Isolated single-stage ac / dc converter, control method and related apparatus
By controlling the turn-off sequence of the high-frequency switching transistor and the normally-on transistor in the primary circuit when the AC voltage crosses zero, a freewheeling path is provided, which solves the problem of excessive stress on the switching transistor in the isolated single-stage AC/DC converter, and achieves smooth transition and stress reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUNGROW POWER SUPPLY CO LTD
- Filing Date
- 2026-05-14
- Publication Date
- 2026-07-31
AI Technical Summary
Isolated single-stage AC/DC converters lack a freewheeling path when the AC source switches at zero crossing, resulting in the switching transistors being subjected to greater stress.
Within a preset range of the AC voltage zero-crossing point, the high-frequency switching transistor of the primary circuit is controlled to turn off, and the normally conducting transistor is controlled to turn off after a preset time. Alternatively, after the first time period, some normally conducting transistors are controlled to turn off, and then during the second time period, the normally conducting transistors that have not been turned off are controlled to turn on the high-frequency switching transistor of the same half-bridge arm to provide a freewheeling circuit.
It achieves a smooth transition from normal operation to zero-crossing freewheeling state in isolated single-stage AC/DC converters, reducing voltage stress on switching transistors and preventing damage to them.
Smart Images
Figure CN122495875A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of rectification and conversion technology, specifically to an isolated single-stage AC / DC converter, control method, and related devices. Background Technology
[0002] An isolated single-stage AC / DC converter includes a primary circuit, a transformer, and a secondary circuit. The first terminal of the primary circuit is connected to an AC source, the second terminal of the primary circuit is connected to the primary winding of the transformer, the secondary winding of the transformer is connected to the first terminal of the secondary circuit, and the second terminal of the secondary circuit is connected to a DC source or load.
[0003] In actual operation, in order to prevent the upper and lower arms of the primary circuit from being directly connected and causing the AC source to be short-circuited, there is a dead time between the upper and lower arm switches. For example, there is a dead time delay between the lower arm switch being turned off and the upper arm switch being turned on.
[0004] However, when the AC source switches at the zero-crossing point, the switching transistor in the primary circuit lacks a freewheeling path, causing stress problems in the switching transistor. Summary of the Invention
[0005] This application provides an isolated single-stage AC / DC converter that can provide a freewheeling path for the switching transistors of the primary circuit during zero-crossing switching, thereby reducing the stress on the switching transistors.
[0006] The isolated single-stage AC / DC converter provided in this application includes: a controller, a primary-side circuit, a resonant cavity, and a secondary-side circuit; The first end of the primary circuit is used to connect to an AC source, the second end of the primary circuit is connected to the first end of the resonant cavity, and the second end of the resonant cavity is connected to the secondary circuit. The primary circuit includes a bidirectional switching bridge arm, the upper bridge arm of the bidirectional switching bridge arm includes two switching transistors connected in series, and the lower bridge arm of the bidirectional switching bridge arm includes two switching transistors connected in series. The controller is configured to, when the AC voltage is within a preset range of zero crossing, control the high-frequency switching transistor of the primary circuit to turn off, and after a preset time, control the normally conducting transistor of the primary circuit to turn off, so that the resonant cavity can dissipate energy; or, control the high-frequency switching transistor of the primary circuit to turn off, and after a first time period, control some normally conducting transistors of the primary circuit to turn off, and after a second time period of partial normally conducting transistors being turned off, control the normally conducting transistors that have not been turned off to turn off, and during the second time period, control the high-frequency switching transistor in the same half-bridge arm as the normally conducting transistors that have not been turned off to turn on again to provide a freewheeling circuit, so that the resonant cavity can dissipate energy.
[0007] One possible implementation is that the primary-side circuit includes two bidirectional switching bridge arms connected in parallel, or the primary-side circuit includes one bidirectional switching bridge arm and one capacitor bridge arm. The secondary circuit includes a full-bridge circuit or a half-bridge circuit, and the secondary circuit includes a switching transistor.
[0008] One possible implementation is that, when the primary-side circuit includes a first bidirectional switch bridge arm and a second bidirectional switch bridge arm connected in parallel, the upper arm of the first bidirectional switch bridge arm includes a first switch and a second switch connected in series, and the lower arm of the first bidirectional switch bridge arm includes a third switch and a fourth switch connected in series; the upper arm of the second bidirectional switch bridge arm includes a fifth switch and a sixth switch connected in series, and the lower arm of the second bidirectional switch bridge arm includes a seventh switch and an eighth switch connected in series. The controller is configured to turn off the second, fourth, sixth, and eighth switches within a preset range, and after a preset time, turn off the first, third, fifth, and seventh switches.
[0009] One possible implementation is that, when the primary-side circuit includes a first bidirectional switch bridge arm and a second bidirectional switch bridge arm connected in parallel, the upper arm of the first bidirectional switch bridge arm includes a first switch and a second switch connected in series, and the lower arm of the first bidirectional switch bridge arm includes a third switch and a fourth switch connected in series; the upper arm of the second bidirectional switch bridge arm includes a fifth switch and a sixth switch connected in series, and the lower arm of the second bidirectional switch bridge arm includes a seventh switch and an eighth switch connected in series. The controller is configured to turn off the first, third, fifth, and seventh switches within a preset range, and after a preset time, turn off the second, fourth, sixth, and eighth switches.
[0010] One possible implementation is that, when the primary-side circuit includes a first bidirectional switch bridge arm and a second bidirectional switch bridge arm connected in parallel, the upper arm of the first bidirectional switch bridge arm includes a first switch and a second switch connected in series, and the lower arm of the first bidirectional switch bridge arm includes a third switch and a fourth switch connected in series; the upper arm of the second bidirectional switch bridge arm includes a fifth switch and a sixth switch connected in series, and the lower arm of the second bidirectional switch bridge arm includes a seventh switch and an eighth switch connected in series. The controller is configured to turn off the second, fourth, sixth, and eighth switches within a preset range, turn off the third and seventh switches after a first time period, turn off the first and fifth switches after the third and seventh switches have turned off for a second time period, and turn on the second and sixth switches during the second time period to provide a freewheeling circuit.
[0011] One possible implementation is that, when the primary-side circuit includes a first bidirectional switch bridge arm and a second bidirectional switch bridge arm connected in parallel, the upper arm of the first bidirectional switch bridge arm includes a first switch and a second switch connected in series, and the lower arm of the first bidirectional switch bridge arm includes a third switch and a fourth switch connected in series; the upper arm of the second bidirectional switch bridge arm includes a fifth switch and a sixth switch connected in series, and the lower arm of the second bidirectional switch bridge arm includes a seventh switch and an eighth switch connected in series. The controller is configured to turn off the second, fourth, sixth, and eighth switches within a preset range, turn off the first and fifth switches after a first time period, turn off the third and seventh switches after the first and fifth switches have turned off for a second time period, and turn on the fourth and eighth switches during the second time period to provide a freewheeling circuit.
[0012] In one possible implementation, the controller is also configured to control the switching of the secondary circuit to turn off within a preset range, based on the turn-off time of the high-frequency switching transistor or the turn-off time of the normally-on transistor.
[0013] This application also provides a power supply device, including the isolated single-stage AC / DC converter described in the above embodiments.
[0014] This application embodiment also provides a control method for an isolated single-stage AC / DC converter. The converter includes a primary-side circuit, a resonant cavity, and a secondary-side circuit. The primary-side circuit includes a bidirectional switching bridge arm, the upper bridge arm of which includes two switches connected in series, and the lower bridge arm of which includes two switches connected in series. The method includes: When the AC voltage is within a preset range of zero crossing, the high-frequency switching transistor of the primary circuit is turned off; after a preset time, the normally conducting transistor of the primary circuit is turned off, so that the resonant cavity can release energy. or, The high-frequency switching transistors of the primary circuit are turned off. After the first time period, some normally-conducting transistors of the primary circuit are turned off. After the second time period when some normally-conducting transistors are turned off, the normally-conducting transistors that have not been turned off are turned off. During the second time period, the high-frequency switching transistors in the same half-bridge arm as the normally-conducting transistors that have not been turned off are turned on again to provide a freewheeling circuit, so that the resonant cavity can discharge energy.
[0015] One possible implementation method further includes: controlling the turn-off of the secondary circuit's switching transistors based on the turn-off time of the high-frequency switching transistor or the turn-off time of the normally-on transistor within a preset range.
[0016] This application also provides a controller for executing the methods described above.
[0017] The isolated single-stage AC / DC converter provided in this application allows the controller to turn off the high-frequency switching transistors in the primary circuit when the AC voltage is within a preset range of zero crossing. After a preset time, the controller then turns off the normally-conducting transistors in the primary circuit. Alternatively, the controller turns off the high-frequency switching transistors in the primary circuit, then turns off some of the normally-conducting transistors in the primary circuit after a first time period. After a second time period of partial transistor turn-off, the controller turns off the remaining normally-conducting transistors. During the second time period, the controller turns on the high-frequency switching transistors in the same half-bridge arm as the remaining normally-conducting transistors to provide a freewheeling path. Because there is a freewheeling path in the primary circuit, the energy in the resonant cavity can be discharged, enabling a smooth transition of the isolated single-stage AC / DC converter from normal operation to zero-crossing freewheeling state. This allows the energy in the resonant cavity to decay to zero, reducing the stress on each switching transistor. Attached Figure Description
[0018] Figure 1 A schematic diagram of a first type of isolated single-stage AC / DC converter provided in the embodiments of this application; Figure 2 A schematic diagram of a second isolated single-stage AC / DC converter provided in the embodiments of this application; Figure 3 A schematic diagram of the switching timing in the first type of isolated single-stage AC / DC converter provided in this application embodiment; Figure 4A A schematic diagram of the switching timing in a second type of isolated single-stage AC / DC converter provided in this application embodiment; Figure 4B for Figure 4A The corresponding continuing path diagram; Figure 5A A schematic diagram of the switching timing in a third type of isolated single-stage AC / DC converter provided in this application embodiment; Figure 5B for Figure 5A The corresponding continuing path diagram; Figure 6 A schematic diagram of a third type of isolated single-stage AC / DC converter provided in the embodiments of this application; Figure 7 A flowchart illustrating a control method for an isolated single-stage AC / DC converter provided in this application embodiment; Figure 8 This is a schematic diagram of a controller provided in an embodiment of this application. Detailed Implementation
[0019] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0020] In related technologies, the switching transistors of isolated single-stage AC / DC converters may experience significant stress in the transition freewheeling range due to the lack of a freewheeling path.
[0021] In order to reduce the stress on the switching transistor, the first aspect of the present application provides an isolated single-stage AC / DC converter that can provide a new freewheeling path for the switching transistor and reduce the voltage stress on the switching transistor.
[0022] See Figure 1 The figure is a schematic diagram of the first isolated single-stage AC / DC converter provided in the embodiments of this application.
[0023] The isolated single-stage AC / DC converter provided in this application includes a controller 40, a primary-side circuit 10, a resonant cavity 20, and a secondary-side circuit 30. The resonant cavity 20 includes a resonant inductor L. pr Resonant capacitor C pr And transformers, where the transformer is taken as an ideal transformer, the inductance of the primary winding of the transformer is equivalent to the magnetizing inductance L. m .
[0024] The first terminal of the primary circuit 10 is used to connect to the AC source V. ac The second end of the primary circuit 10 is connected to the first end of the resonant cavity 20, and the second end of the resonant cavity 20 is connected to the secondary circuit 30. The primary circuit 10 includes a bidirectional switching bridge arm, the upper bridge arm of which includes two switching transistors connected in series, and the lower bridge arm of which includes two switching transistors connected in series.
[0025] The controller 40 is configured to, when the AC voltage is within a preset range of zero crossing, control the high-frequency switching transistor of the primary circuit to turn off, and after a preset time, control the normally conducting transistor of the primary circuit to turn off; or, control the high-frequency switching transistor of the primary circuit to turn off, and after a first time period, control some normally conducting transistors of the primary circuit to turn off, and after a second time period of partial normally conducting transistors being turned off, control the normally conducting transistors that have not been turned off to turn off, and during the second time period, control the high-frequency switching transistors in the same half-bridge arm as the normally conducting transistors that have not been turned off to turn on again to provide a freewheeling circuit, so that the resonant cavity can dissipate energy.
[0026] The anti-parallel diode of the switching transistor can be a parasitic diode of the switching transistor or an external diode; this application does not impose specific limitations on the embodiments thereof.
[0027] The embodiments of this application do not specifically limit the structure of the primary circuit 10 and the secondary circuit 30. Some possible implementations include the primary circuit 10 including two bidirectional switching bridge arms connected in parallel, or the primary circuit 10 including one bidirectional switching bridge arm and one capacitor bridge arm; the secondary circuit 30 includes a full-bridge circuit or a half-bridge circuit, and the secondary circuit 30 includes a switching transistor, that is, the secondary circuit 30 includes a controllable full-bridge circuit or a controllable half-bridge circuit.
[0028] To enable those skilled in the art to fully understand the control logic of controller 40, the following will be used as an example. Figure 1 The primary circuit 10 of the provided isolated single-stage AC / DC converter includes two parallel bidirectional switching bridge arms as an example for illustration.
[0029] See Figure 2 This figure is a schematic diagram of a second type of isolated single-stage AC / DC converter provided in an embodiment of this application.
[0030] Figure 2 In the provided isolated single-stage AC / DC converter, when the primary-side circuit 10 includes a first bidirectional switching bridge arm and a second bidirectional switching bridge arm connected in parallel, the upper bridge arm of the first bidirectional switching bridge arm includes a first switching transistor Q connected in series. p1 Second switch Q p2 The lower arm of the first bidirectional switching bridge arm includes a third switch Q connected in series. p3 and the fourth switch Q p4 The upper arm of the second bidirectional switching bridge arm includes a fifth switching transistor Q connected in series. p5 and the sixth switch Q p6 The lower arm of the second bidirectional switching bridge arm includes a seventh switch Q connected in series. p7 and the eighth switch Q p8 The anti-parallel diodes of the two series-connected switching transistors are either top-to-top or back-to-back, meaning the anti-parallel diodes of the two switching transistors are in opposite directions, thus providing a freewheeling path.
[0031] In the exchange source V ac During the positive half-cycle of the AC voltage, the first switching transistor Q... p1 The third switch Q p3 Fifth switch Q p5 and the seventh switch Q p7 Normally on, second switching transistor Q p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 It is a high-frequency switch.
[0032] To enable those skilled in the art to fully understand the control logic of the controller, the following description uses the example of an isolated single-stage AC / DC converter provided in this application, in which the primary circuit includes two parallel bidirectional switching bridge arms.
[0033] First, let's introduce the controller. It is configured to turn off the high-frequency switching transistor in the primary circuit when the AC voltage is within a preset range of zero crossing, and then turn off the normally-continuous transistor in the primary circuit after a preset time, so that the resonant cavity dissipates energy within a preset time. The following will first combine... Figure 3This section describes the scenario where all normally-conducting transistors in the primary circuit are turned off after a preset time.
[0034] See Figure 3 The figure is a schematic diagram of the switching timing of the first type of isolated single-stage AC / DC converter provided in the embodiments of this application.
[0035] In the isolated single-stage AC / DC converter provided in this application embodiment, the high-frequency switching transistor includes the second switching transistor Q. p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 The normally-continuous transistor includes the first switching transistor Q. p1 The third switch Q p3 Fifth switch Q p5 and the seventh switch Q p7 For example. Figure 3 The interval within the dashed box represents the transition freewheeling interval where the AC voltage of the AC source transitions from the positive half-cycle to the negative half-cycle.
[0036] The controller 40 is configured to control the second switch Q within a preset range when the AC voltage is at its zero-crossing point. p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 After being turned off and after a preset time, the first switching transistor Q is controlled. p1 The third switch Q p3 Fifth switch Q p5 and the seventh switch Q p7 Turn off.
[0037] Specifically, the controller 40 controls the second switch Q at the third time t3. p2 and the eighth switch Q p8 Turn off, and at the fourth time t4, control the first switch Q. p1 The third switch Q p3 Fifth switch Q p5 and the seventh switch Q p7 The time period between the third time t3 and the fourth time t4 is the preset time. The second switch Q... p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 With all switches in the off state, the forward current of the resonant cavity flows through the fourth switch Q. p4 Anti-parallel diode, third switch Q p3 After passing through the resonant inductor and resonant capacitor in sequence, it then passes through the sixth switch Q. p6The anti-parallel diode and the fifth switch Q p5 Freewheeling; for the negative current in resonant cavity 20, through the eighth switch Q p8 Anti-parallel diode, seventh switch Q p7 After passing through the resonant capacitor and resonant inductor in sequence, it then passes through the second switching transistor Q. p2 The anti-parallel diode and the first switching transistor Q p1 Freewheeling. That is, within a preset time, an isolated single-stage AC / DC converter can have a freewheeling path to dissipate energy.
[0038] The isolated single-stage AC / DC converter provided in this application embodiment controls the high-frequency switching transistors of the primary circuit to turn off when the AC voltage is within a preset range of zero crossing. After a preset time, the controller then controls the normally conducting transistors of the primary circuit to turn off, or, after a preset time, controls some of the normally conducting transistors of the primary circuit to turn off. During the conduction time of the normally conducting transistors that are not turned off, the controller controls the high-frequency switching transistors in the same half-bridge arm as the normally conducting transistors that are not turned off to turn on again to provide a freewheeling path. Because there is a freewheeling path in the primary circuit within the preset time, the energy in the resonant cavity can be discharged, enabling a smooth transition of the isolated single-stage AC / DC converter from normal operation to zero-crossing freewheeling state. This allows the energy in the resonant cavity to decay to zero, reducing the stress on each switching transistor.
[0039] The control logic when the AC voltage of the AC source enters the positive half-cycle from the negative half-cycle is similar to the control logic when the AC voltage of the AC source enters the negative half-cycle.
[0040] In one possible implementation, the controller is configured to control the first switching transistor Q within a preset range where the AC voltage is at a zero-crossing point. p1 The third switch Q p3 Fifth switch Q p5 and the seventh switch Q p7 After being turned off and after a preset time, the second switch Q is controlled. p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 Shutdown. Within a preset time period, the isolated single-stage AC / DC converter has a freewheeling path to dissipate energy, which will not be elaborated here.
[0041] The following description, with reference to the attached diagram, illustrates the situation where, after the first preset time, the controller turns off some normally-continuous transistors in the primary circuit.
[0042] See Figure 4A The figure is a schematic diagram of the switching timing in the second type of isolated single-stage AC / DC converter provided in the embodiments of this application.
[0043] The controller is configured to control the second switch Q within a preset range. p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 After the first time period, the first switch Q is controlled. p1 and the fifth switch Q p5 Turn off, in the first switching transistor Q p1 and the fifth switch Q p5 After the second time period is turned off, control the third switch Q. p3 and the seventh switch Q p7 Turn off, and control the fourth switch Q during the second time period. p4 and the eighth switch Q p8 The circuit is turned on to provide a freewheeling loop.
[0044] See details Figure 4B ,for Figure 4A A diagram showing the corresponding continuation path.
[0045] The following is combined Figure 4A and Figure 4B Let's introduce the freewheeling path. At the first time t1, the four high-frequency switching transistors, namely the second switching transistor Q... p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 All are turned off. The first time period is from the first time t1 to the second time t2. That is, at the second time t2, some normally conducting transistors are turned off, taking the first switching transistor Q as an example. p1 and the fifth switch Q p5 Taking turn-off as an example, the first switch Q p1 and the fifth switch Q p5 After being turned off, the third switch Q p3 and the seventh switch Q p7 The transistor is turned on from time t2 to time t3, and the second time period is from time t2 to time t3. This is because the first switch Q... p1 and the fifth switch Q p5 Shut down, therefore Figure 4B The freewheeling path indicated by the dashed arrow in the diagram is invalid; the fourth switch Q can be used instead. p4 and the eighth switch Q p8 The circuit is activated to provide a freewheeling loop, meaning the freewheeling path at this time is as follows: Figure 4B As shown by the solid line with arrows, both the positive and negative currents of the resonant cavity are controlled by the third switch Q. p3 The seventh switch Q p7 The fourth switch Q p4 and the eighth switch Q p8 To provide.
[0046] Figure 4A Therefore, the normally conducting transistors are turned off after the first time period, and the first switching transistor Q is turned off. p1 and the fifth switch Q p5 Taking turn-off as an example, the following describes how the turn-off of some normally-conducting transistors can also be achieved using a third switching transistor Q. p3 and the seventh switch Q p7 .
[0047] See Figure 5A The figure is a schematic diagram of the switching timing of the third type of isolated single-stage AC / DC converter provided in the embodiments of this application.
[0048] The controller is configured to control the second switch Q within a preset range. p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 After the first time period, the third switch Q is controlled. p3 and the seventh switch Q p7 Turn off, in the third switch Q p3 and the seventh switch Q p7 After the second time period is turned off, control the first switch Q. p1 and the fifth switch Q p5 Turn off, and control the second switch Q during the second time period. p2 and the sixth switch Q p6 The circuit is turned on to provide a freewheeling loop.
[0049] See Figure 5B ,for Figure 5A A diagram showing the corresponding continuation path.
[0050] The following is combined Figure 5A and Figure 5B Let's introduce the continuation path.
[0051] At the first time t1, the four high-frequency switching transistors, namely the second switching transistor Q... p2 The fourth switch Q p4 The sixth switch Q p6 and the eighth switch Q p8 All are turned off. The first time period is from the first time t1 to the second time t2. That is, at the second time t2, some normally conducting transistors are turned off, and the third switching transistor Q is turned off. p3 and the seventh switch Q p7 For example, the third switch Q p3 and the seventh switch Q p7 After being turned off, the first switch Q p1 and the fifth switch Q p5The device is turned on from time t2 to time t3, and the second time period is from time t2 to time t3. During the second time period from time t2 to time t3, the third switch Q is turned on. p3 and the seventh switch Q p7 Shut down, therefore Figure 5B The freewheeling path indicated by the dashed arrow in the diagram is invalid; the second switch Q can be used instead. p2 and the sixth switch Q p6 The circuit is activated to provide a freewheeling loop, meaning the freewheeling path at this time is as follows: Figure 5B As shown by the solid line with arrows, both the positive and negative currents of the resonant cavity are controlled by the first switching transistor Q. p1 Second switch Q p2 Fifth switch Q p5 and the sixth switch Q p6 To provide.
[0052] In one possible implementation, to prevent the energy of the resonant cavity from increasing when the upper and lower bridge arms switch, the isolated single-stage AC / DC converter provided in this application embodiment is further configured to control the switching of the secondary circuit to turn off according to the turn-off time of the high-frequency switching transistor or the turn-off time of the normally-on transistor when the AC voltage is within a preset range of zero crossing, thereby preventing the energy of the secondary circuit from being transferred to the resonant cavity.
[0053] The isolated single-stage AC / DC converter provided in this application embodiment controls the high-frequency switching transistors of the primary circuit to turn off when switching between the upper and lower bridge arms, and then controls the normally-conducting transistors of the primary circuit to turn off after a preset time; or, controls the high-frequency switching transistors of the primary circuit to turn off, and then controls some normally-conducting transistors of the primary circuit to turn off after a first time period, and after a second time period of partial normally-conducting transistors being turned off, controls the remaining normally-conducting transistors to turn off, and during the second time period, controls the high-frequency switching transistors in the same half-bridge arm as the remaining normally-conducting transistors to turn on again to provide a freewheeling circuit. Both the positive and negative currents of the resonant cavity can freewheel through the normally-conducting transistors and the anti-parallel diodes of the high-frequency switching transistors, meaning there is a freewheeling path in the primary circuit, which can attenuate the energy in the resonant cavity to zero, thereby reducing the stress on each switching transistor.
[0054] The isolated single-stage AC / DC converters provided in the above embodiments all take the primary side circuit including two bidirectional switching bridge arms connected in parallel as an example. The primary side circuit may also include one bidirectional switching bridge arm and one capacitor bridge arm. The following is a description in conjunction with the accompanying drawings.
[0055] See Figure 6 This figure is a schematic diagram of a third type of isolated single-stage AC / DC converter provided in an embodiment of this application.
[0056] Figure 6In the provided isolated single-stage AC / DC converter, the primary-side circuit 10 includes a bidirectional switching bridge arm and a capacitor bridge arm. The upper arm of the bidirectional switching bridge arm includes a first switching transistor Q connected in series. p1 Second switch Q p2 The lower arm of the bidirectional switching bridge arm includes a third switch Q connected in series. p3 and the fourth switch Q p4 The upper arm of the capacitor bridge includes a first capacitor C1, and the lower arm of the capacitor bridge includes a second capacitor C2.
[0057] In another isolated single-stage AC / DC converter provided in this application embodiment, the primary-side circuit may also include a bidirectional switching bridge arm and a capacitor bridge arm. The control logic of the controller is similar and will not be described in detail here.
[0058] Based on any of the isolated single-stage AC / DC converters provided in the above embodiments, this application also provides a power supply device, which is an inverter, a charging pile, or an on-board charger, etc.
[0059] The power supply device provided in this application includes the isolated single-stage AC / DC converter and other components (such as AC switches, DC switches, etc.). It can provide a freewheeling path for both the positive and negative currents of the resonant cavity when the upper and lower bridge arms are switching. It can achieve a smooth transition of the isolated single-stage AC / DC converter from the normal operation state to the zero-crossing freewheeling state, so that the energy in the resonant cavity can decay to zero, reduce the stress on each switching transistor, and eliminate the need for additional hardware costs.
[0060] Based on the isolated single-stage AC / DC converter provided in the above embodiments, this application also provides a control method for the isolated single-stage AC / DC converter.
[0061] The control method for an isolated single-stage AC / DC converter provided in this application embodiment is applicable to any of the above-mentioned isolated single-stage AC / DC converters. The isolated single-stage AC / DC converter includes: a primary-side circuit, a resonant cavity, and a secondary-side circuit; the resonant cavity includes a resonant inductor, a resonant capacitor, and a transformer; the first terminal of the primary-side circuit is connected to an AC source, the second terminal of the primary-side circuit is connected to the first terminal of the resonant cavity, and the second terminal of the resonant cavity is connected to the secondary-side circuit; the primary-side circuit includes a bidirectional switching bridge arm, the upper bridge arm of which includes two switches connected in series, and the lower bridge arm of which includes two switches connected in series.
[0062] See Figure 7 The figure is a flowchart of a control method for an isolated single-stage AC / DC converter provided in an embodiment of this application.
[0063] The method includes: S701: When the AC voltage is within a preset range of zero crossing, control the high-frequency switch of the primary circuit to turn off, and after a preset time, control the normally conducting switch of the primary circuit to turn off; or, control the high-frequency switch of the primary circuit to turn off, and after a first time period, control some normally conducting switches of the primary circuit to turn off, and after a second time period of partial normally conducting switch turn-off, control the normally conducting switches that have not been turned off to turn off, and during the second time period, control the high-frequency switch of the same half-bridge arm as the normally conducting switch that has not been turned off to turn on again to provide a freewheeling circuit, so that the resonant cavity can discharge energy.
[0064] For example, after a preset time, all normally-conducting transistors can be turned off. The controller determines whether the converter is within a preset range of the AC voltage zero-crossing point based on the AC voltage of the AC source. If the converter is within the preset range of the AC voltage zero-crossing point, the high-frequency switching transistor is turned off and all normally-conducting transistors are turned on. After a preset time, the controller controls the normally-conducting transistors of the primary circuit to turn off again. Since there is a freewheeling path in the primary circuit within the preset time, the resonant cavity can dissipate energy within the preset time.
[0065] Another possible implementation is to control the normally-on transistors to turn off after a preset time. For details on the specific implementation, please refer to the description of the converter embodiment, which will not be repeated here.
[0066] The isolated single-stage AC / DC converter provided in this application, when the AC voltage is within a preset range of zero crossing, controls the high-frequency switching transistors of the primary circuit to turn off, and after a preset time, controls the normally-conducting transistors of the primary circuit to turn off; or, controls the high-frequency switching transistors of the primary circuit to turn off, and after a first time period, controls some normally-conducting transistors of the primary circuit to turn off, and after a second time period of partial normally-conducting transistors being turned off, controls the remaining normally-conducting transistors to turn off, and during the second time period, controls the high-frequency switching transistors in the same half-bridge arm as the remaining normally-conducting transistors to turn on again to provide a freewheeling circuit. Because there is a freewheeling path in the primary circuit, the energy in the resonant cavity can be discharged, enabling a smooth transition of the isolated single-stage AC / DC converter from normal operation to zero-crossing freewheeling state, allowing the energy in the resonant cavity to decay to zero, and reducing the stress on each switching transistor.
[0067] In one possible implementation, the method further includes: controlling the switching transistor of the secondary circuit to turn off within a preset range according to the turn-off time of the high-frequency switching transistor or the turn-off time of the normally-on transistor, so as to prevent the energy of the resonant cavity from being transferred to the secondary circuit.
[0068] The controller provided in this application embodiment may include software to implement the control methods described above. Alternatively, the controller provided in this application embodiment may include hardware to implement the control methods described above. Or, the controller provided in this application embodiment may include both software and hardware, using a combination of software and hardware to execute the control methods described above.
[0069] In one possible implementation, see Figure 8 This figure is a schematic diagram of a controller provided in an embodiment of this application.
[0070] The controller may include a memory 1011 and a processor 1012. The processor 1012 can be connected to the primary-side circuit and the secondary-side circuit, and can drive the various switching transistors in the primary-side circuit and the secondary-side circuit. The memory may be random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (Electronic Programmable ROM), registers, hard disk, removable disk, etc.
[0071] The memory 1011 can store computer instructions. When the computer instructions stored in the memory 1011 are executed by the processor 1012, the processor 1012 can be used to execute the control method of the isolated single-stage AC / DC converter. The memory 1011 can also store data, such as preset time information involved in the above embodiments.
[0072] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape) or a semiconductor medium (e.g., solid-state disk (SSD)).
[0073] This application also provides a readable storage medium for storing the methods provided in the above embodiments. Examples include random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (EPROM), registers, hard disks, removable disks, or any other form of storage medium in the art.
[0074] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0075] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An isolated single-stage AC / DC converter, characterized by, include: Controller, primary circuit, resonant cavity, and secondary circuit; The first end of the primary circuit is used to connect to an AC source, the second end of the primary circuit is connected to the first end of the resonant cavity, and the second end of the resonant cavity is connected to the secondary circuit; the primary circuit includes a bidirectional switching bridge arm, the upper bridge arm of the bidirectional switching bridge arm includes two switching transistors connected in series, and the lower bridge arm of the bidirectional switching bridge arm includes two switching transistors connected in series. The controller is configured to, when the AC voltage is within a preset range of zero crossing, control the high-frequency switch of the primary circuit to turn off, and after a preset time, control the normally-conducting switch of the primary circuit to turn off, so that the resonant cavity can dissipate energy; or, control the high-frequency switch of the primary circuit to turn off, and after a first time period, control some normally-conducting switches of the primary circuit to turn off, and after a second time period of the partial normally-conducting switches being turned off, control the remaining normally-conducting switches to turn off, and during the second time period, control the high-frequency switch of the same half-bridge arm as the remaining normally-conducting switches to turn on again to provide a freewheeling circuit, so that the resonant cavity can dissipate energy.
2. The transformer of claim 1, wherein, The primary-side circuit includes two bidirectional switch bridge arms connected in parallel, or the primary-side circuit includes one bidirectional switch bridge arm and one capacitor bridge arm. The secondary circuit includes a full-bridge circuit or a half-bridge circuit, and the secondary circuit includes a switching transistor.
3. The transformer of claim 2, wherein, When the primary-side circuit includes a first bidirectional switch bridge arm and a second bidirectional switch bridge arm connected in parallel, the upper bridge arm of the first bidirectional switch bridge arm includes a first switch and a second switch connected in series, and the lower bridge arm of the first bidirectional switch bridge arm includes a third switch and a fourth switch connected in series; the upper bridge arm of the second bidirectional switch bridge arm includes a fifth switch and a sixth switch connected in series, and the lower bridge arm of the second bidirectional switch bridge arm includes a seventh switch and an eighth switch connected in series. The controller is configured to turn off the second switch, the fourth switch, the sixth switch, and the eighth switch within the preset range, and after the preset time, to turn off the first switch, the third switch, the fifth switch, and the seventh switch.
4. The transformer of claim 2, wherein, When the primary-side circuit includes a first bidirectional switch bridge arm and a second bidirectional switch bridge arm connected in parallel, the upper bridge arm of the first bidirectional switch bridge arm includes a first switch and a second switch connected in series, and the lower bridge arm of the first bidirectional switch bridge arm includes a third switch and a fourth switch connected in series; the upper bridge arm of the second bidirectional switch bridge arm includes a fifth switch and a sixth switch connected in series, and the lower bridge arm of the second bidirectional switch bridge arm includes a seventh switch and an eighth switch connected in series. The controller is configured to turn off the first switch, the third switch, the fifth switch, and the seventh switch within the preset range, and after the preset time, to turn off the second switch, the fourth switch, the sixth switch, and the eighth switch.
5. The transformer of claim 2, wherein, When the primary-side circuit includes a first bidirectional switch bridge arm and a second bidirectional switch bridge arm connected in parallel, the upper bridge arm of the first bidirectional switch bridge arm includes a first switch and a second switch connected in series, and the lower bridge arm of the first bidirectional switch bridge arm includes a third switch and a fourth switch connected in series; the upper bridge arm of the second bidirectional switch bridge arm includes a fifth switch and a sixth switch connected in series, and the lower bridge arm of the second bidirectional switch bridge arm includes a seventh switch and an eighth switch connected in series. The controller is configured to, within the preset range, control the second switch, the fourth switch, the sixth switch, and the eighth switch to turn off; after the first time period, control the third switch and the seventh switch to turn off; after the third switch and the seventh switch are turned off for a second time period, control the first switch and the fifth switch to turn off; and during the second time period, control the second switch and the sixth switch to turn on to provide a freewheeling circuit.
6. The transformer of claim 2, wherein, When the primary-side circuit includes a first bidirectional switch bridge arm and a second bidirectional switch bridge arm connected in parallel, the upper bridge arm of the first bidirectional switch bridge arm includes a first switch and a second switch connected in series, and the lower bridge arm of the first bidirectional switch bridge arm includes a third switch and a fourth switch connected in series; the upper bridge arm of the second bidirectional switch bridge arm includes a fifth switch and a sixth switch connected in series, and the lower bridge arm of the second bidirectional switch bridge arm includes a seventh switch and an eighth switch connected in series. The controller is configured to, within the preset range, control the second switch, the fourth switch, the sixth switch, and the eighth switch to turn off; after the first time period, control the first switch and the fifth switch to turn off; after the first switch and the fifth switch are turned off for a second time period, control the third switch and the seventh switch to turn off; and during the second time period, control the fourth switch and the eighth switch to turn on to provide a freewheeling circuit.
7. The inverter of any of claims 3-6, wherein, The controller is further configured to control the switching transistor of the secondary circuit to turn off within the preset range, based on the turn-off time of the high-frequency switching transistor or the turn-off time of the normally-on transistor.
8. A power supply device characterized by comprising: Includes the isolated single-stage AC / DC converter as described in any one of claims 1-7.
9. A control method for an isolated single-stage AC / DC converter, characterized in that, The converter includes: a primary-side circuit, a resonant cavity, and a secondary-side circuit; the primary-side circuit includes a bidirectional switching bridge arm, the upper bridge arm of the bidirectional switching bridge arm includes two switching transistors connected in series, and the lower bridge arm of the bidirectional switching bridge arm includes two switching transistors connected in series. The method includes: When the AC voltage is within a preset range of zero crossing, the high-frequency switching transistor of the primary circuit is turned off; after a preset time, the normally conducting transistor of the primary circuit is turned off, so that the resonant cavity discharges energy. or, The high-frequency switching transistor of the primary circuit is turned off. After a first time period, some normally-conducting transistors of the primary circuit are turned off. After a second time period, the normally-conducting transistors that have not been turned off are turned off. During the second time period, the high-frequency switching transistors that are in the same half-bridge arm as the normally-conducting transistors that have not been turned off are turned on again to provide a freewheeling circuit, so that the resonant cavity can discharge energy.
10. The method according to claim 9, characterized in that, Also includes: Within the preset range, the switching transistor of the secondary circuit is turned off according to the turn-off time of the high-frequency switching transistor or the turn-off time of the normally-on transistor.
11. A controller, characterized in that, Used to perform the method according to any one of claims 9 or 10.