AC current conversion circuit and power adapter

Abstract

The present invention discloses an AC current conversion circuit and a power adapter. The circuit comprises: AC input terminals TC1 and TC2, for inputting AC current; a Wheatstone bridge using a gallium nitride tube and a Wheatstone bridge using a MOS tube, for rectifying the AC current respectively; DC output terminals V1 and V2, for outputting rectified DC current; a first comparator, for driving the gallium nitride tube according to the current signals of the AC input terminals TC1 and TC2; and a second comparator, for driving the MOS tube and turning off the first comparator according to the current signals of the AC input terminals TC1 and TC2 and the current signals of the DC output terminals V1 and V2. The circuit is stable during the initial AC current conversion and is suitable for use in high-power and high-speed circuits.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular to an alternating current conversion circuit and a power adapter. Background Art

[0002] Currently, AC current conversion circuits usually use the Wheatstone bridge form.

[0003] Figure 1 The invention is an AC current conversion circuit using a diode Wheatstone bridge according to the related art. Figure 1 As shown, D1, D2, D3 and D4 are diodes; TC1 and TC2 are AC input terminals for inputting AC current; V1 and V2 are DC output terminals for outputting DC current. When the AC current inputted by the AC input terminal TC1 is greater than the AC current inputted by the AC input terminal TC2, the diodes D1 and D4 are turned on, and the diodes D2 and D3 are turned off, so the DC current outputted by the DC output terminal V1 is greater than the DC current outputted by the DC output terminal V2. When the AC current inputted by the AC input terminal TC1 is less than the AC current inputted by the AC input terminal TC2, the diodes D2 and D3 are turned on, and the diodes D1 and D4 are turned off, so the DC current outputted by the DC output terminal V1 is less than the DC current outputted by the DC output terminal V2. It can be seen that the AC input can be converted into a DC output through the diode Wheatstone bridge.

[0004] However, when using an AC current conversion circuit using a diode Wheatstone bridge, when the AC power is large, the diode conversion power loss is also large. Summary of the invention

[0005] The present invention aims to provide an alternating current conversion circuit, which can solve the problem in the related art that the power loss of a diode Wheatstone bridge is also large when the alternating current power is large.

[0006] According to one aspect of the present invention, an AC current conversion circuit is provided. The circuit includes: AC input terminals TC1 and TC2, for inputting AC current; a Wheatstone bridge using a gallium nitride tube and a Wheatstone bridge using a MOS tube, respectively for rectifying the AC current; DC output terminals V1 and V2, for outputting rectified DC current; a first comparator, for driving the gallium nitride tube according to the current signals of the AC input terminals TC1 and TC2; and a second comparator, for driving the MOS tube and turning off the first comparator according to the current signals of the AC input terminals TC1 and TC2 and the current signals of the DC output terminals V1 and V2.

[0007] Preferably, the second comparator includes: a first operational amplifier for comparing the current signals of the AC input terminals TC1 and TC2; a second operational amplifier for comparing the current signals of the DC output terminals V1 and V2; and a clock control circuit for generating a first control signal (S1, S2, S3, S4) for turning on or off the MOS tube according to the comparison result of the first operational amplifier and the comparison result of the second operational amplifier, and generating a second control signal (ST) for starting or shutting down the first comparator.

[0008] Preferably, the second operational amplifier is used to compare the current signals of the DC output terminals V1 and V2 with a preset initial reference voltage (VREF); the clock control circuit is used to generate a first control signal (S1, S2, S3, S4) for turning on the MOS tube when the current signals of the DC output terminals V1 and V2 are less than the initial reference voltage (VREF), and to generate a second control signal (ST) for turning off the first comparator.

[0009] Preferably, the first comparator includes: a third operational amplifier, used for comparing the current signals of the AC input terminals TC1 and TC2 according to the second control signal (ST) generated by the clock control circuit to obtain a differential signal; a non-overlapping circuit, used for correcting the differential signal; and a gallium nitride driver, used for generating a driving signal (A1, A1BP, A1B, A1P) for driving the gallium nitride tube according to the corrected differential signal.

[0010] Preferably, the AC current conversion circuit further includes: a switching circuit TR; and a third comparator, for driving the gallium nitride tube to invert the input DC current to output AC current according to the current signals of the AC input terminals TC1 and TC2 and according to the switching switch signals (TR1, TR2, TR3, TR4) from the switching circuit.

[0011] Preferably, the second comparator includes: a first operational amplifier for comparing the current signals of the AC input terminals TC1 and TC2; a second operational amplifier for comparing the current signals of the DC output terminals V1 and V2; and a clock control circuit for generating a first control signal (S1, S2, S3, S4) for turning on or off the MOS tube according to the comparison result of the first operational amplifier and the comparison result of the second operational amplifier, and generating a second control signal (ST) for starting or shutting down the first comparator.

[0012] Preferably, the second operational amplifier is used to compare the current signals of the DC output terminals V1 and V2 with a preset initial reference voltage (VREF); the clock control circuit is used to generate a first control signal (S1, S2, S3, S4) for turning on the MOS tube when the current signals of the DC output terminals V1 and V2 are less than the initial reference voltage (VREF), and to generate a second control signal (ST) for turning off the first comparator.

[0013] Preferably, the third comparator includes: a fourth operational amplifier, used for comparing the current signals of the AC input terminals TC1 and TC2 according to the second control signal (ST) generated by the clock control circuit to obtain a differential signal; a non-overlapping circuit, used for correcting the differential signal according to the switching signal (TR1, TR2, TR3, TR4) from the switching circuit; and a gallium nitride driver, used for generating a driving signal (A1, A1BP, A1B, A1P) for driving the gallium nitride tube according to the corrected differential signal.

[0014] Preferably, when the switching switch signal (TR1, TR2, TR3, TR4) from the switching switch circuit is at a high potential, the gallium nitride tube is driven to invert the input direct current to output alternating current; when the switching switch signal (TR1, TR2, TR3, TR4) from the switching switch circuit is at a low potential, the gallium nitride tube is driven to rectify the input alternating current to output direct current.

[0015] According to another aspect of the present invention, a power adapter using an AC current conversion circuit is provided. The power adapter includes: a power input port for inputting AC current; a Wheatstone bridge using a gallium nitride tube and a Wheatstone bridge using a MOS tube, respectively used to rectify the AC current; a power output port for outputting a rectified DC current; a first comparator for driving the gallium nitride tube according to a current signal from the power input port; and a second comparator for driving the MOS tube and turning off the first comparator according to a current signal from the power input port and a current signal of the rectified DC current.

[0016] Since the gallium nitride tube has a small on-resistance, a high speed, is resistant to high voltage and has fast heat dissipation, the AC current conversion circuit and the power adapter of the present invention are more suitable for application in high-power electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 is a schematic diagram of an AC current conversion circuit using a diode Wheatstone bridge according to the related art;

[0019] Figure 2 is a schematic diagram of an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a first embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of a second comparator in an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a first embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of a first comparator in an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a first embodiment of the present invention;

[0022] Figure 5 is a schematic diagram of an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a second embodiment of the present invention; and

[0023] Figure 6 4 is a schematic diagram of a third comparator in an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] An embodiment of the present invention provides an alternating current conversion circuit. Figure 2 FIG. 1 is a schematic diagram of an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a first embodiment of the present invention. Figure 2 As shown, the circuit includes: AC input terminals TC1 and TC2, used for inputting AC current; a Wheatstone bridge using a gallium nitride tube and a Wheatstone bridge using a MOS tube, respectively used for rectifying the AC current; DC output terminals V1 and V2, used for outputting the rectified DC current; a first comparator, used for driving the gallium nitride tube according to the current signals of the AC input terminals TC1 and TC2; and a second comparator, used for driving the MOS tube and turning off the first comparator according to the current signals of the AC input terminals TC1 and TC2 and the current signals of the DC output terminals V1 and V2.

[0026] In the related art, when the AC power is large, the power loss of the AC current conversion circuit using a diode Wheatstone bridge is also large. The AC current conversion circuit in the embodiment of the present invention uses a gallium nitride tube Wheatstone bridge. Since the gallium nitride tube has a small on-resistance, high speed, high voltage resistance and fast heat dissipation, it is more suitable for use in high-power and high-speed circuits and can solve the above problems.

[0027] At the same time, the biggest problem of using gallium nitride tubes to replace diodes to form a Wheatstone bridge is that during the initial AC current conversion, the first comparator misjudges the AC current input to the AC input terminals TC1 and TC2 and the timing problem of the control signal, which may cause the startup process of the AC current conversion to be interrupted. Therefore, in order to solve this derived problem, the embodiment of the present invention also provides a MOS tube Wheatstone bridge and a second comparator to serve as an auxiliary circuit for the first comparator. That is to say, during the initial AC current conversion, when the gallium nitride tube Wheatstone bridge does not operate, the MOS tube Wheatstone bridge performs low current conversion to stabilize the initial condition.

[0028] Figure 3 FIG. 1 is a schematic diagram of a second comparator in an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a first embodiment of the present invention. Figure 3 As shown, the second comparator includes: a first operational amplifier, used to compare the current signals of the AC input terminals TC1 and TC2; a second operational amplifier, used to compare the current signals of the DC output terminals V1 and V2; and a clock control circuit, used to generate first control signals S1, S2, S3, S4 for turning on or off the MOS tube according to the comparison results of the first operational amplifier and the comparison results of the second operational amplifier, and generate a second control signal ST for starting or shutting down the first comparator.

[0029] Specifically, the second operational amplifier compares the current signals of the DC output terminals V1 and V2 with a preset initial reference voltage VREF; when the current signals of the DC output terminals V1 and V2 are less than the initial reference voltage VREF, the clock control circuit generates first control signals S1, S2, S3, S4 for turning on the MOS tube, and generates a second control signal ST for turning off the first comparator.

[0030] Therefore, by comparing the current signals of the DC output terminals V1 and V2 with the initial reference voltage VREF, the clock control circuit can determine that the current signals of the AC input terminals TC1 and TC2 are in the initial AC current conversion stage, and accordingly turn on the MOS tube Wheatstone bridge for low current conversion to stabilize the initial condition.

[0031] Thereafter, when the current signals of the DC output terminals V1 and V2 gradually increase until they are greater than the initial reference voltage VREF, the clock control circuit generates first control signals S1, S2, S3, and S4 for turning off the MOS tube, and generates a second control signal ST for starting the first comparator. Therefore, the gallium nitride tube Wheatstone bridge will be used, and the gallium nitride tube has very low power loss and low heat generation rate, so the above problems can be solved.

[0032] Figure 4 FIG. 1 is a schematic diagram of a first comparator in an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a first embodiment of the present invention. Figure 4 As shown, the first comparator includes: a third operational amplifier, used to compare the current signals of the AC input terminals TC1 and TC2 according to the second control signal ST generated by the clock control circuit to obtain a differential signal; a non-overlapping circuit, used to correct the differential signal; and a gallium nitride driver, used to generate driving signals A1, A1BP, A1B, and A1P for driving the gallium nitride tube according to the corrected differential signal.

[0033] Therefore, by means of the second control signal ST, the first comparator can determine that the MOS tube Wheatstone bridge is converting low current, and thus correspondingly shuts down the AC current conversion of the gallium nitride tube Wheatstone bridge. Thereafter, when the first comparator is activated by the second control signal ST, the gallium nitride tube Wheatstone bridge will be used, and the power loss of the gallium nitride tube is very low, and the heat generation rate is also very low, so the above problem can be solved.

[0034] Figure 5 FIG. 1 is a schematic diagram of an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a second embodiment of the present invention. Figure 5 As shown, the AC current conversion circuit of the embodiment of the present invention further includes a switching circuit TR and a third comparator, wherein the third comparator is used to drive the gallium nitride tube to invert the input DC current to output AC current according to the current signals of the AC input terminals TC1 and TC2 and the switching signals TR1, TR2, TR3, and TR4 from the switching circuit.

[0035] In the embodiment of the present invention, a switching circuit TR and a third comparator are added to expand the functional use of the gallium nitride tube Wheatstone bridge. Specifically, on the basis of rectifying the input AC current to output DC current, the embodiment of the present invention also has the opposite functional use, that is, inverting the input DC current to output AC current. This helps to provide a reverse charging function for the power adapter using the AC current conversion circuit of the gallium nitride tube Wheatstone bridge of the present invention.

[0036] According to an embodiment of the present invention, the second comparator includes: a first operational amplifier for comparing the current signals of the AC input terminals TC1 and TC2; a second operational amplifier for comparing the current signals of the DC output terminals V1 and V2; and a clock control circuit for generating first control signals S1, S2, S3, S4 for turning on or off the MOS tube according to the comparison result of the first operational amplifier and the comparison result of the second operational amplifier, and generating a second control signal ST for starting or shutting down the first comparator. Specifically, the second operational amplifier is used to compare the current signals of the DC output terminals V1 and V2 with a preset initial reference voltage VREF; the clock control circuit is used to generate the first control signals S1, S2, S3, S4 for turning on the MOS tube, and generating the second control signal ST for shutting down the first comparator when the current signals of the DC output terminals V1 and V2 are less than the initial reference voltage VREF. Since the function and use of the second comparator of the second embodiment of the present invention are consistent with those of the first embodiment, they will not be described in detail here.

[0037] Figure 6 1 is a schematic diagram of a third comparator in an AC current conversion circuit using a gallium nitride tube Wheatstone bridge according to a second embodiment of the present invention. The third comparator includes: a fourth operational amplifier, used to compare the current signals of the AC input terminals TC1 and TC2 according to the second control signal ST generated by the clock control circuit to obtain a differential signal; a non-overlapping circuit, used to correct the differential signal according to the switching signals TR1, TR2, TR3, and TR4 from the switching circuit; and a gallium nitride driver, used to generate driving signals A1, A1BP, A1B, and A1P for driving the gallium nitride tube according to the corrected differential signal. In which, when the switching signals TR1, TR2, TR3, and TR4 from the switching circuit are high potential, the gallium nitride tube is driven to invert the input DC current to output AC current; when the switching signals TR1, TR2, TR3, and TR4 from the switching circuit are low potential, the gallium nitride tube is driven to rectify the input AC current to output DC current. The embodiment of the present invention switches the functional use of the gallium nitride tube by means of the high potential and the low potential of the switching signal of the switching circuit, and the switching action is simple and fast.

[0038] According to an embodiment of the present invention, a power adapter using an AC current conversion circuit is also provided. The power adapter includes: a power input port for inputting AC current; a Wheatstone bridge using a gallium nitride tube and a Wheatstone bridge using a MOS tube, respectively used to rectify the AC current; a power output port for outputting a rectified DC current; a first comparator for driving the gallium nitride tube according to a current signal from the power input port; and a second comparator for driving the MOS tube and turning off the first comparator according to a current signal from the power input port and a current signal of the rectified DC current. The AC current conversion circuit in the embodiment of the present invention uses a gallium nitride tube Wheatstone bridge. Since the gallium nitride tube has a small on-resistance, a fast speed, high voltage resistance and fast heat dissipation, the power adapter is more suitable for use in high-power electrical equipment.

[0039] At the same time, the biggest problem of using gallium nitride tubes to replace diodes to form a Wheatstone bridge is that during the initial AC current conversion, the first comparator misjudges the AC current input to the AC input terminals TC1 and TC2 and the timing problem of the control signal, which may cause the startup process of the AC current conversion to be interrupted. Therefore, in order to solve this derived problem, the embodiment of the present invention also provides a MOS tube Wheatstone bridge and a second comparator to serve as an auxiliary circuit for the first comparator. That is to say, during the initial AC current conversion, when the gallium nitride tube Wheatstone bridge does not operate, the MOS tube Wheatstone bridge performs low current conversion to stabilize the initial condition.

[0040] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An alternating current conversion circuit, characterized in that: include: AC input terminals TC1 and TC2, used for inputting AC current; A Wheatstone bridge using a gallium nitride tube and a Wheatstone bridge using a MOS tube are respectively used to rectify the alternating current; DC output terminals V1 and V2, for outputting rectified DC current; A first operational amplifier, used for comparing the current signals of the AC input terminals TC1 and TC2; A second operational amplifier, used for comparing the current signals of the DC output terminals V1 and V2; as well as A clock control circuit, used for generating a first control signal (S1, S2, S3, S4) for turning on or off the MOS tube and generating a second control signal (ST) according to a comparison result of the first operational amplifier and a comparison result of the second operational amplifier; a third operational amplifier, configured to compare the current signals of the AC input terminals TC1 and TC2 according to the second control signal (ST) generated by the clock control circuit to obtain a differential signal; A non-overlapping circuit for modifying the differential signal; The gallium nitride driver is used to generate a driving signal (A1, A1BP, A1B, A1P) for driving the gallium nitride tube according to the modified differential signal.

2. The AC current conversion circuit according to claim 1, characterized in that: The second operational amplifier is used to compare the current signals of the DC output terminals V1 and V2 with a preset initial reference voltage (VREF); The clock control circuit is used to generate a first control signal (S1, S2, S3, S4) for turning on the MOS tube and to generate a second control signal (ST) for turning off the MOS tube when the current signal of the DC output terminals V1 and V2 is less than the initial reference voltage (VREF).

3. The AC current conversion circuit according to claim 1, characterized in that: Also includes: Switching switch circuit TR; as well as a fourth operational amplifier, configured to compare the current signals of the AC input terminals TC1 and TC2 according to the second control signal (ST) generated by the clock control circuit to obtain a differential signal; a non-overlapping circuit for modifying the differential signal according to the switching signal (TR1, TR2, TR3, TR4) from the switching circuit; as well as The gallium nitride driver is used to generate a driving signal (A1, A1BP, A1B, A1P) for driving the gallium nitride tube according to the modified differential signal.

4. The AC current conversion circuit according to claim 3, characterized in that: The second operational amplifier is used to compare the current signals of the DC output terminals V1 and V2 with a preset initial reference voltage (VREF); The clock control circuit is used to generate a first control signal (S1, S2, S3, S4) for turning on the MOS tube and to generate a second control signal (ST) for turning off the MOS tube when the current signal of the DC output terminals V1 and V2 is less than the initial reference voltage (VREF).

5. The AC current conversion circuit according to claim 3 or 4, characterized in that: When the switching switch signal (TR1, TR2, TR3, TR4) from the switching switch circuit is at a high potential, the gallium nitride tube is driven to invert the input direct current to output alternating current; when the switching switch signal (TR1, TR2, TR3, TR4) from the switching switch circuit is at a low potential, the gallium nitride tube is driven to rectify the input alternating current to output direct current.

6. A power adapter using the AC current conversion circuit according to any one of claims 1 to 5, characterized in that: include: Power input port, used to input AC current; A Wheatstone bridge using a gallium nitride tube and a Wheatstone bridge using a MOS tube are respectively used to rectify the alternating current; A power output port, used to output rectified direct current; a third operational amplifier, configured to compare the current signals of the AC input terminals TC1 and TC2 according to the second control signal (ST) generated by the clock control circuit to obtain a differential signal; A non-overlapping circuit for modifying the differential signal; A gallium nitride driver, used to generate a driving signal (A1, A1BP, A1B, A1P) for driving the gallium nitride tube according to the modified differential signal; a first operational amplifier, used to compare the current signals of the AC input terminals TC1 and TC2; A second operational amplifier, used for comparing the current signals of the DC output terminals V1 and V2; as well as A clock control circuit is used to generate a first control signal (S1, S2, S3, S4) for turning on or off the MOS tube according to a comparison result of the first operational amplifier and a comparison result of the second operational amplifier, and to generate a second control signal (ST) for starting or turning off the MOS tube.

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