Harmonic optimization circuit

Abstract

The utility model relates to a harmonic optimization circuit, which solves the problem that a harmonic optimization circuit applied to a low-power variable frequency water pump in the prior art is large in size, and adopts the technical scheme that the harmonic optimization circuit is characterized by comprising an EMC (Electro Magnetic Compatibility) module and a rectifying and filtering module connected with the EMC module; the EMC module is used for suppressing differential mode and common mode interference and optimizing circuit harmonics; the rectifying and filtering module is used for converting the alternating-current sine-wave voltage into direct-current voltage; the EMC module comprises a resistor group circuit, a differential mode circuit and a common mode circuit; the resistor group circuit is used for improving a circuit power factor, one end of the resistor group circuit is connected with an alternating-current power supply, and the other end is connected with one of the differential-mode circuit, the common-mode circuit and the rectifying and filtering module; the differential mode circuit is used for suppressing differential mode interference; the common-mode circuit is used for suppressing common-mode interference. The variable-frequency water pump has the advantages that when the variable-frequency water pump is applied to the variable-frequency water pump with the power section ranging from 75 W to 180 W, harmonic wave optimization is facilitated, the overall size of a product is reduced, and the product cost is reduced.

Description

Technical Field

[0001] The utility model relates to a circuit field, in particular to a harmonic optimization circuit applied to a variable frequency water pump. Background Art

[0002] The power control board circuits on existing variable frequency water pumps basically adopt traditional bridge rectification plus capacitor filtering circuits. When the variable frequency water pump works with a full load greater than 75W, the current at the AC end (i.e., the access end of Alternating Current) generates serious distortion, causing relatively serious interference and pollution to the power grid. The commonly used solution mainly introduces a PFC (Power Factor Correction) circuit to effectively reduce harmonic current and improve the power factor. The PFC circuit includes an active PFC circuit and a passive PFC circuit. The active PFC circuit consists of inductors, capacitors and electronic components, with a small volume and can achieve a very high power factor. For example, if the active power factor correction adopts a Boost boost PFC circuit, the power factor can be increased to above 0.98, making the harmonic current very small, but the cost of the active PFC is higher than that of the passive PFC. The passive PFC generally uses an inductance compensation method to reduce the phase difference between the fundamental wave current and voltage of the AC input to improve the power factor, but the power factor of the passive PFC is not very high and can only reach 0.7 - 0.8. In practical applications, products in the power range of 75 - 180W often use the passive PFC solution, which is characterized by a large volume and low cost. Products with a power above 180W use the active PFC solution, which is characterized by a small volume and high cost. Summary of the Invention

[0003] The purpose of the utility model is to solve the above problems existing in the prior art and provide a harmonic optimization circuit, which replaces the passive PFC inductor with a resistor group, is beneficial to reducing the cost of the harmonic optimization circuit, has a small volume, and when applied to products in the 75 - 180W power range, is beneficial to optimizing harmonics, reducing the overall volume of the product, and reducing the product cost.

[0004] The above technical purpose of the utility model is mainly solved by the following technical scheme: A harmonic optimization circuit, characterized in that,

[0005] It includes an EMC module and a rectification and filtering module connected to the EMC module;

[0006] The EMC module is used to suppress differential mode and common mode interference and optimize circuit harmonics;

[0007] The rectification and filtering module is used to convert the AC sine wave voltage into a DC voltage;

[0008] The EMC module includes a resistor group circuit, a differential mode circuit and a common mode circuit;

[0009] The resistor group circuit is used to improve the power factor of the circuit. One end of it is used to connect to the AC power supply, and the other end is used to connect to the differential mode circuit, common mode circuit, or rectification and filtering module selectively.

[0010] The differential mode circuit is used to suppress differential mode interference.

[0011] The common mode circuit is used to suppress common mode interference.

[0012] This technical solution replaces the passive PFC inductor with a resistor group, which is beneficial to reducing the cost of harmonic optimization circuit, and has a small volume. When applied to products in the power range of 75 - 180W (such as variable frequency water pumps), it is beneficial to optimize harmonics, reduce the interference and pollution caused by harmonics to the power grid, and is also beneficial to reducing the overall volume of the product and lowering the product cost.

[0013] As a further improvement and supplement to the above technical solution, the present utility model adopts the following technical measures: the differential mode circuit includes a first differential mode circuit and a second differential mode circuit, and the first differential mode circuit and the second differential mode circuit are respectively used to suppress the differential mode generated by the resistor group circuit.

[0014] Preferably, the first differential mode circuit is a first capacitor circuit, and the second differential mode circuit is a second capacitor circuit.

[0015] Preferably, the common mode circuit includes a common mode inductor circuit and a common mode capacitor circuit. The common mode inductor circuit and the common mode capacitor circuit cooperate with the differential mode circuit to suppress the common mode generated by the differential mode circuit.

[0016] Preferably, the common mode capacitor circuit is a bridge common mode capacitor circuit, on which there are a third capacitor and a fourth capacitor with a connection relationship. The common mode capacitor circuit is connected in parallel with the second capacitor circuit on the differential mode circuit.

[0017] Preferably, the rectification and filtering module includes a rectification circuit and a filtering circuit connected in series. The filtering circuit is connected to the EMC module. The rectification circuit is a diode circuit, and the diode circuit is at least a parallel circuit of two or more diodes with the same direction. The filtering circuit is a fifth capacitor circuit, and the fifth capacitor circuit is a circuit in which at least two capacitors are connected in parallel.

[0018] Preferably, the first differential mode circuit is connected in parallel with the resistor group circuit and then connected in series with the common mode circuit. The common mode circuit is connected in series with the second differential mode circuit, and the second differential mode circuit is connected in series with the rectification circuit on the rectification and filtering module.

[0019] Preferably, the first differential-mode circuit, the common-mode circuit, and the second differential-mode circuit are connected in series in sequence. The resistor group circuit is connected in series with the second differential-mode circuit and then in parallel with the rectification circuit on the rectification and filtering module. The power supply terminal of the first differential-mode circuit is used to connect to a power supply.

[0020] Preferably, after the first differential-mode circuit, the common-mode circuit, and the second differential-mode circuit are connected in series in sequence, they are connected in series with the rectification and filtering module, and the resistor group circuit is connected in parallel with the rectification and filtering module.

[0021] Preferably, the resistor group circuit includes a circuit formed by N resistors connected in parallel or in series, where N ≥ 2.

[0022] The beneficial effects of the present utility model are as follows: 1. By replacing the passive PFC inductor with a resistor group, it is beneficial to reduce the cost of the harmonic optimization circuit, and it has a small volume. When applied to products in the power range of 75 - 180W (such as variable-frequency water pumps), it is beneficial to optimize harmonics, reduce the interference and pollution caused by harmonics to the power grid, and is also beneficial to reducing the overall volume of the product and lowering the product cost. 2. The resistors in the resistor group circuit include power resistors such as wire-wound resistors, cement resistors, and surface-mount resistors. The connection form of the resistors in the resistor group circuit can be set in parallel or in series. By flexibly setting the number of resistors and the connection method, the space utilization rate can be improved, and the copper content rate of the resistors is relatively low, thus being beneficial to reducing costs. 3. Setting the resistor group circuit can limit the peak value of the instantaneous current when the capacitor is charging, thereby optimizing the harmonic current to meet the harmonic current limit value. Description of the Drawings

[0023] Figure 1 is a circuit principle block diagram of Embodiment 1.

[0024] Figure 2 is a circuit structure schematic diagram of Embodiment 1.

[0025] Figure 3 is a circuit principle block diagram of Embodiment 2.

[0026] Figure 4 is a circuit structure schematic diagram of Embodiment 2.

[0027] Figure 5 is a circuit principle block diagram of Embodiment 3.

[0028] Figure 6 is a circuit structure schematic diagram of Embodiment 3. Detailed Embodiments

[0029] The technical solutions of the present utility model will be further specifically described below through embodiments and in conjunction with the drawings.

[0030] Embodiment 1: AsFigure 1 and Figure 2 As shown in Figure 2 , a harmonic optimization circuit includes an EMC module and a rectifying and filtering module connected to the EMC module;

[0031] The EMC module is used to suppress differential-mode and common-mode interferences and optimize the circuit harmonics;

[0032] The rectifying and filtering module is used to convert the AC sine-wave voltage into a DC voltage;

[0033] The EMC module includes a resistor group circuit, a differential-mode circuit, and a common-mode circuit;

[0034] The resistor group circuit is used to improve the power factor of the circuit. One end of it is used to connect to the AC power supply, and the other end is used to connect to one of the differential-mode circuit, the common-mode circuit, and the rectifying and filtering module;

[0035] The differential-mode circuit is used to suppress differential-mode interference;

[0036] The common-mode circuit is used to suppress common-mode interference.

[0037] In this technical solution, the resistor group replaces the passive PFC inductor (the higher the inductance of the inductor, the higher the copper proportion and the more expensive the cost). The resistor group circuit can limit the peak value of the instantaneous current when each relevant capacitor is charging, so as to achieve the purpose of optimizing the harmonic current and meet the harmonic current limit value. The resistor group circuit includes power resistors such as wire-wound resistors, cement resistors, and chip resistors. The connection form of the resistors in the resistor group circuit can be set in parallel or in series. By using the power resistor to limit the peak value of the instantaneous current when the capacitor is charging, the harmonic current is optimized to meet the harmonic current limit value, and the copper content of the power resistor is relatively low. Therefore, the cost is lower at the same power, which is beneficial to reducing the cost of the harmonic optimization circuit and is also beneficial to reducing the volume. When applied to products in the power range of 75 - 180W (such as variable-frequency water pumps), it is beneficial to optimize the harmonics, reduce the interference and pollution caused by the harmonics to the power grid, and is also beneficial to reducing the overall volume of the product and lowering the product cost.

[0038] In practical applications, the resistor group circuit includes a circuit formed by N resistors connected in parallel, where N≥2. In this embodiment, N is 7, and the resistor group circuit is formed by 7 resistors (RX1~RX7) connected in parallel.

[0039] Next, the above technical solution will be further elaborated:

[0040] In practical applications, the differential-mode circuit includes a first differential-mode circuit C1 and a second differential-mode circuit C2, and the first differential-mode circuit C1 and the second differential-mode circuit C2 are respectively used to suppress the differential-mode generated by the resistor group circuit.

[0041] In practical applications, the first differential-mode circuit C1 is a first capacitor circuit, and the second differential-mode circuit C2 is a second capacitor circuit.

[0042] In practical applications, the common-mode circuit includes a common-mode inductor circuit T1 and a common-mode capacitor circuit. The common-mode inductor circuit T1 and the common-mode capacitor circuits C3 and C4 cooperate with the differential-mode circuit to suppress the generation of common mode by the differential-mode circuit.

[0043] In practical applications, the common-mode capacitor circuit is a bridge-type common-mode capacitor circuit, on which a third capacitor and a fourth capacitor with a connection relationship are provided. The common-mode capacitor circuit is connected in parallel with the second capacitor circuit on the differential-mode circuit.

[0044] In practical applications, the rectifier filter module includes a series-connected rectifier circuit (such as a rectifier bridge circuit DB1) and a filter circuit (on which electrolytic capacitors E1 and E2 are connected in parallel). The filter circuit is connected to the EMC module. The rectifier circuit is a diode circuit, and the diode circuit is at least a parallel circuit of two diodes with the same direction. Each diode circuit includes two series-connected diodes. The filter circuit is a fifth capacitor circuit, and the fifth capacitor circuit is a circuit in which at least two capacitors (electrolytic capacitors E1 and E2) are connected in parallel.

[0045] In practical applications, the first differential-mode circuit C1 is connected in parallel with the resistor group circuit and then connected in series with the common-mode circuit. The common-mode circuit is connected in series with the second differential-mode circuit C2. The second differential-mode circuit C2 is connected in series with the rectifier circuit on the rectifier filter module.

[0046] Next, the connection method of the components involved in the technical solution of this embodiment will be specifically described:

[0047] As Figure 2 shown, the resistor group circuit has two connection pins. One connection pin is connected to the AC live wire L, and the other connection pin is respectively connected to the corresponding end of the first differential-mode circuit C1 and the L1 end of the common-mode inductor circuit T1. The N1 pin of the common-mode inductor circuit T1 is connected to the corresponding end of the first differential-mode circuit C1, and at the same time, the N1 pin of the common-mode inductor circuit T1 is connected to the AC neutral wire N; the L2 pin and the N2 pin of the common-mode inductor circuit T1 are respectively connected to both ends of the second differential-mode circuit C2 connected in parallel, and are respectively connected to the corresponding ends of the common-mode capacitor circuits C3 and C4. The rectifier bridge circuit DB1 has pins 1 to 4. Among them, pins 2 and 3 are respectively connected to both ends of the L1 pin and the N1 pin of the common-mode inductor circuit T1 connected in parallel, and pins 1 and 4 are respectively connected to both ends of the electrolytic capacitors E1 and E2 connected in parallel.

[0048] The principle of filtering optimization of this technical solution is:

[0049] After the alternating current enters the EMC module and is optimized for harmonics by the EMC module, the alternating current is rectified and filtered by the rectifying and filtering module, and the rectified output voltage flows into the electrolytic capacitors E1, E2 and the subsequent load; since a resistor group is added to the EMC module circuit, the peak value of the instantaneous charging current of the entire capacitor (including the capacitors in the first differential mode circuit C1, the capacitors in the second differential mode circuit C2, the two capacitors in the common mode capacitor circuits C3, C4, and the two electrolytic capacitors E1, E2 in the filtering circuit) is reduced, and the harmonic current is optimized to a certain extent to meet the harmonic current limit. The capacitors in the first differential mode circuit C1 and the capacitors in the second differential mode circuit C2 effectively suppress differential mode interference, and the inductor in the common mode inductor circuit T1 and the two capacitors in the common mode capacitor circuits C3, C4 can effectively suppress common mode interference. The main function of the rectifying and filtering module is to convert the AC sine wave voltage into a DC voltage.

[0050] Embodiment 2: As Figure 3 and Figure 4 shown, the difference from Embodiment 1 is that: the first differential mode circuit C1, the common mode circuit C34, and the second differential mode circuit C2 are connected in series in sequence, the resistor group circuit is connected in series with the second differential mode circuit C2 and then connected in parallel with the rectifying circuit on the rectifying and filtering module, and the power supply end of the first differential mode circuit C1 is used to connect to the power supply.

[0051] Further elaborate on the connection relationship of each component for the technical solution involved in this embodiment:

[0052] As Figure 4 shown, the live wire L and neutral wire N of the alternating current are respectively connected to the L1 and N1 ends of the first differential mode circuit C1 and the common mode inductor circuit T1 connected in parallel; the L2 pin of the common mode inductor circuit T1 is connected in series with one end of the resistor group (RX1~RX7), and the other end of the resistor group (RX1~RX7) is respectively connected to one end of the second differential mode circuit C2 connected in parallel, and is connected to one end of the common mode capacitor circuits C3, C4; the N2 pin of the common mode inductor circuit T1 is respectively connected to the other end of the second differential mode circuit C2 connected in parallel, and is connected to the other end of the common mode capacitor circuits C3, C4. The rectifier bridge circuit DB1 has pins 1 to 4. Among them, pins 2 and 3 are respectively connected to both ends of the second differential mode circuit C2 connected in parallel, and pins 1 and 4 are respectively connected to the corresponding ends of the electrolytic capacitors E1, E2 connected in parallel.

[0053] Embodiment 3: As Figure 5 and Figure 6 shown, the difference from Embodiment 1 is that: the first differential mode circuit C1, the common mode circuit C34, and the second differential mode circuit C2 are connected in series in sequence and then connected in series with the rectifying and filtering module, and the resistor group circuit is connected in parallel with the rectifying and filtering module.

[0054] Further elaboration on the connection relationships of each component for the technical solution involved in this embodiment:

[0055] As Figure 6 shown, the live wire L and neutral wire N of the alternating current are respectively connected to the L1 and N1 terminals of the first differential mode circuit C1 and the common mode inductance circuit T1 arranged in parallel; the L2 and N2 pins of the common mode inductance circuit T1 are respectively connected to both ends of the second differential mode circuit C2 arranged in parallel, and one end of the common mode capacitor circuits C3 and C4 respectively. The rectifier bridge circuit DB1 has pins 1 to 4. Among them, pins 2 and 3 are respectively connected to both ends of the second differential mode circuit C2 arranged in parallel, pin 4 is connected to one end of the series resistor group RX1 to RX7, and the other ends of the resistor group RX1 to RX7 are respectively connected to one end of the electrolytic capacitors E1 and E2 arranged in parallel, and pin 1 is connected to the other ends of the electrolytic capacitors E1 and E2 arranged in parallel.

[0056] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. In the above embodiments, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A harmonic optimization circuit, characterized in that: It includes an EMC module and a rectifier and filter module connected to the EMC module; The EMC module is used to suppress differential mode and common mode interference and optimize circuit harmonics; The rectification and filtering module is used to convert the AC sinusoidal wave voltage into a DC voltage; The EMC module includes a resistor group circuit, a differential mode circuit and a common mode circuit; The resistor group circuit is used to improve the power factor of the circuit, one end of which is used to connect to an AC power supply, and the other end of which is used to connect to one of the differential mode circuit, the common mode circuit, and the rectifier filter module; The differential mode circuit is used to suppress differential mode interference; The common mode circuit is used to suppress common mode interference.

2. The harmonic optimization circuit according to claim 1, characterized in that The differential mode circuit includes a first differential mode circuit and a second differential mode circuit, and the first differential mode circuit and the second differential mode circuit are respectively used to suppress the resistor group circuit from generating a differential mode.

3. The harmonic optimization circuit according to claim 2, characterized in that The first differential mode circuit is a first capacitor circuit, and the second differential mode circuit is a second capacitor circuit.

4. The harmonic optimization circuit according to claim 1, characterized in that The common mode circuit includes a common mode inductor circuit and a common mode capacitor circuit, and the common mode inductor circuit and the common mode capacitor circuit cooperate with the differential mode circuit to suppress the differential mode circuit from generating a common mode.

5. The harmonic optimization circuit according to claim 4, characterized in that The common-mode capacitor circuit is a bridge-type common-mode capacitor circuit, on which a third capacitor and a fourth capacitor having a connection relationship are provided. The common-mode capacitor circuit is connected in parallel with the second capacitor circuit on the differential-mode circuit.

6. The harmonic optimization circuit according to any one of claims 1 to 5, characterized in that The rectifier and filter module includes a rectifier circuit and a filter circuit connected in series, the filter circuit is connected to the EMC module, the rectifier circuit is a diode circuit, the diode circuit is at least a two-way diode parallel circuit with the same direction, and the filter circuit is a fifth capacitor circuit, and the fifth capacitor circuit is a circuit with at least two capacitors in parallel.

7. The harmonic optimization circuit according to any one of claims 2 to 5, characterized in that The first differential mode circuit on the differential mode circuit is connected in parallel with the resistor group circuit and then in series with the common mode circuit. The common mode circuit is connected in series with the second differential mode circuit on the differential mode circuit. The second differential mode circuit is connected in series with the rectifier circuit on the rectifier and filter module.

8. The harmonic optimization circuit according to any one of claims 2 to 5, characterized in that The first differential mode circuit on the differential mode circuit, the common mode circuit and the second differential mode circuit on the differential mode circuit are connected in series in sequence, the resistor group circuit is connected in series with the second differential mode circuit and then connected in parallel with the rectifier circuit on the rectifier and filter module, and the power supply end of the first differential mode circuit is used to be connected to a power supply.

9. The harmonic optimization circuit according to any one of claims 2 to 5, characterized in that The first differential mode circuit on the differential mode circuit, the common mode circuit and the second differential mode circuit on the differential mode circuit are sequentially connected in series and then connected in series with the rectification and filtering module, and the resistor group circuit is connected in parallel with the rectification and filtering module.

10. The harmonic optimization circuit according to any one of claims 1 to 5, characterized in that The resistor group circuit includes a circuit formed by N resistors connected in parallel or in series, where N≥2.

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