CN214707541U - Switching power supply error compensation circuit and switching power supply - Google Patents
Switching power supply error compensation circuit and switching power supply Download PDFInfo
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- CN214707541U CN214707541U CN202120941758.0U CN202120941758U CN214707541U CN 214707541 U CN214707541 U CN 214707541U CN 202120941758 U CN202120941758 U CN 202120941758U CN 214707541 U CN214707541 U CN 214707541U
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Abstract
The utility model discloses a switching power supply error compensation circuit and switching power supply, including error conversion circuit, compensating circuit, nonlinear compensating circuit and conduction control circuit. This application has add non-linear compensation circuit on the former control loop of power, and the purpose is to realize: when the fluctuation amplitude of the output voltage of the switching power supply exceeds a preset fluctuation range (transient response stage), the control loop superposes compensation adjustment voltage which changes in the opposite direction along with the fluctuation amplitude value under the first compensation voltage generated by the original compensation circuit, and the compensation adjustment voltage jointly control the conduction time of the power switch to accelerate the response speed of the control loop and help to accelerate the stability of the output voltage; when the fluctuation amplitude does not exceed the preset fluctuation range (steady-state response stage), the control loop only controls the conduction time of the power switch under the first compensation voltage generated by the original compensation circuit, and under the condition, the compensation voltage has small ripple waves, thus being beneficial to improving the harmonic distortion of the input current and having good error compensation effect.
Description
Technical Field
The utility model relates to a switching power supply field especially relates to a switching power supply error compensation circuit and switching power supply.
Background
The switching power supply comprises a rectifying circuit and a transformer; the rectifying circuit is used for rectifying alternating current input by the switching power supply into direct current; the transformer is used for transforming the rectified direct current and then providing the load with the required electric energy.
At present, in order to ensure the stability of the output voltage of the switching power supply, a control circuit for error compensation is usually arranged in the switching power supply, as shown in fig. 1, a conventional control circuit includes an error conversion circuit, a compensation circuit, a conduction control circuit, and a power switch Q connected to a primary winding L of a transformer, and the error compensation principle is as follows: the error conversion circuit is used for solving the error voltage between the output feedback voltage FBSH of the switching power supply and the preset voltage-stabilizing reference voltage VREF, and converting the error voltage between the output feedback voltage FBSH and the preset voltage-stabilizing reference voltage VREF into error current to be output; the compensation circuit is used for integrating the error current converted by the error conversion circuit to obtain compensation voltage; the conduction control circuit is used for controlling the conduction time of the power switch Q according to the compensation voltage generated by the compensation circuit so as to adjust the output current of the switching power supply and further adjust the output voltage of the switching power supply, so that the output feedback voltage FBSH is stabilized to the preset voltage stabilization reference voltage VREF.
It is known that there is a certain conflict between the response speed of the control loop and the compensation voltage ripple generated by the compensation circuit, that is, if the response speed of the control loop is increased, the compensation voltage ripple generated by the compensation circuit cannot be decreased, that is, the faster the response speed of the control loop, the larger the compensation voltage ripple generated by the compensation circuit is, which may cause harmonic distortion of the input current of the switching power supply. It can be understood that, when the output voltage of the switching power supply is in the transient response stage, attention is paid to the fast and slow response speed of the control loop (if the response speed of the control loop is fast, it is helpful to accelerate the output voltage stabilization); when the output voltage of the switching power supply is in a steady-state response stage, the compensation voltage ripple generated by the compensation circuit is emphasized (if the compensation voltage ripple is small, the harmonic distortion of the input current of the switching power supply can be improved). However, the existing control circuit adopts the same compensation circuit to perform error compensation no matter when the output voltage of the switching power supply is in a transient response stage or a steady-state response stage, which results in poor error compensation effect.
Therefore, how to provide a solution to the above technical problem is a problem that needs to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a switching power supply error compensation circuit and switching power supply, control loop when switching power supply output voltage is in the transient response stage, under the first compensation voltage that former compensation circuit produced, the compensation adjustment voltage that the range of amplitude that the range of fluctuation surpassed changes in the opposite direction of stack again, the two come control power switch's on-time jointly to accelerate control loop's response speed, help accelerating switching power supply output voltage's stability; when the output voltage of the switching power supply is in a steady-state response stage, the control loop controls the conduction time of the power switch only under the first compensation voltage generated by the original compensation circuit, and under the condition, the compensation voltage ripple is small, so that the harmonic distortion of the input current of the switching power supply is improved, and the error compensation effect is good.
In order to solve the technical problem, the utility model provides a switching power supply error compensation circuit, include:
the error conversion circuit is used for solving a first error voltage between the output feedback voltage of the switching power supply and a preset first reference voltage, and converting the first error voltage between the output feedback voltage and the preset first reference voltage into a first error current for output;
the compensation circuit is connected with the output end of the error conversion circuit and is used for integrating the first error current to obtain a first compensation voltage;
the nonlinear compensation circuit is connected with the output end of the compensation circuit and is used for detecting whether the fluctuation amplitude of the output feedback voltage exceeds a preset fluctuation range or not, and if so, generating compensation adjustment voltage changing in the opposite direction along with the amplitude value exceeding the fluctuation amplitude; if not, generating a compensation adjustment voltage with the amplitude smaller than a preset amplitude threshold; superposing the compensation adjustment voltage on the first compensation voltage to obtain a second compensation voltage;
the conduction control circuit is connected with the nonlinear compensation circuit and is used for controlling the conduction time of a power switch connected with a primary winding of a transformer in the switching power supply according to the second compensation voltage so as to stabilize the output feedback voltage to a preset first reference voltage; wherein the higher the second compensation voltage, the longer the on-time.
Preferably, the error conversion circuit includes:
the inverting input end is connected to the output feedback voltage, the non-inverting input end is connected to a first transconductance amplifier with a preset first reference voltage, and the first transconductance amplifier is used for solving a first error voltage between the output feedback voltage and the preset first reference voltage, amplifying the first error voltage and converting the amplified first error voltage into a first error current to be output.
Preferably, the compensation circuit includes:
and the first end of the compensation capacitor is respectively connected with the output end of the error conversion circuit and the nonlinear compensation circuit, and the second end of the compensation capacitor is grounded.
Preferably, the non-linearity compensation circuit includes:
the nonlinear transconductance circuit is used for detecting whether the fluctuation amplitude of the output feedback voltage exceeds a preset fluctuation range or not, and if so, generating compensation current which changes in the opposite direction along with the amplitude value exceeding the fluctuation amplitude; if not, generating a compensation current with the amplitude smaller than a preset amplitude threshold value;
and the voltage compensation circuit is used for converting the compensation current into compensation adjustment voltage and superposing the compensation adjustment voltage on the first compensation voltage to obtain second compensation voltage.
Preferably, the nonlinear transconductance circuit comprises a second transconductance amplifier, a third transconductance amplifier, a forward diode and a reverse diode; wherein:
a non-inverting input end of the second transconductance amplifier is connected with a preset second reference voltage, an inverting input end of the second transconductance amplifier is connected with the output feedback voltage, an output end of the second transconductance amplifier is connected with an anode of the forward diode, a non-inverting input end of the third transconductance amplifier is connected with a preset third reference voltage, an inverting input end of the third transconductance amplifier is connected with the output feedback voltage, an output end of the third transconductance amplifier is connected with a cathode of the backward diode, a cathode of the forward diode is connected with an anode of the backward diode, and a common end of the forward diode is used as an output end of the nonlinear transconductance circuit; the preset second reference voltage is less than the preset first reference voltage and less than the preset third reference voltage;
the Nth transconductance amplifier is used for solving an Nth error voltage between the output feedback voltage and a preset Nth reference voltage, amplifying the Nth error voltage and converting the amplified Nth error voltage into an Nth error current to be output; wherein, N is 2, 3.
Preferably, the nonlinear transconductance circuit comprises a second transconductance amplifier, a third transconductance amplifier, a forward diode and a reverse diode; wherein:
a non-inverting input end of the second transconductance amplifier is connected with a preset second reference voltage, an inverting input end of the second transconductance amplifier is connected with the output feedback voltage, an output end of the second transconductance amplifier is connected with an anode of the forward diode, a common end of the second transconductance amplifier is connected with a preset first bias current, a non-inverting input end of the third transconductance amplifier is connected with a preset third reference voltage, an inverting input end of the third transconductance amplifier is connected with the output feedback voltage, an output end of the third transconductance amplifier is connected with a cathode of the backward diode, a common end of the third transconductance amplifier is connected with a preset second bias current, a cathode of the forward diode is connected with an anode of the backward diode, and a common end of the forward diode is used as an output end of the nonlinear transconductance circuit; the preset second reference voltage and the preset third reference voltage are equal to the preset first reference voltage; the preset first bias current flows from the output end of the second transconductance amplifier; the preset second bias current flows into the output end of the third transconductance amplifier;
the Nth transconductance amplifier is used for solving an Nth error voltage between the output feedback voltage and a preset Nth reference voltage, amplifying the Nth error voltage and converting the amplified Nth error voltage into an Nth error current to be output; wherein, N is 2, 3.
Preferably, the voltage compensation circuit includes:
and the first end of the compensation resistor is connected with the output end of the nonlinear transconductance circuit, and the second end of the compensation resistor is connected with the output end of the compensation circuit.
Preferably, the switching power supply error compensation circuit further includes:
and the voltage buffer is connected with the output end of the compensation circuit at the first end and connected with the second end of the voltage compensation circuit at the second end.
Preferably, the switching power supply error compensation circuit is entirely built in a control chip of the switching power supply.
In order to solve the technical problem, the utility model also provides a switching power supply, including any kind of switching power supply error compensation circuit of the aforesaid.
The utility model provides a switching power supply error compensation circuit, including error conversion circuit, compensating circuit, nonlinear compensating circuit and conduction control circuit. This application has add non-linear compensation circuit on switching power supply original control loop, and the purpose is to realize: when the fluctuation amplitude of the output voltage of the switching power supply exceeds a preset fluctuation range (transient response stage), the control loop superposes compensation adjustment voltage which changes in the opposite direction along with the fluctuation amplitude value under the first compensation voltage generated by the original compensation circuit, and the compensation adjustment voltage jointly control the conduction time of the power switch to accelerate the response speed of the control loop and contribute to accelerating the stability of the output voltage of the switching power supply; when the fluctuation amplitude of the output voltage of the switching power supply does not exceed the preset fluctuation range (steady-state response stage), the compensation adjustment voltage is smaller than the preset amplitude threshold, and actually, the compensation adjustment voltage is very small and close to zero at the moment, namely, the control loop only controls the conduction time of the power switch under the first compensation voltage generated by the original compensation circuit, and under the condition, the compensation voltage ripple is small, so that the harmonic distortion of the input current of the switching power supply is favorably improved, and the error compensation effect is good.
The utility model also provides a switching power supply has the same beneficial effect with above-mentioned error compensation circuit.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the prior art and the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic diagram of error compensation of a control circuit in a switching power supply according to the prior art;
fig. 2 is a schematic structural diagram of an error compensation circuit of a switching power supply according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a specific structure of an error compensation circuit of a switching power supply according to an embodiment of the present invention;
fig. 4 is a specific signal waveform diagram of an error compensation circuit for a switching power supply according to an embodiment of the present invention.
Detailed Description
The core of the utility model is to provide a switching power supply error compensation circuit and switching power supply, when switching power supply output voltage was in the transient response stage, under the first compensation voltage that former compensation circuit produced, the compensation adjustment voltage of the amplitude value opposite direction change that the range of fluctuation exceeded that superposes again, the two come control power switch's on-time jointly to accelerate control loop's response speed, help accelerating switching power supply output voltage's stability; when the output voltage of the switching power supply is in a steady-state response stage, the control loop controls the conduction time of the power switch only under the first compensation voltage generated by the original compensation circuit, and under the condition, the compensation voltage ripple is small, so that the harmonic distortion of the input current of the switching power supply is improved, and the error compensation effect is good.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Referring to fig. 2, fig. 2 is a schematic structural diagram of an error compensation circuit of a switching power supply according to an embodiment of the present invention.
The switching power supply error compensation circuit includes:
the error conversion circuit 100 is configured to obtain a first error voltage between an output feedback voltage of the switching power supply and a preset first reference voltage, and convert the first error voltage between the output feedback voltage and the preset first reference voltage into a first error current for output;
the compensation circuit 200 is configured to integrate the first error current to obtain a first compensation voltage;
the nonlinear compensation circuit 400 is used for detecting whether the fluctuation amplitude of the output feedback voltage exceeds a preset fluctuation range, and if so, generating a compensation adjustment voltage which changes in the opposite direction along with the amplitude value exceeding the fluctuation amplitude; if not, generating a compensation adjustment voltage with the amplitude smaller than a preset amplitude threshold; superposing the compensation adjustment voltage on the first compensation voltage to obtain a second compensation voltage;
the conduction control circuit 300 is configured to control, according to the second compensation voltage, conduction time of a power switch connected to a primary winding of a transformer in the switching power supply, so that the output feedback voltage is stabilized to a preset first reference voltage; wherein the higher the second compensation voltage, the longer the on-time.
Specifically, the switching power supply error compensation circuit of the present application includes an error conversion circuit 100, a compensation circuit 200, a nonlinear compensation circuit 400, and a conduction control circuit 300, and its working principle is:
the error conversion circuit 100 has two input terminals, one of the input terminals inputs an output feedback voltage FBSH (specifically, the output feedback voltage FBSH can be obtained by sampling by the voltage sampling circuit), and the other input terminal inputs a preset first reference voltage Vref1, and the error conversion circuit 100 is configured to obtain a first error voltage between the output feedback voltage FBSH of the switching power supply and the preset first reference voltage Vref1, and convert the first error voltage between the output feedback voltage FBSH and the preset first reference voltage Vref1 into a first error current lc1 for output.
The input end of the compensation circuit 200 is connected to the output end of the error conversion circuit 100, and the compensation circuit 200 is configured to integrate the first error current lc1 output by the error conversion circuit 100 to obtain a first compensation voltage Vc 1. The first terminal of the non-linear compensation circuit 400 is connected to the input terminal of the conduction control circuit 300, the second terminal of the non-linear compensation circuit 400 is connected to the output terminal of the compensation circuit 200, and the non-linear compensation circuit 400 is configured to detect whether the fluctuation range of the output feedback voltage FBSH of the switching power supply exceeds a preset fluctuation range: 1) if the fluctuation range exceeds the preset fluctuation range, the output voltage of the switching power supply is in a transient response stage, a compensation adjustment voltage which changes in the opposite direction along with the amplitude value exceeding the fluctuation range is generated, namely the larger the amplitude value of the fluctuation range of the output feedback voltage FBSH exceeding the upper limit of the preset fluctuation range is (the larger the output feedback voltage FBSH is), the larger the negative value of the compensation adjustment voltage is, the larger the negative value is, the compensation adjustment voltage is superposed on the first compensation voltage Vc1, and the second compensation voltage Vc2 which is smaller than the first compensation voltage Vc1 is obtained; the larger the amplitude value of the fluctuation range of the output feedback voltage FBSH exceeds the lower limit of the preset fluctuation range (the smaller the output feedback voltage FBSH is), the larger the forward value of the compensation adjustment voltage is, the compensation adjustment voltage is superimposed on the first compensation voltage Vc1, and the second compensation voltage Vc2 which is larger than the first compensation voltage Vc1 is obtained (in summary, when the fluctuation range of the output feedback voltage FBSH exceeds the preset fluctuation range, the larger the compensation adjustment voltage is, so that the fluctuation range of the second compensation voltage Vc2 is increased, and the change of the load current is offset by the change range of the output current of the switching power supply. 2) If the output voltage of the switching power supply is not beyond the preset fluctuation range, the output voltage of the switching power supply is in a steady-state response stage, a compensation adjustment voltage with the amplitude close to zero is generated, the compensation adjustment voltage with the amplitude close to zero is superposed with the first compensation voltage Vc1, and a second compensation voltage Vc2 approximately equal to the first compensation voltage Vc1 is obtained.
The conduction control circuit 300 is configured to control a conduction time of the power switch Q connected to the primary winding L of the transformer in the switching power supply according to the second compensation voltage Vc2 obtained by the nonlinear compensation circuit 400, so as to stabilize the output feedback voltage FBSH of the switching power supply to a preset first reference voltage Vref 1. It should be noted that the lower the output feedback voltage FBSH of the switching power supply, the higher the second compensation voltage Vc2, and the longer the on-time of the power switch Q, so that the larger the output current of the switching power supply, the larger the difference between the output current of the switching power supply and the load current is integrated in the load capacitor to obtain the output voltage, thereby forming negative feedback closed-loop control, and making the output voltage of the switching power supply always tend to be stabilized at the preset first reference voltage Vref 1.
It can be seen that, this application has add non-linear compensation circuit on switching power supply original control loop, and the purpose is to realize: when the fluctuation amplitude of the output voltage of the switching power supply exceeds a preset fluctuation range (transient response stage), the control loop superposes compensation adjustment voltage which changes in the opposite direction along with the fluctuation amplitude value under the first compensation voltage generated by the original compensation circuit, and the compensation adjustment voltage jointly control the conduction time of the power switch to accelerate the response speed of the control loop and contribute to accelerating the stability of the output voltage of the switching power supply; when the fluctuation amplitude of the output voltage of the switching power supply does not exceed the preset fluctuation range (steady-state response stage), the compensation adjustment voltage is smaller than the preset amplitude threshold, and actually, the compensation adjustment voltage is very small and close to zero at the moment, namely, the control loop only controls the conduction time of the power switch under the first compensation voltage generated by the original compensation circuit, and under the condition, the compensation voltage ripple is small, so that the harmonic distortion of the input current of the switching power supply is favorably improved, and the error compensation effect is good.
On the basis of the above-described embodiment:
referring to fig. 3, fig. 3 is a schematic diagram of a specific structure of an error compensation circuit of a switching power supply according to an embodiment of the present invention.
As an alternative embodiment, the error conversion circuit 100 includes:
the inverting input end is connected with the output feedback voltage, the non-inverting input end is connected with a first transconductance amplifier GM1 with a preset first reference voltage, and the first transconductance amplifier GM1 is used for solving a first error voltage between the output feedback voltage and the preset first reference voltage, amplifying the first error voltage and converting the amplified first error voltage into a first error current to be output.
Specifically, the error conversion circuit 100 of the present application includes a first transconductance amplifier GM1, which operates on the principle:
an inverting input terminal of the first transconductance amplifier GM1 serves as one of the input terminals of the error conversion circuit 100, a non-inverting input terminal of the first transconductance amplifier GM1 serves as the other input terminal of the error conversion circuit 100, and an output terminal of the first transconductance amplifier GM1 serves as the output terminal of the error conversion circuit 100. The first transconductance amplifier GM1 is configured to obtain a first error voltage between an output feedback voltage FBSH of the switching power supply and a preset first reference voltage Vref1, amplify the first error voltage between the output feedback voltage FBSH and the preset first reference voltage Vref1, and convert the amplified first error voltage into a first error current lc1 for output.
As an alternative embodiment, the compensation circuit 200 includes:
and a compensation capacitor C1 having a first terminal connected to the output terminal of the error conversion circuit 100 and the non-linear compensation circuit 400, and a second terminal connected to ground.
Specifically, the conventional compensation circuit is composed of a plurality of components such as resistors and capacitors, and presents different impedance characteristics at different frequencies, so that the frequency characteristic of the compensation voltage is adjusted. However, in different application scenarios of different switching power supplies, the parameter values of the compensation circuit are different, so that components of the compensation circuit need to be subjected to parameter adjustment according to the switching power supply, and therefore the compensation circuit cannot be integrated inside a control chip along with a control circuit, and the design complexity and the cost of the switching power supply are increased.
In order to reduce the cost and the design complexity of the periphery of the control chip, the compensation circuit 200 is simplified to the greatest extent into a compensation capacitor C1, the first end of the compensation capacitor C1 serves as both the input end of the compensation circuit 200 and the output end of the compensation circuit 200, and the compensation capacitor C1 is used for integrating the first error current lc1 output by the first transconductance amplifier GM1 to obtain the first compensation voltage Vc 1.
In addition, in order to filter the power frequency ripple input by the switching power supply and reduce the harmonic distortion of the input current, the value of the compensation capacitor C1 may be several times of the sum of all capacitors in the conventional compensation circuit, so that the high frequency component in the first compensation voltage Vc1, which is higher than the power frequency ripple frequency, is correspondingly several times lower than the high frequency component in the conventional compensation voltage. Specifically, when the load current of the switching power supply is stable and unchanged, the switching power supply is in a steady-state response stage, the dc component of the output feedback voltage FBSH of the switching power supply is equal to the first reference voltage Vref1, the compensation adjustment voltage approaches zero, and the second compensation voltage Vc2 approaches the first compensation voltage Vc1, so that the high-frequency component in the second compensation voltage Vc2 is also reduced accordingly. Because the high-frequency component in the second compensation voltage Vc2 is reduced, the high-frequency component in the input current of the switching power supply is correspondingly reduced, thereby reducing the harmonic distortion of the input current and improving the power factor of the system.
As an alternative embodiment, the non-linearity compensation circuit 400 includes:
the nonlinear transconductance circuit 401 is configured to detect whether a fluctuation range of the output feedback voltage exceeds a preset fluctuation range, and if so, generate a compensation current that changes in an opposite direction along with the amplitude value that the fluctuation range exceeds; if not, generating a compensation current with the amplitude smaller than a preset amplitude threshold value;
and the voltage compensation circuit 402, of which the first end is connected to the output end of the non-linear transconductance circuit 401 and the second end is connected to the output end of the compensation circuit 200, is configured to convert the compensation current into a compensation adjustment voltage, and superimpose the compensation adjustment voltage on the first compensation voltage to obtain a second compensation voltage.
Specifically, the nonlinear compensation circuit 400 of the present application includes a nonlinear transconductance circuit 401 and a voltage compensation circuit 402, and the operation principle thereof is as follows:
the output terminal of the non-linear transconductance circuit 401 is connected to the first terminal of the voltage compensation circuit 402, the common terminal is used as the first terminal of the non-linear compensation circuit 400, and the second terminal of the voltage compensation circuit 402 is used as the second terminal of the non-linear compensation circuit 400. The nonlinear transconductance circuit 401 is configured to detect whether a fluctuation range of the output feedback voltage FBSH of the switching power supply exceeds a preset fluctuation range: 1) if the fluctuation range exceeds the preset fluctuation range, which indicates that the output voltage of the switching power supply is in a transient response stage, a compensation current lc2 which changes in a reverse direction along with the amplitude value exceeding the fluctuation range is generated, that is, the larger the amplitude value of the fluctuation range of the output feedback voltage FBSH exceeding the upper limit of the preset fluctuation range is, the larger the negative value of the compensation current lc2 is, the larger the negative value of the compensation adjustment voltage obtained by converting the compensation current lc2 by the voltage compensation circuit 402 is, the larger the negative value of the compensation adjustment voltage is, the compensation adjustment voltage with the larger negative value is superposed on the first compensation voltage Vc1, and the second compensation voltage Vc2 which is smaller than the first compensation voltage Vc1 is obtained; the larger the amplitude value of the fluctuation range of the output feedback voltage FBSH exceeds the lower limit of the preset fluctuation range, the larger the forward value of the compensation current lc2 is, the larger the forward value of the compensation adjustment voltage converted by the voltage compensation circuit 402 from the compensation current lc2 is, and the larger the forward value of the compensation adjustment voltage is, the first compensation voltage Vc1 is superimposed on the compensation adjustment voltage having the larger forward value, so that the second compensation voltage Vc2 which is larger than the first compensation voltage Vc1 is obtained. 2) If the fluctuation range is not exceeded, it is indicated that the output voltage of the switching power supply is in a steady-state response stage, a compensation current lc2 with an amplitude close to zero is generated, the compensation adjustment voltage obtained by converting the compensation current lc2 by the voltage compensation circuit 402 is also close to zero, and the compensation adjustment voltage with the amplitude close to zero is superimposed on the first compensation voltage Vc1 to obtain a second compensation voltage Vc2 approximately equal to the first compensation voltage Vc 1.
As an alternative embodiment, the non-linear transconductance circuit 401 includes a second transconductance amplifier GM2, a third transconductance amplifier GM3, a forward diode Dp, and a reverse diode Dn; wherein:
the non-linear transconductance circuit 401 comprises a non-linear transconductance circuit, a first transconductance amplifier GM2, a second transconductance amplifier GM2, a third transconductance amplifier GM3, a third transconductance amplifier GM3, a non-linear transconductance circuit 401 and a third transconductance amplifier GM3, wherein the non-linear transconductance circuit 401 is connected with the non-linear transconductance circuit, the non-linear transconductance circuit and the non-linear transconductance circuit, the non-linear transconductance circuit is connected with the non-linear transconductance circuit, the non-linear transconductance amplifier GM2 is connected with the non-linear amplifier GM2, the non-linear transconductance circuit is connected with the non-linear transconductance circuit, the non-linear diode Dn is connected with the non-linear diode Dn, and the non-linear diode Dn is connected with the non-linear circuit; the preset second reference voltage is less than the preset first reference voltage and less than the preset third reference voltage;
the Nth transconductance amplifier is used for solving an Nth error voltage between the output feedback voltage and a preset Nth reference voltage, amplifying the Nth error voltage and converting the amplified Nth error voltage into an Nth error current to be output; wherein, N is 2, 3.
Specifically, the first embodiment of the non-linear transconductance circuit 401 of the present application: the nonlinear transconductance circuit 401 includes a second transconductance amplifier GM2, a third transconductance amplifier GM3, a forward diode Dp, and a reverse diode Dn (without bias currents lb1 and lb2), and its operation principle is:
the preset fluctuation range of the output feedback voltage FBSH of the switching power supply may be set by the second reference voltage Vref2 and the third reference voltage Vref3, as shown in fig. 4, the second reference voltage Vref2 < the first reference voltage Vref1 < the third reference voltage Vref 3.
When the output feedback voltage FBSH of the switching power supply is lower than the second reference voltage Vref2, the compensation current Ic2 flows from the output terminal of the second transconductance amplifier GM2, flows through the forward diode Dp, and then flows into the voltage compensation circuit 402, so that the second compensation voltage Vc2 is higher than the first compensation voltage Vc1, and the lower the output feedback voltage FBSH is lower than the second reference voltage Vref2, the larger the forward value of the compensation current Ic2 is, the higher the second compensation voltage Vc2 is than the first compensation voltage Vc 1. When the output feedback voltage FBSH of the switching power supply is higher than the second reference voltage Vref2, i.e., the output feedback voltage FBSH of the switching power supply is closer to the first reference voltage Vref1, the forward diode Dp prevents the compensation current Ic2 from flowing through, so that the second compensation voltage Vc2 is equal to the first compensation voltage Vc 1.
When the output feedback voltage FBSH of the switching power supply is higher than the third reference voltage Vref3, the compensation current Ic2 flows from the output terminal of the third transconductance amplifier GM3, flows through the backward diode Dn, and flows out from the voltage compensation circuit 402, so that the second compensation voltage Vc2 is lower than the first compensation voltage Vc1, the higher the output feedback voltage FBSH is higher than the third reference voltage Vref3, the larger the negative value of the compensation current Ic2 is, and the lower the second compensation voltage Vc2 is lower than the first compensation voltage Vc 1. When the output feedback voltage FBSH of the switching power supply is lower than the third reference voltage Vref3, i.e., the output feedback voltage FBSH of the switching power supply is closer to the first reference voltage Vref1, the reverse diode Dn prevents the compensation current Ic2 from flowing through, so that the second compensation voltage Vc2 is equal to the first compensation voltage Vc 1.
As an alternative embodiment, the non-linear transconductance circuit 401 includes a second transconductance amplifier GM2, a third transconductance amplifier GM3, a forward diode Dp, and a reverse diode Dn; wherein:
the non-linear transconductance circuit 401 comprises a non-linear transconductance circuit 401, a first transconductance amplifier GM2, a second transconductance amplifier GM2, a third transconductance amplifier GM3, a third transconductance amplifier GM3, a third transconductance amplifier GM3, a third transconductance amplifier GM2, a non-linear transconductance amplifier Dn, a first reference voltage, a second reference voltage, a third bias current, a third reference voltage, a third bias current, a third reference voltage, a third bias current, a positive diode Dn, a negative diode Dn, a common terminal, a positive diode Dp, a negative diode Dn, and a common terminal; the preset second reference voltage and the preset third reference voltage are equal to the preset first reference voltage; presetting the flow direction of the first bias current to flow out of the output end of the second transconductance amplifier GM 2; presetting the flow direction of a second bias current to flow into the output end of the third transconductance amplifier GM 3;
the Nth transconductance amplifier is used for solving an Nth error voltage between the output feedback voltage and a preset Nth reference voltage, amplifying the Nth error voltage and converting the amplified Nth error voltage into an Nth error current to be output; wherein, N is 2, 3.
Specifically, the second embodiment of the non-linear transconductance circuit 401 of the present application: the nonlinear transconductance circuit 401 includes a second transconductance amplifier GM2, a third transconductance amplifier GM3, a forward diode Dp and a reverse diode Dn (including bias currents lb1 and lb2), and the operation principle is as follows:
the preset fluctuation range of the output feedback voltage FBSH of the switching power supply can also be set by the first bias current Ib1 and the second bias current Ib 2. When the difference value of the output feedback voltage FBSH minus the second reference voltage Vref2 of the switching power supply is multiplied by the transconductance of the second transconductance amplifier GM2, and the product is larger than the first bias current Ib1, the difference value of the current at the output end of the second transconductance amplifier GM2 and the first bias current Ib1 flows through the forward diode Dp, and the compensation current Ic2 is formed. When the product of the difference of the output feedback voltage FBSH minus the second reference voltage Vref2 multiplied by the transconductance of the second transconductance amplifier GM2 is larger than the first bias current Ib1, the larger the forward value of the compensation current Ic2, the higher the second compensation voltage Vc2 is relative to the first compensation voltage Vc 1.
When the difference of the output feedback voltage FBSH subtracted from the third reference voltage Vref3 multiplied by the transconductance of the third transconductance amplifier GM3 is greater than the second bias current Ib2, the difference between the current at the output terminal of the third transconductance amplifier GM3 and the second bias current Ib2 flows through the reverse diode Dn to form the compensation current Ic2, and when the difference of the output feedback voltage FBSH subtracted from the third reference voltage Vref3 multiplied by the transconductance of the third transconductance amplifier GM3 multiplied by the second bias current Ib2 is greater, the negative value of the compensation current Ic2 is greater, and the second compensation voltage Vc2 is lower than the first compensation voltage Vc 1.
As an alternative embodiment, the voltage compensation circuit 402 includes:
and a compensation resistor R1 having a first terminal connected to the output terminal of the non-linear transconductance circuit 401 and a second terminal connected to the output terminal of the compensation circuit 200.
Specifically, the voltage compensation circuit 402 of the present application includes a compensation resistor R1, and its operation principle is:
the first terminal of the compensation resistor R1 is used as the first terminal of the voltage compensation circuit 402, and the second terminal of the compensation resistor R1 is used as the second terminal of the voltage compensation circuit 402. The compensation current Ic2 flows through the compensation resistor R1, and the voltage drop generated across the compensation resistor R1 constitutes the compensation adjustment voltage. It should be noted that the compensation current Ic2 also flows into the compensation capacitor C1 to accelerate the stabilization of the first compensation voltage Vc 1.
As an alternative embodiment, the switching power supply error compensation circuit further includes:
a voltage buffer having a first terminal connected to the output terminal of the compensation circuit 200 and a second terminal connected to the second terminal of the voltage compensation circuit 402.
Further, the switching power supply error compensation circuit of the present application further includes a voltage buffer, and the working principle thereof is:
the first compensation voltage Vc1 is output to the compensation resistor R1 through the voltage buffer, which has the advantage of preventing the transient compensation current Ic2 from flowing into the compensation capacitor C1, so that the voltage of the compensation capacitor C1 is not affected by the transient response process.
As an alternative embodiment, the switching power supply error compensation circuit is entirely built inside a control chip of the switching power supply.
Based on this, compare traditional switching power supply error compensation circuit and the switching power supply error compensation circuit of this application: 1) the conventional error compensation circuit of the switching power supply: the compensation circuit of switching Power supply (PFC (Power Factor Correction) CV (constant voltage) system) comprises components (generally 3 RC components) such as a plurality of resistances and electric capacity, and the electric capacity makes switching Power supply's input current produce the phase shift, and resistance makes switching Power supply's input current produce the ripple to reduce Power Factor (PF), increase harmonic distortion (THD). In order to improve the power factor/harmonic distortion, a compensation circuit is needed to compensate for low-bandwidth over-damping; in order to improve the response speed of the control loop, the compensation of the compensation circuit is required to be high-bandwidth underdamping, so that the parameters of components of the compensation circuit need to be adjusted in a compromise mode between the response speed of the control loop and the power factor/harmonic distortion, and the compensation circuit cannot be integrated in the control chip along with the control circuit, so that the design complexity and the cost of the switching power supply are increased. 2) The application discloses switching power supply error compensation circuit: the whole compensation circuit of the switching power supply is reduced from a plurality of RC components to 1 RC component, wherein the compensation resistor is controlled by P (proportion), the compensation capacitor is controlled by I (Integration), namely, PI control is split into independent P and I, the respective adjusting range of PI is increased by multiple times, the compensation resistor and the compensation capacitor can be built in a control chip, and the control chip does not need a compensation pin any more. The control principle of the compensation resistor and the compensation capacitor is as follows: increasing output voltage range detection, and closing P control (a compensation resistor does not work) within a preset fluctuation range to enable I control (a compensation capacitor) to independently adjust power factor/harmonic distortion; and starting P control (the compensation resistor acts) outside the preset fluctuation range, so that the P control independently adjusts the response speed of the system.
In summary, the switching power supply error compensation circuit of the present application utilizes the low frequency pole of the compensation circuit to independently adjust the harmonic distortion in the steady state response stage according to the transient response and the steady state response of the output feedback voltage division system; in the transient response stage, nonlinear compensation voltage is generated by utilizing nonlinear error amplification and compensation to independently adjust the response speed of the system, and the error compensation effect is good.
The application also provides a switching power supply, which comprises any one of the switching power supply error compensation circuits.
For the introduction of the switching power supply provided in the present application, reference is made to the embodiments of the error compensation circuit, which are not repeated herein.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A switching power supply error compensation circuit, comprising:
the error conversion circuit is used for solving a first error voltage between the output feedback voltage of the switching power supply and a preset first reference voltage, and converting the first error voltage between the output feedback voltage and the preset first reference voltage into a first error current for output;
the compensation circuit is connected with the output end of the error conversion circuit and is used for integrating the first error current to obtain a first compensation voltage;
the nonlinear compensation circuit is connected with the output end of the compensation circuit and is used for detecting whether the fluctuation amplitude of the output feedback voltage exceeds a preset fluctuation range or not, and if so, generating compensation adjustment voltage changing in the opposite direction along with the amplitude value exceeding the fluctuation amplitude; if not, generating a compensation adjustment voltage with the amplitude smaller than a preset amplitude threshold; superposing the compensation adjustment voltage on the first compensation voltage to obtain a second compensation voltage;
the conduction control circuit is connected with the nonlinear compensation circuit and is used for controlling the conduction time of a power switch connected with a primary winding of a transformer in the switching power supply according to the second compensation voltage so as to stabilize the output feedback voltage to a preset first reference voltage; wherein the higher the second compensation voltage, the longer the on-time.
2. The switching power supply error compensation circuit of claim 1, wherein the error conversion circuit comprises:
the inverting input end is connected to the output feedback voltage, the non-inverting input end is connected to a first transconductance amplifier with a preset first reference voltage, and the first transconductance amplifier is used for solving a first error voltage between the output feedback voltage and the preset first reference voltage, amplifying the first error voltage and converting the amplified first error voltage into a first error current to be output.
3. The switching power supply error compensation circuit of claim 1, wherein the compensation circuit comprises:
and the first end of the compensation capacitor is respectively connected with the output end of the error conversion circuit and the nonlinear compensation circuit, and the second end of the compensation capacitor is grounded.
4. The switching power supply error compensation circuit of any of claims 1-3, wherein the non-linear compensation circuit comprises:
the nonlinear transconductance circuit is used for detecting whether the fluctuation amplitude of the output feedback voltage exceeds a preset fluctuation range or not, and if so, generating compensation current which changes in the opposite direction along with the amplitude value exceeding the fluctuation amplitude; if not, generating a compensation current with the amplitude smaller than a preset amplitude threshold value;
and the voltage compensation circuit is used for converting the compensation current into compensation adjustment voltage and superposing the compensation adjustment voltage on the first compensation voltage to obtain second compensation voltage.
5. The switching power supply error compensation circuit of claim 4, wherein the non-linear transconductance circuit comprises a second transconductance amplifier, a third transconductance amplifier, a forward diode, and a reverse diode; wherein:
a non-inverting input end of the second transconductance amplifier is connected with a preset second reference voltage, an inverting input end of the second transconductance amplifier is connected with the output feedback voltage, an output end of the second transconductance amplifier is connected with an anode of the forward diode, a non-inverting input end of the third transconductance amplifier is connected with a preset third reference voltage, an inverting input end of the third transconductance amplifier is connected with the output feedback voltage, an output end of the third transconductance amplifier is connected with a cathode of the backward diode, a cathode of the forward diode is connected with an anode of the backward diode, and a common end of the forward diode is used as an output end of the nonlinear transconductance circuit; the preset second reference voltage is less than the preset first reference voltage and less than the preset third reference voltage;
the Nth transconductance amplifier is used for solving an Nth error voltage between the output feedback voltage and a preset Nth reference voltage, amplifying the Nth error voltage and converting the amplified Nth error voltage into an Nth error current to be output; wherein, N is 2, 3.
6. The switching power supply error compensation circuit of claim 4, wherein the non-linear transconductance circuit comprises a second transconductance amplifier, a third transconductance amplifier, a forward diode, and a reverse diode; wherein:
a non-inverting input end of the second transconductance amplifier is connected with a preset second reference voltage, an inverting input end of the second transconductance amplifier is connected with the output feedback voltage, an output end of the second transconductance amplifier is connected with an anode of the forward diode, a common end of the second transconductance amplifier is connected with a preset first bias current, a non-inverting input end of the third transconductance amplifier is connected with a preset third reference voltage, an inverting input end of the third transconductance amplifier is connected with the output feedback voltage, an output end of the third transconductance amplifier is connected with a cathode of the backward diode, a common end of the third transconductance amplifier is connected with a preset second bias current, a cathode of the forward diode is connected with an anode of the backward diode, and a common end of the forward diode is used as an output end of the nonlinear transconductance circuit; the preset second reference voltage and the preset third reference voltage are equal to the preset first reference voltage; the preset first bias current flows from the output end of the second transconductance amplifier; the preset second bias current flows into the output end of the third transconductance amplifier;
the Nth transconductance amplifier is used for solving an Nth error voltage between the output feedback voltage and a preset Nth reference voltage, amplifying the Nth error voltage and converting the amplified Nth error voltage into an Nth error current to be output; wherein, N is 2, 3.
7. The switching power supply error compensation circuit of claim 4, wherein the voltage compensation circuit comprises:
and the first end of the compensation resistor is connected with the output end of the nonlinear transconductance circuit, and the second end of the compensation resistor is connected with the output end of the compensation circuit.
8. The switching power supply error compensation circuit of claim 4, further comprising:
and the voltage buffer is connected with the output end of the compensation circuit at the first end and connected with the second end of the voltage compensation circuit at the second end.
9. The switching power supply error compensation circuit of claim 1, wherein the switching power supply error compensation circuit is entirely built inside a control chip of the switching power supply.
10. A switching power supply comprising a switching power supply error compensation circuit according to any one of claims 1-9.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116388713A (en) * | 2023-03-31 | 2023-07-04 | 杭州晶丰明源半导体有限公司 | Error amplifier and power supply |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116388713A (en) * | 2023-03-31 | 2023-07-04 | 杭州晶丰明源半导体有限公司 | Error amplifier and power supply |
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