CN211701861U

CN211701861U - Switching power supply circuit

Info

Publication number: CN211701861U
Application number: CN201922306793.0U
Authority: CN
Inventors: 邓建; 黄秋凯; 赵晨
Original assignee: Hangzhou Silergy Semiconductor Technology Ltd
Current assignee: Hangzhou Silergy Semiconductor Technology Ltd
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-10-16
Anticipated expiration: 2029-12-20

Abstract

The utility model discloses a switching power supply circuit, which comprises a high-frequency switch network, a low-frequency AC input signal is received, high-frequency chopping is carried out on the low-frequency AC input signal, and a high-frequency AC signal is output; the primary winding of the transformer receives a high-frequency alternating current signal, and the high-frequency alternating current signal is output from the secondary winding of the transformer after voltage conversion is carried out on the high-frequency alternating current signal; and the rectification module is used for rectifying the output signal of the secondary winding and outputting a direct current signal. The utility model discloses a switching power supply circuit need not the rectifier bridge, directly converts alternating current signal into direct current signal, uses the switch tube of less quantity, has reduced network progression and energy loss, has improved efficiency.

Description

Switching power supply circuit

Technical Field

The utility model relates to a power electronics field, more specifically the utility model relates to a switching power supply circuit that says so.

Background

In daily life, many semiconductor electronic devices require a switching power supply circuit that converts ac power to dc power in order to obtain dc power necessary for operation from an ac utility network. In most cases, in order to satisfy the requirement of safety performance, it is necessary to isolate the load terminal from the power supply terminal. A switching power supply circuit in the prior art is shown in fig. 1, and includes a rectifier bridge, a DC-DC converter, and a transformer, where the rectifier bridge receives an ac input voltage, an output terminal of the rectifier bridge is connected to an input terminal of the DC-DC converter, an output terminal of the DC-DC converter is coupled to a primary winding of the transformer, a secondary winding of the transformer is coupled to a load, and the rectifier bridge converts a received ac signal into a DC signal and transmits energy to the load through the DC-DC converter and the transformer.

Because of the rectifier bridge, the switching power supply circuit in the prior art needs more switching tubes, has larger energy loss and lower efficiency, and is more obvious particularly when the alternating-current input voltage is lower.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model provides a need not the rectifier bridge, directly convert alternating current signal into direct current signal's switching power supply circuit has solved among the prior art because there is the rectifier bridge and the switching tube figure that needs that arouses is more, and energy loss is great, the lower technical problem of efficiency.

The utility model provides a switching power supply circuit, include: the high-frequency switch network receives a low-frequency alternating current input signal, performs high-frequency chopping on the low-frequency alternating current input signal and outputs a high-frequency alternating current signal;

the primary winding of the transformer receives the high-frequency alternating current signal, and outputs the high-frequency alternating current signal from the secondary winding of the transformer after voltage conversion is carried out on the high-frequency alternating current signal;

and the rectification module is used for rectifying the output signal of the secondary winding and outputting a direct current signal.

Preferably, the high-frequency switch network comprises an energy storage module, and when the first loop of the high-frequency switch network works, the low-frequency alternating-current input signal charges the energy storage module and the primary winding; when the second loop of the high-frequency switch network works, the energy storage module discharges the primary winding, and the first loop and the second loop do not work at the same time.

Preferably, the high-frequency switch network further includes a low-frequency alternating-current input end, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and an energy storage module, the low-frequency alternating-current input end, the first switch tube, the second switch tube, the primary winding and the energy storage module are connected to form a first loop, the third switch tube, the fourth switch tube, the primary winding and the energy storage module are connected to form a second loop, and the first loop and the second loop do not work at the same time.

Preferably, the first end of the first switching tube and the first end of the second switching tube are respectively connected to two ports of the low-frequency ac input end, the second end of the first switching tube is connected to the first end of the third switching tube, the second end of the second switching tube is connected to the first end of the fourth switching tube, the second end of the third switching tube is connected to the second end of the fourth switching tube, the energy storage module and the primary winding are connected between the first node and the second node,

the first node is a common end of the first switching tube and the third switching tube, and the second node is a common end of the second switching tube and the fourth switching tube.

Preferably, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are sequentially connected in series, a first end of the first switch tube and a second end of the fourth switch tube are respectively connected with two ports of the low-frequency alternating current input end, the energy storage module and the primary winding are connected between the first node and the second node,

the first node is a common end of a second switching tube and a third switching tube, and the second node is a common end of a fourth switching tube and the low-frequency alternating current input end.

Preferably, the high-frequency switch network comprises a low-frequency alternating current input end, first to eighth switch tubes, a third capacitor, a fourth capacitor and an energy storage module, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are sequentially connected in series, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube are sequentially connected in series, the first end of the first switch tube and the first end of the fifth switch tube are respectively connected with two ports of the low-frequency alternating current input end, the second end of the fourth switch tube is connected with the second end of the eighth switch tube, one end of the third capacitor is connected with a common end of the first switch tube and the second switch tube, the other end of the third switch tube is connected with a common end of the third switch tube and the fourth switch tube, one end of the fourth capacitor is connected with a common end of the fifth switch tube and the sixth switch tube, the other end of the energy storage module is connected with the common end of the seventh switching tube and the eighth switching tube, the energy storage module and the primary winding are connected between the first node and the second node,

the first node is a common end of a second switching tube and a third switching tube, and the second node is a common end of a sixth switching tube and a seventh switching tube.

Preferably, the energy storage module includes N inductors and/or N capacitors, where N is greater than or equal to 0.

Preferably, the high frequency switching network operates in one of a resonant state and a half bridge buck state.

Preferably, the energy storage module includes a first capacitor, and the first capacitor is connected in series with the primary winding and then connected between the first node and the second node.

Preferably, the energy storage module further includes a first inductor, and the first inductor, the first capacitor and the primary winding are connected in series and then connected between the first node and the second node.

Preferably, the energy storage module further includes a second capacitor, and the second capacitor is connected in parallel with the primary winding.

Preferably, during a positive half cycle of the low-frequency alternating-current input signal, the first switching tube and the third switching tube are always conducted, and the second switching tube and the fourth switching tube are conducted alternately in a high-frequency PWM manner; during the negative half period of the low-frequency alternating current input signal, the second switching tube and the fourth switching tube are always conducted, and the first switching tube and the third switching tube are conducted alternately in a high-frequency PWM mode.

Preferably, during a positive half cycle of the low-frequency alternating-current input signal, the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are always on, and the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are turned on or off in a high-frequency PWM manner; and when the negative half period of the low-frequency alternating current input signal is in the positive half period, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are always conducted, and the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are conducted or disconnected in a high-frequency PWM mode.

Preferably, when the high-frequency switching network operates in the first mode, during a positive half cycle of a low-frequency alternating-current input signal, the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are always on, the first switching tube and the second switching tube are simultaneously turned on or off, the third switching tube and the fourth switching tube are simultaneously turned on or off, and the first switching tube and the second switching tube, the third switching tube and the fourth switching tube are alternately turned on in a high-frequency PWM manner; when the negative half period of the low-frequency alternating-current input signal is detected, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are always conducted, the fifth switch tube and the sixth switch tube are conducted or turned off at the same time, the seventh switch tube and the eighth switch tube are conducted or turned off at the same time, and the fifth switch tube and the sixth switch tube and the seventh switch tube and the eighth switch tube are alternately conducted in a high-frequency PWM mode.

Preferably, when the high-frequency switching network operates in the second mode, during a positive half cycle of the low-frequency alternating-current input signal, the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are always on, the first switching tube and the fourth switching tube are turned on or off in an opposite manner, and the second switching tube and the third switching tube are turned on or off in an opposite manner; during a negative half period of a low-frequency alternating-current input signal, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are always conducted, the fifth switching tube and the eighth switching tube are conducted or disconnected in an opposite mode, and the sixth switching tube and the seventh switching tube are conducted or disconnected in an opposite mode.

Preferably, the switching power supply circuit is used as a high-frequency transformer, and the switching state of the high-frequency switching network is controlled in an open loop mode.

Preferably, the switching state of the high frequency switching network is controlled such that the rectifier module output voltage and/or current meets the load requirements.

Preferably, the switching frequency of the high frequency switching network is controlled such that the rectifier module output voltage and/or current meets the load requirements.

Preferably, the high frequency switching network operates only for a period of time in a cycle of the low frequency ac input signal such that the rectifier module outputs a current in the form of pulses.

Preferably, when the absolute value of the low-frequency alternating-current input signal voltage is greater than a first threshold value, the high-frequency switch network is operated, otherwise, the high-frequency switch network is not operated, so that the rectifier module outputs current in a pulsating mode.

Preferably, the high-frequency switching network further includes an EMI filter circuit, and the EMI filter circuit is disposed at the low-frequency ac input end and controls a switching state of the high-frequency switching network so that an input current changes synchronously with the low-frequency ac input signal.

Preferably, the rectification module is one of a full-wave rectification circuit and a full-bridge rectification circuit.

Preferably, the high-frequency switch network further includes a low-frequency ac input terminal, a first switch tube, and a second switch tube, and the low-frequency ac input terminal, the first switch tube, the second switch tube, and the primary winding are connected in series to form a loop.

Preferably, the rectifier module includes first rectifier tube, second rectifier tube, inductance and electric capacity, the one end of series structure after inductance and electric capacity establish ties is connected the first end of first rectifier tube, the second end of first rectifier tube is connected the first end of secondary winding, the other end of series structure connects the intermediate end of secondary winding, the first end of second rectifier tube is connected the second end of secondary winding, the second end of second rectifier tube is connected first rectifier tube with the common port of series structure.

Preferably, the rectifying module includes a first rectifying tube, a second rectifying tube, a third rectifying tube, a fourth rectifying tube, a capacitor and an inductor, one end of a series structure composed of the inductor and the capacitor in series is connected to the first end of the first rectifying tube and the first end of the second rectifying tube, the other end of the series structure is connected to the second end of the third rectifying tube and the second end of the fourth rectifying tube, the second end of the first rectifying tube is connected to the first end of the third rectifying tube, the second end of the second rectifying tube is connected to the first end of the fourth rectifying tube, the secondary winding is connected between the first node and the second node,

wherein, the first node is the first rectifier tube with the common terminal of third rectifier tube, the second node is the second rectifier tube with the common terminal of fourth rectifier tube.

Preferably, during a positive half cycle of the low-frequency alternating-current input signal, the first switching tube is always turned on or off, and the second switching tube is turned on or off in a high-frequency PWM manner; and when the negative half period of the low-frequency alternating current input signal is in the positive half period, the second switching tube is always switched on or off, and the first switching tube is switched on or off in a high-frequency PWM mode.

Compared with the prior art, the technical scheme of the utility model have following advantage: the utility model discloses a switching power supply circuit directly converts low frequency AC input signal into high frequency AC signal, and rethread transformer and secondary rectifier circuit change high frequency AC signal into direct current output. The utility model discloses a switching power supply circuit need not the rectifier bridge, directly converts alternating current signal into direct current signal, uses the switch tube of less quantity, has reduced network progression and energy loss, has improved efficiency. And the utility model discloses can switch power supply circuit be converting alternating current signal into direct current signal's in-process, realized power factor's adjustment function.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 is a circuit schematic of a prior art switching power supply circuit;

fig. 2 is a schematic block diagram of the switching power supply circuit of the present invention;

fig. 3 is a schematic circuit diagram of a switching power supply circuit according to a first embodiment of the present invention;

fig. 4 is a waveform diagram illustrating the operation of the switching power supply circuit during the positive half cycle of the input voltage according to the first embodiment of the present invention;

fig. 5 is a waveform diagram illustrating the operation of the switching power supply circuit during the negative half cycle of the input voltage according to the first embodiment of the present invention;

fig. 6 is a signal waveform diagram of a switching power supply circuit according to a first embodiment of the present invention;

fig. 7 is a circuit diagram of a switching power supply circuit according to a second embodiment of the present invention;

fig. 8 is a waveform diagram illustrating the operation of a switching power supply circuit according to a second embodiment of the present invention;

fig. 9 is a circuit diagram of a switching power supply circuit according to a third embodiment of the present invention;

fig. 10 is a waveform diagram illustrating the operation of a switching power supply circuit according to a third embodiment of the present invention;

fig. 11 is a signal waveform diagram of a switching power supply circuit according to a third embodiment of the present invention in a first mode;

fig. 12 is a signal waveform diagram of a switching power supply circuit according to a third embodiment of the present invention in a second mode;

fig. 13 is a schematic circuit diagram of a switching power supply circuit according to a fourth embodiment of the present invention;

fig. 14 is a schematic circuit diagram of a switching power supply circuit according to a fifth embodiment of the present invention;

fig. 15 is an operation waveform diagram of the switching power supply of the fourth and fifth embodiments of the present invention;

fig. 16 is a schematic circuit diagram of the switching power supply circuit of the present invention applied to power factor adjustment;

fig. 17 is a waveform diagram of the input voltage and current after the power factor of the switching power supply circuit of the present invention is adjusted;

fig. 18 is a schematic circuit diagram of the switching power supply circuit of the present invention applied to output current control;

fig. 19 is a waveform diagram illustrating the operation of the driving circuit of the switching power supply circuit according to the present invention;

fig. 20 is a schematic circuit diagram of the switching power supply circuit of the present invention applied to output an intermittent current;

fig. 21 is a waveform diagram of the switching power supply circuit applied to output discontinuous current.

Detailed Description

The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in detail. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

Meanwhile, it should be understood that, in the following description, a "circuit" refers to a conductive loop constituted by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.

Fig. 2 is a schematic block diagram of the switching power supply circuit of the present invention, the switching power supply circuit includes:

a high-frequency switch network 1 for receiving a low-frequency alternating current input signal (generally, a power-frequency alternating current signal), performing high-frequency chopping on the low-frequency alternating current input signal, and outputting a high-frequency alternating current signal;

the primary winding of the transformer 2 receives a high-frequency alternating current signal, and the high-frequency alternating current signal is output from the secondary winding of the transformer 2 after voltage conversion is carried out on the high-frequency alternating current signal;

and the rectification module 3 is used for rectifying the output signal of the secondary winding and outputting a direct current signal.

It should be noted that the low-frequency ac input signal may be a sine wave, or may be another type of ac signal such as a rectangular wave, for convenience of description, the following portions of the present invention are all described by sine waves, but the present invention is not limited thereto. The transformer can be ordinary transformer, also can be piezoelectric transformer, the utility model discloses do not restrict to this.

Further, the high-frequency switch network includes an energy storage module, when the first loop of the high-frequency switch network operates, the low-frequency ac input signal charges the energy storage module and the primary winding, and the polarity of the voltage on the primary winding does not necessarily correspond to the polarity of the low-frequency ac input signal, and may be the same or opposite; when the second loop of the high-frequency switch network works, the energy storage module discharges the primary winding, and the first loop and the second loop do not work at the same time.

Further, the energy storage module includes N inductors and/or N capacitors, where N is greater than or equal to 0. Preferably, the energy storage module includes a capacitor and a first inductor. Preferably, the energy storage module comprises a capacitor. Preferably, the energy storage module comprises two capacitors and an inductor.

Furthermore, the high-frequency switch network further comprises a low-frequency alternating current input end, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and an energy storage module, the low-frequency alternating current input end, the first switch tube, the second switch tube, the primary winding and the energy storage module are connected to form a first loop, the third switch tube, the fourth switch tube, the primary winding and the energy storage module are connected to form a second loop, and the first loop and the second loop do not work at the same time.

Further, the high frequency switching network operates in one of a resonant state and a half bridge buck state.

The switch tube of the present invention can be implemented by various existing electrically controllable switch devices, such as Metal Oxide Semiconductor Field Effect Transistor (MOSFET), Bipolar Junction Transistor (BJT), or Insulated Gate Bipolar Transistor (IGBT), without limitation.

The output end of the switching power supply circuit of the utility model can be directly coupled with a load to supply power, for example, the output end of the switching power supply circuit supplies power to an LED, and a battery is charged, etc., the switching power supply circuit of the utility model can control the output voltage and/or current by single-stage active control, frequency regulation, etc., and at the moment, if the output voltage or/and current is controlled, the control of the output voltage or/and current can be completed by regulating the switching state of the high-frequency switch network 1, such as the switching frequency; switching power supply circuit also can the single-stage not active control frequency, open loop output will switching power supply circuit uses as high frequency transformer. The switching power supply circuit of the present invention can further connect a second stage circuit at the rear stage, the second stage circuit is coupled to the load to supply power to the load, for example, to supply power to the LED, to charge the battery, etc., the second stage circuit is generally a DC-DC circuit, and at this time, if the output voltage or/and the current is controlled, the control of the output voltage or/and the current can be completed by adjusting the switching state of the high frequency switching network and/or the DC-DC circuit, for example, the switching frequency; when the control of the output voltage or/and current of the DC-DC circuit is done by adjusting only the switching frequency of the DC-DC circuit, the switching frequency in the high frequency switching network is open loop control. Further, the switching power supply circuit can be applied to the PFC. Furthermore, the utility model discloses switch among the rectifier module can be by former limit control, also can carry out the independent control by the secondary, does not restrict to this. The utility model discloses a switching power supply circuit directly converts low frequency AC input signal into high frequency AC signal, and rethread transformer and secondary rectifier circuit change high frequency AC signal into direct current output. The utility model discloses a switching power supply circuit need not the rectifier bridge, directly converts alternating current signal into direct current signal, uses the switch tube of less quantity, has reduced network progression and energy loss, has improved efficiency, has solved among the prior art because there is the rectifier bridge and the needs switch tube figure that arouses is more, and energy loss is great, the lower technical problem of efficiency.

Fig. 3 is a schematic circuit diagram of a switching power supply circuit according to a first embodiment of the present invention; the switching power supply circuit comprises a high-frequency switching network 1, a transformer 2 and a rectification module 3, wherein the high-frequency switching network 1 comprises a low-frequency alternating current input end, a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4 and an energy storage module, a first end of a first switching tube Q1 and a first end of a second switching tube Q2 are respectively connected with two ports N, L of the low-frequency alternating current input end, a second end of the first switching tube Q1 is connected with a first end of a third switching tube Q3, a second end of the second switching tube Q2 is connected with a first end of a fourth switching tube Q4, a second end of the third switching tube Q3 is connected with a second end of a fourth switching tube Q4, the energy storage module and a winding L2 of the transformer 2 are connected between a first node and a second node, the first node is a common end of the first switching tube Q1 and the third switching tube Q3, the second node is a common terminal of the second switch tube Q2 and the fourth switch tube Q4.

The energy storage module comprises N inductors and/or N capacitors, wherein N is larger than or equal to 0. In this embodiment, the energy storage module includes a first inductor L1 and a first capacitor C1, and the first capacitor C1, the first inductor L1 and the primary winding L2 are connected in series between a first node and a second node. In other embodiments, the energy storage module may include only a first capacitor, and the first capacitor and the primary winding are connected in series between a first node and a second node; in other embodiments, the energy storage module includes a first capacitor, a second capacitor, and a first inductor, the first capacitor, the first inductor, and the primary winding are connected in series between a first node and a second node, and the second capacitor and the primary winding are connected in parallel; in some embodiments, the energy storage module includes only a first inductor, and the first inductor and the primary winding are connected in series between the first node and the second node. In another embodiment, the energy storage module may be in other inductor and capacitor combination forms, all within the scope of the present invention.

Transformer 2 still includes two secondary windings L3, L4, two secondary windings are in the same place in series, secondary winding L3 with the common terminal of secondary winding L4 is the middle-end of secondary winding, the other end of secondary winding L3 is the first end of secondary winding, the other end of secondary winding L4 is the second end of secondary winding. In other embodiments, the transformer 2 includes a secondary winding having a center tap, the center tap is a middle end of the secondary winding, and the other two ends are a first end and a second end of the secondary winding respectively.

The rectifying module 3 is a full-wave rectifying circuit, and includes a first rectifying tube D1 and a second rectifying tube D2, wherein a first end of the first rectifying tube D1 is connected to a first end of the secondary winding, a second end of the first rectifying tube D1 is used as a high-potential end of the output voltage, a first end of the second rectifying tube D2 is connected to a second end of the secondary winding, and a second end of the second rectifying tube D2 is connected to a second end of the first rectifying tube D1. And the middle end of the secondary winding is used as a low potential end of the output voltage. In other embodiments, the rectifier module 3 may be a full-bridge rectifier circuit or other types of rectifier circuits, and the present invention is not limited thereto. In the present embodiment, the rectifier is a diode, and various existing electrically controllable switching devices, such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a Bipolar Junction Transistor (BJT), or an Insulated Gate Bipolar Transistor (IGBT), may be used without limitation. When the rectifier tube of the secondary side rectifying module is the existing electrically controllable switching device, the primary side can be used for controlling the on and off of the rectifier tube, and the secondary side can also be used for controlling.

In this embodiment, the switching power supply circuit further includes a capacitor C2 connected to the output terminal of the rectifier module 3 for filtering the output signal of the rectifier module 3.

Fig. 4 is a diagram showing an operation waveform of the switching power supply circuit of the first embodiment of the present invention during the positive half period of the input voltage; fig. 4(a) is a flow chart of an average current of the input voltage in a positive half period, and fig. 4(b) is an operation waveform chart of the switching power supply circuit of the input voltage in the positive half period. As shown in fig. 4, when the low-frequency ac input signal Vin is a positive half-cycle, that is, the voltage at the L terminal is greater than the voltage at the N terminal, the first switching tube Q1 and the third switching tube Q3 are always turned on, and the second switching tube Q2 and the fourth switching tube Q4 are alternately turned on in a high-frequency PWM manner, at this time, in the first embodiment, the first capacitor C1, the first inductor L1 and the primary winding L2 form an LLC resonant circuit, and the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 work in a resonant state, so that high-frequency chopping is achieved; if the first capacitor C1 is too large to resonate, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 work in a half-bridge buck state at the moment, so that high-frequency chopping is realized; the frequency of the high frequency PWM is much greater than the frequency of the low frequency ac input signal.

When the second switching tube Q2 is turned on and the fourth switching tube Q4 is turned off, the low-frequency ac input signal Vin charges the energy storage module and the primary winding, and at this time, the direction of the average current is shown by a dashed line with an arrow in fig. 4 (a); when the second switching tube Q2 is turned off and the fourth switching tube Q4 is turned on, the energy storage module discharges to the primary winding, and the direction of the average current is shown by a dotted line with an arrow in fig. 4 (a).

Fig. 5 is a diagram showing an operation waveform of the switching power supply circuit of the first embodiment of the present invention during the negative half cycle of the input voltage; fig. 4(a) is a flow chart of the average current of the input voltage in the negative half cycle, and fig. 4(b) is an operation waveform chart of the switching power supply circuit in the negative half cycle of the input voltage. As shown in fig. 4, when the low-frequency ac input signal Vin has a negative half-cycle, that is, the voltage at the N terminal is greater than that at the L terminal, the second switching tube Q2 and the fourth switching tube Q4 are always turned on, and the first switching tube Q1 and the third switching tube Q3 are alternately turned on in a high-frequency PWM manner, at this time, in the first embodiment, the first capacitor C1, the first inductor L1 and the primary winding L2 form an LLC resonant circuit, and the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 work in a resonant state, thereby implementing high-frequency chopping; if the first capacitor C1 is too large to resonate, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 work in a half-bridge buck state at the moment, so that high-frequency chopping is realized; the frequency of the high frequency PWM is much greater than the frequency of the low frequency ac input signal.

When the first switching tube Q1 is turned on and the third switching tube Q3 is turned off, the low-frequency ac input signal Vin charges the energy storage module and the primary winding, and at this time, the direction of the average current is shown by a dashed line with an arrow in fig. 4 (a); when the first switching tube Q1 turns off and the third switching tube Q3 turns on, the energy storage module discharges the primary winding, and the direction of the average current is shown by the dotted line with an arrow in fig. 4 (a).

Fig. 6 is a signal waveform diagram of a switching power supply circuit according to a first embodiment of the present invention; as shown in fig. 6, when the low-frequency ac input signal Vin is in a positive half-cycle, the second switching tube Q2 and the fourth switching tube Q4 are alternately turned on in a high-frequency PWM manner; when the input voltage Vin is in a negative half period, the first switching tube Q1 and the third switching tube Q3 are alternately conducted in a high-frequency PWM manner.

It should be noted that, the complementary conduction is a special case of alternate conduction, and the efficiency is the highest when the complementary conduction is performed, but in order to prevent the transient short-circuit phenomenon caused by the off delay of the switching tube, a dead time is inserted between the state switching of the second switching tube Q2 and the fourth switching tube Q4 or between the first switching tube Q1 and the third switching tube Q3. The subsequent alternate conduction includes such a situation, and is not described in detail.

Fig. 7 is a circuit diagram of a switching power supply circuit according to a second embodiment of the present invention; the switching power supply circuit comprises a high-frequency switching network 1, a transformer 2 and a rectification module 3, wherein the high-frequency switching network 1 comprises a low-frequency alternating-current input end, a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4 and an energy storage module, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are sequentially connected in series, a first end of the first switching tube Q1 and a second end of the fourth switching tube Q4 are respectively connected with two ports N, L of the low-frequency alternating-current input end, the energy storage module and the primary winding L2 are connected between a first node and a second node,

the first node is a common terminal of a second switching tube Q2 and a third switching tube Q3, and the second node is a common terminal of a fourth switching tube Q4 and the low-frequency alternating current input end.

The energy storage module, the transformer 2 and the rectification module 3 in this embodiment are similar to the energy storage module, the transformer and the rectification module in this embodiment, and are not described herein again.

Fig. 8 is a waveform diagram illustrating the operation of a switching power supply circuit according to a second embodiment of the present invention; when the low-frequency alternating-current input signal Vin is a positive half cycle, that is, the voltage at the L end is greater than the N end, the first switching tube Q1 and the third switching tube Q3 are always conducted, the second switching tube Q2 and the fourth switching tube Q4 are conducted alternately in a high-frequency PWM manner, at this time, in the second embodiment, the first capacitor C1, the first inductor L1 and the primary winding L2 form an LLC resonant circuit, and the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 work in a resonant state; if the first capacitor is too large to resonate, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 operate in a half-bridge buck state. When the low-frequency alternating-current input signal Vin is a negative half cycle, that is, the voltage at the N end is greater than that at the L end, the second switching tube Q2 and the fourth switching tube Q4 are always conducted, the first switching tube Q1 and the third switching tube Q3 are conducted alternately in a high-frequency PWM manner, at this time, in the second embodiment, the first capacitor C1, the first inductor L1 and the primary winding L2 form an LLC resonant circuit, and the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 work in a resonant state; if the first capacitor is too large to resonate, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 work in a half-bridge buck state at the moment, and therefore high-frequency chopping is achieved.

Fig. 9 is a circuit diagram of a switching power supply circuit according to a third embodiment of the present invention; the switching power supply circuit comprises a high-frequency switching network 1, a transformer 2 and a rectification module 3, wherein the high-frequency switching network 1 comprises a low-frequency alternating current input end, a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4, a fifth switching tube Q5, a sixth switching tube Q6, a seventh switching tube Q7, an eighth switching tube Q8, a capacitor C3, a capacitor C4 and an energy storage module, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are sequentially connected in series, the fifth switching tube Q5, the sixth switching tube Q6, the seventh switching tube Q7 and the eighth switching tube Q8 are sequentially connected in series, a first end of the first switching tube Q1 and a first end of the fifth switching tube Q5 are respectively connected with two low-frequency input ends L, N of the second switching tube Q4, and a second end 4 of the second switching tube Q4 and a common end 4 of the second switching tube 4 are respectively connected with a second end 4 of the capacitor C4, the other end of the capacitor C4 is connected with the common end of the third switch tube Q3 and the fourth switch tube Q4, one end of the capacitor C4 is connected with the common end of the fifth switch tube Q5 and the sixth switch tube Q6, the other end of the capacitor C4 is connected with the common end of the seventh switch tube Q7 and the eighth switch tube Q8, the energy storage module and the primary winding are connected between the first node and the second node,

the first node is a common terminal of the second switch tube Q2 and the third switch tube Q3, and the second node is a common terminal of the sixth switch tube Q6 and the seventh switch tube Q7.

The energy storage module, the transformer 2 and the rectification module 3 in this embodiment are similar to the energy storage module, the transformer and the rectification module in the first embodiment, and are not described herein again.

Fig. 10 is a waveform diagram illustrating the operation of a switching power supply circuit according to a third embodiment of the present invention; when the low-frequency alternating-current input signal Vin is a positive half-cycle, that is, the voltage at the L terminal is greater than the N terminal, the fifth switching tube Q5, the sixth switching tube Q6, the seventh switching tube Q7 and the eighth switching tube Q8 are always turned on, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are turned on or off in a high-frequency PWM manner, at this time, in the third embodiment, the first capacitor C1, the first inductor L1 and the primary winding L2 form an LLC resonant circuit, and the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 operate in a resonant state; if the first capacitor is too large to resonate, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 operate in a half-bridge buck state. When the low-frequency alternating-current input signal Vin is a negative half-cycle, that is, the voltage at the N end is greater than that at the L end, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are always on, the fifth switching tube Q5, the sixth switching tube Q6, the seventh switching tube Q7 and the eighth switching tube Q8 are turned on or off in a high-frequency PWM manner, at this time, in the third embodiment, the first capacitor C1, the first inductor L1 and the primary winding L2 form an LLC resonant circuit, and the fifth switching tube Q5, the sixth switching tube Q6, the seventh switching tube Q7 and the eighth switching tube Q8 work in a resonant state; if the first capacitor is too large to resonate, the fifth switching tube Q5, the sixth switching tube Q6, the seventh switching tube Q7 and the eighth switching tube Q8 work in a half-bridge buck state, so that high-frequency chopping is realized.

The high-frequency switch network 1 of the third embodiment in fig. 10 can operate in the first mode, i.e., the two-level mode, and can also operate in the second mode, i.e., the three-level mode. When the high frequency switch network 1 of the third embodiment operates in the first mode, i.e., the two-level mode, signal waveforms are as shown in fig. 11, when the low frequency ac input signal Vin is a positive half cycle, i.e., the voltage at the L terminal is greater than the N terminal, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 are always turned on, the first switch tube Q1 and the second switch tube Q2 are turned on or off at the same time, the third switch tube Q3 and the fourth switch tube Q4 are turned on or off at the same time, and the first switch tube Q1 and the second switch tube Q2 and the third switch tube Q3 and the fourth switch tube Q4 are alternately turned on in the high frequency PWM manner. When Vin is a negative half-cycle, that is, the voltage at the N terminal is greater than the voltage at the L terminal, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are always turned on, the fifth switching tube Q5 and the sixth switching tube Q6 are turned on or off at the same time, the seventh switching tube Q7 and the eighth switching tube Q8 are turned on or off at the same time, and the fifth switching tube Q5 and the sixth switching tube Q6, the seventh switching tube Q7 and the eighth switching tube Q8 are alternately turned on in a high-frequency PWM manner.

When the high frequency switch network 1 of the third embodiment operates in the second mode, i.e., the three-level mode, the signal waveforms are as shown in fig. 12, when Vin is a positive half-cycle, i.e., the voltage at the L terminal is greater than that at the N terminal, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 are always turned on, the first switch tube Q1 and the fourth switch tube Q4 are turned on or off in an opposite manner, and the second switch tube Q2 and the third switch tube Q3 are turned on or off in an opposite manner; when Vin is a negative half-cycle, that is, the voltage at the N terminal is greater than that at the L terminal, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are always turned on, the fifth switching tube Q5 and the eighth switching tube Q8 are turned on or off in an opposite manner, and the sixth switching tube Q6 and the seventh switching tube Q7 are turned on or off in an opposite manner.

Fig. 13 is a schematic circuit diagram of a switching power supply circuit according to a fourth embodiment of the present invention; the switching power supply circuit comprises a high-frequency switching network 1, a transformer 2 and a rectifying module 3, wherein the high-frequency switching network 1 comprises a low-frequency alternating current input end, a first switching tube Q1 and a second switching tube Q2, and the low-frequency alternating current input end, the first switching tube Q1, the second switching tube Q2 and a primary winding L2 are connected in series to form a loop.

Rectifier module 3 includes first rectifier tube D1, second rectifier tube D2, inductance L and electric capacity C, the one end of the series structure after inductance L and electric capacity C establish ties is connected first rectifier tube D1's first end, first rectifier tube D1's second end is connected the first end of secondary winding, the other end of series structure is connected the middle-end of secondary winding, second rectifier tube D2's first end is connected the second end of secondary winding, second rectifier tube D2's second end is connected first rectifier tube D1 with the common port of series structure. In the present embodiment, the rectifier is a diode, and various existing electrically controllable switching devices, such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a Bipolar Junction Transistor (BJT), or an Insulated Gate Bipolar Transistor (IGBT), may be used without limitation. When the rectifier tube of the secondary side rectifying module is the existing electrically controllable switching device, the primary side can be used for controlling the on and off of the rectifier tube, and the secondary side can also be used for controlling.

The energy storage module and the transformer 2 in this embodiment are similar to those in the first embodiment, and are not described herein again.

Fig. 14 is a schematic circuit diagram of a switching power supply circuit according to a fifth embodiment of the present invention; the switching power supply circuit comprises a high-frequency switching network 1, a transformer 2 and a rectifying module 3, wherein the transformer 2 comprises a primary winding L2 and a secondary winding L3, the high-frequency switching network 1 comprises a low-frequency alternating current input end, a first switching tube Q1 and a second switching tube Q2, and the low-frequency alternating current input end, the first switching tube Q1, the second switching tube Q2 and the primary winding L2 are connected in series to form a loop.

The rectifying module 3 comprises a first rectifying tube S1, a second rectifying tube S2, a third rectifying tube S3, a fourth rectifying tube S4, a capacitor C and an inductor L, one end of a series structure formed by the inductance L and the capacitance C in series is connected with the first end of the first rectifier tube S1 and the first end of the second rectifier tube S2, the other end of the series structure is connected with the second end of the third rectifier tube S3 and the second end of the fourth rectifier tube S4, a second end of the first rectifier tube S1 is connected to a first end of the third rectifier tube S3, a second end of the second rectifier tube S2 is connected to a first end of the fourth rectifier tube S4, the secondary winding L3 is connected between a first node and a second node, wherein the first node is a common end of the first rectifier tube S1 and the third rectifier tube S3, the second node is a common end of the second rectifier tube S2 and the fourth rectifier tube S4. In this embodiment, the rectifier is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a diode, or other existing electrically controllable switching devices, such as a Bipolar Junction Transistor (BJT), or an Insulated Gate Bipolar Transistor (IGBT), which is not limited herein. When the rectifier tube of the secondary side rectifying module is the existing electrically controllable switching device, the primary side can be used for controlling the on and off of the rectifier tube, and the secondary side can also be used for controlling.

The energy storage module in this embodiment is similar to the energy storage module in the first embodiment, and details are not described here.

The operating waveform diagrams of the switching power supply circuits according to the fourth and fifth embodiments of the present invention are shown in fig. 15; when the low-frequency ac input signal Vin is a positive half-cycle, that is, the voltage at the L terminal is greater than that at the N terminal, the first switching tube Q1 is always turned on, the second switching tube Q2 is turned on in a high-frequency PWM manner, or the first switching tube Q1 is always turned off (the body diode of the first switching tube Q1 is turned on), the second switching tube Q2 is turned on in a high-frequency PWM manner, and at this time, the switching power supply circuit of this embodiment operates in a Buck state; when the Vin is in a negative half-cycle, that is, the voltage at the N terminal is greater than that at the L terminal, the second switch tube Q2 is always turned on, the first switch tube Q1 is turned on in a high-frequency PWM manner, or the second switch tube Q2 is always turned off (the body diode of the second switch tube Q2 is turned on), the first switch tube Q1 is turned on in a high-frequency PWM manner, and at this time, the switching power supply circuit of this embodiment operates in a Buck state.

The utility model discloses a switching power supply circuit can be through the on-off state of control high frequency switch network for input current Iin's envelope curve follows the sine wave synchronous variation of low frequency AC input signal Vin, thereby accomplishes power factor adjustment function (PFC). For convenience of illustration, the first embodiment is described below, but any other embodiment can be applied to power factor adjustment, and the method is similar to the method applied to power factor adjustment.

As shown in fig. 16, the switching power supply circuit in the first embodiment further includes an EMI filter circuit 4 and a control circuit 5, the EMI filter circuit 4 is disposed at an input end of the low-frequency ac input signal Vin, and the control circuit 5 controls a switching state of the high-frequency switching network 1, so that the input current Iin is changed synchronously with a sine wave of the low-frequency ac input signal Vin, so as to implement a power factor adjustment (PFC) function.

The EMI filter circuit 4 comprises a capacitor C4, a capacitor C5 and an inductor L5, wherein the capacitor C4 and the capacitor C5 are both connected in parallel with an input end of a low-frequency alternating current input signal Vin, and the inductor L5 is connected between the capacitor C4 and the capacitor C5. It should be understood that the EMI filter circuit 4 may take other forms, and the present invention is not limited thereto.

The control circuit 5 includes a first error amplifier Gm1, a second error amplifier Gm2, and a drive circuit. Wherein the first error amplifier Gm1 is used for comparing the input current sampling signal V_IinAnd a current reference signal Iref to obtain a first error signal V1. The second error amplifier Gm2 is used for comparing the input current sampling signal V_IinAnd the first error signal V1 to obtain a second error signal V2. The driving circuit is used for generating a driving signal according to the second error signal V2 to control the switching state of the switching tube in the high-frequency switching network 1.

Specifically, the current reference signal Iref is input to the non-inverting input terminal of the first error amplifier Gm1, and the current sampling signal V is input to the inverting input terminal thereof_Iin. The input current sampling signal is a voltage signal and is used for representing the input current Iin; the current reference signal Iref is used to characterize the current that varies in synchronism with the sine wave of the low frequency ac input signal Vin. Thus, an input current control loop may be formed to control the input current Iin towards the current reference signal Iref. The first error signal V1 is used as a reference signal and is input to the non-inverting input terminal of the second error amplifier Gm2, and the inverting input terminal of the second error amplifier Gm2 is input with the input current sampling signal V_IinBy comparing the input current sampling signal V_IinAnd the first error signal V1 to obtain a second error signal V2. The driving circuit comprises a first comparator comp1, one end of the comparator receives a second error signal V2, the other end of the first comparator comp1 receives a ramp signal Vslope, and the comparator outputs a driving signal for controlling the driving module to generate control signals G1 and G2, so as to control the switching state of the switching tubes in the high-frequency switching network 1. Because the utility model discloses switching power supply circuit all has only two sets of switch tubes to switch on in turn in the positive and negative half of alternating current input signal Vin, and control signal G1 and G2 are used for controlling at the positive and negative half of alternating current input signal VinAnd the two groups of switching tubes are alternately conducted.

The control circuit 5 further includes a capacitor C6 connected between the output terminal of the first error amplifier Gm1 and the ground terminal for converting the current signal output by the first error amplifier Gm1 into a voltage signal, i.e., a first error signal V1. The control circuit 5 further includes a capacitor C7 connected between the output terminal of the second error amplifier Gm2 and the ground terminal for converting the current signal outputted from the second error amplifier into a corresponding voltage signal, i.e., a second error signal V2.

The utility model discloses switching power supply circuit is shown in fig. 17 through the work waveform after the power factor adjustment, and input current Iin follows the sine wave synchronous variation of alternating current input signal Vin. The utility model discloses a control circuit 5 for accomplishing power factor adjustment is only an embodiment, control circuit 5 also can utilize other modes to carry out power factor adjustment, the utility model discloses do not restrict to this. It should be understood that the control circuit 5 is not limited to the manner described herein, and that other equivalent or existing manners may be used by those skilled in the art for power factor adjustment.

The switching power supply circuit of the present invention can further connect a second stage circuit at the output end, the second stage circuit is coupled to the load to supply power to the load, the second stage circuit is generally a DC-DC circuit, and at this time, if the switching frequency of the high frequency switching network and/or the DC-DC circuit is controlled, the control of the output voltage or/and the current can be completed by adjusting the switching frequency of the high frequency switching network and/or the DC-DC circuit; when the control of the output voltage or/and current of the DC-DC circuit is done by adjusting only the switching frequency of the DC-DC circuit, the switching frequency in the high frequency switching network is open loop control.

The output end of the switching power supply circuit of the utility model can be directly coupled with a load to supply power, for example, the output end of the switching power supply circuit supplies power to an LED, and a battery is charged, etc. the switching power supply circuit of the utility model can control the output voltage and current by single-stage active control, frequency regulation, etc., and can control the output voltage and/or current by regulating the switching frequency of the high-frequency switch network 1 when controlling the output voltage and/or current; switching power supply circuit also can the single-stage not active control frequency, and the open-loop output uses as high frequency transformer.

The utility model discloses only carry out detailed explanation to the condition that switch power supply circuit single-stage used control output current, nevertheless the utility model discloses do not restrict this, other situations should also be in the utility model discloses a protection range. The output current meets the load requirement by controlling the switching state of a switching tube in the high-frequency switching network. For convenience of illustration, the first embodiment is used to describe the following, but any other embodiments can be applied to the power factor adjustment, and the method of the embodiment applied to the power factor adjustment is similar to the method of the embodiment applied to the power factor adjustment.

As shown in fig. 18, the switching power supply circuit further includes a control circuit 6 for controlling the output current Io to meet the load requirement. The control circuit 6 includes a first error amplifier Gm1, a second error amplifier Gm2, a compensation circuit, and a drive circuit. The first error amplifier Gm1 is configured to compare the output current sampling signal Vfb with the current reference signal Iref to obtain a first error signal Vref. The second error amplifier Gm2 is used to compare the output current sample signal Vfb with the first error signal Vref to obtain a second error signal Vcs. The compensation circuit is used for generating a compensation signal Vcp according to the second error signal Vcs. The driving circuit is used for generating driving signals (PWMH and PWML) according to the compensation signal Vcp so as to control the switching state of the switching tubes in the high-frequency switching network 1.

In this embodiment, the current reference signal Iref is input to the non-inverting input terminal of the first error amplifier Gm1, and the output current sampling signal Vfb is input to the inverting input terminal thereof. The output current sampling signal is a voltage signal and is used for representing output current; the current reference signal Iref is used to characterize the output current requirement, so that the output signal of the first error amplifier Gm1 characterizes the difference between the actual output current Io and the required output current Io, and thus, an average current loop can be formed to control the average value of the output current Io to approach the current reference signal Iref. The first error signal Vref is used as a reference signal and is input into a non-inverting input end of the second error amplifier Gm2, an inverting input end of the second error amplifier Gm2 is input with an output current sampling signal Vfb, and the output current sampling signal Vfb is compared with the first error signal Vref to obtain a second error signal Vcs. Thereby, an instantaneous current loop can be formed to control the magnitude of the instantaneous value of the output current Io by adjusting the operating frequency of the high frequency switching network 1. The compensation circuit comprises a resistor R1, a resistor R4 and an optical coupler and is used for generating a compensation signal Vcp according to the second error signal Vcs. The driving circuit is used for generating PWM (pulse width modulation) driving signals (PWMH and PWML) according to the compensation signal Vcp, and is used for controlling the driving module to generate control signals G1-G2 so as to control the switching state of the switching tubes in the high-frequency switching network 1. The control signals G1 and G2 are used to control the on/off states of two sets of switching tubes that are alternately turned on during the positive and negative half cycles of the low frequency ac input signal Vin. In one embodiment, the driving circuit generates the driving signals PWMH and PWML by comparing the compensation signal Vcp and the ramp signal Vsaw.

Further, the control circuit 6 further includes a capacitor C4 connected between the output terminal of the first error amplifier Gm1 and the ground terminal, for converting the current signal output by the first error amplifier Gm1 into a voltage signal, i.e., a first error signal Vref. The control circuit 6 further includes a capacitor C5 connected between the output terminal of the second error amplifier Gm2 and the ground terminal, for converting the current signal output by the second error amplifier into a corresponding voltage signal Vcs.

It is to be understood that the control circuit 6 is not limited to the manner described herein, and may be controlled in other equivalent manners or in a manner known per se by those skilled in the art.

Because the utility model discloses switch circuit all has two sets of switching on in turn in the positive and negative half cycle of AC input signal Vin, and control signal G1 and G2 are used for controlling the on-off state of two sets of switch tubes that switch on in turn in the positive and negative half cycle of AC input signal Vin. In other words, in the positive half cycle of the ac input signal Vin of the high-frequency switching network 1, the first switching tube Q1 and the third switching tube Q3 are always turned on, and the control signals G1 and G2 respectively control the switching states of the second switching tube Q2 and the fourth switching tube Q4; the utility model discloses a high frequency switch network 1 is in the negative half-cycle of input voltage Vin, and second switch tube Q2 and fourth switch tube Q4 switch on always, and control signal G1 and G2 control first switch tube Q1 and third switch tube Q3's on-off state respectively.

Fig. 19 shows an operation waveform diagram of the driving circuit, which shows waveform diagrams of the compensation signal Vcp, the ramp signal Vsaw and the PWM (PWMH and PWML) signals when two groups of switching tubes of the high-frequency switching network are in the period of the alternate on or off state. Wherein the abscissa is time t and the ordinate is each component.

Specifically, during the time period when the first switching tube Q1 and the third switching tube Q3 (or the second switching tube Q2 and the fourth switching tube Q4) are in the alternate on or off state, at time t4, the ramp signal Vsaw starts to rise, PWMH switches to high level, and PWML keeps low level unchanged. At time t5, ramp signal Vsaw rises to be equal to compensation signal Vcp, PWMH switches to low level, and PWML remains at low level. After the read time Δ t (dead time) elapses, that is, at time t6, the ramp signal Vsaw starts rising, PWMH remains low, and PWML switches to high. And circulating in this way, the duty ratio of the PWM signal is always 50%, and controlling the DC-DC converter 2 to work at a fixed duty ratio under the working frequency.

Therefore, the working frequency of the high-frequency switch network 1 can be adjusted according to the difference value between the current reference signal Iref and the output current sampling signal Vfb, and the DC-DC converter 2 is enabled to work at a fixed duty ratio under the working frequency, so that the average value of the output current Io is adjusted to meet the charging requirement to charge the battery. The output current controlled at this time is continuous.

The first switching tube, the second switching tube, the third switching tube and the fourth switching tube in the high-frequency switching network only work within a period of time in a low-frequency alternating current input signal period, so that the rectifying module outputs current in a pulse form. Preferably, when the absolute value of the low-frequency alternating-current input signal voltage is greater than a first threshold, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube in the high-frequency switch network work, otherwise, the high-frequency switch network does not work, so that the rectifier module outputs a pulse-form current, and the working efficiency of the circuit is high at the moment.

Fig. 20 shows a switching power supply circuit of the present invention, which controls the output current to be intermittent. The control circuit further comprises a control circuit 6, a control circuit 7 and a logic circuit, the control circuit 6 being arranged to generate drive signals PWMH and PWML in dependence on an output current demand and the output current Io. The control circuit 6 in fig. 20 is similar to the control circuit 6 in fig. 18, and the description thereof is omitted. The output of the control circuit 6 is connected with the input end of the logic circuit, the output end of the control circuit 7 is connected with the logic circuit, and the logic circuit outputs control signals G1 and G2 for controlling the switch state of the switch tube in the high-frequency switch network 1. The control circuit 7 is configured to generate a first control signal En according to the ac input signal Vin and a first threshold Vth. The logic circuit is used for controlling the working state of the high-frequency switch network according to the first control signal En and the driving signals PWMH and PWML so as to regulate the output current Io.

Further, the logic circuit is configured to control the high frequency switching network 1 to operate at an operating frequency at a fixed duty ratio according to the driving signals PWMH and PWML in response to the first control signal En being active; and responding to the invalidity of the first control signal En, and controlling the high-frequency switch network 1 not to work.

The control circuit 7 includes a comparison circuit and an input signal sampling circuit. The input signal sampling circuit comprises resistors R2 and R3, wherein the resistors R2 and R3 are connected in series between the alternating current input ends L, N to sample the low-frequency alternating current input signal Vin to obtain an input voltage sampling signal Vs. The comparison circuit is used for comparing the input voltage sampling signal Vs with a first threshold Vth to obtain the first control signal En.

When the absolute value of the low-frequency alternating current input signal voltage is smaller than the first threshold value, the first control signal En is invalid, and at this time En is at a low level. It is to be understood that the control circuit 7 is not limited to the manner described herein and that other equivalent or existing manners may be used by those skilled in the art to generate the first control signal.

Further, in response to the first control signal En being low level, the logic circuit does not output the control signals G1 and G2. In response to the first control signal En being high level, the logic circuit generates control signals G1 and G2 according to the driving signals PWMH and PWML to control the high frequency switching network 1 to operate at a fixed duty ratio at the operating frequency. It should be understood that the operation of the logic circuit is not limited to the above-described manner, for example, in response to the first control signal En being low, the control signals G1 and G2 are both outputted as low. The driving signals PWMH and PWML are output as control signals G1 and G2 in response to the first control signal En being high level. Because the utility model discloses switching power supply circuit all has two sets of switching on in turn in the positive and negative half cycle of AC input signal Vin, and control signal G1 and G2 are used for controlling the on-off state of two sets of switch tubes that switch on in turn in the positive and negative half cycle of AC input signal Vin.

Fig. 21 is an operation waveform diagram of the intermittent current control of the present invention. Fig. 21 shows waveforms of the absolute value Vs', the first threshold Vth, the first control signal En, the output current sampling signal Vfb, and the control signals G1 and G2(PWM signals) of the input voltage sampling signal Vs, where the abscissa is time t and the ordinate is the components.

Specifically, at time t1, the absolute value VS' of the input voltage sampling signal falls to be equal to the first threshold Vth, the first control signal En switches to a low level, the logic circuit 33 does not output the control signals G1 and G2, and the high-frequency switch network 1 is controlled not to operate, that is, the second switch tube Q2 and the fourth switch tube Q4 (or the first switch tube Q1 and the third switch tube Q3) are turned off, so that the output current Io is zero (or close to zero), and further the output current sampling signal Vfb is 0. At time t2, the absolute value VS' of the input voltage sampling signal rises to be equal to the predetermined threshold Vth, the first control signal En switches to a high level, the logic circuit 33 outputs control signals G1 and G2, and controls the high-frequency switch network 1 to operate, so that the second switch tube Q2 and the fourth switch tube Q4 (or the first switch tube Q1 and the third switch tube Q3) are alternately turned on, the output current Io is high, and the output current sampling signal Vfb is high. At time t3, the absolute value VS' of the input voltage sample signal again drops to equal the predetermined threshold Vth, and so on. The second switching tube Q2 and the fourth switching tube Q4 (or the first switching tube Q1 and the third switching tube Q3) are in an off state at the same time in a period of time in each period, so that the output current Io is zero; and in the alternate conducting state at the same time for another period in each period, so that the output current Io is high. Thus, the output current Io can be made to be one pulse current.

Further, the utility model discloses a high frequency switch network 1 is in the positive half cycle of exchanging input signal Vin, and first switch tube Q1 and third switch tube Q3 switch on always, if first control signal En switches over to the low level this moment, second switch tube Q2 and fourth switch tube Q4 turn-off for output current Io is zero, if first control signal En switches over to the high level this moment, second switch tube Q2 and fourth switch tube Q4 switch on in turn, make output current Io higher; the utility model discloses a high frequency switch network 1 is in the negative half cycle of exchanging input signal Vin, second switch tube Q2 and fourth switch tube Q4 switch on always, if first control signal En switches over to the low level this moment, first switch tube Q1 and third switch tube Q3 turn-offs for output current Io is zero, if first control signal En switches over to the high level this moment, first switch tube Q1 and third switch tube Q3 switch on in turn, make output current Io higher.

Although the embodiments have been described and illustrated separately, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and reference may be made to one of the embodiments not explicitly described, or to another embodiment described.

In accordance with the present invention, as described above, these embodiments do not set forth all of the details nor limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A switching power supply circuit, comprising:

the high-frequency switch network receives a low-frequency alternating current input signal, performs high-frequency chopping on the low-frequency alternating current input signal and outputs a high-frequency alternating current signal;

2. The switching power supply circuit according to claim 1, wherein: the high-frequency switch network comprises an energy storage module, and when a first loop of the high-frequency switch network works, the low-frequency alternating current input signal charges the energy storage module and the primary winding; when the second loop of the high-frequency switch network works, the energy storage module discharges the primary winding, and the first loop and the second loop do not work at the same time.

3. The switching power supply circuit according to claim 1, wherein: the high-frequency switch network comprises a low-frequency alternating current input end, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and an energy storage module, the low-frequency alternating current input end, the first switch tube, the second switch tube, the primary winding and the energy storage module are connected to form a first loop, the third switch tube, the fourth switch tube, the primary winding and the energy storage module are connected to form a second loop, and the first loop and the second loop do not work at the same time.

4. The switching power supply circuit according to claim 3, wherein: the first end of the first switch tube and the first end of the second switch tube are respectively connected with two ports of a low-frequency alternating current input end, the second end of the first switch tube is connected with the first end of the third switch tube, the second end of the second switch tube is connected with the first end of the fourth switch tube, the second end of the third switch tube is connected with the second end of the fourth switch tube, the energy storage module and the primary winding are connected between a first node and a second node,

5. The switching power supply circuit according to claim 3, wherein: the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are sequentially connected in series, the first end of the first switch tube and the second end of the fourth switch tube are respectively connected with two ports of the low-frequency alternating current input end, the energy storage module and the primary winding are connected between a first node and a second node,

6. The switching power supply circuit according to claim 1, wherein: the high-frequency switch network comprises a low-frequency alternating current input end, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and an energy storage module, wherein the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are sequentially connected in series, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube are sequentially connected in series, the first end of the first switch tube and the first end of the fifth switch tube are respectively connected with two ports of the low-frequency alternating current input end, the second end of the fourth switch tube is connected with the second end of the eighth switch tube, one end of the third capacitor is connected with the common ends of the first switch tube and the second switch tube, the other end of the third capacitor is connected with the common ends of the third switch tube and the fourth switch tube, one end of the fourth capacitor is connected with the common ends of the fifth switch tube and the sixth switch tube, and the other end of the fourth capacitor is connected with the common ends of the seventh switch tube and the eighth switch tube, the energy storage module and the primary winding are connected between a first node and a second node,

7. The switching power supply circuit according to any one of claims 2 to 6, wherein: the energy storage module comprises N inductors and/or N capacitors, wherein N is larger than or equal to 0.

8. The switching power supply circuit according to any one of claims 1 to 6, wherein: the high frequency switching network operates in one of a resonant state and a half bridge buck state.

9. The switching power supply circuit according to any one of claims 4 to 6, wherein: the energy storage module comprises a first capacitor, and the first capacitor is connected with the primary winding in series and then connected between the first node and the second node.

10. The switching power supply circuit according to claim 9, wherein: the energy storage module further comprises a first inductor, and the first inductor, the first capacitor and the primary winding are connected in series and then connected between the first node and the second node.

11. The switching power supply circuit according to claim 10, wherein: the energy storage module further comprises a second capacitor, and the second capacitor is connected with the primary winding in parallel.

12. The switching power supply circuit according to claim 4 or 5, characterized in that: during the positive half period of the low-frequency alternating current input signal, the first switching tube and the third switching tube are always conducted, and the second switching tube and the fourth switching tube are conducted alternately in a high-frequency PWM mode; during the negative half period of the low-frequency alternating current input signal, the second switching tube and the fourth switching tube are always conducted, and the first switching tube and the third switching tube are conducted alternately in a high-frequency PWM mode.

13. The switching power supply circuit according to claim 6, wherein: when the low-frequency alternating current input signal is in a positive half period, the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are always conducted, and the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are conducted or disconnected in a high-frequency PWM mode; and when the negative half period of the low-frequency alternating current input signal is in the positive half period, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are always conducted, and the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube are conducted or disconnected in a high-frequency PWM mode.

14. The switching power supply circuit according to claim 13, wherein: when the high-frequency switch network works in a first mode, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube are always conducted during a positive half period of a low-frequency alternating-current input signal, the first switch tube and the second switch tube are conducted or turned off simultaneously, the third switch tube and the fourth switch tube are conducted or turned off simultaneously, and the first switch tube and the second switch tube, the third switch tube and the fourth switch tube are conducted alternately in a high-frequency PWM mode; when the negative half period of the low-frequency alternating-current input signal is detected, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are always conducted, the fifth switch tube and the sixth switch tube are conducted or turned off at the same time, the seventh switch tube and the eighth switch tube are conducted or turned off at the same time, and the fifth switch tube and the sixth switch tube and the seventh switch tube and the eighth switch tube are alternately conducted in a high-frequency PWM mode.

15. The switching power supply circuit according to claim 13, wherein: when the high-frequency switch network works in a second mode, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube are always conducted during a positive half period of a low-frequency alternating-current input signal, the first switch tube and the fourth switch tube are conducted or disconnected in an opposite mode, and the second switch tube and the third switch tube are conducted or disconnected in an opposite mode; during a negative half period of a low-frequency alternating-current input signal, the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are always conducted, the fifth switching tube and the eighth switching tube are conducted or disconnected in an opposite mode, and the sixth switching tube and the seventh switching tube are conducted or disconnected in an opposite mode.

16. The switching power supply circuit according to any one of claims 1 to 6, wherein: the switching power supply circuit is used as a high-frequency transformer, and the switching state of the high-frequency switching network is controlled in an open loop mode.

17. The switching power supply circuit according to any one of claims 1 to 6, wherein: and controlling the switching state of the high-frequency switching network so that the output voltage and/or current of the rectifying module meets the load requirement.

18. The switching power supply circuit according to any one of claims 1 to 6, wherein: and controlling the switching frequency of the high-frequency switching network so that the output voltage and/or current of the rectifying module meets the load requirement.

19. The switching power supply circuit according to any one of claims 1 to 6, wherein: the high-frequency switch network works only in a period of time in a low-frequency alternating current input signal period, so that the rectifying module outputs current in a pulsating mode.

20. The switching power supply circuit according to any one of claims 1 to 6, wherein: when the absolute value of the low-frequency alternating current input signal voltage is larger than a first threshold value, the high-frequency switch network works, otherwise, the high-frequency switch network does not work, so that the rectifier module outputs current in a pulsating mode.

21. The switching power supply circuit according to any one of claims 1 to 6, wherein: the high-frequency switch network further comprises an EMI filter circuit, wherein the EMI filter circuit is arranged at the low-frequency alternating current input end and controls the switching state of the high-frequency switch network, so that the input current is synchronously changed along with the low-frequency alternating current input signal.

22. The switching power supply circuit according to claim 1, wherein: the rectification module is one of a full-wave rectification circuit and a full-bridge rectification circuit.

23. The switching power supply circuit according to claim 1, wherein: the high-frequency switch network further comprises a low-frequency alternating current input end, a first switch tube and a second switch tube, wherein the low-frequency alternating current input end, the first switch tube, the second switch tube and the primary winding are connected in series to form a loop.

24. The switching power supply circuit according to claim 23, wherein: rectifier module includes first rectifier tube, second rectifier tube, inductance and electric capacity, the one end of series structure after inductance and electric capacity establish ties is connected the first end of first rectifier tube, the second end of first rectifier tube is connected the first end of secondary winding, the other end of series structure is connected the middle end of secondary winding, the first end of second rectifier tube is connected the second end of secondary winding, the second end of second rectifier tube is connected first rectifier tube with the common port of series structure.

25. The switching power supply circuit according to claim 23, wherein: the rectifying module comprises a first rectifying tube, a second rectifying tube, a third rectifying tube, a fourth rectifying tube, a capacitor and an inductor, wherein one end of a series structure formed by connecting the inductor and the capacitor in series is connected with the first end of the first rectifying tube and the first end of the second rectifying tube, the other end of the series structure is connected with the second end of the third rectifying tube and the second end of the fourth rectifying tube, the second end of the first rectifying tube is connected with the first end of the third rectifying tube, the second end of the second rectifying tube is connected with the first end of the fourth rectifying tube, the secondary winding is connected between a first node and a second node,

26. The switching power supply circuit according to claim 24 or 25, wherein: when the positive half period of the low-frequency alternating current input signal is detected, the first switching tube is always switched on or off, and the second switching tube is switched on or off in a high-frequency PWM mode; and when the negative half period of the low-frequency alternating current input signal is in the positive half period, the second switching tube is always switched on or off, and the first switching tube is switched on or off in a high-frequency PWM mode.