Power supply control circuit and method

Abstract

The present invention discloses a power supply control circuit and method, the power supply control circuit includes a first capacitor, a drive control circuit, a charging circuit and a first voltage generating circuit, the control end of the drive control circuit is connected to the control end of the rectifier switch tube in the power stage circuit, the rectifier switch tube is connected to the high potential end of the output voltage of the power stage circuit, the power supply end of the drive control circuit is connected to one end of the first capacitor, the other end of the first capacitor is connected to the ground of the drive control circuit, the ground of the drive control circuit is the source of the rectifier switch tube, the first voltage generating circuit receives the output voltage of the power stage circuit, and its output end is connected to the power supply end of the drive control circuit via the charging circuit. The present invention improves the power supply capacity.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and more particularly to a power supply control circuit and method. Background Art

[0002] In practical applications, it is necessary to power the drive control circuit that controls the on and off of the rectifier switch tube in the power stage circuit. In the prior art, the output voltage is generally used directly to charge the energy storage element of the drive control circuit of the rectifier switch tube, and the energy storage element powers the drive control circuit. Figure 1 As shown, taking a flyback switching power supply as an example, the flyback switching power supply includes a main power switch tube M1, a transformer and a rectifier switch tube M2, the transformer includes a primary winding L1 and a secondary winding L2, the main power switch tube M1 and the primary winding L1 are connected in series at both ends of the input voltage Vin, the rectifier switch tube M2 is connected to the high potential end of the output voltage Vout, and the rectifier switch tube M2 and the secondary winding L2 are connected in series at both ends of the output voltage Vout. The control end of the drive control circuit is connected to the control end of the secondary rectifier switch tube M2, one end of the energy storage capacitor C1 is connected to the power supply end of the drive control circuit, the other end of the energy storage capacitor C1 is connected to the common end of the secondary rectifier switch tube M2 and the secondary winding L2, and the output end is connected to the power supply end of the drive control circuit via a charging circuit. When the main power switch tube M1 is turned on, the rectifier switch tube is turned off, the output voltage Vout charges the energy storage capacitor C1, and the energy storage capacitor C1 supplies power to the drive control circuit.

[0003] In the above charging circuit, when the main power switch tube M1 is turned on, the actual voltage charged to the energy storage capacitor C1 is the output voltage Vout and the voltage on the secondary winding V L2 The expected value Vcc of the voltage at the power supply end of the drive control circuit is generally small. When the input voltage Vin is large, the voltage V on the secondary winding L2 The voltage charged to the energy storage capacitor C1 is larger, so the charging efficiency is lower, and when the output voltage is not high, its power supply capacity is lower. Summary of the invention

[0004] In view of this, the present invention provides a power supply control circuit and method for improving power supply capacity, which are used to solve the technical problem of low power supply capacity in the prior art.

[0005] The present invention provides a power supply control circuit, comprising a first capacitor, a drive control circuit, a charging circuit and a first voltage generating circuit, wherein the control end of the drive control circuit is connected to the control end of a rectifier switch tube in a power stage circuit, the rectifier switch tube is connected to the high potential end of the output voltage of the power stage circuit, the power supply end of the drive control circuit is connected to one end of the first capacitor, the other end of the first capacitor is connected to the ground of the drive control circuit, the ground of the drive control circuit is the source of the rectifier switch tube, the first voltage generating circuit receives the output voltage of the power stage circuit, and its output end is connected to the power supply end of the drive control circuit via the charging circuit.

[0006] Optionally, when the rectifier switch tube is turned on, the first voltage charges the first capacitor, and the first capacitor supplies power to the drive control circuit.

[0007] Optionally, the difference between the first voltage and the output voltage of the power stage circuit approaches an expected value of the voltage at the power supply end of the drive control circuit.

[0008] Optionally, the difference between the first difference and an expected value of the voltage at the power supply end of the drive control circuit is a first threshold, and the first difference is the difference between the first voltage and the output voltage of the power stage circuit.

[0009] Optionally, the first voltage generating circuit includes a charge pump, which generates a first voltage from an output voltage of the power stage circuit.

[0010] Optionally, the first voltage generating circuit is a boost circuit, the input voltage of the boost circuit is the output voltage of the power stage circuit, and the output voltage of the boost circuit is a first voltage.

[0011] Optionally, the boost circuit includes a first switching tube, a first freewheeling tube and a first inductor, the first inductor and the first switching tube are connected in series at both ends of the output voltage of the power stage circuit, the second end of the first switching tube is connected to the low potential end of the output voltage of the power stage circuit, one end of the first freewheeling tube is connected to the common end of the first inductor and the first switching tube, the other end of the first freewheeling tube is the high potential end of the first voltage, and the low potential end of the first voltage is the low potential end of the output voltage of the power stage circuit.

[0012] The present invention also provides a power supply control method, based on a power supply control circuit, the power supply circuit includes a first capacitor, a drive control circuit, a charging circuit and a first voltage generating circuit, the control end of the drive control circuit is connected to the control end of the rectifier switch tube in the power stage circuit, the rectifier switch tube is connected to the high potential end of the output voltage of the power stage circuit, the power supply end of the drive control circuit is connected to one end of the first capacitor, the other end of the first capacitor is connected to the ground of the drive control circuit, the ground of the drive control circuit is the source of the rectifier switch tube, the first voltage generating circuit receives the output voltage of the power stage circuit, and its output end is connected to the power supply end of the drive control circuit via the charging circuit;

[0013] When the rectifier switch tube is turned on, the first voltage charges the first capacitor, and the first capacitor supplies power to the drive control circuit.

[0014] Optionally, the difference between the first voltage and the output voltage of the power stage circuit approaches an expected value of the voltage at the power supply end of the drive control circuit.

[0015] Optionally, the difference between the first difference and an expected value of the voltage at the power supply end of the drive control circuit is a first threshold, and the first difference is the difference between the first voltage and the output voltage of the power stage circuit.

[0016] The present invention further proposes a switching power supply, comprising the power supply control circuit and the power stage circuit as described in any one of the above items, wherein the power stage circuit is any one of buck, boost and flyback.

[0017] Compared with the prior art, the present invention has the following advantages: the present invention provides a power supply control circuit and method, which uses the output voltage of the power stage circuit to generate a first voltage, the first voltage is greater than the output voltage of the power stage circuit, and the first voltage is used to charge the first capacitor, thereby improving the power supply capacity. Furthermore, the difference between the first voltage and the output voltage of the power stage circuit is close to or slightly greater than the expected value of the power supply terminal voltage of the drive control circuit. When the main switch tube in the power stage circuit is turned off, the rectifier tube is turned on, and the first voltage is used to charge the first capacitor, and the first capacitor supplies power to the drive control circuit, thereby improving the charging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of an embodiment of a power supply control circuit in the prior art;

[0019] Figure 2 This is a schematic diagram of the structure of an embodiment of a power supply control circuit of the present invention;

[0020] Figure 3 This is a working waveform diagram of the power supply control circuit of the present invention;

[0021] Figure 4 It is a schematic structural diagram of an embodiment of a first voltage generating circuit of the present invention. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitution, modification, equivalent method and scheme made within the spirit and scope of the present invention.

[0023] In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without these detailed descriptions.

[0024] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the accompanying drawings are all simplified and not in exact proportion, and are only used for the purpose of conveniently and clearly assisting in explaining the embodiments of the present invention.

[0025] The power supply control circuit described in the present invention includes a first capacitor, a drive control circuit, a charging circuit and a first voltage generating circuit. The control end of the drive control circuit is connected to the control end of the rectifier switch tube in the power stage circuit, and the rectifier switch tube is connected to the high potential end of the output voltage of the power stage circuit. The power supply end of the drive control circuit is connected to one end of the first capacitor, and the other end of the first capacitor is connected to the ground of the drive control circuit. The ground of the drive control circuit is the source of the rectifier switch tube. The first voltage generating circuit receives the output voltage of the power stage circuit, and its output end is connected to the power supply end of the drive control circuit via the charging circuit.

[0026] The first voltage is greater than the output voltage of the power stage circuit, and the first voltage is used to charge the first capacitor, which supplies power to the drive control circuit, thereby improving the power supply capacity. Here, the first voltage can charge the first capacitor at any time.

[0027] Preferably, when the main power switch tube is turned off and the rectifier switch tube is turned on, the first voltage charges the first capacitor, and the first capacitor supplies power to the drive control circuit, which can improve charging efficiency.

[0028] The difference between the first voltage and the output voltage of the power stage circuit approaches the expected value of the voltage at the power supply end of the drive control circuit.

[0029] Or the difference between the first difference and the expected value of the voltage at the power supply end of the drive control circuit is a first threshold, and the first difference is the difference between the first voltage and the output voltage of the power stage circuit.

[0030] Figure 2A schematic diagram of the structure of an embodiment of the power supply control circuit of the present invention is given, wherein the power stage circuit is a flyback conversion circuit, the flyback switching power supply includes a main power switch tube M1, a transformer and a rectifier switch tube M2, the transformer includes a primary winding L1 and a secondary winding L2, the main power switch tube M1 and the primary winding L1 are connected in series at both ends of the input voltage Vin, the rectifier switch tube M2 is connected to the high potential end of the output voltage Vout of the flyback conversion circuit, and the rectifier switch tube M2 and the secondary winding L2 are connected in series at both ends of the output voltage Vout of the flyback conversion circuit. The power supply control circuit includes a first capacitor C1, a drive control circuit, a charging circuit and a first voltage generating circuit, the control end of the drive control circuit is connected to the control end of the rectifier switch tube M2, the rectifier switch tube M2 is connected to the high potential end of the output voltage Vout of the flyback conversion circuit, the power supply end of the drive control circuit is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to the ground of the drive control circuit, and the ground of the drive control circuit is the source of the rectifier switch tube, Figure 1 The source of the rectifier switch tube is the common end S of the secondary winding L2 and the rectifier switch tube M2, the first voltage generating circuit receives the output voltage Vout of the flyback conversion circuit, and its output end outputs the first voltage V1 to the charging circuit, the output end of the charging circuit is connected to the power supply end of the drive control circuit, the first voltage charges the first capacitor through the charging circuit, and the charging circuit has a voltage stabilization function.

[0031] Figure 3 The working waveform of the power supply control circuit of the present invention is given, where T is the control signal of the main switch tube in the flyback conversion circuit, Vds is the voltage across the drain and source of the switch tube, that is, the voltage of the output voltage relative to the ground of the drive control circuit, V1 is the first voltage, and Vcc is the expected value of the voltage at the power supply end of the drive control circuit. When the main switch tube M1 is turned on, Vds is equal to the output voltage Vout and the voltage V on the secondary winding. L2 The sum of Vds = Vout + V L2 , when the main switch tube M1 is turned off, Vds is close to 0, that is, Vds≈0.

[0032] In a preferred embodiment of the present invention, the difference V1-Vout between the first voltage V1 and the output voltage Vout approaches the expected value Vcc of the voltage at the power supply end of the drive control circuit, or the difference V1-Vout between the first voltage V1 and the output voltage Vout is greater than the expected value Vcc of the voltage at the power supply end of the drive control circuit by a first threshold value V11, and the first threshold value V11 is relatively small. When the main switch tube M1 is turned off, the Vds approaches V1, and when the main switch tube M1 is turned off, the Vds approaches V1. Figure 3It can be seen that when the main switch tube M1 is turned off, the first voltage V1 approaches the expected value Vcc of the voltage at the power supply end of the drive control circuit or the first voltage is greater than the expected value Vcc of the voltage at the power supply end of the drive control circuit by a first threshold, that is, V1≈Vcc or V1=Vcc+V11.

[0033] In the prior art, when the main switch tube M1 is turned on, Vout is directly used to charge the first capacitor, and the charging efficiency is Vcc / (Vout+V L2 ). In the present invention, when the main switch tube M1 is turned off, the first voltage is used to charge the first capacitor, and the charging efficiency is Vcc / V1, Vout+V L2 When the main switch tube M1 is not turned off long enough, the capacitor may not be charged to Vcc. The first capacitor may also be charged with the first voltage at other times.

[0034] It should be noted that the use of the first voltage V1 approaching Vcc to charge the first capacitor when the main switch tube M1 is turned off and the rectifier switch tube is turned on is only a preferred example of the present invention. The present invention can also charge the first capacitor in other time periods, such as when the main switch tube M1 is turned on.

[0035] Figure 4 An embodiment of a first voltage generating circuit is provided, wherein the first voltage generating circuit is a boost circuit, wherein the input voltage of the boost circuit is the output voltage Vout of the power stage circuit, and the output voltage of the boost circuit is a first voltage V1. The boost circuit comprises a first switch tube Q1, a first freewheeling tube Q2 and a first inductor L1, wherein the first inductor L1 and the first switch tube Q1 are connected in series at two ends of the output voltage Vout of the power stage circuit, the second end of the first switch tube Q1 is connected to the low potential end of the output voltage Vout of the power stage circuit, one end of the first freewheeling tube Q2 is connected to the common end of the first inductor L1 and the first switch tube Q1, the other end of the first freewheeling tube Q2 is the high potential end of the first voltage V1, and the low potential end of the first voltage V1 is the low potential end of the output voltage Vout of the power stage circuit.

[0036] Figure 4 Only one embodiment of the first voltage generating circuit is given. In other embodiments, the first voltage generating circuit includes a charge pump, and the charge pump generates the first voltage from the output voltage of the power stage circuit. This is not limited here.

[0037] Although the embodiments are described and illustrated separately above, some common technologies are involved. It is the opinion of ordinary technicians in this field that the embodiments can be replaced and integrated. If the content is not clearly recorded in one of the embodiments, reference can be made to another recorded embodiment.

[0038] The above-described implementation methods do not constitute a limitation on the protection scope of the technical solution. Any modification, equivalent replacement and improvement made within the spirit and principle of the above-described implementation methods shall be included in the protection scope of the technical solution.

Claims

1. A power supply control circuit, characterized in that: It includes a first capacitor, a drive control circuit, a charging circuit and a first voltage generating circuit, The control end of the drive control circuit is connected to the control end of the rectifier switch tube in the power stage circuit, the rectifier switch tube is connected to the high potential end of the output voltage of the power stage circuit, the power supply end of the drive control circuit is connected to one end of the first capacitor, and the other end of the first capacitor is connected to the ground of the drive control circuit, wherein the power stage circuit is a flyback conversion circuit or Boost, The ground of the driving control circuit is the source of the rectifier switch tube. The first voltage generating circuit receives the output voltage of the power stage circuit, and outputs a first voltage at an output end, and the output end is connected to the power supply end of the drive control circuit via the charging circuit. When the rectifier switch tube is turned on, the first voltage charges the first capacitor, and the first capacitor supplies power to the drive control circuit. The first voltage generating circuit includes a charge pump, which generates a first voltage from the output voltage of the power stage circuit or the first voltage generating circuit is a boost circuit, the input voltage of the boost circuit is the output voltage of the power stage circuit, and the output voltage of the boost circuit is the first voltage.

2. The power supply control circuit according to claim 1, characterized in that: The difference between the first voltage and the output voltage of the power stage circuit approaches the expected value of the voltage at the power supply end of the drive control circuit.

3. The power supply control circuit according to claim 1, characterized in that: The difference between the first difference and the expected value of the voltage at the power supply terminal of the drive control circuit is a first threshold, and the first difference is the difference between the first voltage and the output voltage of the power stage circuit.

4. The power supply control circuit according to claim 1, characterized in that: When the first voltage generating circuit is a boost circuit, the boost circuit includes a first switching tube, a first freewheeling tube and a first inductor, the first inductor and the first switching tube are connected in series at both ends of the output voltage of the power stage circuit, the second end of the first switching tube is connected to the low potential end of the output voltage of the power stage circuit, one end of the first freewheeling tube is connected to the common end of the first inductor and the first switching tube, the other end of the first freewheeling tube is the high potential end of the first voltage, and the low potential end of the first voltage is the low potential end of the output voltage of the power stage circuit.

5. A power supply control method, based on a power supply control circuit, the power supply control circuit includes a first capacitor, a drive control circuit, a charging circuit and a first voltage generating circuit, the control end of the drive control circuit is connected to the control end of the rectifier switch tube in the power stage circuit, the rectifier switch tube is connected to the high potential end of the output voltage of the power stage circuit, the power supply end of the drive control circuit is connected to one end of the first capacitor, the other end of the first capacitor is connected to the ground of the drive control circuit, the ground of the drive control circuit is the source of the rectifier switch tube, the first voltage generating circuit receives the output voltage of the power stage circuit, the output end outputs the first voltage, and the output end is connected to the power supply end of the drive control circuit via the charging circuit; characterized in that: When the rectifier switch tube is turned on, the first voltage charges the first capacitor, and the first capacitor supplies power to the drive control circuit; The first voltage generating circuit includes a charge pump, which generates a first voltage from the output voltage of the power stage circuit or the first voltage generating circuit is a boost circuit, the input voltage of the boost circuit is the output voltage of the power stage circuit, and the output voltage of the boost circuit is the first voltage.

6. The power supply control method according to claim 5, characterized in that: The difference between the first voltage and the output voltage of the power stage circuit approaches the expected value of the voltage at the power supply end of the drive control circuit.

7. The power supply control method according to claim 6, characterized in that: The difference between the first difference and the expected value of the voltage at the power supply terminal of the drive control circuit is a first threshold, and the first difference is the difference between the first voltage and the output voltage of the power stage circuit.

8. A switching power supply, comprising the power supply control circuit and the power stage circuit according to any one of claims 1 to 4.

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