voltage feedforward module.
Optionally, the pulse width modulation module comprises a secondary current control type pulse width modulation module, and the current control type pulse width modulation module is internally provided with a reference voltage output port and a current sampling port.
Optionally, the flyback topology auxiliary power supply module comprises a flyback transformer, an NMOS tube, a first diode and a first capacitor, the flyback transformer comprises a primary winding and at least two secondary windings, the input voltage is connected with the drain electrode of the NMOS tube after passing through the primary winding in series, the source electrode of the NMOS tube is grounded, the gate electrode of the NMOS tube is connected with a switch control signal, the anode of the first diode is connected with the secondary winding in series and then grounded, the cathode of the first diode is connected with one end of the first capacitor, the other end of the first capacitor is grounded, and two ends of the first capacitor output an auxiliary power supply voltage to the pulse width modulation module.
Optionally, the voltage feedforward module includes:
the input end of the input sampling unit is connected with the output end of the auxiliary power supply module, and the auxiliary power supply voltage is sampled in real time to obtain and output a sampling voltage;
the first input end of the voltage conversion unit is connected with the output end of the input sampling unit, the second input end of the voltage conversion unit is connected with the reference voltage output port of the pulse width modulation module, and the voltage-current conversion is carried out on the sampling voltage to obtain and output sampling current;
and the input end of the filtering voltage dividing unit is connected with the output end of the voltage conversion unit, current-voltage conversion is carried out on the sampling current, the input feedback voltage is obtained and output, and the input feedback voltage is connected with the current sampling port of the pulse width modulation module.
Optionally, the input sampling unit includes a second diode, a first resistor and a second capacitor, wherein a cathode of the second diode is connected with an anode of the first diode, an anode of the second diode is connected with one end of the second capacitor after being connected with the first resistor in series, the other end of the second capacitor is grounded, and one end of the second capacitor connected with the first resistor outputs the sampling voltage.
Optionally, the voltage conversion unit includes a second resistor, a third resistor, a fourth resistor, a third diode and a PNP triode, one end of the second resistor is connected with the sampling voltage, the other end of the second resistor is connected with the cathode of the third diode, the anode of the third diode is connected with the reference voltage output port of the pulse width modulation module after being connected in series with the third resistor, the other end of the second resistor is also connected with the base of the PNP triode, the emitter of the PNP triode is connected with the reference voltage output port of the pulse width modulation module after being connected in series with the fourth resistor, the collector of the PNP triode outputs the sampling current, and the PNP triode works in an amplifying region.
Optionally, the filtering voltage dividing unit includes a fifth resistor, a sixth resistor, a fourth diode, a third capacitor and a fourth capacitor, where the sampling current flows through the fifth resistor and the sixth resistor in serial connection and then is grounded, the third capacitor is connected in parallel with the fifth resistor, the fourth capacitor is connected in parallel with the sixth resistor, an anode of the fourth diode is connected with the sampling current, a cathode of the fourth diode is connected with a driving output port of the pulse width modulation module, and a common end of the fifth resistor and the sixth resistor outputs the input feedback voltage.
A control method of a dc converter of a secondary control mode, comprising:
providing a secondary control mode dc converter as claimed in any one of the preceding claims;
the auxiliary power supply voltage is acquired in real time through the voltage feedforward module, so that the input feedback voltage is obtained, and the input feedback voltage follows the input voltage in real time;
and when the input feedback voltage fluctuates, before the output sampling module acts, adjusting a pulse width modulation signal output by the pulse width modulation module to stabilize the output voltage, and improving the step response speed of the input voltage of the direct current converter.
Optionally, the step of acquiring the auxiliary power supply voltage in real time through the voltage feedforward module to obtain the input feedback voltage includes:
the auxiliary power supply voltage is sampled in real time through an input sampling unit to obtain a sampling voltage, wherein the sampling voltage is a negative voltage which follows the input voltage in real time;
performing voltage-current conversion on the sampling voltage through the voltage conversion unit to obtain sampling current;
and performing current-voltage conversion on the sampling current through the filtering voltage dividing unit to obtain the input feedback voltage, wherein the input feedback voltage is a positive voltage which follows the input voltage in real time, and the input feedback voltage is a sawtooth wave signal.
As described above, the secondary control mode dc converter and the control method thereof according to the present invention have at least the following advantages:
the direct current converter with the secondary control mode is designed by combining the structure that the voltage feedforward module is feedforward to the pulse width modulation module, the input voltage can be sampled and followed in real time through the voltage feedforward module to obtain the input feedback voltage, and then the input feedback voltage and the input feedback voltage are combined to perform pulse width modulation control through the pulse width modulation module.
Drawings
Fig. 1 shows a block diagram of a dc converter in a secondary control mode according to the present invention.
Fig. 2 shows a partial circuit diagram of the dc converter in the secondary control mode in the present invention.
Detailed Description
As mentioned in the foregoing background, the inventors have studied to find: the output voltage error signal of the direct current converter aiming at the secondary control mode can be directly transmitted to the secondary pulse width modulator after being sampled, so that delay caused by optocoupler isolation in the direct current converter of the primary control mode is avoided, and the load dynamic performance is superior; however, the pulse width modulator on the secondary side cannot directly sample the input voltage signal, when the input voltage transitions, the output voltage is suddenly changed, and then the output voltage sampling network samples the output voltage error signal into the pulse width modulator, but due to the delay of the output voltage feedback loop, the pulse width modulator cannot immediately respond, so that the input step response of the direct current converter in the secondary control mode is limited, and when the input voltage has transient transitions, the output voltage of the converter may have larger overshoot or drop, and the stability of the system is affected.
Based on this, the inventor proposes an input step dynamic response boost technique for a dc converter in a secondary control mode: the voltage feedforward module connected with the pulse width modulation module is designed, the input voltage is sampled in real time based on the voltage feedforward module, the sampled input voltage is combined for pulse width modulation control, when the input voltage has transient transition, the pulse width modulation signal output by the pulse width modulation module is regulated before the action of the output sampling module so as to stabilize the output voltage, the phenomenon that the output voltage can have larger overshoot or drop during the transient transition of the input voltage is avoided, and the step response speed of the input voltage of the direct current converter is improved.
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to fig. 1-2. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings rather than the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be arbitrarily changed, and the layout of the components may be more complex. The structures, proportions, sizes, etc. shown in the drawings are shown only in connection with the present disclosure for the purpose of understanding and reading by those skilled in the art, and are not intended to limit the scope of the invention, so that any structural modifications, proportional changes, or dimensional adjustments should not be construed as essential to the invention, but should still fall within the scope of the invention as defined by the appended claims without affecting the efficacy or achievement of the invention.
Firstly, as shown in fig. 1, the invention provides a direct current converter in a secondary control mode, which comprises a power input port, a main power module, a power output port, an auxiliary power supply module, a driving isolation module, a primary driving control module, a secondary driving control module, a pulse width modulation module, a voltage feedforward module and an output sampling module, wherein the power input port, the main power module and the power output port are sequentially connected in series, the power input port is connected with an input voltage Vin, the main power module performs power conversion on the input voltage Vin to obtain an output voltage Vout, the output voltage Vout is output outwards after passing through the power output port, the output sampling module is connected with the power output port, the output sampling module samples the output voltage Vout to obtain an output feedback voltage Voutf, the output feedback voltage Voutf is fed back to the pulse width modulation module, the pulse width modulation module is respectively connected with the voltage feedforward module and the secondary driving control module, the output end of the auxiliary power supply module is connected with the primary driving control module after passing through the driving isolation module, the output end of the auxiliary power supply module is connected with the power input port, and the pulse width modulation module and the voltage feedforward module are respectively connected with the primary driving control module, the output end of the auxiliary power supply module is connected with the pulse width modulation module and the voltage feedforward module, and the auxiliary power supply module is subjected to input change of the voltage Vin to obtain auxiliary power 1;
the voltage feedforward module samples and converts the auxiliary power supply voltage Vin1 in real time to obtain an input feedback voltage Vinf, the input feedback voltage Vinf follows the input voltage Vin in real time, and the pulse width modulation module receives an output feedback voltage Voutf and the input feedback voltage Vinf and performs pulse width modulation control based on the output feedback voltage Voutf and the input feedback voltage Vinf: when the input feedback voltage Vinf fluctuates (representing the fluctuation of the input voltage Vin), the pulse width modulation signal of the pulse width modulation module is regulated to stabilize the output voltage Vout before the output sampling module acts, so that the input voltage step response speed of the direct current converter is improved.
It should be noted that, the main power module may adopt various isolation conversion structures such as forward, flyback, bridge structures, etc., that is, the dc converter based on the secondary control mode of the voltage feedforward module in the present invention may be used in various isolation conversion modes such as forward, flyback, bridge structures, etc., which is not limited herein.
In an alternative embodiment of the present invention, the auxiliary power supply module may at least include a flyback topology auxiliary power supply module, where the flyback topology auxiliary power supply module includes a primary winding and at least two secondary windings, and converts the flyback topology auxiliary power supply module to obtain at least two auxiliary power supply voltages Vin1 with different magnitudes, so as to supply power to the primary drive control module, the secondary drive control module and the pulse width modulation module, and supply the voltage feedforward module to input and sample, thereby further implementing voltage isolation; the pulse width modulation module comprises a secondary current control type pulse width modulation module, wherein a reference voltage output port VREF and a current sampling port CS are arranged in the current control type pulse width modulation module, and the pulse width modulation module can adopt a UC1843 chip for the supplementary control and sampling input of input voltage.
It will be appreciated that in other alternative embodiments of the present invention, the auxiliary power module may be an auxiliary power module with other topologies, and the pulse width modulation module may also use chips with other types, which are not limited herein.
In detail, in an alternative embodiment of the present invention, the auxiliary power supply module is a flyback topology auxiliary power supply module, as shown in fig. 2, the flyback topology auxiliary power supply module includes a flyback transformer T1, an NMOS tube Q1, a first diode D1 and a first capacitor C1, the flyback transformer T1 includes a primary winding and at least two secondary windings (not shown in fig. 2), an input voltage Vin is connected to the drain of the NMOS tube Q1 after passing through the primary windings in series, the source of the NMOS tube Q1 is grounded, the gate of the NMOS tube Q1 is connected to a switch control signal, the anode of the first diode D1 is grounded after passing through the secondary windings in series, the cathode of the first diode D1 is connected to one end of the first capacitor C1, the other end of the first capacitor C1 is grounded, and two ends of the first capacitor C1 output an auxiliary power supply voltage Vin1 to the pulse width modulation module, i.e., one end of the first capacitor C1 is connected to the power supply end VCC of the pulse width modulation module, and the other end of the first capacitor C1 is connected to the ground end GND of the pulse width modulation module.
In more detail, the flyback topology auxiliary power supply module further comprises an alternating current power supply V1, the negative end of the alternating current power supply V1 is grounded, and the positive end of the alternating current power supply V1 outputs a switch control signal to the grid electrode of the NMOS tube Q1.
In detail, in an alternative embodiment of the present invention, as shown in fig. 2, the voltage feedforward module includes:
the input end of the input sampling unit is connected with the output end of the auxiliary power supply module, and the auxiliary power supply voltage Vin1 is sampled in real time to obtain and output a sampling voltage Vin0;
the first input end of the voltage conversion unit is connected with the output end of the input sampling unit, the second input end of the voltage conversion unit is connected with the reference voltage output port VREF of the pulse width modulation module, and voltage-current conversion is carried out on the sampling voltage Vin0 to obtain and output sampling current I0;
and the input end of the filtering voltage dividing unit is connected with the output end of the voltage conversion unit, current-voltage conversion is carried out on the sampling current I0, the input feedback voltage Vinf is obtained and output, and the input feedback voltage Vinf is connected with the current sampling port CS of the pulse width modulation module.
In more detail, as shown in fig. 2, the input sampling unit includes a second diode D2, a first resistor R1 and a second capacitor C2, wherein a cathode of the second diode D2 is connected to an anode of the first diode D1, the anode of the second diode D2 is connected to one end of the second capacitor C2 after passing through the first resistor R1 in series, the other end of the second capacitor C2 is grounded, and one end of the second capacitor C2 connected to the first resistor R1 outputs a sampling voltage Vin0.
In more detail, as shown in fig. 2, the voltage conversion unit includes a second resistor R2, a third resistor R3, a fourth resistor R4, a third diode D3 and a PNP triode Q2, one end of the second resistor R2 is connected to the sampling voltage Vin0, the other end of the second resistor R2 is connected to the cathode of the third diode D3, the anode of the third diode D3 is connected to the reference voltage output port VREF of the pulse width modulation module after passing through the third resistor R3 connected in series, the other end of the second resistor R2 is also connected to the base of the PNP triode Q2, the emitter of the PNP triode Q2 is connected to the reference voltage output port VREF of the pulse width modulation module after passing through the fourth resistor R4 connected in series, the collector of the PNP triode Q2 outputs the sampling current I0, and the PNP triode Q2 works in the amplifying region.
In more detail, as shown in fig. 2, the filtering voltage dividing unit includes a fifth resistor R5, a sixth resistor R6, a fourth diode D4, a third capacitor C3 and a fourth capacitor C4, the sampling current I0 is grounded after passing through the fifth resistor R5 and the sixth resistor R6 which are sequentially connected in series, the third capacitor C3 is connected in parallel with the fifth resistor R5, the fourth capacitor C4 is connected in parallel with the sixth resistor R6, the anode of the fourth diode D4 is connected with the sampling current I0, the cathode of the fourth diode D4 is connected with the driving output port OUT of the pulse width modulation module, and the common terminal of the fifth resistor R5 and the sixth resistor R6 outputs the input feedback voltage Vinf.
In more detail, the dc converter in the secondary control mode shown in fig. 2 operates as follows:
1) When the auxiliary power supply module works, an input voltage Vin of a primary winding on the flyback transformer T1 is coupled to a secondary through a secondary winding, and when the NMOS tube Q1 is conducted, the anode of the first diode D1 generates a negative voltage pulse power supply voltage Vin1, and the negative voltage amplitude of the power supply voltage Vin1 is in direct proportion to the input voltage Vin; when the input voltage Vin is in forward transition, the negative voltage pulse amplitude of the supply voltage Vin1 is increased, the corresponding potential is reduced, and the second capacitor C2 in the input sampling unit discharges through the second diode D2 and the first resistor R1, so that the sampling voltage Vin0 on the second capacitor C2 follows the supply voltage Vin1 or the input voltage Vin; when the input voltage Vin changes negatively, the negative voltage pulse amplitude of the supply voltage Vin1 decreases, the second diode D2 in the input sampling unit is turned off reversely, and the output voltage of the reference voltage output port VREF of the pulse width modulation module charges the second capacitor C2 after passing through the third resistor R3 and the second resistor R2, so that the sampling voltage Vin0 of the second capacitor C2 follows the supply voltage Vin1 or the input voltage Vin.
2) In the voltage conversion unit, after the sampling voltage Vin0 on the second capacitor C2 is divided by the second resistor R2, the third resistor R3 and the third diode D3, the on state of the PNP triode Q2 is controlled; the PNP triode Q2 is a current control type device, the PNP triode Q2 works in an amplifying region, the voltage difference between an emitter electrode and a base electrode of the PNP triode Q2 controls the opening amplitude of the PNP triode Q2, the sampling voltage Vin0 is smaller, the voltage difference is larger, the opening amplitude is larger, the emitter electrode current is larger, the corresponding base electrode current is larger, the corresponding collector electrode current (sampling current I0) is larger, and the sampling current I0 which changes along with the sampling voltage Vin0 on the second capacitor C2 is generated at the collector electrode of the PNP triode Q2; in the filtering voltage dividing unit, the collector current of the PNP triode Q2 flows through a fifth resistor R5 and a sixth resistor R6 which are sequentially connected in series, and based on the sampling of the sixth resistor R6, an input feedback voltage Vinf is obtained at the common end of the fifth resistor R5 and the sixth resistor R6, so as to generate the input feedback voltage Vinf which changes along with the sampling current I, and the larger the collector current or the sampling current I0, the larger the input feedback voltage Vinf.
3) Based on the sequential transmission along with the change, the finally obtained input feedback voltage Vinf changes along with the input voltage Vin in real time, the real-time sampling of the input voltage Vin is completed through the voltage feedforward module, the auxiliary power supply voltage Vin1 of the transition square wave type is converted into the input feedback voltage Vinf of the stable sawtooth wave type, and the waveform of the input voltage Vin is more attached to the actual reduction. The input feedback voltage Vinf which stabilizes the sawtooth waveform and meets the voltage effective range of the current sampling port CS of the pulse width modulation module is input to the pulse width modulation module, and the pulse width modulation module combines the output feedback voltage Voutf and the input feedback voltage Vinf to carry out pulse width modulation control: when the input feedback voltage Vinf fluctuates (representing the fluctuation of the input voltage Vin), before the output sampling module acts, the pulse width modulation signal of the pulse width modulation module is regulated to stabilize the output voltage Vout, so that the phenomenon that the output voltage Vout can overshoot or drop greatly when the input voltage Vin transiently jumps is avoided, and the input voltage step response speed of the direct current converter is improved.
Parameters such as base voltage of the PNP triode Q2 and port effective voltage of the pulse width modulation module jointly determine the parameter values of the components; for the pulse width modulation module similar to UC1843, the effective voltage range of the current sampling port is 0V-1.1V, and the peak value can be 0.7V.
Secondly, based on the DC converter of the secondary control mode, the invention also provides a control method of the DC converter of the secondary control mode, which comprises the following steps:
s1, providing a direct current converter in the secondary control mode;
s2, acquiring auxiliary power supply voltage in real time through a voltage feedforward module to obtain input feedback voltage, wherein the input feedback voltage follows the input voltage in real time;
and S3, performing pulse width modulation control through a pulse width modulation module, and adjusting a pulse width modulation signal output by the pulse width modulation module to stabilize output voltage before the action of the output sampling module when the input feedback voltage fluctuates, so as to improve the step response speed of the input voltage of the direct current converter.
In detail, the step S2 of acquiring the auxiliary power supply voltage in real time through the voltage feedforward module to obtain the input feedback voltage further includes:
s21, sampling the auxiliary power supply voltage Vin1 in real time through an input sampling unit to obtain a sampling voltage Vin0, wherein the sampling voltage Vin0 is a negative voltage which follows the input voltage Vin in real time;
s22, performing voltage-current conversion on the sampling voltage Vin0 through a voltage conversion unit to obtain sampling current I0;
s23, performing current-voltage conversion on the sampling current I0 through a filtering voltage division unit to obtain an input feedback voltage Vinf, wherein the input feedback voltage Vinf is a positive voltage which follows the input voltage Vin in real time, and the input feedback voltage Vinf is a sawtooth wave signal.
In more detail, in step S21, as shown in fig. 2, the auxiliary power supply voltage Vin1 is sampled in real time by the input sampling unit, and the auxiliary power supply voltage Vin1 is sampled in real time by the second capacitor C2 under the participation of the output voltage of the reference voltage output port VREF of the pulse width modulation module, so as to obtain the sampled voltage Vin0 that follows the input voltage Vin in real time.
In more detail, in step S22, as shown in fig. 2, the sampling voltage Vin0 is subjected to voltage-current conversion by the PNP transistor Q2 in the amplifying region in the voltage conversion unit, so as to obtain a sampling current I0, and the magnitude of the sampling current I0 is related to the voltage pulse amplitude of the sampling voltage Vin0, so that the sampling current I0 follows the sampling voltage Vin0 in real time.
In more detail, in step S23, as shown in fig. 2, the sampling current I0 is subjected to current-voltage conversion by the filtering voltage dividing unit to obtain an input feedback voltage Vinf, the input feedback voltage Vinf follows the sampling current I0 in real time, and the input feedback voltage Vinf is a sawtooth wave signal that follows the input voltage Vin in real time based on sequential transmission of following changes, so that the input feedback voltage Vinf is sufficiently close to the input voltage Vin, and the sampling precision of the input voltage Vin is improved.
In detail, in step S3, the pwm module performs pwm control by combining the output feedback voltage Voutf and the input feedback voltage Vinf: when the input feedback voltage Vinf fluctuates (namely the input voltage Vin fluctuates), before the output sampling module acts, the pulse width modulation signal of the pulse width modulation module is regulated to stabilize the output voltage Vout, so that overshoot or drop phenomenon possibly occurring in the output voltage Vout when the input voltage Vin transiently jumps is avoided, and the input voltage step response speed of the direct current converter is improved.
In summary, in the dc converter with the secondary control mode and the control method thereof provided by the present invention, the voltage feedforward module is combined to feed forward to the dc converter with the secondary control mode of the structural design of the pulse width modulation module, the voltage feedforward module is used to sample and follow the input voltage in real time to obtain the input feedback voltage, and then the pulse width modulation module is used to perform pulse width modulation control in combination with the output feedback voltage and the input feedback voltage, when the input feedback voltage fluctuates, the pulse width modulation signal of the pulse width modulation module is quickly adjusted to stabilize the output voltage before the output sampling module acts, so that the phenomenon that the output voltage may overshoot or sag greatly during transient transition of the input voltage can be effectively avoided, the input voltage step response speed of the dc converter is improved, and the stability of the dc converter is improved.
In the above embodiments, while the present invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art in light of the foregoing description. The embodiments of the invention are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (10)
1. The DC converter is characterized by comprising a power input port, a main power module, a power output port, an auxiliary power supply module, a driving isolation module, a primary driving control module, a secondary driving control module, a pulse width modulation module, a voltage feedforward module and an output sampling module, wherein the power input port, the main power module and the power output port are sequentially connected in series, the power input port is connected with an input voltage, the main power module performs power conversion on the input voltage to obtain an output voltage, the output voltage is output to the outside after passing through the power output port, the output sampling module is connected with the power output port, the output sampling module samples the output voltage to obtain an output feedback voltage, the output feedback voltage is fed back to the pulse width modulation module, the pulse width modulation module is connected with the voltage feedforward module and the secondary driving control module respectively, the pulse width modulation module is connected with the primary driving control module after passing through the driving isolation module, the input end of the auxiliary power supply module is connected with the power input port, the output end of the auxiliary power supply module is connected with the primary driving control module and the secondary driving control module to obtain the output feedback voltage, and the output feedback voltage is changed;
the voltage feedforward module samples and converts the auxiliary power supply voltage in real time to obtain an input feedback voltage, the input feedback voltage follows the input voltage in real time, and the pulse width modulation module receives the output feedback voltage and the input feedback voltage and performs pulse width modulation control based on the output feedback voltage and the input feedback voltage: when the input feedback voltage fluctuates, before the output sampling module acts, the pulse width modulation signal of the pulse width modulation module is adjusted to stabilize the output voltage, and the step response speed of the input voltage of the direct current converter is improved.
2. The secondary control mode dc converter of claim 1, wherein the auxiliary power module comprises a flyback topology auxiliary power module comprising a primary winding and at least two secondary windings, the flyback topology auxiliary power module converting to at least two different magnitudes of the auxiliary power voltage to power the primary drive control module, the secondary drive control module, and the pulse width modulation module and provide input sampling to the voltage feed forward module.
3. The secondary control mode dc converter of claim 2, wherein the pulse width modulation module comprises a secondary current control type pulse width modulation module having a reference voltage output port and a current sampling port built in.
4. The secondary control mode direct current converter according to claim 3, wherein the flyback topology auxiliary power supply module comprises a flyback transformer, an NMOS tube, a first diode and a first capacitor, the flyback transformer comprises a primary winding and at least two secondary windings, the input voltage is connected with the drain electrode of the NMOS tube after passing through the primary windings in series, the source electrode of the NMOS tube is grounded, the grid electrode of the NMOS tube is connected with a switch control signal, the anode of the first diode is connected with the ground after passing through one secondary winding in series, the cathode of the first diode is connected with one end of the first capacitor, the other end of the first capacitor is grounded, and the two ends of the first capacitor output an auxiliary power supply voltage to the pulse width modulation module.
5. The secondary control mode dc converter of claim 4, wherein the voltage feed forward module comprises:
the input end of the input sampling unit is connected with the output end of the auxiliary power supply module, and the auxiliary power supply voltage is sampled in real time to obtain and output a sampling voltage;
the first input end of the voltage conversion unit is connected with the output end of the input sampling unit, the second input end of the voltage conversion unit is connected with the reference voltage output port of the pulse width modulation module, and the voltage-current conversion is carried out on the sampling voltage to obtain and output sampling current;
and the input end of the filtering voltage dividing unit is connected with the output end of the voltage conversion unit, current-voltage conversion is carried out on the sampling current, the input feedback voltage is obtained and output, and the input feedback voltage is connected with the current sampling port of the pulse width modulation module.
6. The secondary control mode dc converter of claim 5 wherein the input sampling unit includes a second diode, a first resistor and a second capacitor, the cathode of the second diode is connected to the anode of the first diode, the anode of the second diode is connected to one end of the second capacitor after being connected in series with the first resistor, the other end of the second capacitor is grounded, and the end of the second capacitor connected to the first resistor outputs the sampling voltage.
7. The secondary control mode dc converter of claim 5 wherein the voltage conversion unit includes a second resistor, a third resistor, a fourth resistor, a third diode, and a PNP transistor, one end of the second resistor is connected to the sampling voltage, the other end of the second resistor is connected to the cathode of the third diode, the anode of the third diode is connected to the reference voltage output port of the pwm module after passing through the third resistor in series connection, the other end of the second resistor is also connected to the base of the PNP transistor, the emitter of the PNP transistor is connected to the reference voltage output port of the pwm module after passing through the fourth resistor in series connection, the collector of the PNP transistor outputs the sampling current, and the PNP transistor operates in an amplifying region.
8. The secondary control mode dc converter of claim 5, wherein the filtering voltage dividing unit includes a fifth resistor, a sixth resistor, a fourth diode, a third capacitor and a fourth capacitor, the sampling current flows through the fifth resistor and the sixth resistor connected in series in sequence and then is grounded, the third capacitor is connected in parallel with the fifth resistor, the fourth capacitor is connected in parallel with the sixth resistor, an anode of the fourth diode is connected with the sampling current, a cathode of the fourth diode is connected with a driving output port of the pulse width modulation module, and a common terminal of the fifth resistor and the sixth resistor outputs the input feedback voltage.
9. A control method of a dc converter in a secondary control mode, comprising:
providing a secondary control mode dc converter as claimed in any one of claims 5 to 8;
the auxiliary power supply voltage is acquired in real time through the voltage feedforward module, so that the input feedback voltage is obtained, and the input feedback voltage follows the input voltage in real time;
and when the input feedback voltage fluctuates, before the output sampling module acts, adjusting a pulse width modulation signal output by the pulse width modulation module to stabilize the output voltage, and improving the step response speed of the input voltage of the direct current converter.
10. The method for controlling a dc conversion circuit according to claim 9, wherein the step of acquiring the auxiliary power supply voltage in real time by the voltage feedforward module to obtain the input feedback voltage includes:
the auxiliary power supply voltage is sampled in real time through an input sampling unit to obtain a sampling voltage, wherein the sampling voltage is a negative voltage which follows the input voltage in real time;
performing voltage-current conversion on the sampling voltage through the voltage conversion unit to obtain sampling current;
and performing current-voltage conversion on the sampling current through the filtering voltage dividing unit to obtain the input feedback voltage, wherein the input feedback voltage is a positive voltage which follows the input voltage in real time, and the input feedback voltage is a sawtooth wave signal.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116470733A (en) * | 2023-06-15 | 2023-07-21 | 捷蒽迪电子科技(上海)有限公司 | Novel input voltage acquisition circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116470733A (en) * | 2023-06-15 | 2023-07-21 | 捷蒽迪电子科技(上海)有限公司 | Novel input voltage acquisition circuit |
| CN116470733B (en) * | 2023-06-15 | 2024-07-12 | 捷蒽迪电子科技(上海)有限公司 | Input voltage acquisition circuit |
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