CN112886823B - Primary side control circuit, control method and isolated switching power supply - Google Patents
Primary side control circuit, control method and isolated switching power supply Download PDFInfo
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- CN112886823B CN112886823B CN202110193950.0A CN202110193950A CN112886823B CN 112886823 B CN112886823 B CN 112886823B CN 202110193950 A CN202110193950 A CN 202110193950A CN 112886823 B CN112886823 B CN 112886823B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
- H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
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Abstract
The invention provides a primary side control circuit, a control method and an isolated switching power supply. The primary side control circuit comprises a charge-discharge circuit and a drive signal generation circuit. The input end of the charge-discharge circuit receives the first detection signal, and the charge-discharge circuit controls the charge quantity in unit time in the charge-discharge circuit according to the first detection signal. The charge-discharge circuit controls the discharge amount in unit time in the charge-discharge circuit according to the median current of the primary side inductance and the demagnetization time of the secondary side circuit so as to control the charge process and the discharge process to keep dynamic balance. The input end of the driving signal generating circuit is coupled with the charge-discharge circuit, and the output end of the driving signal generating circuit is coupled with the main switch tube in the primary side circuit. The primary side control circuit, the control method and the isolated switch power supply provided by the invention can set different output current constant current values according to the output voltage of the isolated switch power supply, so that the high-precision constant power output or adjustable constant current output of the isolated switch power supply can be effectively realized.
Description
Technical Field
The invention belongs to the technical field of power electronics, relates to an isolated switching power supply technology, and in particular relates to a primary side control circuit, a control method and an isolated switching power supply.
Background
The isolation type switching power supply is widely applied to the switching power supply due to the safety and the higher noise resistance. The isolated switching power supply comprises a transformer winding, a primary side circuit and a secondary side circuit. The traditional isolation type switching power supply obtains sampling signals through a primary side circuit and controls the switching state of a main switching tube, so that the control of constant current output of a secondary side circuit is realized. Specifically, as shown in fig. 1, the isolated switching power supply is specifically a flyback switching power supply, the median value of the current CS flowing through the primary inductor is sampled in the primary circuit, and the conduction duty ratio of the current of the secondary circuit is obtained, and the constant current output control of the flyback switching power supply is realized by controlling the median value of the current CS and the conduction duty ratio. In the application of the isolated switch power supply, the output power is often required to be controlled, such as the application of constant power output, and the high-precision output power control of the isolated switch power supply cannot be effectively realized in the above manner.
In view of the foregoing, there is a need to provide a new structure or control method for solving the above-mentioned technical problems.
Disclosure of Invention
In order to solve at least part of the above problems, the present invention provides a primary side control circuit, a control method and an isolated switching power supply.
The invention discloses a primary side control circuit, which is used for primary side control of an isolated switching power supply, the isolated switching power supply comprises a primary side circuit and a secondary side circuit, and the primary side control circuit comprises:
The input end of the charge-discharge circuit is coupled with the first detection signal end to obtain a first detection signal representing the output voltage, and the charge-discharge circuit controls the charge quantity in unit time in the charge-discharge circuit according to the first detection signal; the charge-discharge circuit controls the discharge amount in unit time in the charge-discharge circuit according to the primary inductance median current and the demagnetization time of the secondary circuit so as to control the charge process and the discharge process to keep dynamic balance; and
The input end of the driving signal generating circuit is coupled with the charge-discharge circuit, and the output end of the driving signal generating circuit is coupled with the main switch tube in the primary side circuit.
As an embodiment of the present invention, the charge-discharge circuit controls the discharge current according to the primary inductance median current, and the charge-discharge circuit controls the discharge time according to the degaussing time of the secondary circuit.
As an embodiment of the present invention, a charge/discharge circuit includes:
the charging circuit is coupled with the first detection signal end and is used for outputting charging current according to the first detection signal;
the first end of the first capacitor is coupled with the output end of the charging circuit, and the second end of the first capacitor is coupled with the ground; and
And the first input end of the discharging circuit is coupled with the first end of the first capacitor, the second input end of the discharging circuit receives the degaussing time of the secondary side circuit, and the third input end of the discharging circuit receives a sampling signal representing the median current of the primary side inductor and is used for discharging the first capacitor according to the degaussing time of the secondary side circuit and the sampling signal.
As an embodiment of the present invention, the charging circuit includes a first current source for outputting a charging current according to a first detection signal; the discharge circuit includes:
The first end of the first switch is coupled with the first end of the first capacitor, and the switch control end of the first switch receives the degaussing time of the secondary circuit;
The drain electrode of the second switch tube is coupled with the second end of the first switch;
the non-inverting input end of the operational amplifier is coupled with the sampling signal, the inverting input end of the operational amplifier is coupled with the source electrode of the second switching tube, and the output end of the operational amplifier is coupled with the control end of the second switching tube; and
And the first end of the third resistor is coupled with the source electrode of the second switch tube, and the second end of the third resistor is coupled with the ground.
As an embodiment of the invention, the first end of the first capacitor is coupled to the input end of the driving signal generating circuit.
As one embodiment of the invention, the isolated switching power supply is a flyback switching power supply, the flyback switching power supply comprises an auxiliary winding, and the charge-discharge circuit is coupled with the auxiliary winding to obtain the first detection signal.
As an embodiment of the invention, a first adjusting circuit is further coupled between the charge-discharge circuit and the first detection signal terminal, and the first adjusting circuit outputs a first adjusting signal to the charge-discharge circuit according to the first adjusting parameter and the first detection signal, so as to control the charge amount in unit time in the charge-discharge circuit.
As an embodiment of the present invention, a charging circuit in a charging/discharging circuit includes a first current source, and a first adjusting circuit controls an output current I1 of the first current source to be in positive correlation with K/Vdem, where I1 is an output current of the first current source, K is a first adjusting parameter, and Vdem is a first detection signal.
As an embodiment of the present invention, the output current of the first current source satisfies any one of the following three conditions in the setting phase: the output current of the first current source is a fixed value; the output current of the first current source is reduced in a step-like manner along with the increase of the first detection signal; the output current of the first current source is inversely proportional to the first detection signal.
The invention also discloses an isolated switching power supply, which comprises a primary side circuit, a secondary side circuit and a transformer winding, wherein the primary side circuit comprises any primary side control circuit, and the primary side control circuit is used for controlling the switching state of a main switching tube.
The invention also discloses a control method of the primary side control circuit, the control method is used for primary side control of the isolated switch power supply, the isolated switch power supply comprises a primary side circuit and a secondary side circuit, the primary side circuit comprises a primary side control circuit, the primary side control circuit comprises a charging and discharging circuit and a driving signal generating circuit, and the control method comprises the following steps:
Acquiring a first detection signal representing an output voltage;
Controlling the charge amount of the charge-discharge circuit to the first capacitor in unit time according to the first detection signal; controlling the discharge amount of the charge-discharge circuit to the first capacitor in unit time according to the median current of the primary inductor and the demagnetization time of the secondary circuit so as to control the charge process and the discharge process to keep dynamic balance; and
And generating a driving signal according to the voltage at two ends of the first capacitor so as to control the switching state of a main switching tube in the primary side circuit.
As one embodiment of the invention, the isolated switching power supply is a flyback switching power supply, and the control method specifically comprises the following steps: and controlling the discharge current according to the median current of the primary side inductance and controlling the discharge time according to the degaussing time of the secondary side circuit.
As an embodiment of the present invention, the control method further includes:
and outputting a first adjusting signal according to the first adjusting parameter and the first detecting signal, wherein the first adjusting signal is used for controlling the charging amount in unit time in the charging and discharging circuit.
As an embodiment of the present invention, the charging and discharging circuit includes a charging circuit, the charging circuit includes a first current source, and the control method further includes:
And controlling the output current I1 of the first current source to be in positive correlation with K/Vdem, wherein I1 is the output current of the first current source, K is a first adjusting parameter, and Vdem is a first detection signal.
As an embodiment of the present invention, the output current of the first current source satisfies any one of the following three conditions in the setting phase: the output current of the first current source is a fixed value; the output current of the first current source is reduced in a step-like manner along with the increase of the first detection signal; the output current of the first current source is inversely proportional to the first detection signal.
The invention provides a primary side control circuit, a control method and an isolated switching power supply. The primary side control circuit comprises a charge-discharge circuit and a drive signal generation circuit. The input end of the charge-discharge circuit receives the first detection signal, and the charge-discharge circuit controls the charge quantity in unit time in the charge-discharge circuit according to the first detection signal. The charge-discharge circuit controls the discharge amount in unit time in the charge-discharge circuit according to the median current of the primary side inductance and the demagnetization time of the secondary side circuit so as to control the charge process and the discharge process to keep dynamic balance. The input end of the driving signal generating circuit is coupled with the charge-discharge circuit, and the output end of the driving signal generating circuit is coupled with the main switch tube in the primary side circuit. The primary side control circuit, the control method and the isolated switch power supply provided by the invention can set different output current constant current values according to the output voltage of the isolated switch power supply, so that the high-precision constant power output or adjustable constant current output of the isolated switch power supply can be effectively realized.
Drawings
Fig. 1 shows a schematic circuit diagram of a prior art flyback switching power supply.
Fig. 2 shows a schematic circuit diagram of an isolated switching power supply according to an embodiment of the invention.
Fig. 3 shows a schematic circuit diagram of a primary side control circuit according to an embodiment of the invention.
Fig. 4a and 4b show voltage and current curves, respectively, according to an embodiment of the invention.
Fig. 5a and 5b show voltage and current curves, respectively, according to another embodiment of the invention.
Fig. 6a and 6b show voltage and current curves, respectively, according to a further embodiment of the invention.
Fig. 7 is a schematic flow chart of steps of a control method of a primary side control circuit according to an embodiment of the invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
The description of this section is intended to be illustrative of only a few exemplary embodiments and the invention is not to be limited in scope by the description of the embodiments. It is also within the scope of the description and claims of the invention to interchange some of the technical features of the embodiments with other technical features of the same or similar prior art.
"Coupled" or "connected" in the specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediary, such as through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connections may also include connections through other active or passive devices, such as through circuits or components such as switches, follower circuits, and the like, that accomplish the same or similar functional objectives.
The isolated switching power supply comprises a primary side circuit and a secondary side circuit, and in specific applications, the output current or the output power is often required to be controlled so as to realize constant-current output or constant-power output of the isolated switching power supply. The switching state of a main switching tube in the primary side circuit can be controlled according to the average value of the primary side inductive current or the average value of the secondary side inductive current in each switching period so as to realize the control of output current or output power. The primary inductor current is the current flowing through the inductor in the primary circuit, and the secondary inductor current is the current flowing through the inductor in the secondary circuit. The output current Iout of the isolated switching power supply satisfies:
Wherein Is (t) Is real-time current flowing through the secondary inductor or real-time current flowing through the output diode, ip (t) Is real-time current flowing through the primary inductor, N Is turn ratio of primary winding and secondary winding of the transformer in the isolated switching power supply, and Ts Is switching period of the main switching tube. While the average current of the secondary inductor in continuous mode and discontinuous mode can be expressed by the following formula:
Wherein I mid_P is the primary inductor current obtained by the primary switch tube at the middle time point of the on period, and T DIS is the degaussing time of the secondary inductor. The average output current of the isolated switching power supply is as follows
Wherein Rcs is a sampling resistor of the primary inductor, vmid_p is a median voltage obtained by the main switching tube on the sampling resistor Rcs at a middle time point of a conduction time period, and D DIS is equal to T DIS/TS,DDIS and is a conduction duty ratio of the secondary circuit.
The embodiment of the invention discloses a primary side control circuit, which is used for primary side control of an isolated switching power supply, wherein the isolated switching power supply comprises a primary side circuit and a secondary side circuit, and the primary side control circuit comprises a charge-discharge circuit and a driving signal generation circuit. The input end of the charge-discharge circuit is coupled with the first detection signal end to obtain a first detection signal representing the output voltage, and the charge-discharge circuit controls the charge quantity in unit time in the charge-discharge circuit according to the first detection signal. The charge-discharge circuit controls the discharge amount in unit time in the charge-discharge circuit according to the median current of the primary inductor and the demagnetization time of the secondary circuit so as to control the charge process and the discharge process to keep dynamic balance. The output voltage is the output voltage of the isolated switching power supply. The input end of the driving signal generating circuit is coupled with the charge-discharge circuit, and the output end of the driving signal generating circuit is coupled with the main switch tube in the primary side circuit. In an embodiment of the present invention, the primary inductor median current is a primary inductor current obtained by the main switching tube at an intermediate time point of the on period. The unit time can be a single switching period of the main switching tube or a time length formed by a plurality of switching periods of the main switching tube. In one embodiment, the primary side control circuit controls the charging process and the discharging process to maintain dynamic balance, and when the isolated switching power supply is at constant current output or constant power output, the charging process and the discharging process are maintained in balance. When the first detection signal changes to cause the change of the charge amount in the charge-discharge circuit in unit time, the switching state of the main switching tube is caused to change. Correspondingly, the primary side inductance median current and the secondary side circuit degaussing time are correspondingly changed, and meanwhile, the discharge capacity in unit time in the charge-discharge circuit is adjusted, and after dynamic adjustment, the charge process and the discharge process are balanced. According to the invention, different output current constant values can be set according to the output voltage of the isolated switch power supply, and the isolated switch power supply adopts closed-loop control, so that high-precision constant power output or adjustable constant current output of the isolated switch power supply can be effectively realized.
In the invention, the isolated switching power supply can be a typical flyback switching power supply, and can also be other approximate topologies which are suitable for the technical scheme of the invention.
In an embodiment of the present invention, as shown in fig. 2, the isolated switching power supply is a flyback switching power supply, an output voltage of the flyback switching power supply is obtained through an auxiliary winding Na, the primary side control circuit 100 is provided with a pin DEM, the pin DEM is coupled to the auxiliary winding Na, and the pin DEM is used for obtaining a first detection signal representing the output voltage. In another embodiment, a voltage dividing resistor set is further coupled between the pin DEM and the auxiliary winding Na, the voltage dividing resistor set includes a first resistor R1 and a second resistor R2, a first end of the first resistor R1 is coupled to the auxiliary winding Na, a second end of the first resistor R1 is coupled to the pin DEM, a first end of the second resistor R2 is coupled to the second end of the first resistor R1, and a second end of the second resistor R2 is coupled to ground. In an embodiment of the invention, the first detection signal is a first detection voltage Vdem.
In an embodiment of the present invention, as shown in fig. 3, the primary side control circuit 100 includes a charge-discharge circuit and a driving signal generating circuit 120, and the charge-discharge circuit includes a charge circuit, a discharge circuit and a first capacitor C1. The charging circuit is coupled to a first detection voltage Vdem representing an output voltage of the flyback switching power supply, and is configured to output a charging current according to the first detection voltage Vdem. The first end of the first capacitor C1 is coupled to the output end of the charging circuit, and the second end of the first capacitor C1 is coupled to ground. The first input end of the discharging circuit is coupled with the first end of the first capacitor C1, the second input end of the discharging circuit receives the degaussing time of the secondary side circuit, the third input end of the discharging circuit receives a sampling signal representing the median current of the primary side inductance, and the discharging circuit discharges the first capacitor C1 according to the degaussing time of the secondary side circuit and the sampling signal. In one embodiment, the primary side control circuit 100 includes a main switch Q1, and the primary side control circuit 100 has a Drain terminal Drain. In another embodiment, the primary side control circuit 100 does not include the main switching tube Q1, the primary side control circuit 100 is provided with a driving end Gate, and the driving end Gate of the primary side control circuit 100 is coupled to the Gate of the main switching tube.
In an embodiment of the invention, as shown in fig. 3, the charging circuit includes a first current source I1, and an output terminal of the first current source I1 is coupled to a first terminal of the first capacitor C1. In a specific embodiment, the first current source I1 is a voltage-controlled current source. In another embodiment, the first current source I1 may be a current control current source, and a voltage-current conversion circuit is further disposed between the first current source I1 and the pin DEM. In addition, the charge-discharge circuit controls the discharge current according to the primary inductance median current, and the charge-discharge circuit controls the discharge time according to the degaussing time of the secondary circuit, as shown in fig. 3, and the discharge circuit includes a first switch K1, a second switch Q2, an operational amplifier 111, and a third resistor R3. The first end of the first switch K1 is coupled to the first end of the first capacitor C1, and the switch control end of the first switch K1 receives the degaussing time of the secondary circuit, and controls the first switch K1 to be turned on when the secondary circuit is in the degaussing time. When the flyback switching power supply is in a continuous mode (CCM mode for short), the switching period Ts of the main switching tube includes an on time Ton and a demagnetizing time Toff. When the flyback switching power supply is in a discontinuous mode (DCM mode for short), the switching period Ts of the main switching tube comprises a conduction time Ton, a degaussing time Tdem and a dead time Tdie. In an embodiment of the present invention, the switching may be freely performed according to a continuous mode or an intermittent mode to select the corresponding demagnetizing time Toff or Tdem. The drain of the second switch Q2 is coupled to the second terminal of the first switch K1. The non-inverting input of the operational amplifier 111 is coupled to a sampling voltage vmid_p, which is a sampling signal representing the median current of the primary inductor, and can be obtained by sampling the current flowing through the primary inductor or the current flowing through the sampling resistor Rcs. The inverting input terminal of the operational amplifier 111 is coupled to the source of the second switching tube Q2, and the output terminal of the operational amplifier 111 is coupled to the control terminal of the second switching tube Q2. The first end of the third resistor R3 is coupled to the source of the second switching tube Q2, and the second end of the third resistor R3 is coupled to ground. The first end of the first capacitor C1 is coupled to the input end of the driving signal generating circuit 120, and the driving signal generating circuit 120 controls the current peak and the switching frequency of the main switching tube Q1 according to the voltage Vc1 at two ends of the first capacitor C1.
In an embodiment of the present invention, a first adjusting circuit is further coupled between the charge-discharge circuit and the first detection signal terminal DEM, and the first adjusting circuit outputs a first adjusting signal to the charge-discharge circuit according to the first adjusting parameter and the first detection signal, and the charge-discharge circuit controls the charge amount per unit time in the charge-discharge circuit according to the first adjusting signal. In another embodiment, the charge-discharge circuit includes a first current source, and the first adjusting circuit controls the output current I1 of the first current source to be in positive correlation with K/Vdem, where I1 is the output current of the first current source, K is a first adjusting parameter, and Vdem is a first detection signal. In an embodiment, as shown in fig. 4a and 4b, the output current of the first current source is a fixed value, independent of the first detection signal. At this time, the first adjustment parameter K is proportional to the first detection signal Vdem, and K is a positive value. Correspondingly, the flyback switching power supply can keep constant current output. In another embodiment, as shown in fig. 5a and 5b, by adjusting the K value, the output current I1 of the first current source decreases in a stepwise manner with the increase of the first detection signal Vdem. Correspondingly, the flyback switching power supply can realize adjustable constant current output or constant power output. In yet another embodiment, as shown in fig. 6a and 6b, the output current I1 of the first current source is a fixed value in the first stage, and the flyback switching power supply performs constant current output regardless of the first detection signal. The output current I1 of the first current source is inversely proportional to the first detection signal Vdem in the second phase, and the first adjustment parameter K is a fixed positive value. Correspondingly, the flyback switching power supply can maintain constant power output. Based on the primary side control circuit, the first detection signal representing the output voltage is obtained through the charge-discharge circuit, the charge-discharge process is controlled according to the first detection signal, the driving signal generating circuit generates the driving signal according to the voltages at the two ends of the first capacitor to control the switching state of the main switching tube, and high-precision constant-power output or adjustable constant-current output of the flyback switching power supply can be effectively realized.
The embodiment of the invention also discloses an isolated switching power supply, which comprises a primary side circuit, a secondary side circuit and a transformer winding, wherein the primary side circuit transmits energy to the secondary side circuit through the transformer winding. The primary side circuit comprises any primary side control circuit, and the primary side control circuit is used for controlling the switching state of the main switching tube so as to realize high-precision constant power output or adjustable constant current output of the isolated switching power supply. In an embodiment of the present invention, the main switch transistor is a switch transistor, which may be a metal oxide semiconductor field effect transistor (MOSFET transistor for short) or a junction field effect transistor (JFET transistor for short). In another embodiment, the isolated switching power supply is a flyback switching power supply, and the isolated switching power supply can be other approximate topologies suitable for the technical scheme of the invention.
The embodiment of the invention also discloses a control method of the primary side control circuit, which is used for controlling the primary side of the isolated switching power supply, wherein the isolated switching power supply comprises a primary side circuit and a secondary side circuit, the primary side circuit comprises a primary side control circuit, and the primary side control circuit comprises a charge-discharge circuit and a driving signal generation circuit. As shown in fig. 7, the control method of the primary side control circuit includes:
S1OO, acquiring a first detection signal representing output voltage;
Step S2OO, controlling the charge amount of the charge-discharge circuit to the first capacitor in unit time according to the first detection signal; controlling the discharge amount of the charge-discharge circuit to the first capacitor in unit time according to the median current of the primary inductor and the demagnetization time of the secondary circuit so as to control the charge process and the discharge process to keep dynamic balance; and
And S3OO, generating a driving signal according to the voltages at two ends of the first capacitor so as to control the switching state of the main switching tube in the primary circuit.
In a specific embodiment, the charging and discharging circuit obtains a first detection signal representing the output voltage, the charging and discharging circuit controls the charging and discharging of the charging and discharging circuit to the first capacitor in unit time according to the first detection signal, and the charging and discharging circuit controls the discharging amount of the charging and discharging circuit to the first capacitor in unit time according to the primary side inductance median current and the demagnetization time of the secondary side circuit so as to control the charging process and the discharging process to keep dynamic balance. The driving signal generating circuit generates a driving signal according to the voltages at two ends of the first capacitor, and controls the switching state of a main switching tube in the primary side circuit.
In an embodiment of the present invention, the control method specifically includes: and controlling the discharge current according to the median current of the primary side inductance and controlling the discharge time according to the degaussing time of the secondary side circuit. In another embodiment, the isolated switching power supply is a flyback switching power supply, and the isolated switching power supply can be other approximate topologies suitable for the technical scheme of the invention.
In an embodiment of the present invention, the control method further includes: and outputting a first adjusting signal according to the first adjusting parameter and the first detecting signal, wherein the first adjusting signal is used for controlling the charging amount in unit time in the charging and discharging circuit.
In an embodiment of the present invention, the charging and discharging circuit includes a charging circuit, the charging circuit includes a first current source, and the control method further includes: and controlling the output current I1 of the first current source to be in positive correlation with K/Vdem, wherein I1 is the output current of the first current source, K is a first adjusting parameter, and Vdem is a first detection signal.
In an embodiment of the present invention, the output current of the first current source satisfies any one of the following three conditions during the setting phase: the output current of the first current source is a fixed value; the output current of the first current source is reduced in a step-like manner along with the increase of the first detection signal; the output current of the first current source is inversely proportional to the first detection signal. The setting of the setting stage is set according to a specific application scenario, and under the constant current output application scenario, the output current of the first current source may be a fixed value. In order to realize adjustable constant current output or constant power output, the output current of the first current source can be controlled to be reduced in a step-type manner along with the increase of the first detection signal. When the isolated switching power supply needs to be set to constant current output in the first stage and constant power output in the second stage, the output current I1 of the first current source is a fixed value in the first stage, and is irrelevant to the first detection signal, and the isolated switching power supply carries out constant current output. The output current I1 of the first current source is inversely proportional to the first detection signal Vdem in the second stage, and the first adjustment parameter K is a fixed positive value, so as to perform constant power output.
The primary side control circuit, the control method and the isolated switch power supply provided by the invention can set different output current constant current values according to the output voltage of the isolated switch power supply, so that the high-precision constant power output or adjustable constant current output of the isolated switch power supply can be effectively realized.
The description and applications of the present invention herein above are illustrative and are not intended to limit the scope of the invention to the embodiments described above. In the specification, the "output current" and the "output voltage" which are not explicitly described are the output current and the output voltage of the isolated switching power supply. The relevant descriptions of effects or advantages and the like related to the embodiments may not be embodied in experimental examples due to uncertainty of specific condition parameters, and are not intended to limit the embodiments. Variations and modifications of the embodiments disclosed herein are possible, and alternatives and equivalents of the various components of the embodiments are known to those of ordinary skill in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other assemblies, materials, and components, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (15)
1. A primary side control circuit for primary side control of an isolated switching power supply comprising a primary side circuit and a secondary side circuit, the primary side control circuit comprising:
the input end of the charge-discharge circuit is coupled with the first detection signal end to obtain a first detection signal representing the output voltage, and the charge-discharge circuit controls the charge quantity in unit time in the charge-discharge circuit according to the first detection signal; the charge-discharge circuit controls the discharge amount in unit time in the charge-discharge circuit according to the primary inductance median current and the demagnetization time of the secondary circuit so as to control the charge process and the discharge process to keep dynamic balance; and
And the input end of the driving signal generating circuit is coupled with the charge-discharge circuit, and the output end of the driving signal generating circuit is coupled with the main switching tube in the primary side circuit.
2. The primary side control circuit of claim 1, wherein the charge-discharge circuit controls the discharge current based on a primary side inductance median current, and wherein the charge-discharge circuit controls the discharge time based on a secondary side circuit degaussing time.
3. The primary side control circuit of claim 1, wherein the charge-discharge circuit comprises:
The charging circuit is coupled with the first detection signal end and is used for outputting charging current according to the first detection signal;
The first end of the first capacitor is coupled with the output end of the charging circuit, and the second end of the first capacitor is coupled with the ground; and
And the first input end of the discharging circuit is coupled with the first end of the first capacitor, the second input end of the discharging circuit receives the degaussing time of the secondary side circuit, and the third input end of the discharging circuit receives a sampling signal representing the median current of the primary side inductor and is used for discharging the first capacitor according to the degaussing time of the secondary side circuit and the sampling signal.
4. The primary side control circuit of claim 3, wherein the charging circuit comprises a first current source to output a charging current in accordance with the first detection signal; the discharge circuit includes:
The first end of the first switch is coupled with the first end of the first capacitor, and the switch control end of the first switch receives the degaussing time of the secondary circuit;
a second switch tube, the drain electrode of which is coupled with the second end of the first switch;
the non-inverting input end of the operational amplifier is coupled with a sampling signal, the inverting input end of the operational amplifier is coupled with the source electrode of the second switching tube, and the output end of the operational amplifier is coupled with the control end of the second switching tube; and
And the first end of the third resistor is coupled with the source electrode of the second switch tube, and the second end of the third resistor is coupled with the ground.
5. The primary side control circuit of claim 3, wherein a first terminal of the first capacitor is coupled to an input terminal of the drive signal generation circuit.
6. The primary side control circuit of claim 1, wherein the isolated switching power supply is a flyback switching power supply, the flyback switching power supply includes an auxiliary winding, and the charge-discharge circuit is coupled to the auxiliary winding to obtain the first detection signal.
7. The primary side control circuit of claim 1, wherein a first adjusting circuit is further coupled between the charge-discharge circuit and the first detection signal terminal, and the first adjusting circuit outputs a first adjusting signal to the charge-discharge circuit according to the first adjusting parameter and the first detection signal, so as to control the charge amount per unit time in the charge-discharge circuit.
8. The primary side control circuit of claim 7, wherein the charging circuit in the charging and discharging circuit comprises a first current source, the first regulating circuit controlling an output current I1 of the first current source to be positively correlated with K/Vdem, wherein I1 is an output current of the first current source, K is a first regulating parameter, and Vdem is a first detection signal.
9. The primary side control circuit of claim 8, wherein the output current of the first current source satisfies any one of the following three conditions during the set phase: the output current of the first current source is a fixed value; the output current of the first current source is reduced in a step-like manner along with the increase of the first detection signal; the output current of the first current source is inversely proportional to the first detection signal.
10. An isolated switching power supply, characterized in that the isolated switching power supply comprises a primary circuit, a secondary circuit and a transformer winding, the primary circuit comprises a primary control circuit according to any one of claims 1-9, and the primary control circuit is used for controlling the switching state of a main switching tube.
11. A control method of a primary side control circuit, the control method being used for primary side control of an isolated switching power supply, the isolated switching power supply including a primary side circuit and a secondary side circuit, characterized in that the primary side circuit includes a primary side control circuit including a charge-discharge circuit and a drive signal generation circuit, the control method comprising:
Acquiring a first detection signal representing an output voltage;
Controlling the charge amount of the charge-discharge circuit to the first capacitor in unit time according to the first detection signal; controlling the discharge amount of the charge-discharge circuit to the first capacitor in unit time according to the median current of the primary inductor and the demagnetization time of the secondary circuit so as to control the charge process and the discharge process to keep dynamic balance; and
And generating a driving signal according to the voltage at two ends of the first capacitor so as to control the switching state of a main switching tube in the primary side circuit.
12. The control method according to claim 11, wherein the isolated switching power supply is a flyback switching power supply, the control method specifically comprising: and controlling the discharge current according to the median current of the primary side inductance and controlling the discharge time according to the degaussing time of the secondary side circuit.
13. The control method according to claim 11, characterized in that the control method further comprises:
and outputting a first adjusting signal according to the first adjusting parameter and the first detecting signal, wherein the first adjusting signal is used for controlling the charging amount in unit time in the charging and discharging circuit.
14. The control method of claim 13, wherein the charge-discharge circuit comprises a charging circuit comprising a first current source, the control method further comprising:
And controlling the output current I1 of the first current source to be in positive correlation with K/Vdem, wherein I1 is the output current of the first current source, K is a first adjusting parameter, and Vdem is a first detection signal.
15. The control method of claim 11, wherein the output current of the first current source satisfies any one of the following three conditions during the set phase: the output current of the first current source is a fixed value; the output current of the first current source is reduced in a step-like manner along with the increase of the first detection signal; the output current of the first current source is inversely proportional to the first detection signal.
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| CN117081365B (en) * | 2023-09-21 | 2024-01-02 | 茂睿芯（深圳）科技有限公司 | Power supply adjusting circuit, buck converter and direct current power supply |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203014693U (en) * | 2012-12-28 | 2013-06-19 | 杭州士兰微电子股份有限公司 | Controller for controlling switch power supply to output current constantly |
| CN103227576A (en) * | 2013-04-23 | 2013-07-31 | 深圳市明微电子股份有限公司 | Constant current drive control circuit with high power factor and drive device |
| CN107017777A (en) * | 2017-04-28 | 2017-08-04 | 南京微客力科技有限公司 | Constant current mode inverse excitation type converter based on primary side feedback |
| CN111162678A (en) * | 2020-01-24 | 2020-05-15 | 杭州必易微电子有限公司 | Secondary side control circuit and control method of isolated converter and isolated converter |
| CN111585448A (en) * | 2020-06-22 | 2020-08-25 | 上海新进芯微电子有限公司 | Constant current output control circuit, switching power supply controller and switching power supply system |
| CN214900668U (en) * | 2021-02-20 | 2021-11-26 | 深圳市必易微电子股份有限公司 | Primary side control circuit and isolated switching power supply |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8665612B2 (en) * | 2012-07-10 | 2014-03-04 | Immense Advance Technology Corporation | Constant current controller |
| CN105471270A (en) * | 2016-01-22 | 2016-04-06 | 矽力杰半导体技术(杭州)有限公司 | Control circuit and control method with self-adaptive blanking time |
-
2021
- 2021-02-20 CN CN202110193950.0A patent/CN112886823B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203014693U (en) * | 2012-12-28 | 2013-06-19 | 杭州士兰微电子股份有限公司 | Controller for controlling switch power supply to output current constantly |
| CN103227576A (en) * | 2013-04-23 | 2013-07-31 | 深圳市明微电子股份有限公司 | Constant current drive control circuit with high power factor and drive device |
| CN107017777A (en) * | 2017-04-28 | 2017-08-04 | 南京微客力科技有限公司 | Constant current mode inverse excitation type converter based on primary side feedback |
| CN111162678A (en) * | 2020-01-24 | 2020-05-15 | 杭州必易微电子有限公司 | Secondary side control circuit and control method of isolated converter and isolated converter |
| CN111585448A (en) * | 2020-06-22 | 2020-08-25 | 上海新进芯微电子有限公司 | Constant current output control circuit, switching power supply controller and switching power supply system |
| CN214900668U (en) * | 2021-02-20 | 2021-11-26 | 深圳市必易微电子股份有限公司 | Primary side control circuit and isolated switching power supply |
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