TWI886019B - Low-frequency ripple current cancellation circuit and power system with low-frequency ripple current cancellation function - Google Patents

Abstract

A low-frequency ripple current cancellation circuit includes a first step-up circuit and a second step-up circuit. The first step-up circuit includes a first inductor, a first switch assembly, and a first capacitor, wherein the first switch assembly includes a first switch and a second switch. The second step-up circuit includes a second inductor, a second switch assembly, and a second capacitor, wherein the second switch assembly includes a third switch and a fourth switch. The low-frequency ripple current cancellation circuit receives a direct-current current with a ripple component, and the ripple component is cancelled by the first step-up circuit and the second step-up circuit.

Description

Low-frequency ripple current suppression circuit and power supply system having low-frequency ripple current suppression function

The present invention relates to a current suppression circuit and a power supply system with a current suppression function, and in particular to a low-frequency ripple current suppression circuit and a power supply system with a low-frequency ripple current suppression function.

With the rise of environmental awareness, the sales of electric vehicles have doubled and the demand for charging stations has increased. Being able to meet the charging needs of electric vehicles and provide a balance between overall power efficiency and charging quality is the goal that technicians in this field are working towards.

Therefore, how to design a low-frequency ripple current suppression circuit and a power supply system with a low-frequency ripple current suppression function to solve the problems and technical bottlenecks existing in the prior art is an important topic studied by the inventor of this case.

One purpose of the present invention is to provide a low-frequency ripple current suppression circuit. The low-frequency ripple current suppression circuit includes a first boost circuit and a second boost circuit. The first boost circuit includes a first inductor, a first switch group and a first capacitor. The first inductor has a first end and a second end, and the first end of the first inductor is connected to the first DC side. The first switch group includes a first switch and a second switch; the first switch has a first end and a second end, the first end of the first switch is connected to the second end of the first inductor, and the second end of the first switch is connected to an equal potential node; the second switch has a first end and a second end, and the first end of the second switch is connected to the second end of the first inductor. The first capacitor has a first end and a second end, the first end of the first capacitor is connected to the second end of the second switch, and the second end of the first capacitor is connected to the equal potential node. The second boost circuit includes a second inductor, a second switch group and a second capacitor. The second inductor has a first end and a second end, and the first end of the second inductor is connected to the second DC side. The second switch group includes a third switch and a fourth switch; the third switch has a first end and a second end, and the first end of the third switch is connected to the second end of the second inductor, and the second end of the third switch is connected to the equipotential node; the fourth switch has a first end and a second end, and the first end of the fourth switch is connected to the second end of the second inductor. The second capacitor has a first end and a second end, and the first end of the second capacitor is connected to the second end of the fourth switch, and the second end of the second capacitor is connected to the equipotential node. The low-frequency ripple current suppression circuit receives a DC current with a ripple component, and absorbs the ripple component through the first boost circuit and the second boost circuit.

Another object of the present invention is to provide a power supply system with a low-frequency ripple current suppression function. The power supply system with a low-frequency ripple current suppression function includes three single-phase AC-to-DC conversion circuits and a low-frequency ripple current suppression circuit. Each single-phase AC-to-DC conversion circuit is correspondingly coupled to each phase of the three-phase AC power source, and the output side of the single-phase AC-to-DC conversion circuits is connected to the output node and outputs a DC current. The low-frequency ripple current suppression circuit is connected to the output node. The low-frequency ripple current suppression circuit includes a first boost circuit and a second boost circuit. The first boost circuit includes a first inductor, a first switch group, and a first capacitor; the first switch group includes a first switch and a second switch; the first inductor is connected to the first switch at a first common point, and is connected between the first DC side and the equal potential node; the second switch is connected in series to the first capacitor, and is connected between the first common point and the equal potential node. The second boost circuit includes a second inductor, a second switch group, and a second capacitor; the second switch group includes a third switch and a fourth switch; the second inductor is connected to the third switch at a second common point, and is connected between the second DC side and the equal potential node; the fourth switch is connected in series to the second capacitor, and is connected between the second common point and the equal potential node.

Thus, the low-frequency ripple current suppression circuit and the power supply system with the low-frequency ripple current suppression function proposed by the present invention have the following characteristics and advantages: 1. By using the low-frequency ripple current suppression circuit, when light load is required, the system efficiency can be maintained and the ripple component of the DC current can be eliminated, so that the output current flowing to the load is a DC current without ripple components. 2. The low-frequency ripple current suppression circuit can be realized through simple circuit design and control.

In order to further understand the technology, means and effects adopted by the present invention to achieve the intended purpose, please refer to the following detailed description and drawings of the present invention. It is believed that the purpose, features and characteristics of the present invention can be understood in depth and in detail. However, the attached drawings are only provided for reference and explanation, and are not used to limit the present invention.

The technical content and detailed description of the present invention are described as follows with reference to the accompanying drawings.

The following is a description of the implementation of the present invention through specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific examples, and the details in the specification of the present invention can also be modified and changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

It should be noted that the structures, proportions, sizes, number of components, etc. illustrated in the drawings attached to this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modification of the structure, change of the proportion relationship, or adjustment of the size shall fall within the scope of the technical contents disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention.

Please refer to FIG. 1, which is a circuit block diagram of the first embodiment of the multiple sets of single-phase AC-to-DC conversion circuits of the present invention. As shown in FIG. 1, it is a three-phase power supply charging system composed of three sets of single-phase AC-to-DC conversion circuits 100-1, 100-2, and 100-3. The three sets of single-phase AC-to-DC conversion circuits 100-1, 100-2, and 100-3 are respectively coupled to two phases of the three-phase AC power source, for example, the first single-phase AC-to-DC conversion circuit 100-1 is coupled to the R-phase and S-phase AC of the three-phase AC power source; the second single-phase AC-to-DC conversion circuit 100-2 is coupled to the S-phase and T-phase AC of the three-phase AC power source; and the third single-phase AC-to-DC conversion circuit 100-3 is coupled to the T-phase and R-phase AC of the three-phase AC power source. In the embodiment of FIG. 1 , three sets of single-phase isolated AC-to-DC converter circuits are connected in a delta structure. Each single-phase isolated AC-to-DC converter circuit includes a rectifier circuit 101-1, 101-2, 101-3 and a single-phase isolated power factor correction circuit 102-1, 102-2, 102-3. Specifically, the first single-phase AC-to-DC converter circuit 100-1 includes a first rectifier circuit 101-1 and a first single-phase isolated power factor correction circuit 102-1; the second single-phase AC-to-DC converter circuit 100-2 includes a second rectifier circuit 101-2 and a second single-phase isolated power factor correction circuit 102-2; and the third single-phase AC-to-DC converter circuit 100-3 includes a third rectifier circuit 101-3 and a third single-phase isolated power factor correction circuit 102-3.

Please refer to FIG. 2, which is a circuit block diagram of the second embodiment of the present invention with multiple sets of single-phase AC-to-DC conversion circuits. Compared with the embodiment shown in FIG. 1, in the embodiment of FIG. 2, three sets of single-phase isolated AC-to-DC conversion circuits are star-connected. Whether it is a delta connection structure or a star connection structure, it can fully provide the power required under full load or heavy load. Therefore, as shown in FIG. 3, it is a circuit block diagram of the present invention for power supply of three sets of single-phase AC-to-DC conversion circuits. Under a three-phase balanced power supply, three sets of single-phase isolated AC-to-DC conversion circuits can convert the three-phase AC power to provide the load (for example, the battery V _BAT of an electric vehicle) with a ripple-free DC (output) current i _dc as the current required for charging.

However, as the charging load decreases (e.g., reduced to 2/3 load output), in order to maintain system efficiency, a single-phase isolated AC-DC converter circuit is usually turned off to charge the load with a lower output power, resulting in phase shedding power supply. However, in this operating state, due to the asymmetric three-phase power supply, the DC output end contains AC components with more than twice the line frequency (referring to the mains frequency, such as 50Hz or 60Hz) harmonics, as shown in Figure 4. The DC (output) current i _dc will generate ripple components, which will affect the quality of power supply to the load and even the service life of the load. If the charging load is further reduced (for example, reduced to 1/3 load output) or light load charging is used, the second set of single-phase isolated AC-DC converter circuits will be closed again, as shown in FIG5 . However, the ripple component generated by the DC (output) current i _dc will be larger.

Incidentally, each single-phase AC-DC converter circuit shown in FIG. 1 and FIG. 2 further includes a first filter capacitor 103-1, 103-2, 103-3 and a second filter capacitor 104-1, 104-2, 104-3. Take the first single-phase AC-DC converter circuit 100-1 as an example: the first single-phase AC-DC converter circuit 100-1 includes a first filter capacitor 103-1 and a second filter capacitor 104-1, which are respectively coupled to the input side and the output side of the first single-phase isolated power factor correction circuit 102-1. Different from the electrolytic capacitor used in the general PFC circuit, its purpose is to filter out the AC component above the double line frequency harmonic of its output, so its capacitance value is high and the size is large.

In contrast, since the three sets of single-phase AC-to-DC conversion circuits 100-1, 100-2, and 100-3 of the present invention receive two phases of the three-phase AC power source in a phase-shifted AC, respectively, it is not necessary to process the double line frequency harmonics. Specifically, the first filter capacitor 103-1 and the second filter capacitor 104-1 of the first single-phase AC-to-DC conversion circuit 100-1 are high-frequency filter capacitors, and their main purpose is to filter out the high-frequency noise generated by the high-frequency switching of the power electronic high-frequency switch components in the first single-phase AC-to-DC conversion circuit 100-1. Therefore, the first filter capacitor 103-1 and the second filter capacitor 104-1 can be implemented by capacitor components with low capacitance value and small size. The filter capacitors of the second single-phase AC-DC conversion circuit 100 - 2 and the third single-phase AC-DC conversion circuit 100 - 3 also have the same characteristics, so they are not described in detail.

Therefore, based on the aforementioned effect of the ripple component of the DC (output) current generated by shutting down one or two single-phase isolation converters under light-load charging conditions to improve system efficiency, the present invention proposes a low-frequency ripple current suppression circuit and a power supply system with a low-frequency ripple current suppression function, as described in detail below.

Please refer to FIG6 , which is a circuit diagram of the low-frequency ripple current suppression circuit of the present invention. As shown in FIG6 , the low-frequency ripple current suppression circuit 10 includes a first boost circuit 11 and a second boost circuit 12. The first boost circuit 11 includes a first inductor L ₁ , a first switch group S ₁ and a first capacitor C ₁ . The second boost circuit 12 includes a second inductor L ₂ , a second switch group S ₂ and a second capacitor C ₂ .

The first inductor _L1 has a first end and a second end, and the first end of the first inductor _L1 is connected to the first DC side DC1. The first switch group _S1 includes a first switch _S11 and a second switch _S12 . The first switch _S11 has a first end and a second end, and the first end of the first switch _S11 is connected to the second end of the first inductor _L1 , and the second end of the first switch _S11 is connected to the equal potential node O. The second switch _S12 has a first end and a second end, and the first end of the second switch _S12 is connected to the second end of the first inductor _L1 . The first capacitor _C1 has a first end and a second end, and the first end of the first capacitor _C1 is connected to the second end of the second switch _S12 , and the second end of the first capacitor _C1 is connected to the equal potential node O.

The second inductor _L2 has a first end and a second end, and the first end of the second inductor _L2 is connected to the second DC side DC2. The second switch group _S2 includes a third switch _S21 and a fourth switch _S22 . The third switch _S21 has a first end and a second end, and the first end of the third switch _S21 is connected to the second end of the second inductor _L2 , and the second end of the third switch _S21 is connected to the equal potential node O. The fourth switch _S22 has a first end and a second end, and the first end of the fourth switch _S22 is connected to the second end of the second inductor _L2 . The second capacitor _C2 has a first end and a second end, and the first end of the second capacitor _C2 is connected to the second end of the fourth switch _S22 , and the second end of the second capacitor _C2 is connected to the equal potential node O.

The low-frequency ripple current suppression circuit 10 receives the DC current i _dc having the ripple component I _rip and absorbs the ripple component I _rip through the first boost circuit 11 and the second boost circuit 12. Therefore, the circuit structure design of the low-frequency ripple current suppression circuit 10 can eliminate the ripple component I _rip of the DC current i _dc .

Incidentally, since the low-frequency ripple current suppression circuit 10 is composed of two boost circuits (i.e., the first boost circuit 11 and the second boost circuit 12), and the energy of the entire low-frequency ripple is borne by the first capacitor _C1 and the second capacitor _C2 respectively, the specification selection range of the first capacitor _C1 and the second capacitor _C2 can be wider and more flexible in terms of withstand voltage or capacitance value, for example, a low withstand voltage capacitor element can be selected or a wider range of selectable capacitance values can be selected.

Furthermore, the low-frequency ripple current suppression circuit 10 further includes a filter circuit 13. The filter circuit 13 includes a first filter capacitor C _f1 and a second filter capacitor C _f2 . The first filter capacitor C _f1 has a first end and a second end, the first end of the first filter capacitor C _f1 is connected to the first DC side DC1, and the second end of the first filter capacitor C _f1 is connected to the equal potential node O. The second filter capacitor C _f2 has a first end and a second end, the first end of the second filter capacitor C _f2 is connected to the second DC side DC2, and the second end of the second filter capacitor C _f2 is connected to the equal potential node O.

Incidentally, the first filter capacitor C _f1 and the second filter capacitor C _f2 are high-frequency filter capacitors, which are used to filter the high-frequency switching signal generated by the first switch S ₁₁ and the second switch S ₁₂ of the first switch group S ₁ , and to filter the high-frequency switching signal generated by the third switch S ₂₁ and the fourth switch S ₂₂ of the second switch group S _2. Therefore, the first filter capacitor C _f1 and the second filter capacitor C _f2 can be implemented by capacitor elements with low capacitance value and small size.

As mentioned above, in order to eliminate the ripple component I _rip of the DC current i _dc , the control method of the first switch group S ₁ of the first boost circuit 11 and the second switch group S ₂ of the second boost circuit 12 is as follows. Incidentally, the control of the first switch S ₁₁ and the second switch S ₁₂ of the first switch group S ₁ and the third switch S ₂₁ and the fourth switch S ₂₂ of the second switch group S ₂ can be achieved by controlling the control signal generated by the controller or the control unit, so the controller or the control unit is not drawn in the figure separately, and it is better to explain it first.

The control signal generated by the controller is synchronously and complementary to the first switch _S11 and the second switch _S12 of the first switch group _S1 . That is, when the first switch _S11 is turned on, the second switch _S12 is turned off; conversely, when the first switch _S11 is turned off, the second switch _S12 is turned on. In addition, the control signal generated by the controller is synchronously and complementary to the third switch _S21 and the fourth switch _S22 of the second switch group _S2 . That is, when the third switch _S21 is turned on, the fourth switch _S22 is turned off; conversely, when the third switch _S21 is turned off, the fourth switch _S22 is turned on.

In one embodiment, the first switch _S11 of the first switch group _S1 and the third switch _S21 of the second switch group _S2 are turned on and off synchronously. In other words, when the first switch _S11 is turned on and the second switch _S12 is turned off, the third switch _S21 is turned on and the fourth switch _S22 is turned off; conversely, when the first switch _S11 is turned off and the second switch _S12 is turned on, the third switch _S21 is turned off and the fourth switch _S22 is turned on.

In another embodiment, the first switch _S11 of the first switch group _S1 and _the third switch _S21 of the second switch group S2 are turned on and off asynchronously. Compared with the first switch _S11 and the third switch _S21 of the previous embodiment that are turned on and off synchronously, in this embodiment, the first switch _S11 and the third switch _S21 are not controlled synchronously, but are controlled with a time difference (phase difference) between the two. For example, when the first switch _S11 is turned on and the second switch _S12 is turned off, after a certain period of time, the third switch _S21 is turned on and the fourth switch _S22 is turned off; conversely, when the first switch _S11 is turned off and the second switch _S12 is turned on, after a certain period of time, the third switch _S21 is turned off and the fourth switch _S22 is turned on. In this way, the ripple component _Irip of the DC current i _dc can also be eliminated.

In addition, there are also different embodiments for the selection of the first switch group _S1 and the second switch group _S2 . In one embodiment, as shown in FIG6, the first switch _S11 and the second switch _S12 of the first switch group _S1 and the third switch _S21 and the fourth switch _S22 of the second switch group _S2 are transistors. Therefore, the control signal generated by the aforementioned controller can be used to control the corresponding on and off of all switches to achieve the effect of synchronous rectification.

In another embodiment, not shown, the first switch _S11 of the first switch set _S1 and the third switch _S21 of the second switch set _S2 are transistors, and the second switch _S12 of the first switch set _S1 and the fourth switch _S22 of the second switch set _S2 are diodes. Therefore, the first switch _S11 of the first switch set _S1 and the third switch _S21 of the second switch set _S2 can be controlled to be turned on and off correspondingly by the control signal generated by the aforementioned controller.

Please refer to FIG7, which is a circuit block diagram of the power system with low-frequency ripple current suppression function of the present invention. The power system with low-frequency ripple current suppression function (hereinafter referred to as the power system) includes three single-phase AC-DC conversion circuits 100-1, 100-2, and 100-3 (see FIG3 for details), namely, a first single-phase AC-DC conversion circuit 100-1, a second single-phase AC-DC conversion circuit 100-2, and a third single-phase AC-DC conversion circuit 100-3. Each single-phase AC-DC converter circuit 100-1, 100-2, 100-3 is correspondingly coupled to each phase of the three-phase AC power source Vin_R, Vin_S, Vin_T (not limited to the delta connection structure of FIG. 1 or the star connection structure of FIG. 2), and the output sides of the three single-phase AC-DC converter circuits 100-1, 100-2, 100-3 are connected to the output node N _O and output the DC current i _dc .

Furthermore, the power system further includes a low-frequency ripple current suppression circuit 10. Since the low-frequency ripple current suppression circuit 10 has been described in detail in the above content, it is not described in detail here. The input side of the low-frequency ripple current suppression circuit 10, that is, the first DC side DC1 is connected to the output node N _O , so as to receive the output DC current i _dc of the three single-phase AC-DC conversion circuits 100-1, 100-2, and 100-3.

As shown in FIG7, it takes the example of shutting down two sets of single-phase isolated AC-DC converter circuits (i.e. shutting down the second single-phase AC-DC converter circuit 100-2 and the third single-phase AC-DC converter circuit 100-3) to illustrate the action of the low-frequency ripple current suppression circuit 10 to eliminate the ripple component I _rip of the DC current i _dc . According to the content recorded in FIG5, it can be known that under the operation of FIG7, the ripple component I _rip of the DC current i _dc is large.

The output DC current i _dc from the output node _NO (i.e., the synthesized output current of the three sets of single-phase AC-to-DC conversion circuits) flows into the first DC side DC1, and is high-frequency filtered by the filter circuit 13, so that the filtered output DC current i _dc flows into the first boost circuit 11 and the second boost circuit 12. As described above, the DC current i _dc flowing into the first boost circuit 11 and the second boost circuit 12 is turned on by the first switch S ₁₁ of the first switch group S ₁ and turned off by the second switch S ₁₂ , so that the ripple component I _rip is stored in the first inductor L ₁ through the first switch S ₁₁ , and then the energy stored in the first inductor L ₁ is released to the first capacitor C 1 through the second switch S ₁₂ by turning off the first switch S ₁₁ of the first switch group S ₁ and turning on the second switch _{S 12 .}

Similarly, by turning on the third switch S ₂₁ of the second switch group S ₂ and turning off the fourth switch S ₂₂ , the ripple component I _{rip is} transferred to the second inductor L ₂ through the third switch S ₂₁ for energy storage, and then by turning off the third switch S ₂₁ of the second switch group S ₂ and turning on the fourth switch S ₂₂ , the energy stored in the second inductor L ₂ is released to the second capacitor C ₂ through the fourth switch S _22. In this way, the ripple component I _rip of the DC current i _dc can be absorbed by the first boost circuit 11 and the second boost circuit 12, so that the output current I _dc flowing to the load is a DC current without the ripple component I _rip .

Please refer to FIG8 , which is a circuit block diagram of the power system with low-frequency ripple current suppression function of the present invention. The power system is used to charge a load 20, wherein the load 20 can be, for example but not limited to, an electric vehicle (EV). Therefore, the low-frequency ripple current suppression circuit 10 is electrically connected between the single-phase AC-DC conversion circuits 100-1, 100-2, 100-3 and the load 20 to eliminate (absorb) the ripple component I _rip of the DC current i _dc , so that the output current I _dc flowing to the load 20 is a DC current without the ripple component I _rip .

In addition, according to the power supply demand of the load 20, the number of the single-phase AC-to-DC conversion circuits 100-1, 100-2, and 100-3 to be closed can be determined to improve the power supply efficiency of the system. Therefore, the power system includes a power controller 30 for receiving information of the load 20. Taking an electric vehicle as an example of the load 20, the power controller 30 can receive the charging information required by the electric vehicle, represented by the load information signal S _LD . Therefore, when the power controller 30 learns the charging information required by the load 20 according to the load information signal S _LD , the power controller 30 can provide a plurality of conversion circuit control signals S _CAD1 , S _CAD2 , and S _CAD3 to control the closing or enabling of the single-phase AC-to-DC conversion circuits 100-1, 100-2, and 100-3 respectively. If the charging information is light load power supply, as shown in FIG8 , the power controller 30 turns off the second single-phase AC-DC converter circuit 100 - 2 and the third single-phase AC-DC converter circuit 100 - 3 , and only the first single-phase AC-DC converter circuit 100 - 1 is required to provide power.

Furthermore, the power controller 30 can also provide a switch control signal S _CRC for controlling the first switch group S ₁ of the first boost circuit 11 and the second switch group S ₂ of the second boost circuit 12, so that the first boost circuit 11 and the second boost circuit 12 can eliminate the ripple component I _rip of the DC current i _dc , so that the output current I _dc flowing to the load 20 is a DC current without the ripple component I _rip .

In summary, the present invention has the following features and advantages:

1. By using a low-frequency ripple current suppression circuit, the system efficiency can be maintained when light load is required, and the ripple component of the DC current can be eliminated, so that the output current flowing to the load is a DC current without ripple components.

2. Through simple circuit design and control, the low-frequency ripple current suppression circuit can be realized.

The above description is only a detailed description and drawings of the preferred specific embodiments of the present invention, but the features of the present invention are not limited thereto and are not intended to limit the present invention. The entire scope of the present invention shall be subject to the following patent application scope. All embodiments that conform to the spirit of the patent application scope of the present invention and similar variations thereof shall be included in the scope of the present invention. Any changes or modifications that can be easily thought of by anyone familiar with the art within the field of the present invention shall be covered by the following patent scope of the present case.

10: Low-frequency ripple current suppression circuit 100-1, 100-2, 100-3: Single-phase AC to DC conversion circuit 101-1, 101-2, 101-3: Rectifier circuit 102-1, 102-2, 102-3: Single-phase isolated power factor correction circuit Vin_R, Vin_S, Vin_T: Three-phase AC _{11: First boost circuit L 1 :} First inductor S ₁ : First switch group S ₁₁ : First switch S ₁₂ : Second switch C 1 : First capacitor ₁₂ : Second boost circuit L 2 : Second inductor S ₂ : Second switch group S ₂₁ : Third switch S ₂₂ : Fourth switch C ₂ : Second capacitor C _f1 : First filter capacitor C _f2 : second filter capacitor O: equipotential node 13: filter circuit 20: load 30: power controller idc: DC current I _rip : ripple component I _dc : output current N _O : output node DC1: first DC side DC2: second DC side V _BAT : battery S _LD : load information signal S _CAD1 , S _CAD2 , S _CAD3 : conversion circuit control signal S _CRC : switch control signal

FIG1 is a circuit block diagram of a first embodiment of a plurality of single-phase AC-to-DC conversion circuits of the present invention.

FIG. 2 is a circuit block diagram of a second embodiment of the multiple single-phase AC-to-DC conversion circuits of the present invention.

FIG3 is a circuit block diagram of the present invention for supplying power to three sets of single-phase AC to DC conversion circuits.

FIG. 4 is a circuit block diagram of two sets of single-phase AC-to-DC conversion circuits for power supply of the present invention.

FIG. 5 is a circuit block diagram of a single-phase AC-to-DC conversion circuit power supply of the present invention.

FIG6 is a circuit diagram of the low-frequency ripple current suppression circuit of the present invention.

FIG. 7 is a circuit block diagram of the power system with low-frequency ripple current suppression function of the present invention.

FIG8 is a circuit block diagram of the power system operation with low-frequency ripple current suppression function of the present invention.

10: Low frequency ripple current suppression circuit

11: First boost circuit

13: Filter circuit

L ₁ : First inductor

S ₁ : First switch group

S ₁₁ : First switch

S ₁₂ : Second switch

C ₁ : First capacitor

12: Second boost circuit

L ₂ : Second inductor

S ₂ : Second switch group

S ₂₁ : Third switch

S ₂₂ : The fourth switch

C ₂ : Second capacitor

C _f1 : First filter capacitor

C _f2 : Second filter capacitor

O: Equipotential node

i _dc : direct current

I _rip : ripple component

I _dc : output current

DC1: First DC side

DC2: Second DC side

V _BAT :Battery

Claims (15)

A low-frequency ripple current suppression circuit comprises: A first boost circuit comprises: A first inductor having a first end and a second end, the first end of the first inductor being connected to a first DC side; A first switch group comprises a first switch and a second switch; the first switch has a first end and a second end, the first end of the first switch is connected to the second end of the first inductor, and the second end of the first switch is connected to an equal potential node; the second switch has a first end and a second end, the first end of the second switch is connected to the second end of the first inductor; and A first capacitor having a first end and a second end, the first end of the first capacitor is connected to the second end of the second switch, and the second end of the first capacitor is connected to the equal potential node; and A second boost circuit comprises: A second inductor having a first end and a second end, the first end of the second inductor being connected to a second DC side; A second switch group including a third switch and a fourth switch; the third switch having a first end and a second end, the first end of the third switch being connected to the second end of the second inductor, and the second end of the third switch being connected to the equal potential node; the fourth switch having a first end and a second end, the first end of the fourth switch being connected to the second end of the second inductor; and A second capacitor having a first end and a second end, the first end of the second capacitor being connected to the second end of the fourth switch, and the second end of the second capacitor being connected to the equal potential node; wherein the low-frequency ripple current suppression circuit receives a DC current having a ripple component, and absorbs the ripple component through the first boost circuit and the second boost circuit. The low-frequency ripple current suppression circuit as described in claim 1 further includes: A filter circuit, including: A first filter capacitor, having a first end and a second end, the first end of the first filter capacitor is connected to the first DC side, and the second end of the first filter capacitor is connected to the equal potential node; and A second filter capacitor, having a first end and a second end, the first end of the second filter capacitor is connected to the second DC side, and the second end of the second filter capacitor is connected to the equal potential node. A low-frequency ripple current suppression circuit as described in claim 1, wherein the first switch and the second switch of the first switch group are turned on and off in a synchronous and complementary manner; and the third switch and the fourth switch of the second switch group are turned on and off in a synchronous and complementary manner. A low-frequency ripple current suppression circuit as described in claim 1, wherein the first switch and the second switch of the first switch group and the third switch and the fourth switch of the second switch group are transistors. A low-frequency ripple current suppression circuit as described in claim 1, wherein the first switch of the first switch group and the third switch of the second switch group are transistors, and the second switch of the first switch group and the fourth switch of the second switch group are diodes. A low-frequency ripple current suppression circuit as described in claim 1, wherein the first switch of the first switch group and the third switch of the second switch group are turned on and off synchronously. A low-frequency ripple current suppression circuit as described in claim 1, wherein the first switch of the first switch group and the third switch of the second switch group are turned on and off asynchronously. A power supply system with a low-frequency ripple current suppression function, comprising: Three single-phase AC-to-DC conversion circuits, each of which is coupled to each phase of an AC power supply of a three-phase AC power supply, and the output sides of the single-phase AC-to-DC conversion circuits are connected to an output node and output a DC current; and A low-frequency ripple current suppression circuit, connected to the output node, comprising: A first boost circuit, comprising a first inductor, a first switch group and a first capacitor; the first switch group comprises a first switch and a second switch; the first inductor is connected to the first switch at a first common point, and is connected between a first DC side and an equal potential node; the second switch is connected in series with the first capacitor, and is connected between the first common point and the equal potential node; and A second boost circuit includes a second inductor, a second switch group, and a second capacitor; the second switch group includes a third switch and a fourth switch; the second inductor is connected to the third switch at a second common point, and is connected between a second DC side and the potential nodes; the fourth switch is connected in series to the second capacitor, and is connected between the second common point and the potential nodes. A power supply system with low-frequency ripple current suppression function as described in claim 8, wherein the first inductor has a first end and a second end, the first end of the first inductor is connected to the first DC side; the first switch has a first end and a second end, the first end of the first switch is connected to the second end of the first inductor, and the second end of the first switch is connected to the equal potential node; the second switch has a first end and a second end, the first end of the second switch is connected to the second end of the first inductor; the first capacitor has a first end and a second end, the first end of the first capacitor is connected to the second end of the second switch, and the second end of the first capacitor is connected to the equal potential node; The second inductor has a first end and a second end, the first end of the second inductor is connected to the second DC side; the third switch has a first end and a second end, the first end of the third switch is connected to the second end of the second inductor, and the second end of the third switch is connected to the equal potential node; the fourth switch has a first end and a second end, the first end of the fourth switch is connected to the second end of the second inductor; the second capacitor has a first end and a second end, the first end of the second capacitor is connected to the second end of the fourth switch, and the second end of the second capacitor is connected to the equal potential node. A power supply system with low-frequency ripple current suppression function as described in claim 8, wherein as the load supplied by the single-phase AC-to-DC conversion circuits decreases, part of the single-phase AC-to-DC conversion circuits can be shut down. The power supply system with low-frequency ripple current suppression function as described in claim 10 further includes: A power supply controller that receives information about the load; Wherein based on the reduction of the load, the power supply controller is used to shut down part of the single-phase AC-to-DC conversion circuits and activate the low-frequency ripple current suppression circuit. A power supply system with low-frequency ripple current suppression function as described in claim 8, wherein the single-phase AC-to-DC conversion circuits are used to charge a battery of an electric vehicle. A power supply system with low-frequency ripple current suppression function as described in claim 8, wherein the single-phase AC-to-DC conversion circuits form a delta connection structure, or the single-phase AC-to-DC conversion circuits form a star connection structure. A power supply system with low-frequency ripple current suppression function as described in claim 8, wherein the first switch and the second switch of the first switch group are synchronously and complementaryly turned on and off; the third switch and the fourth switch of the second switch group are synchronously and complementaryly turned on and off. A power supply system with low-frequency ripple current suppression function as described in claim 8, wherein the first switch of the first switch group and the third switch of the second switch group are turned on and off synchronously.

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