Voltage conversion circuit and primary side current detection method

Abstract

The invention discloses a voltage conversion circuit and a primary side current detection method. The voltage conversion circuit comprises a main control module, an inductance module, a switch module, an energy storage module and a self-oscillation elimination circuit. The main control module is used for being electrically connected with the inductance module, the switch module, the energy storage module and the self-oscillation elimination circuit. The main control module comprises a first capacitor, a second capacitor and a third capacitor. And the self-excited oscillation elimination circuit is suitable for releasing a high-frequency oscillation signal when the high-frequency oscillation signal is generated at the switch node. Therefore, by releasing the high-frequency oscillation signal, the self-oscillation generated by the circuit is eliminated, so that the stability of the circuit is improved; meanwhile, according to the primary side current detection control method and the current detection circuit, a current mirror can be adopted, the power loss is lower in a standby state, due to the fact that the logic switch control is adopted, the average value of output signals does not need to be detected, and comparison is convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a voltage conversion circuit and a primary current detection method. Background Art

[0002] As we all know, with the rapid development of electronic technology, more and more electronic products are widely used in people's lives. Among them, the power supply is an important part of an electronic product, and the performance of the power supply directly affects the performance and reliability of the appliance. Usually, the power supply consists of a voltage conversion circuit, which converts the alternating current into the voltage required for the electronic product to work, so that the electronic product can operate normally.

[0003] The primary control circuit of the voltage converter usually includes a frequency oscillator to generate high-frequency pulses and turn on the primary switch based on the pulses generated by the oscillator. However, in the standby state, the power consumption is high. Therefore, we propose a voltage conversion circuit and a primary current detection method to solve the above-mentioned problems. Summary of the invention

[0004] The object of the present invention is to provide a voltage conversion circuit and a primary current detection method to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A voltage conversion circuit includes a main control module, an inductor module, a switch module, an energy storage module, and a self-oscillation elimination circuit; the main control module is used to be electrically connected to the inductor module, the switch module, the energy storage module, and the self-oscillation elimination circuit respectively, and the main control module includes a first capacitor, a second capacitor, and a third capacitor;

[0007] The main control module is used to generate a charging control signal, a discharging control signal, a voltage stabilization control signal, and an output control signal respectively;

[0008] An inductor module, a first end of the inductor module is connected to a first power input end of the voltage conversion circuit;

[0009] The switch module includes a first switch unit, a second switch unit, and a third switch unit. The first switch unit is electrically connected to the energy storage module and the ground terminal. The second switch unit is used to be electrically connected to the inductance module and the first switch unit respectively. The third switch unit is used to be electrically connected to the inductance module and the self-oscillation elimination circuit respectively.

[0010] An energy storage module, one end of which is used to be electrically connected to an external power source, and the external power source is used to provide a charging signal;

[0011] The self-oscillation elimination circuit is suitable for releasing a high-frequency oscillation signal when a high-frequency oscillation signal is generated at a switch node.

[0012] As a further solution of the present invention: the first switch unit is used to switch to a charging conduction state according to a charging control signal, so that the energy storage module performs a charging operation according to the charging signal; the first switch unit is used to switch to a discharging conduction state according to a discharging control signal, so that the energy storage module generates a boost signal after the charging operation; the second switch unit is used to switch to a voltage stabilization conduction state according to a voltage stabilization control signal, so that the inductor module generates a target output signal according to the boost signal; the third switch unit is used to be turned on according to the output control signal to send the target output signal to the self-oscillation elimination circuit.

[0013] As a further solution of the present invention: the self-oscillation elimination circuit includes a first NMOS tube and a second NMOS; the self-oscillation elimination circuit provides a grounding path with an equivalent impedance of a first impedance for the high-frequency oscillation signal at the switch node, and provides a grounding path with an equivalent impedance of a second impedance for the low-frequency signal at the switch node, and the first impedance is less than the second impedance.

[0014] As a further solution of the present invention: the first impedance is:

[0015]

[0016] Among them, g mM1 is the transconductance of the first NMOS tube, g mM2 is the transconductance of the second NMOS tube;

[0017] The second impedance is:

[0018] r2=r dsM1

[0019] Among them, r dsM1 is the equivalent impedance between the drain and source of the first NMOS tube.

[0020] As a further solution of the present invention: the first switching unit includes: a voltage-controlled flow element, the source of the first voltage-controlled flow element is used to be electrically connected to an external power supply, the drain of the first voltage-controlled flow element is used to be electrically connected to a first capacitor, and the gate of the first voltage-controlled flow element is used to be electrically connected to a main control module; a second voltage-controlled flow element, the source of the second voltage-controlled flow element is used to be electrically connected to the ground, the drain of the second voltage-controlled flow element is used to be electrically connected to a connection node between the first capacitor and the first voltage-controlled flow element, and the gate of the second voltage-controlled flow element is used to be electrically connected to the main control module.

[0021] As a further solution of the present invention: the second switching unit includes: a third voltage-controlled flow element, the source of the third voltage-controlled flow element is used to be electrically connected to the ground, the drain of the third voltage-controlled flow element is used to be electrically connected to the inductor, and the gate of the third voltage-controlled flow element is used to be electrically connected to the main control module; a fourth voltage-controlled flow element, the source of the fourth voltage-controlled flow element is used to be electrically connected to the connection node between the inductor and the third voltage-controlled flow element, the drain of the fourth voltage-controlled flow element is used to be electrically connected to the second capacitor, and the gate of the fourth voltage-controlled flow element is used to be electrically connected to the main control module.

[0022] As a further solution of the present invention: the third switch unit includes: a fifth voltage-controlled flow element, the source of the fifth voltage-controlled flow element is used to be electrically connected to an external power supply, and the gate of the fifth voltage-controlled flow element is used to be electrically connected to a main control module; a sixth voltage-controlled flow element, the source of the sixth voltage-controlled flow element is used to be electrically connected to the drain of the fifth voltage-controlled flow element, the drain of the sixth voltage-controlled flow element is used to be electrically connected to the third capacitor, and the gate of the sixth voltage-controlled flow element is used to be electrically connected to the main control module; a seventh voltage-controlled flow element, the source of the seventh voltage-controlled flow element is used to be electrically connected to the ground, the drain of the seventh voltage-controlled flow element is used to be electrically connected to a connection node between the third capacitor and the sixth voltage-controlled flow element, and the gate of the seventh voltage-controlled flow element is used to be electrically connected to the main control module.

[0023] As a further solution of the present invention: the voltage conversion circuit also includes a first resistor and a second resistor, the first resistor is connected between the second end of the switch module and the second power input end of the voltage conversion circuit, and the second resistor is connected between the energy storage module and the second power output end.

[0024] As a further solution of the present invention: the main control module also includes a control unit, the control unit includes an analog-to-digital converter, the analog-to-digital converter includes a first analog-to-digital converter and a second analog-to-digital converter, the first analog-to-digital converter is connected between the first resistor and the control unit, and the second analog-to-digital converter is connected between the second resistor and the control unit; the first analog-to-digital converter is used to collect the current of the first resistor as the inductor current; the second analog-to-digital converter is used to collect the voltage of the second resistor as the bus voltage.

[0025] A primary current detection method comprises the following steps:

[0026] Step 1: When the primary current detection circuit detects that the primary current of the optocoupler is less than a set first threshold, the primary current detection circuit sends a control signal to the primary switch to control the switch to be turned on;

[0027] Step 2: When it is detected that the peak value of the current flowing through the primary switch reaches a set second threshold, a control signal capable of controlling the primary switch to be turned off is sent to the primary switch.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The voltage conversion circuit and primary current detection method are suitable for releasing a high-frequency oscillation signal when a high-frequency oscillation signal is generated at a switch node by setting a self-excited oscillation elimination circuit. Thus, by releasing the high-frequency oscillation signal, the self-excited oscillation generated by the circuit is eliminated, thereby improving the stability of the circuit; at the same time, the primary current detection control method, the current detection circuit can use a current mirror, and the power loss is lower in the standby state. Since the switch control using the above logic is adopted, it is not necessary to detect the average value of the output signal, which is relatively convenient; by setting a main control module, an inductor module, a switch module, and an energy storage module, the sampled inductor current and the bus voltage can be adjusted as feedback to achieve a stable output voltage and reduce the fluctuation of the inductor current, thereby improving the power supply efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the voltage conversion circuit of the present invention.

[0031] Figure 2 It is a structural schematic diagram of the main control module in the voltage conversion circuit of the present invention.

[0032] Figure 3 Schematic diagram of a voltage conversion circuit of the present invention.

[0033] Figure 4 It is a schematic diagram of the flow of the primary current detection method of the present invention. DETAILED DESCRIPTION

[0034] In one embodiment, Figure 1-Figure 4 As shown, a voltage conversion circuit includes a main control module, an inductor module, a switch module, an energy storage module, and a self-oscillation elimination circuit; the main control module is used to be electrically connected to the inductor module, the switch module, the energy storage module, and the self-oscillation elimination circuit respectively, and the main control module includes a first capacitor, a second capacitor, and a third capacitor;

[0035] The voltage conversion circuit also includes a feedback module, which is used to generate a feedback signal according to the boost output;

[0036] The main control module is used to generate a charging control signal, a discharging control signal, a voltage stabilization control signal, and an output control signal respectively;

[0037] An inductor module, a first end of the inductor module is connected to a first power input end of the voltage conversion circuit;

[0038] The switch module includes a first switch unit, a second switch unit, and a third switch unit. The first switch unit is electrically connected to the energy storage module and the ground terminal. The second switch unit is used to be electrically connected to the inductance module and the first switch unit respectively. The third switch unit is used to be electrically connected to the inductance module and the self-oscillation elimination circuit respectively.

[0039] An energy storage module, one end of which is used to be electrically connected to an external power source, and the external power source is used to provide a charging signal;

[0040] The self-oscillation elimination circuit is suitable for releasing a high-frequency oscillation signal when the high-frequency oscillation signal is generated at the switch node;

[0041] The first switch unit is used to switch to a charging conduction state according to a charging control signal, so that the energy storage module performs a charging operation according to the charging signal; the first switch unit is used to switch to a discharging conduction state according to a discharging control signal, so that the energy storage module after the charging operation generates a boost signal; the second switch unit is used to switch to a voltage stabilization conduction state according to a voltage stabilization control signal, so that the inductor module generates a target output signal according to the boost signal; the third switch unit is used to switch on according to the output control signal, so as to send the target output signal to the self-oscillation elimination circuit;

[0042] The self-oscillation elimination circuit includes a first NMOS tube and a second NMOS tube; the self-oscillation elimination circuit provides a grounding path with an equivalent impedance of a first impedance for a high-frequency oscillation signal at a switch node, and provides a grounding path with an equivalent impedance of a second impedance for a low-frequency signal at the switch node, and the first impedance is less than the second impedance;

[0043] The first impedance is:

[0044]

[0045] Among them, g mM1 is the transconductance of the first NMOS tube, g mM2 is the transconductance of the second NMOS tube;

[0046] The second impedance is:

[0047] r2=r dsM1

[0048] Among them, r dsM1 is the equivalent impedance between the drain and source of the first NMOS tube;

[0049] That is to say, the first NMOS tube is also suitable for providing a low-frequency micro-current release path for the node. dsM1 The resistance value is generally large, so part of the low-frequency signal is released to the ground and will not have a significant impact on the output signal;

[0050] The voltage conversion circuit includes a switch circuit, which is suitable for outputting a node signal at a switch node based on an input signal, and the node signal has the same phase as the input signal; a voltage conversion circuit, which is suitable for entering a charging mode or a discharging mode according to the received node signal to output an output signal, and filtering the node signal output at the switch node; and a self-excited oscillation elimination circuit, which is suitable for releasing a high-frequency oscillation signal when a high-frequency oscillation signal is generated at the switch node. Thus, by releasing the high-frequency oscillation signal, the self-excited oscillation generated by the circuit is eliminated, thereby improving the stability of the circuit.

[0051] The first switch unit includes: a voltage-controlled flow element, the source of the first voltage-controlled flow element is used to be electrically connected to an external power supply, the drain of the first voltage-controlled flow element is used to be electrically connected to a first capacitor, and the gate of the first voltage-controlled flow element is used to be electrically connected to a main control module; a second voltage-controlled flow element, the source of the second voltage-controlled flow element is used to be electrically connected to a ground terminal, the drain of the second voltage-controlled flow element is used to be electrically connected to a connection node between the first capacitor and the first voltage-controlled flow element, and the gate of the second voltage-controlled flow element is used to be electrically connected to the main control module;

[0052] The second switch unit includes: a third voltage-controlled flow element, the source of the third voltage-controlled flow element is used to be electrically connected to the ground terminal, the drain of the third voltage-controlled flow element is used to be electrically connected to the inductor, and the gate of the third voltage-controlled flow element is used to be electrically connected to the main control module; a fourth voltage-controlled flow element, the source of the fourth voltage-controlled flow element is used to be electrically connected to the connection node between the inductor and the third voltage-controlled flow element, the drain of the fourth voltage-controlled flow element is used to be electrically connected to the second capacitor, and the gate of the fourth voltage-controlled flow element is used to be electrically connected to the main control module;

[0053] The third switch unit includes: a fifth voltage-controlled flow element, the source of the fifth voltage-controlled flow element is used to be electrically connected to an external power supply, and the gate of the fifth voltage-controlled flow element is used to be electrically connected to a main control module; a sixth voltage-controlled flow element, the source of the sixth voltage-controlled flow element is used to be electrically connected to the drain of the fifth voltage-controlled flow element, the drain of the sixth voltage-controlled flow element is used to be electrically connected to a third capacitor, and the gate of the sixth voltage-controlled flow element is used to be electrically connected to the main control module; a seventh voltage-controlled flow element, the source of the seventh voltage-controlled flow element is used to be electrically connected to the ground terminal, the drain of the seventh voltage-controlled flow element is used to be electrically connected to a connection node between the third capacitor and the sixth voltage-controlled flow element, and the gate of the seventh voltage-controlled flow element is used to be electrically connected to the main control module;

[0054] The voltage conversion circuit also includes a first resistor and a second resistor, the first resistor is connected between the second end of the switch module and the second power input end of the voltage conversion circuit, and the second resistor is connected between the energy storage module and the second power output end;

[0055] The main control module also includes a control unit, the control unit includes an analog-to-digital converter, the analog-to-digital converter includes a first analog-to-digital converter and a second analog-to-digital converter, the first analog-to-digital converter is connected between the first resistor and the control unit, and the second analog-to-digital converter is connected between the second resistor and the control unit; the first analog-to-digital converter is used to collect the current of the first resistor as the inductor current; the second analog-to-digital converter is used to collect the voltage of the second resistor as the bus voltage.

[0056] A primary current detection method comprises the following steps:

[0057] Step 1: When the primary current detection circuit detects that the primary current of the optocoupler is less than a set first threshold, the primary current detection circuit sends a control signal to the primary switch to control the switch to be turned on;

[0058] Step 2: When it is detected that the peak value of the current flowing through the primary switch reaches a set second threshold, a control signal capable of controlling the primary switch to be turned off is sent to the primary switch.

[0059] The primary current detection circuit includes a primary switch control circuit, which is used to couple the primary switch; the primary switch control circuit includes a conduction control circuit, a shutdown control circuit and a trigger circuit; the conduction control circuit is used to output a control signal according to the size of the primary current of the optocoupler, and when the primary current of the optocoupler is less than a set first threshold, the conduction control circuit outputs a valid level; the shutdown control circuit is used to output a control signal according to the size of the primary current flowing through the primary switch, and when the primary current flowing through the primary switch reaches a set second threshold, the shutdown control circuit outputs a valid level; the trigger circuit has a first input end coupled to the output end of the conduction control circuit, a second input end of the trigger circuit coupled to the output end of the shutdown control circuit, and the output end of the trigger circuit coupled to the primary switch; when the conduction control circuit outputs a valid level, the trigger circuit outputs a valid level, and the primary switch is turned on; when the shutdown control circuit outputs a valid level, the trigger circuit outputs an invalid level, and the primary switch is turned off.

[0060] In the primary current detection control method, the current detection circuit can use a current mirror, and the power loss in the standby state is lower. Since the switch control using the above logic does not need to detect the average value of the output signal, it is relatively convenient.

[0061] The present invention, by setting a self-excited oscillation elimination circuit, is suitable for releasing a high-frequency oscillation signal when a high-frequency oscillation signal is generated at a switch node. Thus, by releasing the high-frequency oscillation signal, the self-excited oscillation generated by the circuit is eliminated, thereby improving the stability of the circuit; at the same time, the primary current detection control method, the current detection circuit can use a current mirror, the power loss is lower in the standby state, and because the switch control using the above logic is adopted, there is no need to detect the average value of the output signal, which is relatively convenient; by setting a main control module, an inductor module, a switch module, and an energy storage module, the sampled inductor current and the bus voltage can be adjusted as feedback to achieve a stable output voltage and reduce the fluctuation of the inductor current, thereby improving the power supply efficiency.

[0062] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A voltage conversion circuit, characterized in that: It includes a main control module, an inductance module, a switch module, an energy storage module, and a self-oscillation elimination circuit; the main control module is used to be electrically connected to the inductance module, the switch module, the energy storage module, and the self-oscillation elimination circuit respectively, and the main control module includes a first capacitor, a second capacitor, and a third capacitor; The main control module is used to generate a charging control signal, a discharging control signal, a voltage stabilization control signal, and an output control signal respectively; An inductor module, a first end of the inductor module is connected to a first power input end of the voltage conversion circuit; The switch module includes a first switch unit, a second switch unit, and a third switch unit. The first switch unit is electrically connected to the energy storage module and the ground terminal. The second switch unit is used to be electrically connected to the inductance module and the first switch unit respectively. The third switch unit is used to be electrically connected to the inductance module and the self-oscillation elimination circuit respectively. An energy storage module, one end of which is used to be electrically connected to an external power source, and the external power source is used to provide a charging signal; The self-oscillation elimination circuit is suitable for releasing a high-frequency oscillation signal when a high-frequency oscillation signal is generated at a switch node.

2. A voltage conversion circuit according to claim 1, characterized in that: The first switch unit is used to switch to a charging conduction state according to a charging control signal, so that the energy storage module performs a charging operation according to the charging signal; the first switch unit is used to switch to a discharging conduction state according to a discharging control signal, so that the energy storage module generates a boost signal after the charging operation; the second switch unit is used to switch to a voltage stabilization conduction state according to a voltage stabilization control signal, so that the inductor module generates a target output signal according to the boost signal; the third switch unit is used to be turned on according to the output control signal, so as to send the target output signal to the self-oscillation elimination circuit.

3. A voltage conversion circuit according to claim 1, characterized in that: The self-oscillation elimination circuit includes a first NMOS tube and a second NMOS; the self-oscillation elimination circuit provides a grounding path with an equivalent impedance of a first impedance for a high-frequency oscillation signal at a switch node, and provides a grounding path with an equivalent impedance of a second impedance for a low-frequency signal at the switch node, and the first impedance is less than the second impedance.

4. A voltage conversion circuit according to claim 3, characterized in that: The first impedance is: Among them, g mM1 is the transconductance of the first NMOS tube, g mM2 is the transconductance of the second NMOS tube; The second impedance is: r2＝r dsM1 Among them, r dsM1 is the equivalent impedance between the drain and source of the first NMOS tube.

5. A voltage conversion circuit according to claim 1, characterized in that: The first switch unit includes: a voltage-controlled flow element, the source of the first voltage-controlled flow element is used to be electrically connected to an external power supply, the drain of the first voltage-controlled flow element is used to be electrically connected to a first capacitor, and the gate of the first voltage-controlled flow element is used to be electrically connected to a main control module; a second voltage-controlled flow element, the source of the second voltage-controlled flow element is used to be electrically connected to the ground, the drain of the second voltage-controlled flow element is used to be electrically connected to a connection node between the first capacitor and the first voltage-controlled flow element, and the gate of the second voltage-controlled flow element is used to be electrically connected to the main control module.

6. A voltage conversion circuit according to claim 5, characterized in that: The second switch unit includes: a third voltage-controlled flow element, the source of the third voltage-controlled flow element is used to be electrically connected to the ground, the drain of the third voltage-controlled flow element is used to be electrically connected to the inductor, and the gate of the third voltage-controlled flow element is used to be electrically connected to the main control module; a fourth voltage-controlled flow element, the source of the fourth voltage-controlled flow element is used to be electrically connected to the connection node between the inductor and the third voltage-controlled flow element, the drain of the fourth voltage-controlled flow element is used to be electrically connected to the second capacitor, and the gate of the fourth voltage-controlled flow element is used to be electrically connected to the main control module.

7. A voltage conversion circuit according to claim 6, characterized in that: The third switch unit includes: a fifth voltage-controlled flow element, the source of the fifth voltage-controlled flow element is used to be electrically connected to an external power supply, and the gate of the fifth voltage-controlled flow element is used to be electrically connected to a main control module; a sixth voltage-controlled flow element, the source of the sixth voltage-controlled flow element is used to be electrically connected to the drain of the fifth voltage-controlled flow element, the drain of the sixth voltage-controlled flow element is used to be electrically connected to the third capacitor, and the gate of the sixth voltage-controlled flow element is used to be electrically connected to the main control module; a seventh voltage-controlled flow element, the source of the seventh voltage-controlled flow element is used to be electrically connected to the ground, the drain of the seventh voltage-controlled flow element is used to be electrically connected to a connection node between the third capacitor and the sixth voltage-controlled flow element, and the gate of the seventh voltage-controlled flow element is used to be electrically connected to the main control module.

8. A voltage conversion circuit according to claim 1, characterized in that: The voltage conversion circuit also includes a first resistor and a second resistor. The first resistor is connected between the second end of the switch module and the second power input end of the voltage conversion circuit, and the second resistor is connected between the energy storage module and the second power output end.

9. A voltage conversion circuit according to claim 8, characterized in that: The main control module also includes a control unit, the control unit includes an analog-to-digital converter, the analog-to-digital converter includes a first analog-to-digital converter and a second analog-to-digital converter, the first analog-to-digital converter is connected between the first resistor and the control unit, and the second analog-to-digital converter is connected between the second resistor and the control unit; the first analog-to-digital converter is used to collect the current of the first resistor as the inductor current; the second analog-to-digital converter is used to collect the voltage of the second resistor as the bus voltage.

10. A primary current detection method, characterized in that: The following steps are involved: Step 1: When the primary current detection circuit detects that the primary current of the optocoupler is less than a set first threshold, the primary current detection circuit sends a control signal to the primary switch to control the switch to be turned on; Step 2: When it is detected that the peak value of the current flowing through the primary switch reaches a set second threshold, a control signal capable of controlling the primary switch to be turned off is sent to the primary switch.

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