Isolation conversion circuit, isolation conversion circuit control method, controller and vehicle-mounted charger

Abstract

The invention provides an isolation conversion circuit, an isolation conversion circuit control method, a controller and a vehicle-mounted charger. The isolation conversion circuit comprises a transformer isolation assembly which comprises a primary winding and a secondary winding, and the primary winding is provided with a first end, a second end and a primary tap arranged between the first end of the primary winding and the second end of the primary winding; the primary side bridge arm switching circuit is respectively connected with the power supply end, the first end of the primary side winding and the second end of the primary side winding; a secondary bridge arm switching circuit; the first switching circuit is respectively connected with the power supply end and the primary side tap and is used for connecting / disconnecting a path between the power supply end and the primary side tap; when the first switching circuit is in a conducting state, the primary side bridge arm switching circuit is used for carrying out push-pull on the voltage of the power supply end through the first switching circuit and then carrying out inversion output; and when the first switching circuit is in the off state, the primary side bridge arm switching circuit is used for inverting and outputting the voltage of the power supply end. The invention aims to reduce the size of the whole machine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, in particular to an isolated conversion circuit, an isolated conversion circuit control method, a controller and a vehicle-mounted charger. BACKGROUND

[0002] At present, power electronics technology is an important part of modern power systems, which mainly studies how to control and process electric energy by using power semiconductor devices. In power electronics technology, an isolated converter is an important circuit that can convert DC high voltage into DC low voltage or convert AC into DC. Isolated converters are widely used in power systems, communication systems, industrial control and other fields.

[0003] Due to the duty cycle limit, the existing full-bridge isolated converter generally adopts a two-stage scheme to achieve a wide range of output when the input voltage is low, that is, the front stage uses a boost circuit to boost the low-voltage input voltage and then transmits it to the rear stage, and the rear stage uses a resonant converter or a phase-shifted full-bridge circuit to invert and rectify the boosted voltage and then output. However, although the existing two-stage scheme can achieve a wide range of input voltage, it requires more devices, resulting in a large overall volume. SUMMARY

[0004] To achieve the above-mentioned purpose, the present application proposes an isolated conversion circuit, an isolated conversion circuit control method, a controller and a vehicle-mounted charger, aiming to solve the technical problem of the prior art that more devices are required to achieve a wide range of input voltage, resulting in a large overall volume.

[0005] The present application proposes an isolated conversion circuit, which comprises: a power supply end; a transformer isolation component comprising a primary winding and a secondary winding, the primary winding having a first end, a second end and a primary tap provided between the first end of the primary winding and the second end of the primary winding; a primary bridge arm switching circuit connected to the power supply end, the first end of the primary winding and the second end of the primary winding, respectively; a secondary bridge arm switching circuit connected to the secondary winding and configured to have a rectification function; a first switching circuit connected to the power supply end and the primary tap, respectively, for turning on / off the path between the power supply end and the primary tap; When the first switching circuit is in an on state, the primary bridge arm switching circuit is used to push-pull the voltage of the power supply end through the first switching circuit and then invert the output; The primary side bridge arm switch circuit is configured to output a voltage of the power supply end in an inverting manner when the first switch circuit is in the off state.

[0006] In an embodiment, the first switch circuit is further configured to be in the on state when a voltage input of the power supply end is higher than a preset input voltage threshold. The first switch circuit is further configured to be in the off state when the voltage input of the power supply end is not higher than the preset input voltage threshold.

[0007] In an embodiment, the isolation conversion circuit further comprises: A second switch circuit is connected with the power supply end and the primary side bridge arm switch circuit respectively, and is configured to disconnect a path between the power supply end and the primary side bridge arm switch circuit when the first switch circuit is in the on state, and to connect the path between the power supply end and the primary side bridge arm switch circuit when the first switch circuit is in the off state.

[0008] In an embodiment, the isolation conversion circuit further comprises: An energy storage module is connected with the second switch circuit and the primary side bridge arm switch circuit respectively, and is configured to absorb / release peak energy of the primary side bridge arm switch circuit when the primary side bridge arm switch circuit is in a push-pull state.

[0009] In an embodiment, the secondary side bridge arm switch circuit is further configured to have an inverting function. The primary side bridge arm switch circuit is configured to rectify a voltage output by the transformer isolation component via the first switch circuit after the voltage is in a push-pull state when the first switch circuit is in the on state. The primary side bridge arm switch circuit is configured to rectify a voltage output by the transformer isolation component and then output the voltage when the first switch circuit is in the off state.

[0010] In an embodiment, the first switch circuit is further configured to be in the off state when a voltage output of the power supply end is not required to be lower than a preset output voltage threshold. The first switch circuit is further configured to be in the on state when the voltage output of the power supply end is required to be lower than the preset output voltage threshold.

[0011] In an embodiment, the isolation conversion circuit further comprises: A direct current isolation module is connected with the primary side bridge arm switch circuit, the first end of the primary side winding and the second end of the primary side winding respectively, and is configured to perform direct current isolation on an output of the primary side bridge arm switch circuit.

[0012] In addition, to achieve the above object, the application further provides an isolation conversion circuit control method based on the isolation conversion circuit. determining a working mode, and controlling the secondary side bridge arm switching circuit to rectify; in the case that the working mode is the push-pull mode, controlling the first switching circuit to be turned on, and controlling the primary side bridge arm switching circuit to output the voltage of the power supply end after push-pull and inversion; in the case that the working mode is the inversion mode, controlling the first switching circuit to be turned off, and controlling the primary side bridge arm switching circuit to output the voltage of the power supply end after inversion.

[0013] In addition, to achieve the above object, the application further provides a controller, which comprises a memory, a processor, and an isolation conversion circuit control program stored in the memory and executable on the processor, and the isolation conversion circuit control program is configured to implement the isolation conversion circuit control method.

[0014] In addition, to achieve the above object, the application further provides a vehicle-mounted charger, which comprises the isolation conversion circuit and / or the controller.

[0015] In summary, the isolation conversion circuit comprises a power supply end, a transformer isolation assembly comprising a primary winding and a secondary winding, the primary winding having a first end, a second end, and a primary winding tap arranged between the first end of the primary winding and the second end of the primary winding, a primary side bridge arm switching circuit connected with the power supply end, the first end of the primary winding, and the second end of the primary winding respectively, a secondary side bridge arm switching circuit connected with the secondary winding and configured to have a rectification function, and a first switching circuit connected with the power supply end and the primary winding tap respectively and used to turn on / off a path between the power supply end and the primary winding tap; in the case that the first switching circuit is in a turned-on state, the primary side bridge arm switching circuit is used to output the voltage of the power supply end after push-pull and inversion via the first switching circuit; and in the case that the first switching circuit is in a turned-off state, the primary side bridge arm switching circuit is used to output the voltage of the power supply end after inversion.

[0016] With the above configuration, the isolation converter circuit of this application can switch the primary-side bridge arm switching circuit to perform push-pull inversion or direct inversion of the voltage at the power supply terminal by turning the first switching circuit on and off. Furthermore, since the transformer isolation component additionally provides a primary-side tap between the first and second ends of the primary winding, the power supply terminal voltage can be input to the primary winding during push-pull operation using this primary-side tap. At this time, the turns ratio of the primary winding decreases, thereby achieving voltage boost. Compared to existing methods that require a boost circuit to achieve a wide input voltage range, this application can directly achieve voltage boost by reducing the turns ratio of the primary winding, eliminating the need for an additional boost circuit, reducing the required components, and thus reducing the overall size of the device. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 A two-stage full-bridge isolation converter for power transmission; Figure 2 This is a circuit schematic diagram of the first embodiment of the isolation converter circuit of this application; Figure 3 This is a circuit schematic diagram of the second embodiment of the isolation converter circuit of this application; Figure 4 This is a circuit diagram of the first stage in full-bridge mode in the second embodiment of the isolation converter circuit of this application; Figure 5 This is a circuit diagram of the second stage in full-bridge mode in the second embodiment of the isolation converter circuit of this application; Figure 6 This is a circuit diagram of the first stage in the push-pull mode of the second embodiment of the isolation converter circuit of this application; Figure 7 This is a circuit diagram of the second stage in the push-pull mode of the second embodiment of the isolation converter circuit of this application; Figure 8 This is a circuit diagram of the third stage in the push-pull mode of the second embodiment of the isolation converter circuit of this application; Figure 9 This is a circuit diagram of the fourth stage in the push-pull mode of the second embodiment of the isolation converter circuit of this application; Figure 10 This is a flowchart illustrating the first embodiment of the isolation conversion circuit control method of this application.

[0019] Attached icon number

[0020] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments in combination with the accompanying drawings. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0022] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0023] In addition, if the embodiments of the present application involve descriptions such as “first”, “second”, etc., the descriptions of “first”, “second”, etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first”, “second” can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the protection scope claimed by the present application.

[0024] At present, power electronics technology is an important part of modern power systems, which mainly studies how to control and process electric energy by using power semiconductor devices. In power electronics technology, an isolated converter is an important circuit that can convert DC high voltage into DC low voltage or convert AC into DC. Isolated converters are widely used in power systems, communication systems, industrial control and other fields.

[0025] Due to the duty cycle limitation, the existing full-bridge isolated converter generally adopts a two-stage scheme to achieve a wide range of output when the input voltage is low, that is, a boost circuit 1 is used in the front stage to boost the low-voltage input voltage and transmit it to the rear stage, and a resonant converter or a phase-shifted full-bridge circuit is used in the rear stage to invert and rectify the boosted voltage and output. Referring to Figure 1 , Figure 1 For the two-stage full-bridge isolated converter, as shown in FIG. 1, the input voltage is boosted by the boost circuit 1 in the front stage, and then the boosted voltage is inverted and rectified by the phase-shifted full-bridge circuit in the rear stage to output. Figure 1As shown, the full-bridge isolation converter can include: a boost circuit 1, a primary side bridge arm switching circuit 2, a transformer isolation component T and a secondary side bridge arm switching circuit 3 connected in turn; Wherein the boost circuit 1 can include: a first capacitor C1, a second capacitor C2, a first inductor L1, a first switch tube S1 and a first diode D1; When the input voltage is low, the boost circuit 1 can be formed by these devices to realize the function of boosting the voltage at the input end. The boosted voltage can then be transmitted to the primary side bridge arm switching circuit 2, which constitutes a full-bridge through the second switch tube S2 to the fifth switch tube S5 in the primary side bridge arm switching circuit 2. The controller controls the on-off of the four switch tubes, thereby inverting the boosted voltage and transmitting it to the transformer isolation component T. The transformer isolation component T can transmit the inverted voltage to the secondary side bridge arm switching circuit 3 after isolation. The secondary side bridge arm switching circuit 3 can output after rectification. Obviously, in order to achieve a wide range of input voltage, the traditional boost circuit 1 is needed to boost the voltage at the input end when the input voltage is low, so more devices are needed, resulting in a large overall size.

[0026] In order to solve the above defects, the embodiment provides an isolation conversion circuit, which can push-pull the voltage at the power supply end through the on-off of the first switch circuit 4 and then invert it, or directly invert it. In addition, the transformer isolation component T is additionally provided with a primary side tap between the first end of the primary side winding and the second end of the primary side winding, so that the voltage at the power supply end can be input to the primary side winding through the primary side tap when push-pull is performed. At this time, the turns ratio of the primary side winding is reduced, thereby realizing voltage boosting. Compared with the existing boost circuit 1 for realizing a wide range of input voltage, the embodiment can directly realize voltage boosting by reducing the turns ratio of the primary side winding, without the need for additional boost circuit 1, thereby reducing the required devices and the overall size.

[0027] Therefore, the present application provides an isolation conversion circuit. Referring to Figure 2 , Figure 2 The circuit principle diagram of the first embodiment of the isolation conversion circuit of the present application; as Figure 2 shown, the isolation conversion circuit comprises: a power supply end; a transformer isolation component T, comprising a primary side winding and a secondary side winding, the primary side winding having a first end, a second end and a primary side tap provided between the first end of the primary side winding and the second end of the primary side winding; a primary side bridge arm switching circuit 2 connected with the power supply end, the first end of the primary side winding and the second end of the primary side winding respectively; a secondary side bridge arm switching circuit 3 connected with the secondary side winding and configured as a rectification function.

[0028] It should be noted that the power supply end can be an end for receiving a voltage, such as Figure 2 In the embodiment, the power supply end can receive an external output DC voltage, and the power supply end can include a positive end (i.e. Figure 2 Vin+) and a negative end (i.e. Figure 2 Vin-). The transformer isolation component T can be any functional device for realizing isolation transformation, such as a transformer. As shown in Figure 2 In the embodiment, the transformer isolation component T can include a primary winding and a secondary winding, and the primary winding can include a first end and a second end, and the secondary winding can also include a first end and a second end. However, it should be noted that in the embodiment, the first end of the primary winding and the second end of the primary winding are provided with a primary winding tap, which can be understood as a take-off point provided on the primary winding of the transformer. By selecting different positions of the take-off point, the effective number of turns of the primary winding can be adjusted, thereby changing the output voltage of the secondary winding.

[0029] It should also be noted that the primary bridge arm switching circuit 2 can be any circuit that realizes inverting function. As shown in Figure 2 In the embodiment, the primary bridge arm switching circuit 2 can include a second switch tube S2 to a fourth switch tube S4. The first end of the second switch tube S2 can be connected to the positive end of the power supply end and the first end of the fourth switch tube S4, respectively. The second end of the second switch tube S2 is connected to the second end of the transformer isolation component T and the first end of the third switch tube S3, respectively. The second end of the third switch tube S3 is connected to the negative end of the power supply end and the second end of the fifth switch tube S5, respectively. The second end of the fourth switch tube S4 is connected to the first end of the transformer isolation component T and the first end of the fifth switch tube S5, respectively. The control ends of the second switch tube S2 to the fourth switch tube S4 can be connected to the controller to control the on-off.

[0030] It should be understood that the second switch tube S2 to the fifth switch tube S5 can be any controllable switch tube, such as a MOS tube, a triode, etc. The MOS tube is used for illustration in the embodiment.

[0031] It should also be understood that the turns ratio of the primary winding and the secondary winding of the transformer isolation component T in the embodiment can be set according to actual conditions, which is not limited in the embodiment.

[0032] It should be understood that the secondary bridge arm switching circuit 3 can be any circuit that realizes rectification function. As shown in Figure 2 In the embodiment, the secondary bridge arm switching circuit 3 can include a sixth switch tube S6 and a seventh switch tube S7. The first end of the sixth switch S6 can be connected to the first end of the secondary winding, the second end of the sixth switch S6 is connected to the second end of the seventh switch S7, and the first end of the seventh switch S7 is connected to the second end of the secondary winding; the control terminals of the sixth switch S6 and the seventh switch S7 can both be connected to the controller to control the on / off state.

[0033] It should also be understood that the sixth switch S6 and the seventh switch S7 mentioned above can be any controllable switch, such as a MOSFET or a transistor. This embodiment uses a MOSFET for illustration.

[0034] The isolation conversion circuit in this embodiment may also include an output terminal, which may include a positive terminal (i.e., Figure 2 Vout+) and the negative input (i.e. Figure 2 Vout-), where the second end of the seventh switch S7 is connected to the negative end of the output terminal, and the positive end of the output terminal can be connected to the middle tap of the secondary winding of the transformer isolation component T. The middle tap of the secondary winding can be located between the first end and the second end of the secondary winding.

[0035] Furthermore, in order to support a wide range of voltage inputs without using boost circuit 1, the following continues... Figure 2 As shown, in this embodiment, the first switching circuit 4 is connected to the power supply terminal and the primary tap respectively, and is used to connect / disconnect the path between the power supply terminal and the primary tap; When the first switching circuit 4 is in the on state, the primary side bridge arm switching circuit 2 is used to invert and output the voltage of the power supply terminal through the first switching circuit 4 after push-pull operation. When the first switching circuit 4 is in the off state, the primary side bridge arm switching circuit 2 is used to invert and output the voltage at the power supply terminal.

[0036] It should be noted that the first switching circuit 4 described above can be any circuit used to achieve on / off switching, such as a switching transistor, a controllable diode, etc., and this embodiment does not impose any restrictions on it. Furthermore, in order to facilitate the control of the on / off state of the first switching circuit 4, the first switching circuit 4 can also be connected to a controller.

[0037] like Figure 2As shown, in this embodiment, the first switching circuit 4 can be connected to the positive terminal of the power supply and the center tap of the transformer isolation component T. In actual use, the on / off state of the first switching circuit 4 can be controlled. When the first switching circuit 4 is on, the second switching transistor S2 and the fourth switching transistor S4 are turned off, so that the power supply voltage, after passing through the first switching power supply, is input to the center tap of the primary winding. Then, the third switching transistor S3 and the fifth switching transistor S5 are alternately turned on, thus putting it in push-pull mode. Using the center tap of the primary winding as a boundary, the two sets of coils—one from the center tap of the primary winding to the first end of the primary winding, and the other from the center tap of the primary winding to the second end of the primary winding—are sequentially output to the secondary winding, realizing push-pull and inverter functions. Because of the center tap of the primary winding at this time, the effective number of turns of the primary winding decreases, thus increasing the voltage output of the secondary winding, realizing a boost function. The voltage is then transmitted to the secondary bridge arm switching circuit 3 for rectification before being output to the output terminal. Furthermore, compared to the traditional method that can achieve voltage boosting without the need for a boost circuit 1, this reduces the required components and thus reduces the overall size of the device.

[0038] When the first switching transistor S1 is off, similar to the traditional subsequent stage, the voltage at the power supply end is directly input to the primary side bridge arm switching circuit 2. The controller controls the switching transistor in the primary side bridge arm switching circuit 2 to switch it on and off to make it in full-bridge mode, realizing the full-bridge inverter function. After being isolated by the transformer isolation component T, it is output to the secondary side bridge arm switching circuit 3. Under the control of the controller, the secondary side bridge arm switching circuit 3 rectifies the received isolated voltage and outputs it to the output terminal.

[0039] Furthermore, in order to use a push-pull mode for voltage boosting when the input voltage is low, and to use normal isolation conversion when the input voltage is high, push-pull is not required. Therefore, in this embodiment, the first switching circuit 4 is also used to be in the on state when the voltage input at the power supply terminal is higher than a preset input voltage threshold. The first switching circuit 4 is also used to be in an open state when the voltage input at the power supply terminal is not higher than the preset input voltage threshold.

[0040] It should be noted that the aforementioned preset input voltage threshold can be a threshold used to determine whether push-pull voltage boost is required. It can be set according to the actual situation, and this embodiment does not impose any restrictions on it.

[0041] In practical use, the controller can collect the voltage at the power supply terminal and compare it with a preset input voltage threshold. When the voltage at the power supply terminal is higher than the preset input voltage threshold, it indicates that the voltage at the power supply terminal is high and no boosting is required. The controller can then control the first switching circuit 4 to be in the off state and control the switching transistors in the primary side bridge arm switching circuit 2 to be turned on and off, thereby putting the primary side bridge arm switching circuit 2 into full-bridge mode for full-bridge inversion. When the voltage at the power supply terminal is not higher than the preset input voltage threshold, it indicates that the voltage at the power supply terminal is low and boosting is required. The controller can then control the first switching circuit 4 to be in the on state and control the switching transistors in the primary side bridge arm switching circuit 2 to be turned on and off, thereby putting the primary side bridge arm switching circuit 2 into push-pull mode for push-pull inversion.

[0042] Furthermore, in order to control the on / off state and stabilize the voltage flowing through it, such as Figure 2 As shown, in this embodiment, the first switching circuit 4 may include: a first bidirectional diode Q1; The first terminal of the first bidirectional diode Q1 is connected to the positive terminal of the power supply, the second terminal of the first bidirectional diode Q1 is connected to the center tap of the primary winding, and the control terminal of the first bidirectional diode Q1 is connected to the controller.

[0043] In practical use, the controller in this embodiment can control the on and off of the first bidirectional diode Q1, thereby switching the first switching circuit 4 between the on and off states. Furthermore, due to the use of the first bidirectional diode Q1, forward and reverse voltage protection can be provided, improving circuit stability.

[0044] Furthermore, in order to reduce interference, continue as follows Figure 2 As shown, in this embodiment, the isolation transformation circuit further includes: a first filtering module 5; The first filtering module 5 is connected to the power supply terminal, the primary side bridge arm switching circuit 2, and the first switching circuit 4, respectively, and is used to filter the voltage at the power supply terminal.

[0045] It should be understood that the first filtering module 5 mentioned above can be any module that implements the filtering function, such as a filter capacitor, etc., and this embodiment does not limit it.

[0046] In actual use, regardless of whether the first switching circuit 4 is in the on or off state, the voltage at the power supply end is filtered by the first filtering module 5 and then output. The voltage received by the transformer isolation component T is also filtered, which can reduce interference in the circuit and improve the stability of the circuit.

[0047] Furthermore, such as Figure 2 As shown, in order to achieve filtering, the first filtering module 5 in this embodiment includes: a third capacitor C3; The first terminal of the third capacitor C3 is connected to the positive terminal of the power supply, the first terminal of the second switch S2, and the first terminal of the first switch S1, respectively. The second terminal of the third capacitor C3 is connected to the negative terminal of the power supply and the second terminal of the third switch S3, respectively.

[0048] It should also be understood that the third capacitor C3 mentioned above can be any capacitor used to implement filtering, such as a filter capacitor, etc., and this embodiment does not limit it.

[0049] Furthermore, in order to reduce interference, continue as follows Figure 3 As shown, in this embodiment, the isolation transformation circuit further includes a second filtering module 6; The second filter module 6 is connected to the secondary bridge arm switch circuit 3 and its output terminal.

[0050] It should be noted that the second filtering module 6 mentioned above can be any module that implements the filtering function, such as an LC filter circuit, etc., and this embodiment does not limit it.

[0051] In practical use, the secondary bridge arm switching circuit 3 rectifies the voltage and outputs it to the second filter module 6. The second filter module 6 then filters the rectified voltage before outputting it to the output terminal. This reduces interference in the circuit and improves its stability.

[0052] Furthermore, such as Figure 3 As shown, in order to achieve filtering, the second filtering module 6 in this embodiment includes: a second inductor L2 and a fourth capacitor C4; The first end of the second inductor L2 is connected to the center tap of the secondary winding. The second end of the second inductor L2 is connected to the positive terminal of the output and the first end of the fourth capacitor C4. The second end of the fourth capacitor C4 is connected to the second end of the seventh switch S7 and the negative terminal of the output.

[0053] In actual use, the rectified voltage is filtered by the second inductor L2 and the fourth capacitor C4 before being output.

[0054] This embodiment provides an isolated converter circuit that, through the switching of the first switching circuit 4, enables the primary-side bridge arm switching circuit 2 to perform push-pull inversion or direct inversion of the power supply voltage. Furthermore, because the transformer isolation component T has an additional primary-side tap between the first and second ends of the primary winding, the power supply voltage can be input to the primary winding during push-pull operation. This reduces the turns ratio of the primary winding, thereby achieving voltage boost. Compared to existing methods that require a boost circuit 1 to achieve a wide input voltage range, this embodiment directly achieves voltage boost by reducing the turns ratio of the primary winding, eliminating the need for an additional boost circuit 1, thus reducing the required components and overall size.

[0055] Reference Figure 3 , Figure 3 This is a circuit schematic diagram of a second embodiment of the isolation converter circuit of this application. Based on the above embodiments, a second embodiment of the isolation converter circuit of this application is proposed.

[0056] To protect the subsequent stage from the effects of DC bias, such as Figure 3 As shown, in this embodiment, the isolation conversion circuit further includes: The DC isolation module 7 is connected to the primary side bridge arm switch circuit 2, the first end of the primary side winding, and the second end of the primary side winding, respectively, and is used to provide DC isolation for the output of the primary side bridge arm switch circuit 2.

[0057] It should be noted that the DC blocking module 7 mentioned above can be any module used for DC isolation, such as a DC blocking capacitor, and this embodiment does not limit it.

[0058] It should also be noted that in this embodiment, the DC blocking module 7 can be connected to the primary side bridge arm switching circuit 2, the first end of the primary side winding, and the second end of the primary side winding, respectively. In this way, the voltage output by the primary side bridge arm switching circuit 2 can be DC isolated during actual use, blocking the DC component and allowing only AC to pass through, so as to ensure that the secondary side bridge arm switching circuit 3 is not affected by DC bias.

[0059] Furthermore, in order to achieve DC isolation, such as Figure 3 As shown, in this embodiment, the DC blocking module 7 includes: a fifth capacitor C5 and a sixth capacitor C6; The first terminal of the fifth capacitor C5 is connected to the second terminal of the fourth switch S4, and the second terminal of the fifth capacitor C5 is connected to the first terminal of the primary winding. The first terminal of the sixth capacitor C6 is connected to the second terminal of the second switch S2, and the second terminal of the sixth capacitor C6 is connected to the second terminal of the primary winding.

[0060] It is understood that the fifth capacitor C5 and the sixth capacitor C6 mentioned above can both be DC blocking capacitors, and the capacitance values ​​of the fifth capacitor C5 and the sixth capacitor C6 can be set according to the actual situation. This embodiment does not impose any restrictions on this.

[0061] In actual use, whether in full-bridge mode or push-pull mode, the voltage at the power supply end will pass through the fifth capacitor C5 and the sixth capacitor C6, and thus DC isolation can be achieved through the fifth capacitor C5 and the sixth capacitor C6.

[0062] Furthermore, considering that in push-pull mode, in order to facilitate the control of the second switch S2 and the fourth switch S4, and to prevent the voltage at the power supply end from entering the second switch S2 and the fourth switch S4, the following continues... Figure 3As shown, in this embodiment, the isolation conversion circuit further includes: The second switching circuit 8 is connected to the power supply terminal and the primary side bridge arm switching circuit 2 respectively. It is used to disconnect the path between the power supply terminal and the primary side bridge arm switching circuit 2 when the first switching circuit 4 is in the conducting state, and to connect the path between the power supply terminal and the primary side bridge arm switching circuit 2 when the first switching circuit 4 is in the disconnected state.

[0063] It should be understood that the second switching circuit 8 described above can be any circuit used to achieve on / off switching, such as a switching transistor, a controllable diode, etc., and this embodiment does not impose any restrictions on it. Furthermore, in order to facilitate the control of the on / off state of the second switching circuit 8, the second switching circuit 8 can also be connected to the controller.

[0064] like Figure 3 As shown, in this embodiment, the second switching circuit 8 can be set between the positive end of the power supply and the primary side bridge arm switching circuit 2. Specifically, the second switching circuit 8 can be connected to the positive end of the power supply, the first switching circuit 4, and the primary side bridge arm switching circuit 2 respectively.

[0065] It should also be understood that the second switching circuit 8 in this embodiment also includes an on state and an off state, and this state can be the opposite of the first switching circuit 4. Specifically, when the voltage at the power supply terminal is higher than the preset input voltage threshold, it needs to be controlled in full-bridge mode. The controller can then control the second switching circuit 8 to be on and the first switching circuit 4 to be off, so that the voltage at the power supply terminal is transmitted to the primary side bridge arm switching circuit 2 for full-bridge inversion. When the voltage at the power supply terminal is not higher than the preset input voltage threshold, it needs to be controlled in push-pull mode. The controller can then control the second switching circuit 8 to be off and the first switching circuit 4 to be on, so that the voltage at the power supply terminal is transmitted to the intermediate tap for push-pull inversion.

[0066] Furthermore, in order to control the on / off state and stabilize the voltage flowing through it, such as Figure 4 to Figure 5 As shown, in this embodiment, the second switching circuit 8 includes a second bidirectional diode Q2; The first end of the second bidirectional diode Q2 is connected to the first end of the second switching transistor S2. The second end of the second bidirectional diode Q2 is connected to the positive end of the power supply and the first end of the first bidirectional diode Q1. The control end of the first bidirectional diode Q1 is connected to the controller.

[0067] In practical use, the controller can control the switching of the second bidirectional diode Q2, thereby switching the second bidirectional diode Q2 between the conducting and disconnected states. Furthermore, the use of the second bidirectional diode Q2 provides both forward and reverse voltage protection, improving the stability of the circuit.

[0068] Furthermore, considering that during push-pull operation, the switching transistor in the primary side bridge arm switching circuit 2 will experience energy spikes when it is turned off, in order to prevent these energy spikes from affecting the circuit and reduce the voltage stress on the switching transistor, the following steps are continued... Figure 6 to Figure 9 As shown, in this embodiment, the isolation conversion circuit further includes: The energy storage module 9 is connected to the second switching circuit 8 and the primary side bridge arm switching circuit 2 respectively, and is used to absorb / release peak energy of the primary side bridge arm switching circuit 2 when the primary side bridge arm switching circuit 2 is in push-pull mode.

[0069] It should be noted that the energy storage module 9 mentioned above can be any module used for energy storage, such as an energy storage capacitor, etc., and this embodiment does not limit it. In actual use, the energy storage characteristics of the energy storage module 9 can be utilized. When the primary side bridge arm switching circuit 2 is in push-pull mode, it can also be understood that the first switching circuit 4 is in the on state, or the second switching circuit 8 is in the off state, so that the primary side bridge arm switching circuit 2 can absorb / release energy.

[0070] Specifically, in this embodiment, the energy storage module 9 may include: a seventh capacitor C7; The first terminal of the seventh capacitor C7 is connected to the first terminal of the second bidirectional diode Q2, and the second terminal of the seventh capacitor C7 is connected to the second terminal of the third switch S3.

[0071] To facilitate understanding of the function of the energy storage module 9 and the turn-on / off sequence of each switching transistor, please refer to the following: Figure 4 For an explanation of the full-bridge mode, please refer to [reference needed]. Figure 4 The push-pull mode will be explained.

[0072] It should be emphasized that in full-bridge mode, the controller can control the second bidirectional diode Q2 to be in the conducting state, control the first bidirectional diode Q1 to be in the off state, and control the second switch S2 and the third switch S3 to be complementaryly conducting, and the fourth switch S4 and the fifth switch S5 to be complementaryly conducting.

[0073] Reference Figure 5 , Figure 5This is a circuit diagram of the first stage in the full-bridge mode of the second embodiment of the isolation converter circuit of this application. In the first stage of the full-bridge mode, the controller can control the second bidirectional diode Q2, the fourth switch S4, the third switch S3 and the seventh switch S7 to be turned on, and the other switches to be turned off. Then the voltage at the input terminal can pass through the second bidirectional diode Q2, the fourth switch S4, the fifth capacitor C5, the first end of the primary winding, the second end of the primary winding, the sixth capacitor C6 and the third switch S3 to the negative end of the power supply terminal. The secondary winding can generate current from the seventh switch S7, the second end of the secondary winding, the middle tap of the secondary winding and the second inductor L2 to the positive end of the output terminal.

[0074] Reference Figure 6 , Figure 6 This is a circuit diagram of the second stage in the full-bridge mode of the second embodiment of the isolation converter circuit of this application. In the second stage of the full-bridge mode, the controller can control the second bidirectional diode Q2, the second switch S2, the fifth switch S5 and the sixth switch S6 to be turned on, and the other switches to be turned off. Then the voltage at the input terminal can pass through the second bidirectional diode Q2, the second switch S2, the sixth capacitor C6, the second end of the primary winding, the first end of the primary winding, the fifth capacitor C5 and the fifth switch S5 to the negative end of the power supply terminal in sequence. The secondary winding can generate current from the sixth switch S6, the first end of the secondary winding, the middle tap of the secondary winding and the second inductor L2 to the positive end of the output terminal.

[0075] Reference Figure 7 , Figure 7 This is a circuit diagram of the first stage in the push-pull mode of the second embodiment of the isolation converter circuit of this application. In the first stage of the push-pull mode, the controller can control the first bidirectional diode Q1, the third switch S3, the fourth switch S4 and the seventh switch S7 to be turned on, while the other switches are turned off. Thus, the voltage at the input terminal can sequentially pass through the first bidirectional diode Q1, the middle tap of the primary winding, the second end of the primary winding, the sixth capacitor C6, and the third switch S3 to the negative end of the power supply. At the same time, the seventh capacitor C7 can release energy, and the current sequentially passes through the fourth switch S4, the fifth capacitor C5, the first end of the primary winding to the second end of the primary winding for output. The secondary winding can generate current from the seventh switch S7, the second end of the secondary winding, the middle tap of the secondary winding and the second inductor L2 to the positive end of the output terminal.

[0076] Reference Figure 8 , Figure 8This is a circuit diagram of the second stage in the push-pull mode of the second embodiment of the isolation converter circuit of this application. In the second stage of the push-pull mode, the controller can control the second switch S2, the fifth switch S5 and the seventh switch S7 to be turned on, and the other switches to be turned off. Then, the seventh capacitor C7 can absorb the peak energy generated when the third switch S3 is turned off. Specifically, the current can flow through the fifth switch S5, the fifth capacitor C5, the first end of the primary winding, the second end of the primary winding, the sixth capacitor C6 and the second switch S2 to the seventh capacitor C7 in sequence. The secondary winding can generate current from the seventh switch S7, the second end of the secondary winding, the middle tap of the secondary winding and the second inductor L2 to the positive end of the output.

[0077] Reference Figure 9 , Figure 9 This is a circuit diagram of the third stage in the push-pull mode of the second embodiment of the isolation converter circuit of this application. In the third stage of the push-pull mode, the controller can control the first bidirectional diode Q1, the fifth switch S5, the second switch S2 and the sixth switch S6 to be turned on, while the other switches are turned off. Thus, the voltage at the input terminal can sequentially pass through the first bidirectional diode Q1, the middle tap of the primary winding, the first end of the primary winding, the fifth capacitor C5 and the fifth switch S5 to the negative terminal of the power supply. At the same time, the seventh capacitor C7 can release energy, and the current sequentially passes through the second switch S2, the sixth capacitor C6, the second end of the primary winding to the first end of the primary winding for output. The secondary winding can generate current from the sixth switch S6, the first end of the secondary winding, the middle tap of the secondary winding and the second inductor L2 to the positive terminal of the output.

[0078] Reference Figure 10 , Figure 10 This is a circuit diagram of the fourth stage in the push-pull mode of the second embodiment of the isolation converter circuit of this application. In the fourth stage of the push-pull mode, the controller can control the third switch S3, the fourth switch S4 and the sixth switch S6 to be turned on, and the other switches to be turned off. Then, the seventh capacitor C7 can absorb the peak energy generated when the fifth switch S5 is turned off. Specifically, the current can flow through the third switch S3, the sixth capacitor C6, the second end of the primary winding, the first end of the primary winding, the fifth capacitor C5 and the fourth switch S4 to the seventh capacitor C7 in sequence. The secondary winding can generate current from the sixth switch S6, the first end of the secondary winding, the middle tap of the secondary winding and the second inductor L2 to the positive end of the output.

[0079] Thus, through the above control, both full-bridge and push-pull modes can be achieved. Specifically, full-bridge mode is used when the input voltage is sufficient, and push-pull mode is used when the input voltage is insufficient.

[0080] Furthermore, the isolation converter circuit in this embodiment can also perform reverse output, that is, the output terminal serves as the power supply terminal, and the power supply terminal serves as the output terminal. This eliminates the need for an additional step-down circuit when the output voltage requirement is low, thus reducing the overall size of the device. Specifically, the secondary bridge arm switching circuit 3 is also configured for inverter function. When the first switching circuit 4 is in the conducting state, the primary side bridge arm switching circuit 2 is used to rectify and output the voltage output by the transformer isolation component T through the first switching circuit 4 after push-pull operation. When the first switching circuit 4 is in the open state, the primary side bridge arm switching circuit 2 is used to rectify and output the voltage output by the transformer isolation component T.

[0081] In practical use, the controller can control the switching of the sixth switch S6 and the seventh switch S7 in the secondary bridge arm switching circuit 3 to achieve the inverter function. It can also control the first switching circuit 4 to be on. At this time, the controller controls the switching of the second to fourth switches S2 to S4 in the primary bridge arm switching circuit 2 to achieve push-pull and rectified output of the voltage from the transformer isolation component T; that is, it is in push-pull mode. When the controller controls the first switching circuit 4 to be off, the controller controls the switching of the second to fourth switches S2 to S4 in the primary bridge arm switching circuit 2 to achieve rectified output of the voltage from the transformer isolation component T; that is, it is in full-bridge mode.

[0082] Furthermore, the first switching circuit 4 is also used to be in the disconnected state when the voltage output of the power supply terminal is not lower than a preset output voltage threshold. The first switching circuit 4 is also used to be in the conducting state when the voltage output of the power supply terminal is required to be lower than the preset output voltage threshold.

[0083] It should be noted that the aforementioned preset output voltage threshold can be used to determine whether push-pull voltage reduction is required. It can be set according to the actual situation, and this embodiment does not impose any restrictions on it.

[0084] In actual use, the controller can obtain the required output voltage and compare it with the preset output voltage threshold. When the required power supply voltage is not lower than the preset output voltage threshold, it indicates that the voltage expected by the user is higher and there is no need to step down the voltage. The controller can then control the first switching circuit 4 to be in the off state. When the required power supply voltage is lower than the preset output voltage threshold, it indicates that the voltage expected by the user is lower and there is a need to step down the voltage. The controller can then control the first switching circuit 4 to be in the on state.

[0085] This application also proposes an isolation converter circuit control method based on the isolation converter circuit described in any of the above claims. It is understood that the isolation converter circuit control method of this application can be stored in the memory of a controller and executed by the processor in the controller. The controller can be constructed using at least one of the following: a microcontroller unit (MCU), a digital signal processing chip (DSP), a field-programmable gate array (FPGA), a programmable logic controller (PLC), a system-on-chip (SOC), etc. The controller can be a controller within a device equipped with the isolation converter circuit of this application, such as a controller within an on-board charger, a controller within a charging pile, etc. It can also be an independent controller outside the device for connecting to the device to control the isolation converter circuit, or it can be a controller within the isolation converter circuit of this application.

[0086] refer to Figure 10 , ​ This is a flowchart illustrating the first embodiment of the isolation converter circuit control method of this application, as shown below. ​ As shown, in one embodiment of this application, the method includes: Step S10: Determine the operating mode and control the secondary bridge arm switching circuit 3 to perform rectification.

[0087] It should be noted that the above-mentioned operating mode can be the operating mode of the isolation converter circuit in this embodiment. That is, the push-pull mode and full-bridge mode described in the above embodiments. At the same time, the controller can control the on / off state of the sixth switch S6 and the seventh switch S7 in the secondary bridge arm switching circuit 3 to achieve the rectification function. The specific implementation method can be referred to the above embodiments, and this embodiment will not elaborate on it.

[0088] Step S20: When the working mode is push-pull mode, control the first switching circuit 4 to be turned on, and control the primary side bridge arm switching circuit 2 to perform push-pull inversion and output of the voltage at the power supply terminal. Step S30: When the working mode is inverter mode, control the first switching circuit 4 to disconnect and control the primary side bridge arm switching circuit 2 to invert and output the voltage at the power supply terminal.

[0089] It is understood that the controller described above can output electrical signals to the first switching circuit 4 and the primary-side bridge arm switching circuit 2, thereby putting the first switching circuit 4 into an on or off state, and putting the primary-side bridge arm switching circuit 2 into a full-bridge mode or a push-pull mode. Specific details can be found in the above embodiments, and will not be elaborated upon in this embodiment.

[0090] This embodiment provides an isolated converter circuit that, through the switching of the first switching circuit 4, enables the primary-side bridge arm switching circuit 2 to perform push-pull inversion or direct inversion of the power supply voltage. Furthermore, because the transformer isolation component T has an additional primary-side tap between the first and second ends of the primary winding, the power supply voltage can be input to the primary winding during push-pull operation. This reduces the turns ratio of the primary winding, thereby achieving voltage boost. Compared to existing methods that require a boost circuit 1 to achieve a wide input voltage range, this embodiment directly achieves voltage boost by reducing the turns ratio of the primary winding, eliminating the need for an additional boost circuit 1, thus reducing the required components and overall size.

[0091] As one implementation method, the steps for determining the working mode described above include: Step S11: Obtain the voltage at the power supply terminal; Step S12: If the voltage at the power supply terminal is higher than the preset input voltage threshold, the operating mode is determined to be full-bridge mode. Step S13: If the voltage at the power supply terminal is not higher than the preset input voltage threshold, the working mode is determined to be push-pull mode.

[0092] It should be noted that the preset input voltage threshold can be set according to actual conditions, and this embodiment does not impose any restrictions on it. For details, please refer to the above embodiments; this embodiment will not elaborate further.

[0093] As one implementation method, the above-mentioned isolation converter circuit control method also includes: Step S40: When the first switching circuit 4 is on, control the second switching circuit 8 to be off, so as to disconnect the path between the power supply terminal and the primary side bridge arm switching circuit 2. Step S50: When the first switching circuit 4 is in the off state, control the second switching circuit 8 to be turned on so that the path between the power supply terminal and the primary side bridge arm switching circuit 2 is turned on.

[0094] As one implementation method, the above-mentioned isolation converter circuit control method also includes: Step S60: Determine the operating mode and control the secondary bridge arm switching circuit 3 to perform inversion; Step S70: When the working mode is push-pull mode, control the first switching circuit 4 to turn on, and control the primary side bridge arm switching circuit 2 to rectify and output the voltage output by the transformer isolation component T after push-pull operation. Step S80: When the working mode is full bridge mode, control the first switching circuit 4 to disconnect, and control the primary side bridge arm switching circuit 2 to rectify and output the voltage output by the transformer isolation component T.

[0095] As one implementation method, the steps for determining the working mode described above include: Step S61: Obtain the required voltage at the power supply terminal; Step S62: If the voltage output at the power supply terminal is not lower than the preset output voltage threshold, the operating mode is determined to be full-bridge mode. Step S63: If the voltage output at the power supply terminal is lower than the preset output voltage threshold, the operating mode is determined to be half-bridge mode.

[0096] It is worth noting that, since this application includes the aforementioned isolation conversion circuit, all the technical solutions included in this application also possess at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0097] This application also proposes a controller, comprising: a memory, a processor, and an isolation conversion circuit control program stored in the memory and executable on the processor, the isolation conversion circuit control program being configured to implement the isolation conversion circuit control method as described in any of the preceding claims.

[0098] It is worth noting that, since this application includes the aforementioned isolation conversion circuit control method, all the technical solutions included in this application also possess at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0099] This application also proposes an on-board charger, including the isolation conversion circuit as described in any of the above claims; and / or, the controller as described in the above claims.

[0100] It is worth noting that, since this application includes the aforementioned isolation conversion circuit and / or controller, all the technical solutions included in this application also possess at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here.

[0101] The above content is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. An isolation converter circuit, characterized in that, The isolation conversion circuit includes: Power supply end; A transformer isolation assembly includes a primary winding and a secondary winding, wherein the primary winding has a first end, a second end, and a primary tap disposed between the first end and the second end of the primary winding; The primary side bridge arm switching circuit is connected to the power supply terminal, the first terminal of the primary side winding, and the second terminal of the primary side winding, respectively. The secondary bridge arm switching circuit, connected to the secondary winding, is configured for rectification. The first switching circuit is connected to the power supply terminal and the primary tap respectively, and is used to connect / disconnect the path between the power supply terminal and the primary tap; When the first switching circuit is in the ON state, the primary side bridge arm switching circuit is used to invert and output the voltage of the power supply terminal through the first switching circuit. When the first switching circuit is in the off state, the primary side bridge arm switching circuit is used to invert and output the voltage at the power supply terminal.

2. The isolation converter circuit as described in claim 1, characterized in that, The first switching circuit is also used to be in a conducting state when the voltage input at the power supply terminal is higher than a preset input voltage threshold. The first switching circuit is also configured to be in an open state when the voltage input at the power supply terminal is not higher than the preset input voltage threshold.

3. The isolation converter circuit as described in claim 1, characterized in that, The isolation conversion circuit further includes: The second switching circuit is connected to the power supply terminal and the primary side bridge arm switching circuit respectively. It is used to disconnect the path between the power supply terminal and the primary side bridge arm switching circuit when the first switching circuit is in the on state, and to connect the path between the power supply terminal and the primary side bridge arm switching circuit when the first switching circuit is in the off state.

4. The isolation conversion circuit as described in claim 3, characterized in that, The isolation conversion circuit further includes: The energy storage module is connected to the second switching circuit and the primary side bridge arm switching circuit respectively, and is used to absorb / release peak energy to the primary side bridge arm switching circuit when the primary side bridge arm switching circuit is in push-pull mode.

5. The isolation converter circuit as described in claim 1, characterized in that, The secondary side bridge arm switching circuit is also configured for inverter function; When the first switching circuit is in the on state, the primary side bridge arm switching circuit is used to rectify and output the voltage output by the transformer isolation component through the first switching circuit after push-pull operation. When the first switching circuit is in the open state, the primary side bridge arm switching circuit is used to rectify and output the voltage output by the transformer isolation component.

6. The isolation converter circuit as described in claim 5, characterized in that, The first switching circuit is also used to be in the disconnected state when the voltage output of the power supply terminal is not lower than a preset output voltage threshold. The first switching circuit is further configured to be in the conducting state when the voltage output at the power supply terminal is required to be lower than the preset output voltage threshold.

7. The isolation converter circuit as described in claim 1, characterized in that, The isolation conversion circuit further includes: The DC isolation module is connected to the primary side bridge arm switching circuit, the first end of the primary side winding, and the second end of the primary side winding, respectively, and is used to provide DC isolation for the output of the primary side bridge arm switching circuit.

8. A control method for an isolation converter circuit, characterized in that, Based on the isolation conversion circuit as described in any one of claims 1 to 7, the isolation conversion circuit control method includes: Determine the operating mode and control the secondary bridge arm switching circuit to perform rectification; When the working mode is push-pull mode, the first switching circuit is turned on, and the primary side bridge arm switching circuit is controlled to push-pull and invert the voltage at the power supply terminal to output. When the operating mode is inverter mode, the first switching circuit is controlled to open, and the primary side bridge arm switching circuit is controlled to invert and output the voltage at the power supply terminal.

9. A controller, characterized in that, The controller includes: a memory, a processor, and an isolation conversion circuit control program stored in the memory and executable on the processor, the isolation conversion circuit control program being configured to implement the isolation conversion circuit control method as described in claim 8.

10. An on-board charger, characterized in that, The on-board charger includes an isolation conversion circuit as described in any one of claims 1 to 7; and / or includes a controller as described in claim 9.

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