阅读说明：本技术 一种单相Cuk变频AC-AC变换器 (Single-phase Cuk frequency conversion AC-AC converter ) 是由 何良宗 徐鑫勇 于 2021-10-14 设计创作，主要内容包括：本发明一种单相Cuk变频AC-AC变换器,能实现升降压及变频AC-AC变换；所述单相Cuk变频AC-AC变换器由正半周调压单元,负半周调压单元以及输出极性单元组成；其中正半周调压单元与负半周调压单元完全对称,各包括一个单向开关,两个电感,一个无极性电容以及两个二极管；输出极性单元包括四个单向开关组成的H桥网络；通过控制两个高频调压开关(S1和S2)的控制信号占空比,能够调节交流输出电压的幅值,实现升压或降压输出；通过调节输出极性单元四个单向开关的控制信号时序,能够得到变频的交流输出电压；相对于传统AC-AC变换器具有开关器件少、功率密度高、效率高等优点,适用于需要变压变频交流输出的应用场合。(The single-phase Cuk variable-frequency AC-AC converter can realize voltage boosting and reducing and variable-frequency AC-AC conversion; the single-phase Cuk variable-frequency AC-AC converter consists of a positive half-cycle voltage regulating unit, a negative half-cycle voltage regulating unit and an output polarity unit; the positive half-cycle voltage regulating unit and the negative half-cycle voltage regulating unit are completely symmetrical and respectively comprise a one-way switch, two inductors, a non-polar capacitor and two diodes; the output polarity unit comprises an H-bridge network consisting of four unidirectional switches; the amplitude of the alternating current output voltage can be adjusted by controlling the duty ratio of control signals of the two high-frequency voltage regulating switches (S1 and S2), so that the boosting or the step-down output is realized; the variable-frequency alternating-current output voltage can be obtained by adjusting the time sequence of control signals of the four one-way switches of the output polarity unit; compared with the traditional AC-AC converter, the AC-AC converter has the advantages of few switching devices, high power density, high efficiency and the like, and is suitable for application occasions needing voltage transformation and frequency conversion AC output.)

1. A single-phase Cuk frequency conversion AC-AC converter is characterized by comprising a positive half-cycle voltage regulating unit, a negative half-cycle voltage regulating unit and an output polarity unit which are connected with each other; the positive half-cycle voltage regulating unit and the negative half-cycle voltage regulating unit are completely symmetrical and respectively comprise a one-way switch, two inductors, a non-polar capacitor and two diodes; the output polarity unit comprises an H-bridge network consisting of four unidirectional switches; the amplitude of the alternating current output voltage is adjusted by controlling the duty ratio of control signals of the one-way switch of the positive half-cycle voltage regulating unit and the one-way switch of the negative half-cycle voltage regulating unit, so that the boosting or the step-down output is realized; and obtaining the variable-frequency alternating-current output voltage by adjusting the time sequence of control signals of the four one-way switches of the output polarity unit.

2. The single-phase Cuk variable frequency AC-AC converter according to claim 1, wherein the positive half cycle voltage regulation unit comprises a first unidirectional switch S₁A first power inductor L₁A third power inductor L₃A first energy storage capacitor C₁A second diode D₂And a third diode D₃(ii) a The first energy storage capacitor C₁Is connected to the first power inductor L₁And a third power inductor L₃To (c) to (d); the first one-way switch S₁Is connected to the first power inductor L₁And a first energy storage capacitor C₁The joint of (a); the first one-way switch S₁Source and second diode D₂The anodes of the anode groups are connected; the first mentionedThree diodes D₃Is connected to the first energy storage capacitor C₁And a third power inductor L₃The joint of (a); the third diode D₃Is connected to the second diode D₂Of (2) an anode.

3. The single-phase Cuk variable frequency AC-AC converter according to claim 2, wherein the negative half cycle voltage regulation unit comprises a second unidirectional switch S₂A second power inductor L₂A fourth power inductor L₄A second energy storage capacitor C₂A first diode D₁And a fourth diode D₄(ii) a The second energy storage capacitor C₂Is connected to the second power inductor L₂And a fourth power inductor L₄To (c) to (d); the second one-way switch S₂Is connected to the second power inductor L₂And a second energy storage capacitor C₂The joint of (a); the second one-way switch S₂Source stage and first diode D₁The anodes of the anode groups are connected; the fourth diode D₄Is connected to the second energy storage capacitor C₂And a fourth power inductor L₄The joint of (a); the fourth diode D₄Is connected to the first diode D₁Of (2) an anode.

4. The single-phase Cuk variable frequency AC-AC converter according to claim 3, wherein the output polarity unit is provided by a third unidirectional switch S₃And a fourth one-way switch S₄The fifth one-way switch S₅And a sixth one-way switch S₆Composition is carried out; the third one-way switch S₃Drain and fifth unidirectional switch S₅Are connected with each other; the fourth one-way switch S₄And the sixth one-way switch S₆Are connected with each other; the third one-way switch S₃Source and fourth unidirectional switch S₄Are connected with each other; the fifth one-way switch S₅And the sixth one-way switch S₆Are connected.

5. The single-phase Cuk variable frequency AC-AC converter according to claim 4, comprising four operating states, respectively: a positive half cycle in-phase output state, a positive half cycle reverse phase output state, a negative half cycle in-phase output state and a negative half cycle reverse phase output state;

make the first one-way switch S₁High frequency on-off, fourth one-way switch S₄And a fifth one-way switch S₅Remains on and the second one-way switch S₂And a third one-way switch S₃And a sixth one-way switch S₆Keeping turning off, and the circuit is in a positive half cycle in-phase output state; make the first one-way switch S₁High frequency on-off, third one-way switch S₃And a sixth one-way switch S₆Remains on and the second one-way switch S₂And a fourth one-way switch S₄And a fifth one-way switch S₅Keeping the circuit switched off, wherein the circuit is in a positive half cycle inverted output state; make the second one-way switch S₂High frequency on-off, fourth one-way switch S₄And a fifth one-way switch S₅Kept on, the first one-way switch S₁And a third one-way switch S₃And a sixth one-way switch S₆Keeping the circuit switched off, wherein the circuit is in a negative half cycle inverted output state; make the second one-way switch S₂High frequency on-off, third one-way switch S₃And a sixth one-way switch S₆Kept on, the first one-way switch S₁And a fourth one-way switch S₄And a fifth one-way switch S₅Keeping turning off, wherein the circuit is in a negative half cycle in-phase output state; in the four working states, two high-frequency switches S are recorded₁And S₂The duty ratio of the control signal is D, and the amplitude of the output voltage can be adjusted by adjusting the duty ratio D, so that the voltage boosting or reducing function is realized;

by changing the operating state of the circuit at an appropriate timing in one input voltage line period, it is possible to realize a rise or fall in the fundamental frequency of the output voltage.

6. The single-phase Cuk variable frequency AC-AC converter according to claim 5, wherein in the positive half cycle in-phase output state, the ratio of the output voltage to the input voltage is:

when the negative half cycle is in the reverse phase output state, the ratio of the output voltage to the input voltage is as follows:

when the positive half cycle is in the reverse phase output state, the ratio of the output voltage to the input voltage is as follows:

when the negative half cycle is in the same phase output state, the ratio of the output voltage to the input voltage is as follows:

7. the single-phase Cuk variable frequency AC-AC converter according to claim 1, wherein said unidirectional switches are each comprised of one fully controlled device MOSFET.

8. The single-phase Cuk variable frequency AC-AC converter according to claim 1, further comprising: AC power supply V_inInput capacitor, output capacitor C_oAnd a load R_L(ii) a The input capacitor is connected with an input power supply V_inBoth ends of (a); two ends of the input capacitor are respectively connected to the first power inductor L₁And a second diode D₂Both ends of (a); the output capacitor C_oIs connected to a load R_LTwo ends; the output capacitor C_oIs connected to the third one-way switch S₃Drain and fourth unidirectional switch S₄Between the drain and the drain; the third power inductor L₃Is connected to the third one-way switch S at the other end₃A source stage of (a); the fourth power inductor L₄Is connected to the fourth one-way switch S at the other end₄The source stage of (1).

Technical Field

The invention relates to a single-phase AC-AC converter, in particular to a single-phase Cuk variable frequency AC-AC converter.

Background

Many industrial applications, such as adjustable speed drives, require AC-AC power conversion systems to produce flexible output AC voltages. In order to achieve alternating current energy conversion, the simplest way is by a direct type AC-AC converter. The direct AC-AC converter is converted from a basic DC PWM switching converter, and a unidirectional switching tube in a DC topology is replaced by a bidirectional switching tube, so that the converter can output reverse-phase voltage when AC is input for a negative half cycle, and AC-AC conversion is realized. The direct AC-AC converter adopts a single-stage energy conversion structure and has the advantages of simple structure, small volume, strong voltage regulation capability, low cost and the like, but the direct AC-AC converter cannot realize the output of frequency conversion and is not suitable for application occasions needing frequency conversion regulation.

To meet the variable frequency output requirements for AC power supplies in industrial applications, an indirect AC-AC converter may be used. An indirect AC-AC converter is actually a two-stage configuration from AC-DC to DC-AC, connected in between by a DC bus capacitor. The indirect type AC-AC converter can realize alternating current voltage output with any frequency and any shape. However, the bulky dc bus energy storage capacitor and input filter result in a bulky, high loss, high cost and low reliability indirect AC-AC converter.

Therefore, in order to further improve the power density of the AC-AC converter while achieving the inverter/transformer regulation, a single-phase matrix inverter AC-AC converter may be used. The single-phase matrix type variable frequency converter can not only realize output voltage regulation and output frequency regulation, but also adopts a single-stage energy mode directly connected to a load without adopting a middle-stage direct-current energy storage capacitor, thereby reducing the size of the converter and improving the power density. The method is suitable for occasions with low requirements on the quality of the voltage waveform, such as a radio frequency induction heater, a dynamic voltage restorer, a medium-frequency traction converter, a fan converter and the like.

Disclosure of Invention

The invention aims to provide a single-phase Cuk variable-frequency AC-AC converter which can realize voltage boosting and voltage reducing and variable-frequency AC voltage output.

The invention adopts the following technical scheme:

a single-phase Cuk frequency conversion AC-AC converter comprises a positive half-cycle voltage regulating unit, a negative half-cycle voltage regulating unit and an output polarity unit; the positive half-cycle voltage regulating unit and the negative half-cycle voltage regulating unit are completely symmetrical and respectively comprise a one-way switch, two inductors, a non-polar capacitor and two diodes; the output polarity unit comprises an H-bridge network consisting of four unidirectional switches; the amplitude of the alternating current output voltage is adjusted by controlling the duty ratio of control signals of the one-way switch of the positive half-cycle voltage regulating unit and the one-way switch of the negative half-cycle voltage regulating unit, so that the boosting or the step-down output is realized; and obtaining the variable-frequency alternating-current output voltage by adjusting the time sequence of control signals of the four one-way switches of the output polarity unit.

Preferably, the positive half-cycle voltage regulating unit comprises a first one-way switch S₁A first power inductor L₁A third power inductor L₃A first energy storage capacitor C₁A second diode D₂And a third diode D₃(ii) a The first energy storage capacitor C₁Is connected to the first power inductor L₁And a third power inductor L₃To (c) to (d); the first one-way switch S₁Is connected to the first power inductor L₁And a first energy storage capacitor C₁The joint of (a); the first one-way switch S₁Source and second diode D₂The anodes of the anode groups are connected; the third diode D₃Is connected to the first energy storage capacitor C₁And a third power inductor L₃The joint of (a); the third diode D₃Is connected to the second diode D₂Of (2) an anode.

Preferably, the negative half-cycle voltage regulating unit comprises a second one-way switch S₂A second power inductor L₂A fourth power inductor L₄A second energy storage capacitor C₂A first diode D₁And a fourth diode D₄(ii) a The second energy storage capacitor C₂Is connected to the second power inductor L₂And a fourth power inductor L₄To (c) to (d); the second one-way switch S₂Is connected to the second power inductor L₂And a second energy storage capacitor C₂The joint of (a); the second one-way switch S₂Source stage and first diodeD₁The anodes of the anode groups are connected; the fourth diode D₄Is connected to the second energy storage capacitor C₂And a fourth power inductor L₄The joint of (a); the fourth diode D₄Is connected to the first diode D₁Of (2) an anode.

Preferably, the output polarity unit is composed of a third unidirectional switch S₃And a fourth one-way switch S₄The fifth one-way switch S₅And a sixth one-way switch S₆Composition is carried out; the third one-way switch S₃Drain and fifth unidirectional switch S₅Are connected with each other; the fourth one-way switch S₄And the sixth one-way switch S₆Are connected with each other; the third one-way switch S₃Source and fourth unidirectional switch S₄Are connected with each other; the fifth one-way switch S₅And the sixth one-way switch S₆Are connected.

Preferably, the method comprises four working states, which are respectively: a positive half cycle in-phase output state, a positive half cycle reverse phase output state, a negative half cycle in-phase output state and a negative half cycle reverse phase output state;

make the first one-way switch S₁High frequency on-off, fourth one-way switch S₄And a fifth one-way switch S₅Remains on and the second one-way switch S₂And a third one-way switch S₃And a sixth one-way switch S₆Keeping turning off, and the circuit is in a positive half cycle in-phase output state; make the first one-way switch S₁High frequency on-off, third one-way switch S₃And a sixth one-way switch S₆Remains on and the second one-way switch S₂And a fourth one-way switch S₄And a fifth one-way switch S₅Keeping the circuit switched off, wherein the circuit is in a positive half cycle inverted output state; make the second one-way switch S₂High frequency on-off, fourth one-way switch S₄And a fifth one-way switch S₅Kept on, the first one-way switch S₁And a third one-way switch S₃And a sixth one-way switch S₆Keeping the circuit switched off, wherein the circuit is in a negative half cycle inverted output state; make the second one-way switch S₂High frequency on-off, third one-way switch S₃And a sixth one-way switch S₆Kept on, the first one-way switch S₁And a fourth one-way switch S₄And a fifth one-way switch S₅Keeping turning off, wherein the circuit is in a negative half cycle in-phase output state; in the four working states, two high-frequency switches S are recorded₁And S₂The duty ratio of the control signal is D, and the amplitude of the output voltage can be adjusted by adjusting the duty ratio D, so that the voltage boosting or reducing function is realized;

by changing the operating state of the circuit at an appropriate timing in one input voltage line period, it is possible to realize a rise or fall in the fundamental frequency of the output voltage.

Preferably, when the positive half cycle is in the same phase output state, the ratio of the output voltage to the input voltage is:

when the negative half cycle is in the reverse phase output state, the ratio of the output voltage to the input voltage is as follows:

when the positive half cycle is in the reverse phase output state, the ratio of the output voltage to the input voltage is as follows:

when the negative half cycle is in the same phase output state, the ratio of the output voltage to the input voltage is as follows:

preferably, the unidirectional switches are all composed of a full-control type device MOSFET.

Preferably, the single-phase Cuk variable frequency AC-AC converter further includes: AC power supplyV_inInput capacitor, output capacitor C_oAnd a load R_L(ii) a The input capacitor is connected with an input power supply V_inBoth ends of (a); two ends of the input capacitor are respectively connected to the first power inductor L₁And a second diode D₂Both ends of (a); the output capacitor C_oIs connected to a load R_LTwo ends; the output capacitor C_oIs connected to the third one-way switch S₃Drain and fourth unidirectional switch S₄Between the drain and the drain; the third power inductor L₃Is connected to the third one-way switch S at the other end₃A source stage of (a); the fourth power inductor L₄Is connected to the fourth one-way switch S at the other end₄The source stage of (1).

According to the single-phase Cuk variable frequency AC-AC converter, the amplitude of output voltage can be adjusted by changing the duty ratio of a high-frequency switch control signal, boost or buck output is realized, and the change of fundamental frequency of the output voltage can be realized by timely changing the polarity of the output voltage of a circuit. Compared with the traditional AC-AC converter, the invention has the advantages of frequency conversion, less switching devices, high power density, high efficiency and the like.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of the circuit structure of the present invention;

FIG. 2 is a schematic structural diagram of a positive half-cycle voltage regulating unit;

FIG. 3 is a schematic structural diagram of a negative half-cycle voltage regulation unit;

FIG. 4 is a schematic diagram of an output polarity unit;

FIG. 5 is a waveform diagram illustrating exemplary variable frequency operating conditions, including input voltage waveforms, switch drive signal waveforms, and output voltage waveforms; wherein, (a) represents the down-converted output; (b) representing a common frequency output; (c) representing an up-converted output;

FIG. 6 is a circuit diagram of various modes of operation according to an embodiment of the present invention; wherein (a) represents mode 1; (b) represents modality 2; (c) represents modality 3; (d) represents modality 4; (e) represents modality 5; (f) represents modality 6; (g) represents modality 7; (h) representing modality 8.

Detailed Description

The invention will be further elucidated with reference to the drawings and examples.

The first embodiment is as follows:

referring to fig. 1, the invention includes an ac power supply, an input capacitor, a positive half-cycle voltage regulating unit, a negative half-cycle voltage regulating unit, an output polarity unit, an output capacitor and a load; the positive half-cycle voltage regulating unit is composed of a first one-way switch S₁A first power inductor L₁A third power inductor L₃A first energy storage capacitor C₁A second diode D₂And a third diode D₃Composition is carried out; the negative half-cycle voltage regulating unit is composed of a second one-way switch S₂A second power inductor L₂A fourth power inductor L₄A second energy storage capacitor C₂A first diode D₁And a fourth diode D₄Composition is carried out; the output polarity unit is composed of a third one-way switch S₃And a fourth one-way switch S₄The fifth one-way switch S₅And a sixth one-way switch S₆And (4) forming.

Specifically, referring to fig. 2 to 4, the first energy storage capacitor C₁Is connected to the first power inductor L₁And a third power inductor L₃To (c) to (d); the first one-way switch S₁Is connected to the first power inductor L₁And a first energy storage capacitor C₁The joint of (a); the first one-way switch S₁Source and second diode D₂The anodes of the anode groups are connected; the third diode D₃Is connected to the first energy storage capacitor C₁And a third power inductor L₃The joint of (a); the third diode D₃Is connected to the second diode D₂The anode of (1); the second energy storage capacitor C₂Is connected to the second power inductor L₂And a fourth power inductor L₄To (c) to (d); the second one-way switch S₂Is connected to the second power inductor L₂And a second energy storage capacitor C₂The joint of (a); the second one-way switch S₂Source stage and first diode D₁The anodes of the anode groups are connected; the fourth diode D₄Is connected to the second energy storage capacitor C₂And a fourth power inductor L₄The joint of (a); the fourth diode D₄Is connected to the first diode D₁The anode of (1); the third one-way switch S₃Drain and fifth unidirectional switch S₅Are connected with each other; the fourth one-way switch S₄And the sixth one-way switch S₆Are connected with each other; the third one-way switch S₃Source and fourth unidirectional switch S₄Are connected with each other; the fifth one-way switch S₅And the sixth one-way switch S₆Are connected.

The input capacitor is connected to two ends of the input power supply; two ends of the input capacitor are respectively connected to the first power inductor L₁And a second diode D₂Both ends of (a); the output capacitor C_oIs connected to a load R_LTwo ends; the output capacitor C_oIs connected to the third one-way switch S₃Drain and fourth unidirectional switch S₄Between the drain and the drain; the third power inductor L₃Is connected to the third one-way switch S at the other end₃A source stage of (a); the fourth power inductor L₄Is connected to the fourth one-way switch S at the other end₄The source stage of (1).

Further, in this embodiment, the converter is in the 2-fold down-conversion output state, the waveform of the converter is as shown in fig. 5(a), there are four operation states and 8 operation modes, and as shown in fig. 6(a) to (h), the operation states are analyzed as follows:

the first operating state: the positive half cycles are in phase. Mode 1: input AC voltage source is positive half cycle at DT_swWithin the time range, switch S₁、S₄、S₅On, switch S₂、S₃、S₆And (6) turning off. Power supply inductance L₁Charging, capacitance C₁And an inductance L₃Discharging to a load; mode 2: input AC voltage source is positive half cycle at (1-D) T_swWithin the time range, switch S₄、S₅On, switch S₁、S₂、S₃、S₆And (6) turning off. Power supply and inductor L₁Capacitor C₁Charging, load to inductance L₃And (4) discharging. The ratio of the output voltage to the input voltage is:

the second operating state: negative half cycles reversed. Modality 3: input AC voltage source is negative half cycle at DT_swWithin the time range, switch S₂、S₄、S₅On, switch S₁、S₃、S₆And (6) turning off. Power supply inductance L₂Charging, capacitance C₂And an inductance L₄Discharging to a load; modality 4: input AC voltage source is negative half cycle at (1-D) T_swWithin the time range, switch S₄、S₅On, switch S₁、S₂、S₃、S₆And (6) turning off. Power supply and inductor L₂Capacitor C₂Charging, load to inductance L₄And (4) discharging. The ratio of the output voltage to the input voltage is:

a third operating state: the positive half cycle is reversed. Mode 5: input AC voltage source is positive half cycle at DT_swWithin the time range, switch S₁、S₃、S₆On, switch S₂、S₄、S₅And (6) turning off. Power supply inductance L₁Charging, capacitance C₁And an inductance L₃Discharging to a load; modality 6: input AC voltage source is positive half cycle at (1-D) T_swWithin the time range, switch S₃、S₆On, switch S₁、S₂、S₄、S₅And (6) turning off. Power supply and inductor L₁Capacitor C₁Charging, load to inductance L₃And (4) discharging. The ratio of the output voltage to the input voltage is:

a fourth operating state: negative half cycles are in phase. Modality 7: input AC voltage source is negative half cycle at DT_swWithin the time range, switch S₂、S₃、S₆On, switch S₁、S₄、S₅And (6) turning off. Power supply inductance L₂Charging, capacitance C₂And an inductance L₄Discharging to a load; modality 8: input AC voltage source is negative half cycle at (1-D) T_swWithin the time range, switch S₃、S₆On, switch S₁、S₂、S₄、S₅And (6) turning off. Power supply and inductor L₂Capacitor C₂Charging, load to inductance L₄And (4) discharging. The ratio of the output voltage to the input voltage is:

and the step-up or step-down output can be obtained by adjusting the duty ratio D of the driving signal of the high-frequency switch under each circuit state.

Example two:

referring to fig. 5(b), in this embodiment, the converter is in the same-frequency output state, the output and the input are kept in phase, and the operation process of each circuit state is similar to that described in the first embodiment.

Example three:

referring to fig. 5(c), in this embodiment, the converter is in a 2-fold up-conversion output state, and the operation process of each circuit state is similar to that of the first embodiment by changing the circuit operation state from positive half-cycle in-phase output to positive half-cycle inverted output at the time of 1/4 input line cycle and changing the circuit operation state from negative half-cycle inverted output to negative half-cycle in-phase output at the time of 3/4 line cycle.

In summary, the single-phase Cuk variable-frequency AC-AC converter provided by the invention can realize voltage boosting and voltage reducing and variable-frequency AC voltage output, is simple and feasible in control strategy, and has the advantages of fewer switching devices, high power density, high efficiency and the like compared with the conventional AC-AC converter.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.