WO2019033603A1

WO2019033603A1 - Wide-range soft-switch direct-current conversion circuit and control method therefor

Info

Publication number: WO2019033603A1
Application number: PCT/CN2017/112380
Authority: WO
Inventors: 李伦全; 刘嘉键; 燕沙; 郑车晓
Original assignee: 深圳市保益新能电气有限公司
Priority date: 2017-08-14
Filing date: 2017-11-22
Publication date: 2019-02-21
Also published as: CN107276418B; CN107276418A

Abstract

A wide-range soft-switch direct-current conversion circuit and a control method therefor. The circuit comprises first and second series resonance inversion circuits (210, 220), first and second high-frequency isolation transformers (TRA, TRB), a rectification circuit (300) and a controller (400). The input ends of the first and second series resonance inversion circuits (210, 220) are used for connecting to a direct-current source (V1); two output ends of the first and second series resonance inversion circuits (210, 220) are respectively connected to two ends of primary sides of the first and second high-frequency isolation transformers (TRA, TRB); secondary sides of the first and second high-frequency isolation transformers (TRA, TRB) are connected in series and are then connected to the rectification circuit (300); the controller (400) inputs control signals to the first and second series resonance inversion circuits (210, 220); and two output ends of the rectification circuit (300) are used for connecting to a load (V2). By means of the method, the inversion circuits (210, 220) can operate in an in-phase mode or in an anti-phase mode; and same can not only be adaptive to a wide input voltage range, but can also have a wider output voltage range.

Description

Wide-range soft-switching DC conversion circuit and control method thereof

Technical field

The invention relates to a DC switching power supply, in particular to a wide range soft switching DC conversion circuit and a control method thereof.

Background technique

Existing backup applications, such as UPS, car battery, etc., need to transform and release the battery's energy storage. Due to the wide range of voltage conversion, most of the traditional conversion circuits are mainly hard-switching schemes, or components with higher voltage levels are used to meet the voltage stress caused by wide-range conversion, but the output voltage range is still narrow. Limit its scope of application.

In addition, there are problems of inefficiency or large volume. For example, the current 3.5KVA and 110V inverter power products of the railway, the mainstream product efficiency is mostly 85%, even if the phase shift bridge soft switch technology is used, the efficiency is mostly At 88%, and the volume is large. Compared with the relatively mature inverter technology, the key problem lies in the DC/DC conversion part: it fails to solve the problem of efficiency and power density under wide voltage range of the battery.

Summary of the invention

The object of the present invention is to solve the problem of narrow output voltage range in the prior art, and to provide a wide-range soft-switching DC conversion circuit and a control method thereof.

In order to solve the above technical problems, the present invention adopts the following technical solutions:

A wide range soft switching DC conversion circuit, comprising first and second series resonant inverter circuits, first and second high frequency isolation transformers, rectifier circuit and controller; said first and second series resonant inverter circuits The input ends are connected to the DC source, and the two output ends of the first and second series resonant inverter circuits are respectively connected to the two ends of the primary sides of the first and second high frequency isolation transformers, the first And connecting the secondary side of the second high frequency isolation transformer to the rectifier circuit, and the controller inputs a control signal to the first and second series resonant inverter circuits, and two output ends of the rectifier circuit The controller is connected to the load; the controller determines the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the conversion circuit, thereby controlling the turn-on timing of the series resonant inverter circuit to make the first series connection The resonant inverter circuit and the second series resonant inverter circuit operate in a wrong phase mode or an in-phase mode.

In some preferred embodiments, the number of turns of the primary side of the first high frequency isolation transformer is the same as the number of turns of the primary side of the second high frequency isolation transformer, and the coil of the secondary side of the first high frequency isolation transformer The ratio of the number of turns to the number of turns of the secondary side of the second high frequency isolation transformer ranges from 0.5 to 2.

In some preferred embodiments, the first series resonant inverter circuit includes two high frequency switching tubes (Q3A, Q4A), a first driving circuit, a first filtering capacitor, a first resonant capacitor, and a first resonant inductor, a source of the high frequency switch tube (Q3A) is connected to a drain of the high frequency switch tube (Q4A), and one end of the first resonant capacitor is connected to one end of the first filter capacitor, and the high frequency switch tube ( a drain of Q3A) is connected to the other end of the first filter capacitor, a source of the high frequency switch transistor (Q4A) is connected to the other end of the first resonant capacitor, and an output of the first high frequency isolation transformer The end is connected to the intermediate point of the high frequency switch tube (Q3A) and the high frequency switch tube (Q4A) through the first resonant inductor, and the other output end of the first high frequency isolation transformer is opposite to the first a resonant capacitor is connected to an intermediate point of the first filter capacitor, and the first driving circuit is connected to the high frequency switch tube (Q3A) and the high frequency switch tube (Q4A);

The second series resonant inverter circuit includes two high frequency switching tubes (Q3B, Q4B), a second driving circuit, a second filtering capacitor, a second resonant capacitor and a second resonant inductor, and the high frequency switching tube (Q3B) a source is connected to the drain of the high frequency switch tube (Q4B), one end of the second resonant capacitor is connected to one end of the second filter capacitor, and the drain of the high frequency switch tube (Q3B) is The other end of the second filter capacitor is connected, the source of the high frequency switch tube (Q4B) is connected to the other end of the second resonant capacitor, and an output end of the second high frequency isolation transformer passes through the second resonant inductor Connected to an intermediate point between the high frequency switch tube (Q3B) and the high frequency switch tube (Q4B), another output end of the second high frequency isolation transformer and the second resonant capacitor and the second An intermediate point of the filter capacitor is connected, and the second driving circuit is connected to the high frequency switch tube (Q3B) and the high frequency switch tube (Q4B);

The first series resonant inverter circuit is connected in parallel with the second series resonant inverter circuit; or the first series resonant inverter circuit is connected in series with the second series resonant inverter circuit.

In some preferred embodiments, the number of the first series resonant inverter circuit, the second series resonant inverter circuit, the first high frequency isolation transformer, and the second high frequency isolation transformer are all at least one; and the rectifier circuit is rectified The component is a high frequency rectifying diode or a high frequency switching tube having an antiparallel diode; the first and second series resonant inverter circuits comprise a half bridge circuit and a full bridge circuit; and the rectifying circuit of the rectifying circuit Including double voltage rectification and full bridge rectification; the form of DC source includes DC power supply, battery and AC rectified power supply.

In another aspect, the present invention provides a control side of a wide range soft switching DC conversion circuit law:

A control method for a wide-range soft-switching DC conversion circuit, which superimposes the secondary voltage of the first high-frequency isolating transformer and the secondary voltage of the second high-frequency isolating transformer, and includes the following steps:

Setting a predetermined voltage ratio;

Collecting input voltage;

Judging the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the conversion circuit: if the actual ratio is high, controlling the turn-on timing of the series resonant inverter circuit to make the first series resonant inverter circuit The second series resonant inverter circuit operates in a wrong phase mode; if the actual ratio is low, controlling the turn-on timing of the series resonant inverter circuit causes the first series resonant inverter circuit and the second series resonant inverter circuit to operate in the same phase mode;

The inverter circuit operates in the wrong phase mode or the in-phase mode to lower or increase the voltage of the superimposed side, thereby widening the range of the output DC voltage.

In some preferred embodiments, the operating frequencies of the first and second series resonant inverter circuits are varied while controlling the turn-on timing of the first and second series resonant inverter circuits to further increase or decrease the output voltage.

In some preferred embodiments, the rectifying element of the rectifying circuit is a high frequency rectifying diode or a high frequency switching tube with an antiparallel diode. If it is a high frequency switching tube: according to the real-time voltage of the direct current source and the magnitude of the released current, the first The frequency of the first and second series resonant inverter circuits and the rectifier circuit increases or decreases the output voltage.

In some preferred embodiments, when the rectifying element of the rectifying circuit is a high frequency switching tube, the turn-on timing of the rectifying circuit is offset based on the center of the turn-on timing of the series resonant inverter circuit, and a dead zone is left and front; The release current of the source is less than the set current. When the rectifier component of the rectifier circuit is a high frequency switch, the high frequency switch tube is not turned on, and the rectifier circuit operates in a diode rectification state; if the release current of the DC source is above a set current, The high frequency switch tube in the rectifier circuit is turned on, and the rectifier circuit operates in the rectification state of the synchronous tube.

In a further preferred embodiment, if the release current of the DC source is less than the set current, and the rectifier component of the rectifier circuit is a high frequency switch transistor, the high frequency switch transistor is not turned on, and the rectifier circuit operates in a diode rectified state; The release current of the source is above the set current, the high frequency switch tube in the rectifier circuit is turned on, and the rectifier circuit operates in the rectification state of the synchronous tube.

In a further preferred embodiment, the rectifying element of the rectifying circuit is a high frequency switching tube, and the direct current source is a device or circuit that can provide or absorb energy, and the load is a device or circuit capable of storing and releasing electric energy, positive or Reversely controlling the turn-on timing of the first and second series resonant inverter circuits and the turn-on timing of the rectifier circuit can realize bidirectional flow of energy between the DC source and the load.

In another aspect, the present invention also provides an electrical energy conversion device:

An electrical energy conversion apparatus comprising a signal processor, a memory and one or more programs, the one or more programs being stored in the memory and configured to be executed by the signal processor, the program comprising An instruction to perform any of the above methods.

Compared with the prior art, the beneficial effects of the present invention are:

Determining the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the conversion circuit, and controlling the turn-on timing of the first series resonant inverter circuit and the second series resonant inverter circuit by the controller, so that The first series resonant inverter circuit and the second series resonant inverter circuit operate in a synchronous or misphase mode, thereby changing the phase, instantaneous voltage or polarity of the secondary voltage of the first high frequency isolation transformer and the second high frequency isolation transformer One or more of them. Since the secondary sides of the two transformers are connected in series, their secondary voltages are superimposed and add, suppress or cancel each other, so that lower input voltages can achieve higher or lower output voltages. The higher input voltage can achieve a lower or higher output voltage, so that the present invention can not only adapt to a wide input voltage range, but also has a wider output voltage range, which improves the applicability of the present invention.

In addition, the resonant mode of the first and second series resonant inverter circuits can realize soft switching, which can reduce the opening and closing stress of each electronic component in the inverter circuit, thereby reducing switching loss and helping to improve the inverter circuit. Operating frequency or efficiency, which in turn reduces volume or increases power density.

In a preferred embodiment, the present invention also has the following beneficial effects:

Further, since the first and second series resonant inverter circuits are both series resonant topologies, when the operating frequency of the inverter circuit is a resonant frequency, the maximum output voltage is obtained at the secondary side of the high frequency isolation transformer, and thus, is changed. By changing the operating frequency of the inverter circuit at the same time, the output voltage can be further increased or decreased, thereby further improving the applicability of the present invention.

Further, when the rectifying element of the rectifying circuit is a high frequency switching tube having an antiparallel diode, synchronous rectification can be realized, and by controlling the turn-on timing of the rectifying circuit and the inverter circuit, the DC voltage of the output terminal can be reversely converted; In addition, while controlling the turn-on timing of the inverter circuit, changing the operating frequency of the inverter circuit and the rectifier circuit according to the real-time voltage of the DC source and the magnitude of the release current, the output voltage can be increased or decreased, and the output voltage is further broadened. The scope.

Further, the number of turns of the primary side of the first high-frequency isolating transformer is the same as the number of turns of the primary side of the second high-frequency isolating transformer, and the ratio of the turns of the secondary side of the first high-frequency isolating transformer is 0.5 to 2, which can be realized. Optimal power transfer and increased utilization.

Further, the DC source is a device or circuit that can provide or absorb energy, and the load is a device or circuit capable of storing energy, and the turn-on timing of the first and second series resonant inverter circuits and the turn-on timing of the rectifier circuit are controlled by reversely controlling The power supply on the secondary side of the transformer can be sent back to the DC source. Thereby achieving a two-way transformation.

DRAWINGS

1 is a schematic diagram showing the circuit structure of a conversion circuit of the present invention;

2 is a flow chart of a control method of the present invention;

3 is a timing chart of control of the conversion circuit of the present invention operating in the same phase mode;

4 is a timing chart of control of the conversion circuit of the present invention operating in a wrong phase mode;

Figure 5 is a variant of the conversion circuit of Figure 1;

Figure 6 is another variation of the conversion circuit of Figure 1;

Figure 7 is still another variation of the conversion circuit of Figure 1;

FIG. 8 is a schematic structural diagram of a circuit according to another embodiment of the present invention; FIG.

9 is a flow chart of a control method according to still another embodiment of the present invention.

Detailed ways

Embodiments of the invention are described in detail below. It is to be understood that the following description is only illustrative, and is not intended to limit the scope of the invention.

Referring to FIG. 1, the wide range soft switching DC conversion circuit of the present invention includes first and second series

resonant inverter circuits

210 and 220, first and second high frequency isolation transformers T _RA and T _RB , rectifier circuit 300 and controller 400; the input ends of the first and second series

resonant inverter circuits

210 and 220 are connected to the DC side 100; the DC side 100 provides DC power to the first and second series

resonant inverter circuits

210 and 220; the first series resonance inverse The two output ends of the variable circuit 210 are connected to both ends of the primary side of the first high frequency isolation transformer T _RA , and the two outputs of the second series resonant inverter circuit 220 and the primary side of the second high frequency isolation transformer T _RB The two ends of the first and second high-frequency isolating transformers T _RA and T _RB are connected in series with the access rectifier circuit 300, and the controller 400 inputs the control to the first and second series

resonant inverter circuits

210 and 220. The signal, the two output ends of the rectifier circuit 300 are connected to the load V2; the controller 400 determines the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the converter circuit, thereby controlling the series resonant inverter Circuit The turn-on timing causes the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 to operate in a wrong phase mode or an in-phase mode.

Specifically, in the embodiment shown in FIG. 1, the number of the first series resonant inverter circuit 210, the second series resonant inverter circuit 220, the first high frequency isolation transformer T _RA and the second high frequency isolation transformer T _RB The first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 are both half bridge circuits, the rectification mode of the rectifier circuit 300 is voltage doubler rectification, and the rectifying elements of the rectifier circuit 300 are provided with reverse parallel connection. The high frequency switching tube of the diode. The DC side 100 includes a DC source V1 and a high voltage energy storage filter capacitor C1. The positive and negative ends of the high voltage energy storage filter capacitor C1 are respectively connected to the positive and negative ends of the DC source V1. The first series resonant inverter circuit 210 includes two high The frequency switching tubes Q3A and Q4A, the first driving circuit 211, the first filter capacitor Cr2a, the first resonant capacitor Cr1a and the first resonant inductor Lra, the source of the high frequency switching transistor Q3A is connected to the drain of the high frequency switching transistor Q4A, One end of a resonant capacitor Cr1a is connected to one end of the first filter capacitor Cr2a, the drain of the high frequency switch transistor Q3A is connected to the other end of the first filter capacitor Cr2a, and the source of the high frequency switch transistor Q4A is connected to the first resonant capacitor Cr1a. Connected at the other end, an output terminal 4A of the first high-frequency isolating transformer T _RA is connected to an intermediate point between the high-frequency switch tube Q3A and the high-frequency switch tube Q4A through the first resonant inductor Lra, and the other of the first high-frequency isolating transformer T _RA An output terminal 5A is connected to an intermediate point of the first resonant capacitor Cr1a and the first filter capacitor Cr2a, and the first driving circuit 211 is connected to the high frequency switching transistor Q3A and the high frequency switching transistor Q4A, and the first driving circuit 211 is a high frequency switching transistor. Q3A and high frequency switch tube Q4A Providing a driving signal; the second series resonant inverter circuit 220 includes two high frequency switching transistors Q3B and Q4B, a second driving circuit 221, a second filtering capacitor Cr2b, a second resonant capacitor Cr1b, and a second resonant inductor Lrb, and a high frequency switch The source of the tube Q3B is connected to the drain of the high frequency switch tube Q4B, one end of the second resonant capacitor Cr1b is connected to one end of the second filter capacitor Cr2b, and the drain of the high frequency switch tube Q3B is connected to the other end of the second filter capacitor Cr2b. The source of the high frequency switching transistor Q4B is connected to the other end of the second resonant capacitor Cr1b, and one output terminal 4B of the second high frequency isolation transformer T _RB is connected to the high frequency switching transistor Q3B and the high frequency switch through the second resonant inductor Lrb. The intermediate point of the tube Q4B, the other output end 5B of the second high-frequency isolation transformer T _RB is connected to the intermediate point of the second resonant capacitor Cr1b and the second filter capacitor Cr2b, and the second drive circuit 221 and the high-frequency switch tube Q3B are high. The frequency switch tube Q4B is connected, the second driving circuit 221 provides a driving signal for the high frequency switching tube Q3B and the high frequency switching tube Q4B; the controller 400 is connected to the first driving circuit 211 and the second driving circuit 221, respectively to the first driving circuit 211 and Second driving circuit 221 transmits a control signal; secondary side of the transformer, a first high frequency isolation transformer T _RA of the end 2A of the secondary side connected to one end of a second secondary 1B high frequency isolation transformer T _RB; a rectifying circuit 300 includes a high Frequency switch tubes Q1 and Q2, capacitors C4 and C5, filter capacitor C2 and third drive circuit 310, one end of capacitor C4 and one end of C5 are connected in series, and the source of high frequency switch tube Q1 is connected to the drain of high frequency switch tube Q2. The drain of the high frequency switch Q1 is connected to the other end of the capacitor C4 and one end of the filter capacitor C2, and the source of the high frequency switch Q2 is connected to the other end of the capacitor C5 and the other end of the filter capacitor C2. The other end 1A of the secondary side of the isolation transformer T _RA is connected to the intermediate point of the capacitor C4 and the capacitor C5, and the other end 2B of the secondary side of the second high-frequency isolation transformer T _RB is connected between the high-frequency switching tube Q1 and the high-frequency switching tube Q2. At one point, one end of the third driving circuit 310 is connected to the controller 400, and the other ends of the third driving circuit 310 send driving signals to the high frequency switching tubes Q1 and Q2, and the load V2 is connected to both ends of the filtering capacitor C2.

The first high-frequency isolating transformer T _RA and the second high-frequency isolating transformer T _RB are an isolating transformer with an air gap in the core or an isolating transformer with a resonant inductor connected in series or an isolating transformer with a storage inductor in the secondary side. The size of the core air gap is determined by the ratio of the positive and the reverse excitation and the input and output parameters of the system. The original and secondary coupling coefficients do not need to be specially set. The magnetic core of the first high-frequency isolating transformer T _RA and the second high-frequency isolating transformer T _RB have an air gap and a certain leakage inductance, so that the first high-frequency isolating transformer T _RA and the second high-frequency isolating transformer T _RB can Both positive and negative. The leakage inductance is obtained by a natural winding process, and at the same time, according to actual needs, a leakage feeling that can be large or small can be obtained by a change in the winding process. Of course, if the amount of leakage inductance that is naturally wound is not enough, an inductor can be applied to the secondary side. The isolation transformer does not have to intentionally distinguish the end point connection points of the primary side and the secondary side, that is, the starting end of the isolation transformer is not considered.

One end 401 of the controller 400 inputs a sampling signal, and the other end 402 outputs a sampling signal. When the DC side 100 is a low voltage input, referring to FIG. 1, the first series resonant inverter circuit 210 is connected in parallel with the second series resonant inverter circuit 220, and is connected to both ends of the high voltage energy storage filter capacitor C1 +BUS and -BUS, That is, the input end of the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 are connected in parallel with the DC source V1.

Referring to FIG. 2, when the wide-range soft-switching DC conversion circuit of the present invention operates, the secondary voltage of the first high-frequency isolating transformer T _RA is superimposed with the secondary voltage of the second high-frequency isolating transformer T _RB , and the following control is also adopted. method:

Setting a predetermined voltage ratio; generally, the actual output voltage of the conversion circuit cannot be higher than the voltage required by the load. Therefore, the actual output voltage is constrained by setting a predetermined voltage ratio; the controller 400 sets different predetermined voltage ratios according to different loads. ;

Collecting the input voltage; specifically, after the conversion circuit is operated, the controller 400 collects the input voltage V _{IN-TRA of the} first high-frequency isolation transformer T _RA and the input voltage V _{IN-TRB of the} second high-frequency isolation transformer T _RB ;

Judging the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the conversion circuit: if the actual ratio is high, controlling the turn-on timing of the series resonant inverter circuit to make the first series resonant inverter circuit 210 And the second series resonant inverter circuit 220 operates in a wrong phase mode; if the actual ratio is low, controlling the turn-on timing of the series resonant inverter circuit to operate the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 In-phase mode; specifically, the input voltage level affects the actual output voltage level, and the actual output voltage should not be higher than the voltage required by the load, compare the actual ratio with the predetermined voltage ratio, and judge the actual ratio, according to The actual ratio is such that the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 operate in a synchronous or misphase mode, so that the actual output voltage meets the voltage required for the load V2; the actual ratio is (V _{IN - _{_{TRA n TRA + V iN-TRB}}} n TRB) / V out, wherein, n _TRA is a first high frequency isolation transformer turns ratio T _RA (turns ), N _TRB is the second high frequency isolation transformer T _RB turns ratio (turns ratio), V _out is the actual output voltage conversion circuit.

The inverter circuit operates in the wrong phase mode or the in-phase mode to lower or increase the voltage of the superimposed side, thereby widening the range of the output DC voltage; specifically, when the inverter circuit operates in the wrong phase mode, the secondary side of the transformer is superimposed. After the voltage is reduced, when the inverter circuit operates in the same phase mode, the voltage after the superposition of the secondary side of the transformer will increase.

The first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 are both inverted by the high frequency switching tube, and the opening timing of the control inverter circuit is actually controlling the turn-on timing of the high frequency switching tube.

In the same phase mode, the high frequency switching tube of the first series resonant inverter circuit 210 and the high frequency switching tube of the second series resonant inverter circuit 220 are turned on at the same phase, and the secondary side of the first high frequency isolation transformer T _RA The phase of the voltage across the 1A and 2A is the same as the phase of the voltage across the

secondary sides

1B and 2B of the second high-frequency isolating transformer T _RB , the polarity is the same, the two secondary voltages are added, the rectifier circuit 300 operates, and the DC side 100 The energy is delivered to the load V2, and the output voltage can reach a maximum when the phases of the two inverter circuits are exactly the same. Since the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 are series resonant circuits, the conversion circuit can implement a process of resonant transformation, and the inverter circuit is changed according to the condition of the load V2 in the full working range. The working frequency or duty ratio can ensure that the high frequency switching tube in the inverter circuit obtains soft switching, reduces switching loss, effectively utilizes the advantages of the series resonant circuit, and achieves high efficiency conversion. In the high frequency switching tubes Q1 and Q2 in the rectifier circuit 300, if the release current of the DC source V1 is less than the set current, the set current can be specifically set to 0.1 times the rated current, and the switching tube in the rectifier circuit 300 is not turned on, and is rectified. The circuit 300 operates in a diode rectified state, that is, the parasitic diode of the switch tube is naturally rectified; if the release current of the DC source V1 is above the set current, the high frequency switch tubes Q1 and Q2 receive the PWM drive signal, and the rectifier circuit 300 operates as a synchronous tube. Rectification state, related control timing Referring to FIG. 2, the turn-on timing of the rectifying circuit 300 is offset based on the center of the turn-on timing of the series resonant inverter circuit, and a dead zone is left and left. Specifically, the high frequency switching transistors Q1 and Q2 The turn-on timing is offset based on the center of the turn-on timing of the high-frequency switch transistors Q3 and Q4, respectively, and a certain dead time is left to prevent current over-current or short-circuit under the condition that the diode is not turned on, and the high-frequency switch tubes Q3 and Q4 There is also a certain dead time between them to prevent a through short circuit.

Wrong phase mode: The controller 400 determines that the actual ratio is too high according to the predetermined voltage ratio. If the operation is in the same phase mode, the output voltage will be higher than the required voltage, or the modulation frequency and duty ratio cannot be used to achieve the drop. The voltage is controlled so that the controller 400 determines that the inverter circuit needs to operate in the wrong phase mode. If it is in the wrong phase mode, the high frequency switching tube of the first series resonant inverter circuit 210 and the high frequency switching tube of the second series resonant inverter circuit 220 are shifted by a certain phase, and the secondary side 1A of the first high frequency isolation transformer T _RA The phase of the voltage across the 2A and the voltage of the secondary side of the second high-frequency isolating transformer T _RB will be the same as the voltage across the

secondary side

1B and 2B, but the polarity may be opposite; or when the polarity is the same, since the resonance point voltage is not Similarly, the instantaneous voltage is different, so the secondary voltage of the first high-frequency isolating transformer T _{RA and} the secondary voltage of the second high-frequency isolating transformer T _RB are mutually suppressed or canceled, thereby showing that both are subject to The influence of the resonant phase point is no longer the original simple superposition, that is, the highest voltage point will be offset, and the output voltage of the conversion circuit will decrease accordingly. Referring to FIG. 3, the turn-on sequence of the rectifier circuit 300 is offset based on the center of the turn-on sequence of the series resonant inverter circuit, and a dead zone is left and right. Specifically, the high-frequency switch transistors Q3A and Q3B are turned off in phase. The high frequency switching tubes Q4A and Q4B are turned off in phase, and the rest are similar to the in-phase mode.

To further change the output voltage, a method is adopted to control the first series resonant inverter circuit 210 and the second series resonant inverter circuit while controlling the turn-on timing of the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 The operating frequency of 220 is to further increase or decrease the output voltage.

According to the above, the present invention determines the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the conversion circuit, and controls the first series resonant inverter circuit and the second series resonant inverter through the controller. The turn-on timing of the circuit causes the first series resonant inverter circuit and the second series resonant inverter circuit to operate in a synchronous or misphase mode, thereby changing the phase of the secondary voltage of the first high frequency isolation transformer and the second high frequency isolation transformer One or more of instantaneous voltage or polarity. Since the secondary sides of the two transformers are connected in series, their secondary voltages are superimposed and add, suppress or cancel each other, so that lower input voltages can achieve higher or lower output voltages. The higher input voltage can achieve a lower or higher output voltage, so that the present invention can not only adapt to a wide input voltage range, but also has a wider output voltage range, which improves the applicability of the present invention. At the same time, since the first and second series resonant inverter circuits are series resonant topologies, when the operating frequency of the inverter circuit is the resonant frequency, the maximum output voltage can be obtained at the secondary side of the high frequency isolation transformer, and therefore, the inverse is changed. Substation By changing the operating frequency of the turn-on sequence of the circuit, the output voltage can be further increased or decreased, thereby further improving the applicability of the present invention. In addition, the resonant mode of the first and second series resonant inverter circuits can realize soft switching, which can reduce the opening and closing stress of each electronic component in the inverter circuit, thereby reducing switching loss and helping to improve the inverter circuit. Operating frequency or efficiency, which in turn reduces volume or increases power density. In particular, the rectifying element of the rectifying circuit is a high frequency switching tube, which can realize synchronous rectification, and can control the reverse timing of the DC voltage at the output end by controlling the turn-on timing of the rectifying circuit and the inverter circuit.

The embodiment of Fig. 1 of the present invention has been described above, but the present invention may also have some variants, such as:

Referring to FIG. 5, the rectifying component of the rectifying circuit 300 may also be a high frequency rectifying diode, specifically including high frequency rectifying diodes D1 and D2, and the rectifying circuit 300 is rectified by double voltage rectification; similarly, the inverter circuit also has the same phase mode. And the wrong phase mode, when the voltage of the secondary side of the transformer is superimposed and the conduction condition of the high frequency rectifier diode in the rectifier circuit 300 is satisfied, the rectifier circuit 300 is turned on. In the wrong phase mode, the superimposed voltage of the secondary side of the transformer is in a staggered period. Will become low, the rectifier circuit 300 will not conduct, and the output voltage will become low;

Referring to FIG. 6, the rectification mode of the rectifying circuit 300 may also be full-bridge rectification, including four high-frequency rectifying diodes D1 to D4, wherein the high-frequency rectifying diodes D3 and D4 replace the capacitors C4 and C5, respectively; of course, four high frequencies The rectifier diode can also be replaced by a high frequency switch tube with an antiparallel diode;

The same number of coil turns of the primary coil turns of the first high frequency isolation transformer T _RA of the second high frequency isolation transformer T _RB of the primary side, the number of turns of the first sub-frequency side of the isolation transformer T _RA of The ratio of the number of turns of the secondary side of the two high-frequency isolating transformer T _RB is in the range of 0.5 to 2, so that optimal power transmission and improved utilization can be achieved;

The form of the DC source V1 includes a DC power source, a battery, and an AC rectified power supply;

Referring to FIG. 7, the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 may also be in the form of a full bridge circuit; the inverter circuit adopts a full bridge circuit, and the input current of the conversion circuit is the same, and the input voltage is In the same case, the primary side voltage of the full bridge circuit is twice that of the half bridge circuit, then the output power of the power full bridge circuit is twice that of the half bridge circuit, that is, the full bridge circuit is suitable for high power. Output.

FIG. 8 shows another embodiment of the present invention. The difference between this embodiment and the above embodiment is that when the DC side 100 is a high voltage input, the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 are connected in series. Connected to both ends of the high-voltage energy storage filter capacitor C1 +BUS and -BUS, that is, the input after the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 are connected in series The terminal is connected to the DC source V1. This embodiment also has the advantageous effects of the above embodiments, in particular, the embodiment is suitable for the case where the input of the conversion circuit is a high voltage.

Referring to FIG. 9, in still another embodiment of the present invention, the basis of controlling the turn-on timing of the inverter circuit is determined by determining the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the converter circuit. The frequency magnitudes of the first series resonant inverter circuit 210 and the second series resonant inverter circuit 220 and the rectifier circuit 300 are also changed according to the real-time voltage of the DC source V1 and the magnitude of the release current. When the conversion circuit and the load are connected to generate a current, changing the operating frequency of the inverter circuit and the rectifier circuit can increase or decrease the output voltage, thereby further broadening the range of the output voltage.

In another embodiment of the present invention, referring to FIG. 1, the rectifying element of the rectifying circuit 300 is a high frequency switching tube, and the direct current source V1 is a circuit or device capable of providing energy, or a circuit or device capable of absorbing energy, such as a battery. a DC bus or a PFC circuit capable of bidirectional conversion, the load V2 being a circuit or device capable of storing and releasing electrical energy, such as a battery; applying the first series resonant inverter circuit 210 and the second series resonant inverter circuit in a forward or reverse direction The turn-on timing of 220 and the turn-on timing of rectifier circuit 300. The power supply on the secondary side of the transformer can be sent back to the DC source V1 to achieve bidirectional conversion.

In still another embodiment of the present invention, the embodiment is different from the above embodiment in that the number of the first series resonant inverter circuit and the first high frequency isolation transformer are both two. The secondary sides of the two first series resonant inverter circuits are connected in series and then connected in series with the secondary side of the second series resonant inverter circuit.

The present invention also provides a power conversion apparatus comprising a signal processor, a memory and one or more programs, the one or more programs being stored in the memory and configured to be executed by a signal processor, the program comprising An instruction of any of the above methods.

The above is a further detailed description of the present invention in combination with specific/preferred embodiments, and it is not intended that the specific embodiments of the invention are limited to the description. It will be apparent to those skilled in the art that <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; It belongs to the scope of protection of the present invention.

Claims

A wide range soft switching DC conversion circuit, comprising: first and second series resonant inverter circuits, first and second high frequency isolation transformers, rectifier circuit and controller; said first and second series The input end of the resonant inverter circuit is connected to the DC source, and the two output ends of the first and second series resonant inverter circuits are respectively connected to the two ends of the primary sides of the first and second high frequency isolation transformers, After the secondary sides of the first and second high-frequency isolating transformers are connected in series and connected to the rectifier circuit, the controller inputs control signals to the first and second series resonant inverter circuits, and the rectifier circuit Two outputs are connected to the load; the controller determines the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the conversion circuit, thereby controlling the turn-on timing of the series resonant inverter circuit The first series resonant inverter circuit and the second series resonant inverter circuit are operated in a wrong phase mode or an in-phase mode.
The wide-range soft-switching DC conversion circuit according to claim 1, wherein the number of turns of the primary side of the first high-frequency isolating transformer is the same as the number of turns of the primary side of the second high-frequency isolating transformer, The ratio of the number of turns of the secondary side of the first high frequency isolation transformer to the number of turns of the secondary side of the second high frequency isolation transformer ranges from 0.5 to 2.
The wide range soft switching DC conversion circuit of claim 1 wherein:

The first series resonant inverter circuit includes two high frequency switching tubes (Q3A, Q4A), a first driving circuit, a first filtering capacitor, a first resonant capacitor and a first resonant inductor, and the high frequency switching transistor (Q3A) The source is connected to the drain of the high frequency switch tube (Q4A), one end of the first resonant capacitor is connected to one end of the first filter capacitor, and the drain of the high frequency switch tube (Q3A) is The other end of the first filter capacitor is connected, the source of the high frequency switch tube (Q4A) is connected to the other end of the first resonant capacitor, and an output end of the first high frequency isolation transformer passes through the first resonant inductor Connected to an intermediate point between the high frequency switch tube (Q3A) and the high frequency switch tube (Q4A), another output end of the first high frequency isolation transformer and the first resonant capacitor and the first An intermediate point of the filter capacitor is connected, and the first driving circuit is connected to the high frequency switch tube (Q3A) and the high frequency switch tube (Q4A);

The second series resonant inverter circuit includes two high frequency switching tubes (Q3B, Q4B), a second driving circuit, a second filtering capacitor, a second resonant capacitor and a second resonant inductor, and the high frequency switching tube (Q3B) a source is connected to the drain of the high frequency switch tube (Q4B), one end of the second resonant capacitor is connected to one end of the second filter capacitor, and the drain of the high frequency switch tube (Q3B) is The other end of the second filter capacitor is connected, the source of the high frequency switch tube (Q4B) and the second resonant capacitor The other end of the second high frequency isolation transformer is connected to the intermediate point of the high frequency switch tube (Q3B) and the high frequency switch tube (Q4B) through the second resonant inductor, the first The other output end of the two high frequency isolation transformer is connected to an intermediate point of the second resonant capacitor and the second filter capacitor, the second drive circuit and the high frequency switch tube (Q3B) and the high frequency Switch tube (Q4B) connection;

The first series resonant inverter circuit is connected in parallel with the second series resonant inverter circuit; or the first series resonant inverter circuit is connected in series with the second series resonant inverter circuit.
The wide-range soft-switching DC conversion circuit according to any one of claims 1 to 3, characterized by: a first series resonant inverter circuit, a second series resonant inverter circuit, a first high frequency isolation transformer and a second high The number of frequency isolation transformers is at least one; the rectifying element of the rectifier circuit is a high frequency rectifying diode or a high frequency switching tube having an antiparallel diode; and the first and second series resonant inverter circuits are in the form of a half The bridge circuit and the full bridge circuit; the rectification mode of the rectifier circuit includes double voltage rectification and full bridge rectification; the form of the DC source includes a DC power source, a battery, and an AC rectified power supply.
A control method for a wide-range soft-switching DC conversion circuit, which superimposes a secondary voltage of a first high-frequency isolating transformer and a secondary voltage of a second high-frequency isolating transformer, and is characterized by the following steps:

Setting a predetermined voltage ratio;

Collecting input voltage;

Judging the input voltage multiplied by the actual ratio of the transformer turns ratio to the actual output voltage according to the predetermined voltage ratio of the conversion circuit: if the actual ratio is high, controlling the turn-on timing of the series resonant inverter circuit to make the first series resonant inverter circuit The second series resonant inverter circuit operates in a wrong phase mode; if the actual ratio is low, controlling the turn-on timing of the series resonant inverter circuit causes the first series resonant inverter circuit and the second series resonant inverter circuit to operate in the same phase mode;

The inverter circuit operates in the wrong phase mode or the in-phase mode to lower or increase the voltage of the superimposed side, thereby widening the range of the output DC voltage.
The control method according to claim 5, wherein the operating frequencies of the first and second series resonant inverter circuits are changed while controlling the turn-on timing of the first and second series resonant inverter circuits to further increase the output voltage High or low.
The control method according to claim 5, wherein the rectifying element of the rectifying circuit is a high frequency rectifying diode or a high frequency switching tube having an antiparallel diode, if it is a high frequency switching tube: according to a real-time voltage of the direct current source and The magnitude of the current is released, and the frequency of the first and second series resonant inverter circuits and the rectifier circuit are changed to increase or decrease the output voltage.
The control method according to any one of claims 5 to 7, wherein when the rectifying element of the rectifying circuit is a high frequency switching tube, the turn-on timing of the rectifying circuit is based on the center of the turn-on timing of the series resonant inverter circuit. Offset and leaving a dead zone before and after; if the release current of the DC source is less than the set current, when the rectifier component of the rectifier circuit is a high frequency switch transistor, the high frequency switch transistor is not turned on, and the rectifier circuit operates in a diode rectification state; The release current of the DC source is above the set current, the high frequency switch tube in the rectifier circuit is turned on, and the rectifier circuit operates in the rectification state of the synchronous tube.
The control method according to any one of claims 5-7, characterized in that the rectifying element of the rectifying circuit is a high frequency switching tube, and the direct current source is a device or circuit capable of providing or absorbing energy, and the load is energy storage and The device or circuit capable of releasing electrical energy controls the turn-on timing of the first and second series resonant inverter circuits and the turn-on timing of the rectifier circuit in a forward or reverse direction to realize bidirectional flow of energy of the DC source and the load.
An electrical energy conversion apparatus comprising a signal processor, a memory and one or more programs, the one or more programs being stored in the memory and configured to be executed by the signal processor, the program comprising Instructions for performing the method of any of claims 5-9.