A non-isolated single-phase AC voltage-stabilized power supply conversion device and control method thereof

Abstract

The present invention discloses a non-isolated single-phase AC voltage-stabilized power supply conversion device and a control method thereof, comprising a bidirectional conversion switch unit, an input filter unit, a switch conversion unit, an output filter unit, and a control unit. The control unit of the present invention can control the bidirectional conversion switch unit to switch the port connection points of the input and output according to an external communication command or a judgment of other external voltage and current signals, and can make the AC circuit work in three working modes of boost, buck or standby in coordination with the input and output; thereby achieving the required relatively stable output voltage without being affected by the fluctuation of the input voltage; at the same time, the present invention is also applicable to single-phase AC power supply, three-phase three-wire or three-phase four-wire AC power supply.

Description

Technical Field

[0001] The invention relates to a switching power supply, and in particular to a non-isolated single-phase AC voltage-stabilized power supply conversion device and a control method thereof. Background Art

[0002] Nowadays, the power grids in the world are different. There are 110VAC grids, 220VAC, 230VAC, and even 240VAC. At the same time, due to various reasons, the voltage may be positively biased or negatively biased when it reaches the user end or the electrical appliance end, which may cause the electrical load to be unsuitable. Therefore, when Asian users bring their electrical equipment to Europe on a business trip, or when Chinese customers go to Japan, the United States, etc., they may need to add a voltage stabilizer. The traditional solution is to design a universal power supply, or to equip a large and complex voltage stabilizer at the device end. When the electrical equipment is large, if the power quality requirements of the power grid are not very high, the voltage stabilizer may be a traditional low-frequency voltage stabilizer, so it is bulky and has poor cost performance in the field of low power. Therefore, it is necessary to design a new voltage stabilizer that has a better cost performance while meeting the needs of users. Summary of the invention

[0003] Purpose of the invention: The first purpose of the present invention is to provide a non-isolated single-phase AC voltage-stabilized power supply conversion device that can solve the technical problems of the existing AC voltage-stabilized conversion devices, such as complex design, bulky low-frequency non-isolated volume and low cost performance; The second purpose of the present invention is to provide a control method for a non-isolated single-phase AC voltage-stabilized power supply conversion device that can control the conversion device to operate in standby mode, boost mode or buck mode.

[0004] Technical solution: The present invention includes a non-isolated single-phase AC regulated power supply conversion device, including a bidirectional conversion switch unit, an input filter unit, a switch conversion unit, an output filter unit, and a control unit. The first AC input end of the bidirectional conversion switch unit is connected to an input AC source, the second AC output end of the bidirectional conversion switch unit is connected to an output AC equivalent load, the first AC output end of the bidirectional conversion switch unit is connected to the input end of the input filter unit, and the second AC input end of the bidirectional conversion switch unit is connected to the output end of the output filter unit; the output end of the input filter unit is connected to the input end of the switch conversion unit, and the input end of the output filter unit is connected to the output end of the switch conversion unit.

[0005] The control unit comprises an operation processing unit, a signal sampling unit, an auxiliary power supply, and a driving unit, which are respectively connected to an input AC source, an output AC equivalent load, a bidirectional conversion switch unit, and a switch conversion unit.

[0006] The control unit also includes a communication unit for external communication.

[0007] The bidirectional conversion switch unit includes a first dual-selection switch K1 and a second dual-selection switch K2. One end of the first dual-selection switch K1 and the second dual-selection switch K2 are connected to the AC input end, the other end of the first dual-selection switch K1 is connected to the input filter unit, and the other end of the second dual-selection switch K2 is connected to the output filter unit.

[0008] The first dual-selection switch K1 and the second dual-selection switch K2 are both switches that can pass current bidirectionally and can be turned off.

[0009] The switch conversion unit includes a first capacitor C1, a third switch K3, a fourth switch K4, a first inductor L1 and a second capacitor C2, wherein the first capacitor C1 is connected in parallel between ports 1 and 3 of the AC input; one end of the third switch K3 is connected to port 1 of the AC input, and the other end of the third switch K3 is respectively connected to one end of the first inductor L1 and one end of the fourth switch K4; the other end of the fourth switch K4 is connected to port 3 of the AC input; the other end of the first inductor L1 is connected to port 2 of the AC output; and the second capacitor C2 is connected in parallel between ports 2 and 3 of the AC output.

[0010] The present invention also includes a control method for a non-isolated single-phase AC voltage-stabilized power supply conversion device, comprising the following steps:

[0011] (1) The control unit processes the voltage signal or external communication command;

[0012] (2) determining whether the converter needs to operate in a standby mode, a boost mode, or a buck mode;

[0013] (3) The control unit controls the first switch K1 and the second dual-selection switch K2 in the bidirectional conversion switch unit to connect to the high-voltage end or the low-voltage end.

[0014] In step (3), the control unit also applies control signals to the third switch K3 and the fourth switch K4 of the switch conversion unit, so that the switch conversion unit operates in an equivalent boost circuit mode or an equivalent buck circuit mode.

[0015] In the boost or buck mode, the control unit controls the third switch K3 and the fourth switch K4 of the switch conversion unit to operate in a fixed interval of the frequency period of the AC voltage, providing a non-standard sinusoidal AC voltage, so that the output voltage is boosted or bucked in the operating interval compared to the AC input voltage, thereby achieving efficiency improvement and energy saving.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects: (1) by controlling the bidirectional conversion switch unit and the switch conversion unit, the voltage stabilization circuit can achieve voltage boost or voltage reduction, thereby outputting a stable voltage; (2) when the load can accept non-standard sinusoidal AC voltage, the switch conversion unit can also be made to work only at part of the input interval within the frequency cycle, thereby achieving high efficiency; (3) by utilizing the high frequency operation of the switch conversion unit, the change circuit is smaller in size and more cost-effective than the traditional industrial frequency voltage stabilizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural block diagram of the present invention;

[0018] Figure 2 for Figure 1 A circuit diagram of a bidirectional conversion switch unit;

[0019] Figure 3 for Figure 1 The structural block diagram of the control unit;

[0020] Figure 4 for Figure 1 Schematic diagram of the switch conversion unit Figure 1 ;

[0021] Figure 5 for Figure 1 Schematic diagram of the switch conversion unit Figure 2 ;

[0022] Figure 6 for Figure 1 Schematic diagram of the switch conversion unit Figure 3 ;

[0023] Figure 7 for Figure 1 Schematic diagram of switches in the switch conversion unit;

[0024] Figure 8 for Figure 4 Schematic diagram of the converter working in buck mode;

[0025] Fig. 9 for Figure 4 Schematic diagram of the converter working in boost mode. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further introduced below in conjunction with specific implementation methods and drawings of the specification.

[0027] like Figure 1As shown, the present invention includes a bidirectional conversion switch unit, an input filter unit, a switch conversion unit, an output filter unit, and a control unit. The bidirectional conversion switch unit has four interfaces, the first AC input end of the bidirectional conversion switch unit is connected to the input AC source, the second AC output end of the bidirectional conversion switch unit is connected to the output AC equivalent load, the first AC output end of the bidirectional conversion switch unit is connected to the input end of the input filter unit, and the second AC input end of the bidirectional conversion switch unit is connected to the output end of the output filter unit; the output end of the input filter unit is connected to the input end of the switch conversion unit, and the input end of the output filter unit is connected to the output end of the switch conversion unit.

[0028] like Figure 2 As shown, the bidirectional conversion switch unit is connected between the AC L line input terminal and the output terminal, and includes a first dual-selection switch K1 and a second dual-selection switch K2. One end of the first dual-selection switch K1 and the second dual-selection switch K2 is connected to the AC (alternating current) input terminal, the other end of the first dual-selection switch K1 is connected to the input filter unit, and the other end of the second dual-selection switch K2 is connected to the output filter unit. It can also be directly connected to the switch conversion unit, and there can be no input filter unit or no output filter unit.

[0029] like Figure 3 As shown, the control unit includes a processing unit, a signal sampling unit, an auxiliary power supply, and a drive unit, which are respectively connected to the input AC source, the output AC equivalent load, the bidirectional conversion switch unit, and the switch conversion unit. At the same time, the control unit can also include a communication unit, which can communicate with the outside.

[0030] like Figure 4 As shown, the switch conversion unit is a single-phase AC switch conversion unit, including a first capacitor C1, a third switch K3, a fourth switch K4, a first inductor L1 and a second capacitor C2. The first capacitor C1 is connected in parallel between ports 1 and 3 of the AC input; one end of the third switch K3 is connected to port 1 of the AC input, and the other end of the third switch K3 is respectively connected to one end of the first inductor L1 and one end of the fourth switch K4; the other end of the fourth switch K4 is connected to port 3 of the AC input; the other end of the first inductor L1 is connected to port 2 of the AC output; and the second capacitor C2 is connected in parallel between ports 2 and 3 of the AC output.

[0031] like Figure 7 As shown, af is a feasible configuration of the third switch K3 and the fourth switch K4, both of which are switches that can flow current bidirectionally and can be turned off, and are semiconductor devices that can be turned on and off by high-frequency electrical drive signals, such as MOS tubes or IGBT tubes. The anti-parallel diode of the switch tube can be an integrated or parasitic diode, or an external single diode.

[0032] The present invention also includes a control method for a non-isolated single-phase AC voltage-stabilized power supply conversion device, comprising the following steps:

[0033] (1) The control unit processes the voltage signal or external communication command;

[0034] (2) determining whether the converter needs to operate in a standby mode, a boost mode, or a buck mode;

[0035] (3) The control unit controls the first switch K1 and the second dual-selection switch K2 in the bidirectional conversion switch unit to connect to the high-voltage end or the low-voltage end.

[0036] In step (3), the control unit also applies a control signal to the third switch K3 and the fourth switch K4 of the switch conversion unit, so that the switch conversion unit operates in an equivalent boost circuit mode or an equivalent buck circuit mode. In the boost or buck mode, the control unit controls the third switch K3 and the fourth switch K4 of the switch conversion unit to operate in a fixed interval of the frequency period of the AC voltage, providing a non-standard sinusoidal AC voltage, so that the output voltage is boosted or bucked in the operating interval compared to the AC input voltage.

[0037] The control method is further described below by taking the circuit of Embodiment 1 as an example:

[0038] The control unit operates the voltage signal sampled by the sampling circuit or the command obtained by external communication through the program in the operation processor unit. When it is determined that the circuit needs to work in the boost mode, the first dual-selection switch K1 in the bidirectional conversion switch is controlled to be connected to port 1, and the second dual-selection switch K2 is controlled to be connected to port 2; at the same time, a control signal is applied to the third switch K3 and the fourth switch K4 of the switch conversion unit, so that the switch conversion unit works in the equivalent boost circuit mode (boost). When it is determined that the circuit works in the buck mode, the first dual-selection switch K1 in the bidirectional conversion switch is controlled to be connected to port 2, and the second dual-selection switch K2 is controlled to be connected to port 1; at the same time, a control signal is applied to the third switch K3 and the fourth switch K4 of the switch conversion unit, so that the switch conversion unit works in the equivalent buck circuit mode (buck). When the circuit works in the standby mode, the first dual-selection switch K1 and the second dual-selection switch K2 in the bidirectional conversion switch are controlled to be connected to port 1 and port 2 respectively, waiting for the conversion of the boost mode or the buck mode.

[0039] like Figure 8As shown, it is assumed that it has been determined that the converter needs to work in the buck mode, the bidirectional conversion switch has been switched to the corresponding position, or the external conditions (AC input and AC output conditions) of the switch conversion unit have been manually (or artificially) set. Therefore, after the operation processor of the controller unit performs operation, a high-frequency PWM drive signal is issued, which is driven by the drive unit to drive the third switch K3 and the fourth switch K4 in the switch conversion unit. Assuming that Figure 8 In Figure a, the AC is a positive half-wave. When K3 is first turned on, the AC passes through K3 and the first inductor L1 to reach the output load end. The part of the input voltage that is higher than the output voltage is stored in L1, such as Figure 8 In Figure b, when K3 is turned off and K4 is turned on, the energy stored in L1 will continue to flow and be released. On the contrary, when the voltage is a negative half-wave, the current is reversed, corresponding to Figure 8 Figure c and figure d. Then the control and operation are repeated according to the working frequency of the voltage. The working effect under this control method is consistent with the Buck circuit we are familiar with, so the same-phase step-down conversion of the AC input voltage is realized here.

[0040] like Fig. 9 As shown, it is assumed that it has been determined that the converter needs to work in the boost mode, the bidirectional conversion switch has been switched to the corresponding position, or the external conditions (AC input and AC output conditions) of the switch conversion unit have been manually (or artificially) set. Therefore, after the calculation processor of the controller unit calculates, a high-frequency PWM drive signal is issued, which is driven by the drive unit to drive the third switch K3 and the fourth switch K4 in the switch conversion unit. Assuming that Fig. 9 In Figure a, the AC is a positive half-wave. When K4 is first turned on, the AC is applied to both ends of the first inductor L1 through K4, so L1 stores energy. Fig. 9 In Figure b, when K4 is turned off and K3 is turned on, the energy stored in L1 will be released and superimposed with the AC. On the contrary, when the voltage is a negative half-wave, the current is reversed, corresponding to Fig. 9 Figure c and figure d. Then the control and operation are repeated according to the working frequency of the voltage. The working effect under this control method is consistent with the Boost circuit we are familiar with, so the same-phase boost conversion of the AC input voltage is realized here.

[0041] In addition, in the boost or buck mode, the third switch K3 and the fourth switch K4 of the control switch conversion unit can also be controlled to operate only in a certain section of the frequency period of the AC voltage, providing a non-standard sinusoidal AC voltage, so that the output voltage is boosted or bucked only in this working section compared to the AC input voltage, thereby achieving efficiency improvement and energy saving.

[0042] Therefore, no matter it is boost or buck mode, or partial boost or buck, a bidirectional converter is used to realize the circuit mode switching of boost and buck, which is a low-frequency switching, so the circuit is simple; at the same time, the high-frequency operation of the switching conversion device is used to realize the same-phase boost and buck, thereby getting rid of the industrial frequency transformer or self-coupled conversion in the traditional voltage stabilizer, making the circuit small in size, high in density, and cost-effective.

[0043] like Figure 5 and Figure 6 As shown in FIG. 1 , they are other implementations of the first embodiment, such as Figure 5 As shown, Figure 4 The three single-phase conversion devices shown are connected to the three-phase four-wire AC source to work. In essence, they are three single-phase converters with different AC voltage phases. Their specific working principles are consistent with the above-mentioned single-phase converters, thus meeting the voltage stabilization needs of the three-phase four-wire AC system. At the same time, the N line is also suspended and not connected to the input terminal. Figure 6 As shown, the aforementioned single-phase AC conversion device can be connected to any two non-repeating phases of the three phases, so that the three converters are connected to the three-phase AC source. That is, it can be regarded as a single-phase converter whose AC voltage phases are different from L line and N line to LaLb, or LbLc, or LcLa. Its specific working principle is also consistent with the aforementioned single-phase. Figure 5 , Figure 6 The specific working principle analysis will not be introduced one by one.

Claims

1. A non-isolated single-phase AC regulated power supply conversion device, characterized in that: It comprises a bidirectional conversion switch unit, an input filter unit, a switch conversion unit, an output filter unit, and a control unit, wherein the first AC input end of the bidirectional conversion switch unit is connected to an input AC source, the second AC output end of the bidirectional conversion switch unit is connected to an output AC equivalent load, the first AC output end of the bidirectional conversion switch unit is connected to an input end of the input filter unit, and the second AC input end of the bidirectional conversion switch unit is connected to an output end of the output filter unit; the output end of the input filter unit is connected to an input end of the switch conversion unit, and the input end of the output filter unit is connected to an output end of the switch conversion unit; The bidirectional conversion switch unit includes a first dual-selection switch K1 and a second dual-selection switch K2, one end of the first dual-selection switch K1 is connected to the first AC input end, and the other end thereof is respectively connected to the No. 2 port and the No. 1 port of the switch conversion unit, and one end of the second dual-selection switch K2 is connected to the second AC output end, and the other end thereof is respectively connected to the No. 2 port and the No. 1 port of the switch conversion unit; the control unit controls the first dual-selection switch K1 and the second dual-selection switch K2 in the bidirectional conversion switch unit to be connected to the high voltage end or the low voltage end; The switch conversion unit includes a first capacitor C1, a third switch K3, a fourth switch K4, a first inductor L1 and a second capacitor C2, wherein the first capacitor C1 is connected in parallel between ports 1 and 3 of the AC input; one end of the third switch K3 is connected to port 1 of the AC input, and the other end of the third switch K3 is respectively connected to one end of the first inductor L1 and one end of the fourth switch K4; the other end of the fourth switch K4 is connected to port 3 of the AC input; the other end of the first inductor L1 is connected to port 2 of the AC output; and the second capacitor C2 is connected in parallel between ports 2 and 3 of the AC output.

2. The non-isolated single-phase AC regulated power supply conversion device according to claim 1, characterized in that: The control unit comprises an operation processing unit, a signal sampling unit, an auxiliary power supply, and a driving unit. The control unit is respectively connected to an input AC source, an output AC equivalent load, a bidirectional conversion switch unit, and a switch conversion unit.

3. The non-isolated single-phase AC regulated power supply conversion device according to claim 2, characterized in that: The control unit also includes a communication unit for external communication.

4. The non-isolated single-phase AC regulated power supply conversion device according to claim 1, characterized in that: The first dual-selection switch K1 and the second dual-selection switch K2 are both switches that can pass current bidirectionally and can be turned off.

5. A control method for the non-isolated single-phase AC regulated power supply conversion device according to claim 1, characterized in that: The following steps are involved: (1) The control unit processes the voltage signal or external communication command; (2) determining whether the converter needs to operate in a standby mode, a boost mode, or a buck mode; (3) The control unit controls the first dual-selection switch K1 and the second dual-selection switch K2 in the bidirectional conversion switch unit to connect to the high-voltage end or the low-voltage end.

6. The control method of the non-isolated single-phase AC regulated power supply conversion device according to claim 5, characterized in that: In step (3), the control unit also applies control signals to the third switch K3 and the fourth switch K4 of the switch conversion unit, so that the switch conversion unit operates in an equivalent boost circuit mode or an equivalent buck circuit mode.

7. The control method of the non-isolated single-phase AC regulated power supply conversion device according to claim 6, characterized in that: In the boost or buck mode, the control unit controls the third switch K3 and the fourth switch K4 of the switch conversion unit to operate in a fixed interval of the frequency period of the AC voltage to provide a non-standard sinusoidal AC voltage, so that the output voltage is boosted or bucked in a fixed interval compared to the AC input voltage.

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