Circuit for reducing output ripple of power supply

Abstract

The invention relates to a circuit for reducing output ripples of a power supply, which comprises a first capacitor module, a resistor element RS1 and a ripple reduction module, and is characterized in that the ripple reduction module comprises an inductance element, an MOS tube element and a diode element, the inductance element and the capacitor element form an LC filter; the output ripple of the power supply can be properly reduced after the output end of the power supply is filtered by the LC filter, the MOS tube element and the diode element are connected in parallel, the inductance element and the MOS tube element are connected in series, and the MOS tube element can transfer the output ripple of the power supply to the body of the MOS tube element. The control circuit is simple in structure, not only can be used under the condition that the requirement for output ripples of the power supply is low, but also can effectively reduce the output ripples of the power supply when the output ripples of the power supply are small, can be applied to a high-voltage environment, and is wide in application range, so that the problem of reducing the output ripples is well solved.

Description

Technical Field

[0001] The present invention relates to the field of power supply design, and specifically, to a circuit for reducing the output ripple of a power supply. Background Art

[0002] With the continuous improvement of the requirements for the performance of power supply systems in electronic devices, advanced technologies are adopted in power supply systems to provide faster and more stable responses to ensure the reliability and performance of devices under various input conditions. Among them, for precision instruments, a stable current provided by the power supply system is particularly important.

[0003] When a DC power supply outputs, an AC component is still superimposed on it. When viewed with an oscilloscope, the voltage can be seen to fluctuate slightly up and down, like water ripples, which is called ripple. Currently, in the applications of some devices, in order to meet some special requirements during device use, there are relatively strict requirements for the output ripple of the power supply when the power supply is working. For example, for a power supply with an output less than or equal to 48V, the output ripple of the power supply is required to be less than 20mv, and for a power supply greater than 48V, the output ripple of the power supply is required to be less than 30mv, etc.

[0004] In the prior art, generally, by increasing the energy storage capacitor of the 48V power supply PFC of the power supply and changing the loop of the PFC, the low-frequency ripple of 100HZ on the PFC energy storage capacitor is reduced, or by changing the output voltage loop, the high and low frequency ripple of the power supply is reduced. However, the output ripple of these circuits can generally only be made less than 200mv. For a power supply greater than 48V, such as a 200V power supply, the output ripple can generally only be made less than 800mv. Therefore, there is an urgent need for a circuit to reduce the output ripple of the power supply. Summary of the Invention

[0005] In order to overcome the deficiencies of the existing technology, the present invention provides a circuit for reducing the output ripple of a power supply.

[0006] The technical solution of the present invention is as follows:

[0007] A circuit for reducing the output ripple of a power supply, characterized by comprising:

[0008] A ripple reduction circuit, including a first capacitor module, a resistor element RS1, and a ripple reduction module. The ripple reduction module includes an inductor element L2, a MOS transistor element Q1, and a diode element D1. The MOS transistor element Q1 and the diode element D1 are connected in parallel, the inductor element L2 and the MOS transistor element Q1 are connected in series. The ripple reduction module is connected to the input end of the power supply circuit to obtain an input voltage, and the negative input end of the ripple reduction module is connected to the positive input end of the first capacitor module.

[0009] According to the present invention of the above solution, the first capacitor module includes a capacitor element C1, a capacitor element C2, an inductor element L1-A, and an inductor element L2-B. The negative input terminal of the inductor element L1-A is connected to the positive input terminal of the capacitor element C1. The positive input terminal of the capacitor element C1 is connected to the positive input terminal of the inductor element L1-B. The negative input terminal of the inductor element L1-B is connected to the negative input terminal of the capacitor element C2. The positive input terminal of the capacitor element C2 is connected to the positive input terminal of the inductor element L1-A.

[0010] Furthermore, the negative input terminal of the inductor element L1-B in the first capacitor module is connected to the positive input terminal of the resistor element RS1. The negative input terminal of the resistor element RS1 is connected to the output terminal of the power supply circuit. The positive input terminal of the capacitor element C3 is connected to the positive input terminal of the inductor element L2 in the ripple reduction module. The positive input terminal of the capacitor element C4 is connected to the input terminal of the power supply circuit. The negative input terminal of the capacitor element C4 is connected to the output terminal of the power supply circuit.

[0011] Furthermore, the ripple reduction module further includes a ripple control circuit. The ripple control circuit includes a voltage reduction module, a differential pressure amplification module, and a voltage output module. The voltage reduction module is connected to the input terminal of the power supply circuit and obtains the input voltage. The positive input terminal of the differential pressure amplification module is connected to the voltage reduction module. The negative input terminal of the differential pressure amplification module is connected to the voltage output module.

[0012] Furthermore, the ripple reduction module further includes a current sharing control circuit, including an amplification circuit module, an amplifier module, and a MOS transistor element Q1 module. The amplification circuit module is connected to the input terminal of the power supply circuit and obtains the input voltage. The positive input terminal of the amplifier module is connected to the amplification circuit module. The positive input terminal of the MOS module is connected to the amplifier module.

[0013] Furthermore, the voltage reduction module is provided with a first resistor and a second resistor connected in parallel. The parallel-connected first resistor and second resistor are connected to the positive interface of the first amplifier. The negative interface of the first amplifier is grounded through a third resistor. The negative interface of the first amplifier is also connected to the signal amplification terminal of the first amplifier through a fourth resistor.

[0014] Furthermore, the differential pressure amplification module is provided with a fifth resistor connected to the positive interface of the second amplifier. The positive interface of the second amplifier is also connected to the first output voltage through a sixth resistor. The negative interface of the second amplifier is connected to the VREF reference voltage through a seventh resistor. The negative connection of the second amplifier is also connected to the signal amplification terminal of the second amplifier through an eighth resistor.

[0015] Further, a ninth resistor is provided in the voltage output module and is connected to the signal amplification terminal of the second amplifier. The ninth resistor is also connected to the negative interface of the third signal amplifier. The positive interface of the third signal amplifier is connected to the second output voltage through a tenth resistor. The negative interface of the third signal amplifier is also connected to the signal amplification terminal of the third amplifier through a series-connected capacitive element and an eleventh resistor, and a capacitive element is connected in parallel.

[0016] Further, a twelfth resistor is provided in the amplifier module and is connected to the signal amplification terminal of the third amplifier. The twelfth resistor is connected to the positive input terminal of the fourth amplifier. The negative input terminal of the fourth amplifier is also connected to the signal amplification terminal of the fourth amplifier through a fourteenth resistor. The negative input terminal of the fourth amplifier is also connected to the signal amplification terminal of a fifth amplifier provided in the amplification circuit module through a thirteenth resistor.

[0017] In the present invention according to the above solution, the third interface of the MOS transistor element Q1 in the MOS transistor element Q1 module is connected to the first output voltage through a fifteenth resistor. The first interface of the MOS transistor element Q1 is also connected to the first output voltage through a sixteenth resistor. The second interface of the MOS transistor element Q1 is connected to the second output voltage.

[0018] The beneficial effects of the present invention according to the above solution are as follows:

[0019] The control circuit structure of the present invention is simple. By only adding a small number of filter capacitors and components, the power supply output ripple can be greatly reduced. Moreover, the present invention can not only be used when the requirement for the output ripple of the power supply is relatively small, but also effectively reduce the output ripple of the power supply when the output ripple of the power supply is small, and can also be applied in a high-voltage environment, with a wide range of applications. Description of the Drawings

[0020] Figure 1 It is the circuit schematic diagram of the ripple reduction circuit in the present invention;

[0021] Figure 2 It is the circuit schematic diagram of the ripple control circuit in the present invention;

[0022] Figure 3 It is the circuit schematic diagram of the current sharing control circuit in the present invention. Detailed Embodiments

[0023] To better understand the objectives, technical solutions, and technical effects of the present invention, the following further explains and illustrates the present invention in conjunction with the accompanying drawings and embodiments. It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings. At the same time, it is declared that the embodiments described below are only used to explain the present invention and are not used to limit the present invention.

[0024] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0025] The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this application is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art, or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0026] The terms "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "ninth", "tenth", "eleventh", "twelfth", "thirteenth", "fourteenth", "fifteenth", "sixteenth", "seventeenth", "eighteenth", "nineteenth", "twentieth", and "twenty-first" are only used for the purpose of convenient description and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of technical features.

[0027] As Figure 1 and Figure 2 shown, a circuit for reducing the power supply output ripple includes:

[0028] A ripple reduction circuit includes a first capacitor module, a resistor element RS1, and a ripple reduction module. The ripple reduction module includes an inductor element L2, a MOS transistor element Q1, and a diode element D1. The MOS transistor element Q1 and the diode element D1 are connected in parallel. The inductor element L2 and the MOS transistor element Q1 are connected in series. The ripple reduction module is connected to the input end of the power supply circuit and obtains the input voltage. The negative input end of the ripple reduction module is connected to the positive input end of the first capacitor module for reducing the output ripple of the power supply.

[0029] In a specific embodiment, the first capacitor module includes a capacitor element C1, a capacitor element C2, an inductor element L1-A, and an inductor element L2-B. The negative input terminal of the inductor element L1-A is connected to the positive input terminal of the capacitor element C1. The positive input terminal of the capacitor element C1 is connected to the positive input terminal of the inductor element L1-B. The negative input terminal of the inductor element L1-B is connected to the negative input terminal of the capacitor element C2. The positive input terminal of the capacitor element C2 is connected to the positive input terminal of the inductor element L1-A.

[0030] In a specific embodiment, the negative input terminal of the inductor element L1-B in the first capacitor module is connected to the positive input terminal of the resistor element RS1. The negative input terminal of the resistor element RS1 is connected to the output terminal of the power supply circuit. The positive input terminal of the capacitor element C3 is connected to the positive input terminal of the inductor element L2 in the ripple reduction module. The positive input terminal of the capacitor element C4 is connected to the input terminal of the power supply circuit. The negative input terminal of the capacitor element C4 is connected to the output terminal of the power supply circuit.

[0031] In the present invention, the ripple reduction module further includes a ripple control circuit. The ripple control circuit includes a voltage reduction module, a voltage difference amplification module, and a voltage output module. The voltage reduction module is connected to the input terminal of the power supply circuit and obtains the input voltage. The positive input terminal of the voltage difference amplification module is connected to the voltage reduction module. The negative input terminal of the voltage difference amplification module is connected to the voltage output module. The ripple control circuit can generate a VC voltage as the driving voltage of the MOS transistor element Q1 to control the conduction state of Q1.

[0032] The voltage reduction module is provided with a first resistor and a second resistor connected in parallel. The parallel-connected first resistor and second resistor are connected to the positive interface of the first amplifier U3-B. The negative interface of the first amplifier U3-B is grounded through a third resistor. The negative interface of the first amplifier U3-B is also connected to the signal amplification terminal of the first amplifier U3-B through a fourth resistor. Through the voltage reduction module, a voltage that is proportionally reduced compared to the output voltage can be obtained at the signal amplification terminal of the first amplifier U3-B.

[0033] In the differential pressure amplification module, a fifth resistor is provided and connected to the positive interface of the second amplifier U3-A. The positive interface of the second amplifier U3-A is also connected to the first output voltage through a sixth resistor. The negative interface of the second amplifier U3-A is connected to the VREF reference voltage through a seventh resistor. The negative interface of the second amplifier U3-A is also connected to the signal amplification terminal of the second amplifier U3-A through an eighth resistor. Through the differential pressure amplification module, the voltage at the signal amplification terminal of the second amplifier U3-A can be subtracted by a set VREF reference voltage, and then the voltage difference can be amplified by a certain multiple.

[0034] Further, when selecting the VREF reference voltage, it is necessary to select an appropriate voltage to ensure that the output ripple voltage is all dropped on Q1.

[0035] In the voltage output module, a ninth resistor is provided and connected to the signal amplification terminal of the second amplifier U3-A. The ninth resistor is also connected to the negative interface of the third signal amplifier U1-B. The positive interface of the third signal amplifier U1-B is connected to the second output voltage through a tenth resistor. The negative interface of the third signal amplifier U1-B is also connected to the signal amplification terminal of the third amplifier U1-B through a series-connected capacitive element and an eleventh resistor, and a capacitive element is connected in parallel.

[0036] Further, the ripple reduction module further includes a current sharing control circuit, including an amplification circuit module, an amplifier module, and a MOS transistor element Q1 module. The amplification circuit module is connected to the input end of the power supply circuit and obtains the input voltage. The positive input end of the amplifier module is connected to the amplification circuit module, and the positive input end of the MOS module is connected to the amplifier module. The current sharing control circuit is a parallel control circuit and can be used to equalize the current of the MOS transistor element Q1.

[0037] In the amplifier module, a twelfth resistor is provided and connected to the signal amplification terminal of the third amplifier U1-B. The twelfth resistor is connected to the positive input end of the fourth amplifier U4-B. The negative input end of the fourth amplifier U4-B is also connected to the signal amplification terminal of the fourth amplifier U4-B through a fourteenth resistor. The negative input end of the fourth amplifier U4-B is also connected to the signal amplification terminal of the fifth amplifier U4-A provided in the amplification circuit module through a thirteenth resistor. After processing the current signal and the voltage control signal, the amplifier module controls the conduction degree of the MOS transistor element Q1.

[0038] In the present invention, the third interface of the MOS transistor element Q1 in the MOS transistor element Q1 module is connected to the first output voltage through the fifteenth resistor, the first interface of the MOS transistor element Q1 is also connected to the first output voltage through the sixteenth resistor, and the second interface of the MOS transistor element Q1 is connected to the second output voltage.

[0039] The MOS transistor element Q1 is also connected to the signal amplification terminal of the fourth amplifier U4-B through the twenty-first resistor. The third interface of the MOS transistor element Q1 is also connected to the positive input terminal of the fifth amplifier U4-A in the amplifier module through the seventeenth resistor.

[0040] The positive input terminal of the fifth amplifier U4-A provided in the amplifier circuit module is also connected to the first output voltage through the eighteenth resistor, the negative input terminal of the fifth amplifier U4-A is also connected to the first output voltage through the nineteenth resistor, and the negative input terminal of the fifth amplifier U4-A is also connected to the signal amplification terminal of the fifth amplifier U4-A and the thirteenth resistor through the twentieth resistor.

[0041] The circuit principle of the ripple reduction circuit is as follows:

[0042] A ripple reduction module is added to the output circuit of a general power supply. The ripple reduction module includes an inductor element L2, a MOS transistor element Q1, and a diode element D1. Among them, the inductor element L2 and the capacitor element C3 form an LC filter. After the output terminal of the power supply is filtered by the LC filter, the output ripple of the power supply can be appropriately reduced; after the output voltage filtered by the LC filter passes through the MOS transistor element Q1, it is then output to the output terminal of the power supply. The MOS transistor element Q1 can transfer the output ripple of the power supply to its own body, thereby achieving the purpose of reducing the output ripple.

[0043] Through the above ripple reduction circuit, only a small number of filter capacitors and components need to be added to significantly reduce the output ripple of the power supply. The ripple reduction circuit can be used when the requirement for the output ripple of the power supply is relatively small, and it can effectively reduce the output ripple of the power supply.

[0044] The present invention also provides a circuit control method for reducing the output ripple of a power supply based on the above solution.

[0045] The voltage input to the ripple reduction circuit reduces the output ripple of the power supply through an LC filter composed of an inductor element L2 and a capacitor element C3, and reduces the voltage drop to the MOS transistor element Q1 itself through the MOS transistor element Q1, achieving the purpose of reducing the output ripple.

[0046] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0047] The above embodiments only express several implementation manners of the present invention, and the description is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A circuit for reducing power supply output ripple, characterized in that Comprising: A ripple reduction circuit, including a first capacitor module, a resistor element RS1, and a ripple reduction module. The ripple reduction module includes an inductor element L2, a MOS transistor element Q1, and a diode element D1. The MOS transistor element Q1 and the diode element D1 are connected in parallel. The inductor element L2 and the MOS transistor element Q1 are connected in series. The ripple reduction module is connected to the input end of the power supply circuit to obtain an input voltage. The negative input end of the ripple reduction module is connected to the positive input end of the first capacitor module.

2. The circuit for reducing the power supply output ripple according to claim 1, characterized in that, The first capacitor module includes a capacitor element C1, a capacitor element C2, an inductor element L1-A, and an inductor element L2-B. The negative input end of the inductor element L1-A is connected to the positive input end of the capacitor element C1. The positive input end of the capacitor element C1 is connected to the positive input end of the inductor element L1-B. The negative input end of the inductor element L1-B is connected to the negative input end of the capacitor element C2. The positive input end of the capacitor element C2 is connected to the positive input end of the inductor element L1-A.

3. The circuit for reducing the power supply output ripple according to claim 1, characterized in that, The negative input end of the inductor element L1-B in the first capacitor module is connected to the positive input end of the resistor element RS1. The negative input end of the resistor element RS1 is connected to the output end of the power supply circuit. The positive input end of the capacitor element C3 is connected to the positive input end of the inductor element L2 in the ripple reduction module. The positive input end of the capacitor element C4 is connected to the input end of the power supply circuit. The negative input end of the capacitor element C4 is connected to the output end of the power supply circuit.

4. The circuit for reducing the power supply output ripple according to claim 1, characterized in that, The ripple reduction module further includes a ripple control circuit. The ripple control circuit includes a voltage reduction module, a differential pressure amplification module, and a voltage output module. The voltage reduction module is connected to the input end of the power supply circuit to obtain an input voltage. The positive input end of the differential pressure amplification module is connected to the voltage reduction module. The negative input end of the differential pressure amplification module is connected to the voltage output module.

5. The circuit for reducing the power supply output ripple according to claim 1, wherein The ripple reduction module further includes a current sharing control circuit, including an amplification circuit module, an amplifier module, and a MOS transistor element Q1 module. The amplification circuit module is connected to the input end of the power supply circuit to obtain an input voltage. The positive input end of the amplifier module is connected to the amplification circuit module. The positive input end of the MOS module is connected to the amplifier module.

6. The circuit for reducing the power supply output ripple according to claim 4, characterized in that, The voltage reduction module is provided with a first resistor and a second resistor connected in parallel. The parallel-connected first resistor and second resistor are connected to the positive interface of a first amplifier. The negative interface of the first amplifier is grounded through a third resistor. The negative interface of the first amplifier is also connected to the signal amplification end of the first amplifier through a fourth resistor.

7. The circuit for reducing the power supply output ripple according to claim 4, wherein The differential pressure amplification module is provided with a fifth resistor connected to the positive interface of a second amplifier. The positive interface of the second amplifier is also connected to a first output voltage through a sixth resistor. The negative interface of the second amplifier is connected to a VREF reference voltage through a seventh resistor. The negative connection of the second amplifier is also connected to the signal amplification end of the second amplifier through an eighth resistor.

8. The circuit for reducing the power supply output ripple according to claim 4, characterized in that, In the voltage output module, a ninth resistor is provided and connected to the signal amplification terminal of the second amplifier. The ninth resistor is also connected to the negative interface of the third signal amplifier. The positive interface of the third signal amplifier is connected to the second output voltage through a tenth resistor. The negative interface of the third signal amplifier is also connected to the signal amplification terminal of the third amplifier through a series-connected capacitive element and an eleventh resistor, and a capacitive element is connected in parallel.

9. The circuit for reducing the power supply output ripple according to claim 5, characterized in that, In the amplifier module, a twelfth resistor is provided and connected to the signal amplification terminal of the third amplifier. The twelfth resistor is connected to the positive input terminal of the fourth amplifier. The negative input terminal of the fourth amplifier is also connected to the signal amplification terminal of the fourth amplifier through a fourteenth resistor. The negative input terminal of the fourth amplifier is also connected to the signal amplification terminal of a fifth amplifier provided in the amplification circuit module through a thirteenth resistor.

10. The circuit for reducing the power supply output ripple according to claim 5, wherein In the MOS transistor element Q1 module, the third interface of the MOS transistor element Q1 is connected to the first output voltage through a fifteenth resistor. The first interface of the MOS transistor element Q1 is also connected to the first output voltage through a sixteenth resistor. The second interface of the MOS transistor element Q1 is connected to the second output voltage.

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