Filter circuit and method of implementing the same, filter device

Abstract

The application discloses a filter circuit and an implementation method and a filter device thereof, and relates to the technical field of filtering. The filter circuit comprises a signal filtering unit, an active filter unit, a clamping unit, a voltage input end and a voltage output end; wherein the output voltage flows into the signal filtering unit through the voltage input end, and the signal filtering unit is used for filtering the high-frequency small signal interference of the input voltage; the active filter unit is used for filtering the ripple and transient surge of the input voltage, and forming a direct current output voltage; the clamping unit is used for clamping the direct current output voltage at a fixed value and outputting through the voltage output end; wherein the signal filtering unit, the active filter unit and the clamping unit are electrically connected in sequence and arranged between the voltage input end and the voltage output end. According to the filter circuit of the embodiment of the application, the signal filtering unit can filter the high-frequency small signal interference; the active filter unit can filter the ripple and transient surge; and the clamping unit can clamp the direct current output voltage at a fixed value.

Description

Technical Field

[0001] This invention relates to the field of filtering technology, and in particular to a filtering circuit and its implementation method, and a filtering device. Background Technology

[0002] Existing high-voltage DC power supply circuits typically filter the power supply using various filtering circuits, such as capacitors, LC filter circuits composed of capacitors and inductors, and RC filter circuits composed of capacitors and resistors. However, these filtering circuits inevitably require the use of high-voltage capacitors with high withstand voltage. High-voltage, high-capacity filter capacitors are expensive and bulky. Moreover, even when multiple capacitors are connected in parallel, the total capacitance of these filter circuits is relatively small, and their effect on filtering out ripple and suppressing large instantaneous currents is not significant. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a filtering circuit and its implementation method, as well as a filtering device, which can effectively filter out ripple and suppress transient surges.

[0004] On one hand, the filtering circuit according to an embodiment of the present invention includes: a signal filtering unit for filtering out high-frequency small-signal interference of the input voltage; an active filtering unit for filtering out ripple and instantaneous surge of the input voltage to form a DC output voltage; and a clamping unit for clamping the DC output voltage to a fixed value; wherein the filtering circuit has a voltage input terminal and a voltage output terminal, and the signal filtering unit, the active filtering unit and the clamping unit are electrically connected in sequence and disposed between the voltage input terminal and the voltage output terminal.

[0005] According to some embodiments of the present invention, the signal filtering unit includes a filter capacitor, the first end of the filter capacitor being electrically connected to the voltage input terminal, and the second end of the filter capacitor being grounded.

[0006] According to some embodiments of the present invention, the active filter unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a first switch, and a second switch; wherein, the first terminal of the third resistor is electrically connected to the voltage input terminal, the second terminal of the third resistor is electrically connected to the first terminal of the fourth resistor, and the second terminal of the fourth resistor is grounded; the first capacitor is connected in parallel with the third resistor, the first terminal of the second capacitor is electrically connected to the voltage input terminal, and the second terminal of the second capacitor is electrically connected to the controlled terminal of the first switch; the first terminal of the second resistor is electrically connected to the voltage input terminal, and the second terminal of the second resistor is electrically connected to the first terminal of the first switch, the first... The second terminal of the switch is electrically connected to the connection point between the second terminal of the third resistor and the first terminal of the fourth resistor; the first terminal of the first resistor is electrically connected to the connection point between the voltage input terminal and the controlled terminal of the first switch; the second terminal of the first resistor is electrically connected to the connection point between the second terminal of the second resistor and the first terminal of the first switch; the controlled terminal of the second switch is electrically connected to the connection point between the second terminal of the second resistor and the first terminal of the first switch; the first terminal of the second switch is electrically connected to the connection point between the voltage input terminal and the voltage output terminal; and the second terminal of the second switch is electrically connected to the connection point between the second terminal of the third resistor and the first terminal of the fourth resistor.

[0007] According to some embodiments of the present invention, the first switch is a transistor, the controlled terminal of the first switch is the base of the first switch, the first terminal of the first switch is the collector of the first switch, and the second terminal of the first switch is the emitter of the first switch; the second switch is a transistor, the controlled terminal of the second switch is the base of the second switch, the first terminal of the second switch is the collector of the second switch, and the second terminal of the second switch is the emitter of the second switch.

[0008] According to some embodiments of the present invention, the clamping unit includes a varistor, a first end of which is electrically connected to a second end of the first capacitor, and the second end of the varistor is grounded.

[0009] According to some embodiments of the present invention, a load resistor is further included, wherein a first end of the load resistor is electrically connected to the voltage output terminal, and a second end of the load resistor is grounded.

[0010] On the other hand, the implementation method of the filter circuit according to an embodiment of the present invention includes the following steps:

[0011] The input voltage is sent to the signal filtering unit through the voltage input terminal;

[0012] The signal filtering unit filters out high-frequency small-signal interference from the input voltage.

[0013] The input voltage ripple and transient surge are filtered out by an active filter unit to form a DC output voltage;

[0014] The DC output voltage is clamped to a fixed value by the clamping unit and then output through the voltage output terminal.

[0015] According to some embodiments of the present invention, the step of filtering out the ripple and transient surge of the input voltage through an active filter unit to form a DC output voltage; clamping the DC output voltage to a fixed value through a clamping unit and outputting it through a voltage output terminal specifically includes:

[0016] When the input voltage formed by the superposition of DC voltage and AC interference signal is greater than a preset value, the voltage across the varistor is greater than its regulated value, the impedance across the varistor decreases, and the first capacitor is charged through the circuit formed by the first capacitor and the varistor. At this time, the second switch is in the amplification state, the base current of the second switch increases, the output equivalent resistance between the collector and emitter of the second switch decreases, and the charging current of the circuit formed by the first capacitor and the varistor increases, thereby filtering out the ripple and instantaneous surge of the input voltage and forming the DC output voltage.

[0017] When the input voltage formed by the superposition of DC voltage and AC interference signal is less than the preset value, the first capacitor discharges through the circuit formed by the first capacitor and the third resistor, the circuit formed by the first capacitor, the second resistor and the first switch, the circuit formed by the first capacitor, the second resistor and the second switch, and the circuit formed by the first capacitor and the second switch, thereby filtering out the ripple and instantaneous surge of the input voltage and forming the DC output voltage.

[0018] The clamping unit clamps the DC output voltage to a fixed value and outputs it through the voltage output terminal.

[0019] On the other hand, the filtering device according to an embodiment of the present invention includes the filtering circuit described in the above-described aspects of the present invention.

[0020] The filtering circuit and its implementation method and filtering device according to embodiments of the present invention have at least the following beneficial effects: the signal filtering unit can filter out high-frequency small signal interference generated by the external environment and the circuit itself; the active filtering unit can effectively filter out the ripple of the high-voltage DC power supply output and suppress large instantaneous current; the clamping unit can clamp the DC output voltage to a fixed value; the filtering circuit can increase the equivalent capacitance of the filtering circuit without using a high-voltage capacitor, and can effectively filter out the ripple and high-frequency interference of the high-voltage DC power supply output, as well as suppress large instantaneous current, thereby enhancing the load-carrying capacity of the power supply.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0023] Figure 1 This is a schematic diagram of the circuit principle of the filter circuit according to an embodiment of the present invention;

[0024] Figure 2 This is a flowchart illustrating the steps of implementing the filtering circuit according to an embodiment of the present invention.

[0025] Figure label:

[0026] Signal filtering unit 100, active filtering unit 200, clamping unit 300. Detailed Implementation

[0027] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0028] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0029] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0030] On the one hand, such as Figure 1 As shown, the filtering circuit according to an embodiment of the present invention includes a signal filtering unit 100, an active filtering unit 200, a clamping unit 300, a voltage input terminal HV_IN, and a voltage output terminal HV_OUT. The output voltage flows into the signal filtering unit 100 through the voltage input terminal HV_IN, and the signal filtering unit 100 is used to filter out high-frequency small-signal interference from the input voltage. The active filtering unit 200 is used to filter out ripple and instantaneous surges in the input voltage to form a DC output voltage. The clamping unit 300 is used to clamp the DC output voltage to a fixed value and output it through the voltage output terminal HV_OUT. The signal filtering unit 100, the active filtering unit 200, and the clamping unit 300 are sequentially electrically connected and disposed between the voltage input terminal HV_IN and the voltage output terminal HV_OUT.

[0031] According to the filtering circuit of the present invention, the signal filtering unit 100 can filter out high-frequency small signal interference generated by the external environment and the circuit itself; the active filtering unit 200 can effectively filter out the ripple of the high voltage DC power supply output and suppress large instantaneous current, thereby enhancing the load-carrying capacity of the power supply; the clamping unit 300 can clamp the DC output voltage to a fixed value, thereby providing a stable and high-load-carrying capacity high voltage DC power supply for the subsequent circuit.

[0032] Specifically, such as Figure 1 As shown, in some embodiments of the present invention, the signal filtering unit 100 includes a filter capacitor C64. The first end of the filter capacitor C64 is electrically connected to the voltage input terminal HV_IN, and the second end of the filter capacitor C64 is grounded. The filter capacitor C64 can filter out high-frequency small signal interference generated by external factors and the circuit itself.

[0033] like Figure 1As shown, in some embodiments of the present invention, the active filter unit 200 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2, a first switch Q1, and a second switch Q2; wherein, the first end of the third resistor R3 is electrically connected to the voltage input terminal HV_IN, the second end of the third resistor R3 is electrically connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is grounded; the first capacitor C1 is connected in parallel with the third resistor R3, the first end of the second capacitor C2 is electrically connected to the voltage input terminal HV_IN, and the second end of the second capacitor C2 is electrically connected to the controlled terminal of the first switch Q1; the first end of the second resistor R2 is electrically connected to the voltage input terminal HV_IN, and the second end of the second resistor R2 is electrically connected to the controlled terminal of the first switch Q1. One end is electrically connected to the connection point between the second end of the first switch Q1 and the second end of the third resistor R3 and the first end of the fourth resistor R4; the first end of the first resistor R1 is electrically connected to the connection point between the voltage input terminal HV_IN and the controlled end of the first switch Q1; the second end of the first resistor R1 is electrically connected to the connection point between the second end of the second resistor R2 and the first end of the first switch Q1; the controlled end of the second switch Q2 is electrically connected to the connection point between the second end of the second resistor R2 and the first end of the first switch Q1; the first end of the second switch Q2 is electrically connected to the connection point between the voltage input terminal HV_IN and the voltage output terminal HV_OUT; and the second end of the second switch Q2 is electrically connected to the connection point between the second end of the third resistor R3 and the first end of the fourth resistor R4.

[0034] The first switch Q1 and the second switch Q2 can be made of components such as transistors, field-effect transistors, thyristors, operational amplifiers, and comparators. When the first switch Q1 and the second switch Q2 are transistors, the controlled terminal of the first switch Q1 is the base of the first switch Q1, the first terminal of the first switch Q1 is the collector of the first switch Q1, and the second terminal of the first switch Q1 is the emitter of the first switch Q1. The controlled terminal of the second switch Q2 is the base of the second switch Q2, the first terminal of the second switch Q2 is the collector of the second switch Q2, and the second terminal of the second switch Q2 is the emitter of the second switch Q2.

[0035] The clamping unit 300 includes a varistor TVS1. The first terminal of the varistor TVS1 is electrically connected to the second terminal of the first capacitor C1, and the second terminal of the varistor TVS1 is grounded. It should be noted that the clamping unit 300 can use not only a varistor but also a TVS diode, etc. In addition to providing a filtering effect, the clamping unit 300 also clamps the DC output voltage to a fixed value.

[0036] In some embodiments of the present invention, a load resistor RL is also included. After the DC output voltage is clamped to a fixed value, a stable high-voltage DC voltage is provided to the subsequent circuit through the load resistor RL.

[0037] According to an embodiment of the present invention, the high-voltage DC current of the active filter unit 200 (400V or other values) can be divided by the first resistor R1 and the second resistor R2 to form a terminal voltage of Vab = 10V at points a and b; Q1 and Q2 can be NPN transistors of the same type with a current amplification factor of 60 or higher. Meanwhile, in order to ensure that the amplification factor of Q1 and Q2 is very small, almost close to zero, under DC conditions, the resistance value of the fourth resistor R4 needs to be sufficiently large, such as 2MΩ or other reasonable values.

[0038] like Figure 1 As shown, when there is no interference signal and the input voltage is a DC voltage of 400V, since the voltage across the first capacitor C1 cannot change abruptly, the third resistor R3 is equivalent to a short circuit, the voltage across the varistor TVS1 is 400V, and the regulated voltage of the varistor TVS1 is 390V. When the TVS1 is subjected to a reverse transient impact, it can change the high impedance between its two terminals to a low impedance at an extremely fast speed. At this time, the first capacitor C1 is charged through the circuit formed by the first capacitor C1 and the varistor TVS1, and the circuit formed by the first capacitor C1 and the fourth resistor R4, reaching a stable value of 10V.

[0039] When the input voltage formed by the superposition of DC voltage and AC interference signal is greater than 400V, on the one hand, since the voltage across C1 cannot change abruptly, the voltage across the varistor TVS1 exceeds 390V. TVS1 is subjected to a reverse transient impact, which rapidly changes the high impedance between its two terminals to a low impedance. At this time, the first capacitor C1 is charged through the circuit of the first capacitor C1 and TVS1. At the same time, Q1 and Q2 change from the cutoff state to the amplification state. The base current of Q2 increases, and the output equivalent resistance between the collector and emitter decreases, which increases the charging current of C1 through the circuit formed by C1 and TVS1. The equivalent transformation of the current source and voltage source reduces the output voltage ripple and suppresses the transient surge.

[0040] When the input voltage formed by the superposition of DC voltage and AC interference signal is less than 400V, C1 discharges through the circuit formed by C2 and Q1, which leads to an increase in the base current of Q2 and a decrease in the output equivalent resistance between the collector and emitter. C1 also discharges rapidly through the circuits formed by C1 and R3, C1, R2 and Q1, and C1, R2 and Q2, especially the circuit formed by C1 and Q2. For point a, according to Kirchhoff's current law, the energy released by C1 increases the output current, suppresses the surge current, and reduces the output voltage ripple through the equivalent transformation of the current source and voltage source.

[0041] Therefore, the filtering circuit according to the embodiment of the present invention effectively increases the equivalent capacitance of the high voltage DC power supply filtering circuit, eliminating the need for high voltage-rated capacitors and allowing the use of only low voltage-rated capacitors, thereby reducing cost and size. Moreover, the circuit can effectively filter out the ripple and high-frequency small-signal interference of the high voltage DC power supply output, as well as suppress large instantaneous currents, thereby enhancing the load-carrying capacity of the power supply.

[0042] On the other hand, the filtering device according to embodiments of the present invention, by employing the above-described filtering circuit, can provide a stable high-voltage output power supply, which greatly improves product performance and extends product lifespan. For example, applying this filtering circuit in lidar (or other devices) can output a stable high-voltage DC power supply, thereby improving ranging accuracy and increasing the lifespan of components.

[0043] On the other hand, such as Figure 2 As shown, the implementation method of the filter circuit according to an embodiment of the present invention includes the following steps:

[0044] The input voltage is sent to the signal filtering unit 100 through the voltage input terminal HV_IN;

[0045] The signal filtering unit 100 filters out high-frequency small-signal interference from the input voltage;

[0046] The active filter unit 200 filters out the ripple and instantaneous surge of the input voltage to form a DC output voltage;

[0047] The DC output voltage is clamped to a fixed value by the clamping unit 300 and output through the voltage output terminal HV_OUT.

[0048] Specifically, the input voltage is sent to the signal filtering unit 100 through the voltage input terminal HV_IN, where it is filtered by the filter capacitor C64 to remove high-frequency small-signal interference generated by external factors and the circuit itself. Simultaneously, the input voltage is sent to the active filter unit 200. When the input voltage formed by the superposition of DC voltage and AC interference signals exceeds a preset value (e.g., 400V or other values), the voltage across the varistor TVS1 exceeds its regulated voltage, reducing the impedance across the varistor TVS1. The first capacitor C1 is then charged through the circuit formed by the first capacitor C1 and the varistor TVS1. At this time, the second switch Q2 is in an amplified state, increasing the base current of the second switch Q2 and decreasing the output equivalent resistance between the collector and emitter of the second switch Q2, thus increasing the capacitance of the first capacitor C1. The charging current of the circuit formed by the varistor TVS1 filters out the ripple and instantaneous surge of the input voltage, forming a DC output voltage. When the input voltage formed by the superposition of the DC voltage and the AC interference signal is less than the preset value, the first capacitor C1 discharges through the circuit formed by the first capacitor C1 and the third resistor R3, the circuit formed by the first capacitor C1, the second resistor R2 and the first switch Q1, the circuit formed by the first capacitor C1, the second resistor R2 and the second switch Q2, and the circuit formed by the first capacitor C1 and the second switch Q2, thereby filtering out the ripple and instantaneous surge of the input voltage and forming a DC output voltage. Finally, the clamping unit 300 clamps the DC output voltage to a fixed value and outputs it through the voltage output terminal HV_OUT.

[0049] According to the implementation method of the filter circuit of the present invention, the equivalent capacitance of the high voltage DC power supply filter circuit is effectively increased, eliminating the need for high voltage-rated capacitors and allowing the use of only low voltage-rated capacitors, thereby reducing cost and size. Moreover, the circuit can effectively filter out the ripple and high-frequency small-signal interference of the high voltage DC power supply output, as well as suppress large instantaneous currents, thereby enhancing the load-carrying capacity of the power supply.

[0050] In the description of this specification, references to terms such as "one embodiment," "further embodiment," "some specific embodiments," or "some examples," etc., indicate that a specific feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for implementing a filter circuit, characterized in that, The filtering circuit includes: a signal filtering unit for filtering out high-frequency small-signal interference from the input voltage; an active filtering unit for filtering out ripple and transient surges from the input voltage to form a DC output voltage; and a clamping unit for clamping the DC output voltage to a fixed value. The filtering circuit has a voltage input terminal and a voltage output terminal. The signal filtering unit, the active filtering unit, and the clamping unit are sequentially electrically connected and positioned between the voltage input terminal and the voltage output terminal. The implementation method of the filtering circuit includes the following steps: The input voltage is sent to the signal filtering unit through the voltage input terminal; The signal filtering unit filters out high-frequency small-signal interference from the input voltage. The input voltage ripple and transient surge are filtered out by an active filter unit to form a DC output voltage; The DC output voltage is clamped to a fixed value by the clamping unit and then output through the voltage output terminal. The active filter unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a first switch, and a second switch. The first terminal of the third resistor is electrically connected to the voltage input terminal, the second terminal of the third resistor is electrically connected to the first terminal of the fourth resistor, and the second terminal of the fourth resistor is grounded. The first capacitor is connected in parallel with the third resistor. The first terminal of the second capacitor is electrically connected to the voltage input terminal, and the second terminal of the second capacitor is electrically connected to the controlled terminal of the first switch. The first terminal of the second resistor is electrically connected to the voltage input terminal, and the second terminal of the second resistor is electrically connected to the first terminal of the first switch. The first terminal of the first resistor is electrically connected to the connection point between the second end of the third resistor and the first end of the fourth resistor; the first end of the first resistor is electrically connected to the connection point between the voltage input terminal and the controlled terminal of the first switch; the second end of the first resistor is electrically connected to the connection point between the second end of the second resistor and the first end of the first switch; the controlled terminal of the second switch is electrically connected to the connection point between the second end of the second resistor and the first end of the first switch; the first end of the second switch is electrically connected to the connection point between the voltage input terminal and the voltage output terminal; and the second end of the second switch is electrically connected to the connection point between the second end of the third resistor and the first end of the fourth resistor.

2. The method for implementing the filter circuit according to claim 1, characterized in that, The process involves filtering out ripple and transient surges in the input voltage using an active filter unit to form a DC output voltage; clamping the DC output voltage to a fixed value using a clamping unit and outputting it through a voltage output terminal, specifically including: When the input voltage formed by the superposition of DC voltage and AC interference signal is greater than a preset value, the voltage across the varistor is greater than its regulated value, the impedance across the varistor decreases, and the first capacitor is charged through the circuit formed by the first capacitor and the varistor. At this time, the second switch is in the amplification state, the base current of the second switch increases, the output equivalent resistance between the collector and emitter of the second switch decreases, and the charging current of the circuit formed by the first capacitor and the varistor increases, thereby filtering out the ripple and instantaneous surge of the input voltage and forming the DC output voltage. When the input voltage formed by the superposition of DC voltage and AC interference signal is less than the preset value, the first capacitor discharges through the circuit formed by the first capacitor and the third resistor, the circuit formed by the first capacitor, the second resistor and the first switch, the circuit formed by the first capacitor, the second resistor and the second switch, and the circuit formed by the first capacitor and the second switch, thereby filtering out the ripple and instantaneous surge of the input voltage and forming the DC output voltage. The clamping unit clamps the DC output voltage to a fixed value and outputs it through the voltage output terminal.

3. The method for implementing the filter circuit according to claim 1, characterized in that, The signal filtering unit includes a filter capacitor, the first end of which is electrically connected to the voltage input terminal, and the second end of which is grounded.

4. The method for implementing the filter circuit according to claim 1, characterized in that, The first switch is a transistor, with the controlled terminal being the base of the first switch, the first terminal being the collector of the first switch, and the second terminal being the emitter of the first switch; the second switch is a transistor, with the controlled terminal being the base of the second switch, the first terminal being the collector of the second switch, and the second terminal being the emitter of the second switch.

5. The method for implementing the filter circuit according to claim 1, characterized in that, The clamping unit includes a varistor, the first end of which is electrically connected to the second end of the first capacitor, and the second end of the varistor is grounded.

6. The method for implementing the filter circuit according to claim 1, characterized in that, The filter circuit also includes a load resistor, the first end of which is electrically connected to the voltage output terminal, and the second end of which is grounded.

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