Asymmetrical half-bridge converter

Abstract

The present application provides an asymmetric half-bridge converter. The asymmetric half-bridge converter comprises a switching circuit, a resonant tank, a current sensor and a controller. The current sensor senses a waveform of a resonant current flowing through the resonant tank to generate a sensing result. The controller judges the sensing result. When the sensing result represents that an ending current value of a first resonant waveform of the resonant current is greater than a preset value, the controller performs a first switching operation on the switching circuit. When the sensing result represents that the ending current value of the first resonant waveform is less than or equal to the preset value, the controller performs a second switching operation on the switching circuit.

Description

Technical Field

[0001] This invention relates to a power converter, and more particularly to an asymmetric half-bridge converter. Background Technology

[0002] Asymmetrical half-bridge (AHB) converters offer good power conversion efficiency in current AC-DC conversion architectures. However, while maintaining the same operation, the conversion efficiency of AHB converters is affected by different load conditions. Therefore, how to enable AHB converters to provide suitable operation under different load conditions is one of the key research focuses for those skilled in the art. Summary of the Invention

[0003] This invention provides an asymmetric half-bridge converter that can provide suitable operation under different load conditions.

[0004] The asymmetric half-bridge converter of the present invention includes a switching circuit, a resonant tank, a current sensor, and a controller. The switching circuit includes an upper arm switch and a lower arm switch. The upper arm switch and the lower arm switch are connected to a connection node. The resonant tank is coupled between the connection node and a ground terminal. The current sensor is coupled to the resonant tank. The current sensor senses the waveform of the resonant current flowing through the resonant tank to generate a sensing result. The waveform of the resonant current reflects the load conditions. The controller is coupled to the resonant tank and the switching circuit. The controller determines the sensing result. When the sensing result indicates that the end current value of the first resonant waveform of the resonant current is greater than a preset value, the controller performs a first switching operation on the switching circuit. When the sensing result indicates that the end current value of the first resonant waveform is less than or equal to the preset value, the controller performs a second switching operation on the switching circuit.

[0005] Based on the above, the current sensor senses the waveform of the resonant current flowing through the resonant tank to generate a sensing result. When the sensing result indicates that the end current value of the first resonant waveform is greater than a preset value, the controller performs a first switching operation on the switching circuit. When the sensing result indicates that the end current value of the first resonant waveform is less than or equal to the preset value, the controller performs a second switching operation on the switching circuit. Therefore, the asymmetric half-bridge converter of the present invention can perform a switching operation corresponding to the waveform based on the waveform of the resonant current. In this way, the asymmetric half-bridge converter can automatically and in real time adopt appropriate operations under different load conditions.

[0006] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0007] Figure 1This is a schematic diagram of an asymmetrical half-bridge (AHB) converter according to the first embodiment of the present invention;

[0008] Figure 2A This is a first waveform diagram of the resonant current shown according to an embodiment of the present invention;

[0009] Figure 2B This is a second waveform diagram of the resonant current shown according to an embodiment of the present invention;

[0010] Figure 3 This is a schematic diagram of an AHB converter according to a second embodiment of the present invention;

[0011] Figure 4 This is a schematic diagram of an AHB converter according to the third embodiment of the present invention;

[0012] Figure 5 This is a schematic diagram of an AHB converter according to the fourth embodiment of the present invention;

[0013] Figure 6 This is a schematic diagram of an AHB converter according to the fifth embodiment of the present invention.

[0014] Explanation of reference numerals in the attached figures

[0015] 100, 200, 300, 300', 400: Asymmetric half-bridge converters

[0016] 110, 210, 310, 310, 410: Switching circuits

[0017] 120, 220, 320, 320, 420: Resonant groove

[0018] 130, 230, 330, 330, 330', 430: Current sensors

[0019] 140, 240, 340, 340, 440: Controller

[0020] 150, 250, 350, 350, 450: Output circuit

[0021] C1: Capacitor

[0022] CO: Output capacitor

[0023] CR: Resonant capacitor

[0024] DO: Output diode

[0025] DV: Preset value

[0026] GND1, GND2: Grounding terminals

[0027] HG, LG: Control signals

[0028] I0: Current value

[0029] I1: End current value

[0030] IR: Resonant current

[0031] LM: Magnetizing Inductor

[0032] LR: Resonant Inductor

[0033] MH: Upper arm switch

[0034] ML: Lower arm switch

[0035] ND: Connector Node

[0036] NP: Primary winding

[0037] NS: Secondary winding

[0038] SR: Sensing Results

[0039] t: time

[0040] t0, t1, t2: Time points

[0041] td: Preset time length

[0042] TR: Transformer

[0043] VBUS: Power Line

[0044] VIN: Input power

[0045] VO: Output power

[0046] WF, WF1, WF2: Waveforms

[0047] WIR1: First resonant waveform

[0048] WIR2: Secondary Resonance Waveform Detailed Implementation

[0049] Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same component reference numerals are used in the drawings and description to denote the same or similar parts.

[0050] Please refer to Figure 1 , Figure 1This is a schematic diagram of an asymmetrical half-bridge (AHB) converter according to a first embodiment of the present invention. In this embodiment, the AHB converter 100 includes a switching circuit 110, a resonant tank 120, a current sensor 130, and a controller 140. The switching circuit 110 includes an upper arm switch MH and a lower arm switch ML. The upper arm switch MH and the lower arm switch ML are connected to a connection node ND. Taking this embodiment as an example, the first terminal of the upper arm switch MH is used to receive the input power supply VIN through the power transmission line VBUS. The second terminal of the upper arm switch MH is coupled to the connection node ND. The control terminal of the upper arm switch MH is coupled to the controller 140 to receive a control signal HG. The upper arm switch MH is turned on or off in response to the control signal HG. The first terminal of the lower arm switch ML is coupled to the connection node ND. The second terminal of the lower arm switch ML is coupled to the ground terminal GND1. The control terminal of the lower arm switch ML is coupled to the controller 140 to receive a control signal LG. The lower arm switch ML is turned on or off in response to the control signal LG.

[0051] In this embodiment, the resonant tank 120 is coupled between the connection node ND and the ground terminal GND1. A current sensor 130 is coupled to the resonant tank 120. The current sensor 130 senses the waveform WF of the resonant current IR flowing through the resonant tank 120. The current sensor 130 generates a sensing result SR based on the waveform WF of the resonant current IR. The waveform WF of the resonant current IR reflects the current load conditions.

[0052] In this embodiment, the controller 140 is coupled to the resonant tank 120 and the switching circuit 110. The controller 140 determines the sensing result SR. The controller 140 can perform a switching operation on the switching circuit 110 corresponding to the waveform WF of the resonant current IR based on the waveform WF of the resonant current IR. When the sensing result SR indicates that the end current value of the first resonant waveform WF of the resonant current IR is greater than a preset value DV, the controller 140 performs a first switching operation on the switching circuit 110. When the sensing result SR indicates that the end current value of the first resonant waveform WF is less than or equal to the preset value DV, the controller 140 performs a second switching operation on the switching circuit 110. In this embodiment, the first switching operation and the second switching operation correspond to different load modes.

[0053] It is worth mentioning that the AHB converter 100 can perform switching operations corresponding to the waveform WF of the resonant current IR. In this way, the AHB converter 100 can automatically and in real time adopt appropriate operations under different load conditions.

[0054] For an example illustrating the implementation details of the first handover operation, please also refer to... Figure 1 as well as Figure 2A . Figure 2A This is a first waveform diagram of the resonant current according to an embodiment of the present invention. In this embodiment, the current sensor 130 senses the waveform WF1 of the resonant current IR flowing through the resonant tank 120 to generate a sensing result SR. At time point t0, the upper arm switch MH is turned off, and the lower arm switch ML is turned on. The time interval between time points t0 and t1 is the period during which the lower arm switch ML is turned on. In this embodiment, the first resonant waveform WIR1 is the first resonant fluctuation of the resonant current IR during the period when the lower arm switch ML is turned on. The first resonant waveform WIR1 ends at the end current value I1. The controller 140 judges the waveform WF1. When the end current value I1 of the first resonant waveform WIR1 is determined to be greater than the preset value DV, it indicates that the AHB converter 100 is currently applied to a lighter load condition. Therefore, the controller 140 performs a first switching operation on the switching circuit 110 to apply the AHB converter 100 to a light load state.

[0055] For example, the preset value DV is set to 0.1 amps. When the end current value I1 of the first resonant waveform WIR1 is determined to be greater than 0.1 amps, the controller 140 will perform a first switching operation on the switching circuit 110 to apply the AHB converter 100 to the light load state.

[0056] In the first switching operation, the controller 140 controls the resonant current IR to approach zero (i.e., current value I0) at time t1 when the lower arm switch ML is turned off. The controller 140 then turns on the upper arm switch MH at time t2. Time t2 lags time t1 by a preset time length td. Thus, during the preset time length td, the resonant current IR is controlled to approach zero. Therefore, the AHB converter 100 enters burst mode. In burst mode, the power consumption of the AHB converter 100 can be reduced.

[0057] In this embodiment, the waveform WF1 of the resonant current IR is differentiated to determine the slope change of the resonant current IR. Based on the passage of time, when the sensing result SR indicates that the resonant current IR experiences its first decreasing negative slope followed by a positive slope, the resonant current IR is determined to have experienced a resonant waveform WIR1. Therefore, the controller 140 determines the timing of the occurrence of a resonant waveform WIR1 based on the slope change of the resonant current IR. Furthermore, the current value when the aforementioned positive slope changes to a negative slope is the end current value I1. In other words, the controller 140 can also determine the end time point of a resonant waveform WIR1 based on the slope change of the resonant current IR, and obtain the end current value I1 based on the current value at the end time point of the resonant waveform WIR1.

[0058] In this embodiment, the controller 140 also uses the secondary resonant waveform WIR2 following the primary resonant waveform WIR1 for auxiliary judgment. When the sensing result SR indicates that the secondary resonant waveform WIR2 occurs after the primary resonant waveform WIR1 of the resonant current IR ends, the controller 140 performs a first switching operation on the switching circuit 110. In this embodiment, the controller 140 can use the slope change of the second decreasing negative slope followed by a positive slope to determine whether the waveform WF1 of the resonant current IR has produced the secondary resonant waveform WIR2.

[0059] For an example illustrating the implementation details of the first handover operation, please also refer to... Figure 1 as well as Figure 2B . Figure 2B This is a second waveform diagram of the resonant current according to an embodiment of the present invention. In this embodiment, the current sensor 130 senses the waveform WF2 of the resonant current IR flowing through the resonant tank 120 to generate a sensing result SR. The first resonant waveform WIR1 is the first resonant fluctuation of the resonant current IR during the period when the lower arm switch ML is turned on. The first resonant waveform WIR1 ends at the end current value. The controller 140 judges the waveform WF2. When the end current value of the first resonant waveform WIR1 is determined to be less than or equal to a preset value DV, it indicates that the AHB converter 100 is currently applied to a heavier load condition. Therefore, the controller 140 performs a second switching operation on the switching circuit 110 to apply the AHB converter 100 to the heavy load state.

[0060] For example, the preset value DV is set to 0.1 amps. When the end current value of the first resonant waveform WIR1 is determined to be less than or equal to the preset value DV, the controller 140 will perform a second switching operation on the switching circuit 110 to apply the AHB converter 100 to the heavy load state.

[0061] In the second switching operation, the controller controls the resonant current IR to a negative value at time t1 when the lower arm switch ML is turned off, and immediately turns on the upper arm switch MH at time t1 when the lower arm switch is turned off. This puts the AHB converter 100 into continuous mode (or boundary mode). Compared to intermittent mode, continuous mode can improve output power.

[0062] It should be noted that in the second switching operation, the resonant current IR is controlled to a negative current value at time t1. Such a negative current value helps the AHB converter 100 perform zero voltage switching (ZVS), thereby improving the conversion efficiency of continuous mode.

[0063] In this embodiment, the controller 140 also makes an auxiliary judgment based on the secondary resonance waveform after the primary resonance waveform WIR1. When the sensing result SR indicates that the resonant current IR does not have a secondary resonance waveform, the controller 140 performs a second switching operation on the switching circuit 110.

[0064] Please return Figure 1 In this embodiment, the resonant tank 120 includes a resonant inductor LR, a magnetizing inductor LM, and a resonant capacitor CR. The resonant inductor LR, the magnetizing inductor LM, and the resonant capacitor CR are connected in series and coupled to each other. Taking this embodiment as an example, the first end of the resonant inductor LR is coupled to the connection node ND. The first end of the magnetizing inductor LM is coupled to the second end of the resonant inductor LR. The first end of the resonant capacitor CR is coupled to the second end of the magnetizing inductor LM. The second end of the resonant capacitor CR is coupled to the ground terminal GND1. The AHB converter 100 also includes a transformer TR and an output circuit 150. The transformer TR includes a primary winding NP and a secondary winding NS. The primary winding NP is coupled in parallel to the magnetizing inductor LM. The secondary winding NS is coupled to the output circuit 150. The output circuit 150 includes an output diode DO and an output capacitor CO (the invention is not limited thereto). The first end of the secondary winding NS is coupled to the anode of the output diode DO. The second end of the secondary winding NS is coupled to the ground terminal GND2. The cathode of the output diode DO serves as the output terminal to provide the output power VO. The output capacitor CO is coupled between the cathode of the output diode DO and the ground terminal GND2.

[0065] Please refer to Figure 3 , Figure 3This is a schematic diagram of an AHB converter according to a second embodiment of the present invention. In this embodiment, the AHB converter 200 includes a switching circuit 210, a resonant tank 220, a current sensor 230, a controller 240, a transformer TR, and an output circuit 250. The current sensor 230 is coupled between a second terminal of a magnetizing inductor LM and a first terminal of a resonant capacitor CR. In this embodiment, the current sensor 230 can obtain the waveform of the resonant current IR using current sensing methods well known to those skilled in the art. For example, the current sensor 230 includes a sensing resistor. The sensing resistor is coupled between a second terminal of the magnetizing inductor LM and a first terminal of the resonant capacitor CR. The sensing resistor provides a sensed voltage value based on the resonant current IR. The current sensor 230 obtains the waveform of the resonant current IR based on the change in the sensed voltage value and the resistance value of the sensing resistor. As another example, the current sensor 230 includes a coupling inductor. A first inductor of the coupling inductor is coupled between a second terminal of the magnetizing inductor LM and a first terminal of the resonant capacitor CR. The first inductor receives the resonant energy of the resonant current IR and couples the resonant energy to the second inductor via inductive coupling. The current sensor 230 then obtains the waveform of the resonant current IR based on the energy changes on the second inductor.

[0066] The implementation methods of the switching circuit 210, resonant tank 220, controller 240, transformer TR, and output circuit 250 in this embodiment can be referred to... Figure 1 , Figure 2A , Figure 2B Multiple embodiments are provided, and will not be repeated here.

[0067] Please refer to Figure 4 , Figure 4 This is a schematic diagram of an AHB converter according to a third embodiment of the present invention. In this embodiment, the AHB converter 300 includes a switching circuit 310, a resonant tank 320, a current sensor 330, a controller 340, a transformer TR, and an output circuit 350. The current sensor 330 is coupled between the second terminal of the resonant capacitor CR and the ground terminal GND1. In this embodiment, the current sensor 330 can obtain the waveform of the resonant current IR using a current sensing method well known to those skilled in the art. Further, the current sensor 330 is coupled between the second terminal of the resonant capacitor CR and the second terminal of the lower arm switch ML.

[0068] The implementation methods of the switching circuit 310, resonant tank 320, controller 340, transformer TR, and output circuit 350 in this embodiment can be referred to... Figure 1 , Figure 2A , Figure 2BThe various embodiments of the current sensor 330 are given sufficient instruction in the various examples of the current sensor 230 in the second embodiment, and therefore will not be repeated here.

[0069] Please refer to Figure 5 , Figure 5 This is a schematic diagram of an AHB converter according to a fourth embodiment of the present invention. In this embodiment, the AHB converter 300' includes a switching circuit 310, a resonant tank 320, a current sensor 330', a controller 340, a transformer TR, and an output circuit 350. Figure 4 The embodiment differs in that the current sensor 430 is coupled between the second terminal of the lower arm switch ML and the ground terminal GND1.

[0070] Please refer to Figure 6 , Figure 6 This is a schematic diagram of an AHB converter according to a fifth embodiment of the present invention. In this embodiment, the AHB converter 400 includes a switching circuit 410, a resonant tank 420, a current sensor 430, a controller 440, a transformer TR, and an output circuit 450. In this embodiment, the current sensor 430 is coupled in parallel with a resonant capacitor CR. For example, the current sensor 430 may include a capacitor C1. The capacitor C1 is coupled in parallel with the resonant capacitor CR. A first resonant current in the resonant current IR flows through the resonant capacitor CR. A second resonant current in the resonant current IR flows through the capacitor C1. There is a current value ratio between the current value of the first resonant current and the current value of the second resonant current. The aforementioned current value ratio is related to the capacitance relationship between the resonant capacitor CR and the capacitor C1. Therefore, the waveform of the resonant current IR is obtained by the variation of the current value of the second resonant current of the current sensor 430 and the capacitance relationship between the resonant capacitor CR and the capacitor C1.

[0071] The implementation methods of the switching circuit 410, resonant tank 420, controller 440, transformer TR, and output circuit 450 in this embodiment can be referred to... Figure 1 , Figure 2A , Figure 2B Multiple embodiments are provided, and will not be repeated here.

[0072] In summary, the AHB converter of the present invention includes a switching circuit, a resonant tank, a current sensor, and a controller. The current sensor senses the waveform of the resonant current flowing through the resonant tank to generate a sensing result. When the sensing result indicates that the end current value at the end of the first resonant waveform of the resonant current is greater than a preset value, the controller performs a first switching operation on the switching circuit. When the sensing result indicates that the end current value of the first resonant waveform is less than or equal to the preset value, the controller performs a second switching operation on the switching circuit. Therefore, the AHB converter can perform switching operations corresponding to the waveform of the resonant current. In this way, the AHB converter can automatically and in real time adopt appropriate operations under different load conditions.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An asymmetric half-bridge converter, characterized in that, The asymmetric half-bridge converter includes: A switching circuit includes an upper arm switch and a lower arm switch, wherein the upper arm switch and the lower arm switch are connected to a connection node; A resonant groove is coupled between the connection node and the grounding terminal; A current sensor, coupled to the resonant tank, is configured to sense the waveform of the resonant current flowing through the resonant tank to generate a sensing result, wherein the waveform of the resonant current reflects load conditions; and The controller, coupled to the resonant tank and the switching circuit, is configured to: Determine the sensing result. When the sensing result indicates that the end current value of the first resonant waveform of the resonant current is greater than a preset value, a first switching operation is performed on the switching circuit, and When the sensing result indicates that the end current value of the first resonant waveform is less than or equal to a preset value, a second switching operation is performed on the switching circuit.

2. The asymmetric half-bridge converter according to claim 1, characterized in that: The controller performs the first switching operation on the switching circuit to apply the asymmetric half-bridge converter to a light-load state, and The controller performs the second switching operation on the switching circuit to apply the asymmetric half-bridge converter to the heavy-load state.

3. The asymmetric half-bridge converter according to claim 1, characterized in that: The first resonant waveform is the first resonant fluctuation during the period when the lower arm switch is turned on, and The first resonant waveform ends at the ending current value.

4. The asymmetric half-bridge converter according to claim 1, characterized in that, When the sensing result indicates that the resonant current has a first decreasing negative slope and then a positive slope, the resonant current is determined to have the first resonant waveform.

5. The asymmetric half-bridge converter according to claim 4, characterized in that, The current value at which the positive slope changes to a negative slope is the final current value.

6. The asymmetric half-bridge converter according to claim 1, characterized in that: In the first switching operation, the controller controls the resonant current value to approach zero at the first time point when the lower arm switch is turned off, and turns on the upper arm switch at the second time point. The second time point lags behind the first time point by a preset time length.

7. The asymmetric half-bridge converter according to claim 1, characterized in that, When the sensing result indicates that a secondary resonance waveform occurs after the first resonance waveform of the resonant current ends, the controller performs a first switching operation on the switching circuit.

8. The asymmetric half-bridge converter according to claim 1, characterized in that, In the second switching operation, the controller controls the resonant current value to a negative current value at the time when the lower arm switch is turned off, and then turns on the upper arm switch at the same time when the lower arm switch is turned off.

9. The asymmetric half-bridge converter according to claim 1, characterized in that, The resonant groove includes: A resonant inductor, wherein a first end of the resonant inductor is coupled to the connection node; A magnetizing inductor, wherein a first terminal of the magnetizing inductor is coupled to a second terminal of the resonant inductor; and A resonant capacitor, wherein a first end of the resonant capacitor is coupled to a second end of the magnetizing inductor, and a second end of the resonant capacitor is coupled to a ground terminal.

10. The asymmetric half-bridge converter according to claim 9, characterized in that, The current sensor is coupled between the second end of the magnetizing inductor and the first end of the resonant capacitor.

11. The asymmetric half-bridge converter according to claim 9, characterized in that, The current sensor is coupled between the second end of the resonant capacitor and the ground terminal.

12. The asymmetric half-bridge converter according to claim 9, characterized in that, The current sensor is coupled in parallel with the resonant capacitor.

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