Control method, device, controller and system of conversion circuit and vehicle

Abstract

The invention discloses a control method and device of a conversion circuit, a controller, a system and a vehicle. The control method of the conversion circuit comprises the following steps: when a power battery connected with the high-voltage conversion circuit is converted from charging to charging completion, controlling the high-voltage conversion circuit not to work, and controlling the primary side conversion circuit and the low-voltage conversion circuit to work; and a switching tube of the primary side conversion circuit is controlled to work at a preset duty ratio, so that the conversion circuit outputs the target voltage to the low-voltage electric device from the alternating current power supply device. According to the control method of the conversion circuit provided by the embodiment of the invention, when the power battery is charged and is still connected with the external alternating current power supply device, the external alternating current power supply device is utilized to supply power to the low-voltage electric device in an auxiliary manner, and the power battery is not required to supply power any more, so that feed of the fully-charged power battery is avoided.

Description

Technical Field

[0001] The present application relates to the field of power supply circuits, and in particular to a control method, device, controller, system and vehicle for a conversion circuit. Background Art

[0002] In the field of electric vehicles, on-board chargers are an important component of electric vehicles, and high integration is the development trend of on-board chargers.

[0003] The three-port magnetic integration technology enables the on-board charger to connect to the electric vehicle's power battery, low-voltage battery (storage battery) and external AC power supply device or external AC power equipment, which can improve device utilization.

[0004] The conversion circuit of an electric vehicle using three-port magnetic integration technology includes a transformer, a primary conversion circuit connected to the primary winding of the transformer, a high-voltage conversion circuit connected to the high-voltage secondary winding of the transformer, and a low-voltage conversion circuit connected to the low-voltage secondary winding of the transformer. The high-voltage conversion circuit is used to connect to a power battery. In the related art, when charging the power battery, the primary conversion circuit is connected to an AC power supply device. When the power battery is fully charged and the charging gun is still connected to the electric vehicle, there are still some low-voltage electrical devices on the electric vehicle that need to be powered, such as the indicator light at the charging interface. At this time, if the low-voltage electrical device is powered by the power battery, the fully charged power battery will be fed. Summary of the invention

[0005] The present application provides a control method, device, controller, system and vehicle for a conversion circuit, which can supply power to low-voltage electrical devices through a connected AC power supply device after the power battery is fully charged, thereby avoiding power feeding from a fully charged power battery.

[0006] In a first aspect, an embodiment of the present application provides a control method for a conversion circuit, wherein the conversion circuit includes a transformer, a primary conversion circuit connected to a primary winding of the transformer, a high-voltage conversion circuit connected to a high-voltage secondary winding of the transformer, and a low-voltage conversion circuit connected to a low-voltage secondary winding of the transformer, wherein the high-voltage conversion circuit is used to connect a power battery, the primary conversion circuit can be connected to an AC power supply device, and the low-voltage conversion circuit can be connected to a low-voltage electrical device. The control method for the conversion circuit includes: when the power battery connected to the high-voltage conversion circuit changes from charging to charging completion, controlling the high-voltage conversion circuit not to work, and controlling the primary conversion circuit and the low-voltage conversion circuit to work; controlling the switch tube of the primary conversion circuit to work at a preset duty cycle, so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device.

[0007] According to any of the aforementioned embodiments of the first aspect of the present application, the primary conversion circuit includes a DC bus; before the step of controlling the switch tube of the primary conversion circuit to operate at a preset duty cycle so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device, the control method of the conversion circuit also includes: obtaining the DC bus voltage of the primary conversion circuit and the target voltage output by the low-voltage conversion circuit; based on the DC bus voltage, the target voltage and the winding turns ratio of the transformer, calculating the preset duty cycle.

[0008] According to any of the aforementioned embodiments of the first aspect of the present application, the conversion circuit also includes a power factor correction circuit connected to the primary conversion circuit; the step of obtaining the DC bus voltage of the primary conversion circuit and the target voltage output by the low-voltage conversion circuit includes: controlling the DC bus voltage through the power factor correction circuit.

[0009] According to any of the foregoing implementations of the first aspect of the present application, the turns ratio of the primary winding, the high-voltage secondary winding, and the low-voltage secondary winding of the transformer is n1:n2:n3; the step of calculating the preset duty cycle based on the DC bus voltage, the target voltage, and the turns ratio of the transformer winding includes: calculating the preset duty cycle according to the following formula:

[0010] D=VLV×n1 / (2×n3×VBUS); wherein D is the preset duty cycle; VLV is the target voltage; and VBUS is the DC bus voltage.

[0011] According to any of the aforementioned embodiments of the first aspect of the present application, the primary conversion circuit includes a full-bridge conversion circuit, the primary conversion circuit includes a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, and a DC blocking capacitor, the first switch tube and the second switch tube are connected to form a first bridge arm, the third switch tube and the fourth switch tube are connected to form a second bridge arm, the midpoint of the first bridge arm and the midpoint of the second bridge arm are connected in series to the primary winding and the DC blocking capacitor; the low-voltage conversion circuit includes a synchronous rectification circuit and a step-down circuit, the synchronous rectification circuit includes a first rectification switch tube and a second rectification switch tube, the step-down circuit includes a first step-down switch tube and a second step-down switch tube, the first step-down switch tube is connected to the low The center tap of the secondary winding is connected to the first rectifier switch tube, the source of the second rectifier switch tube is connected to the second step-down switch tube, and the drain of the first rectifier switch tube and the drain of the second rectifier switch tube are respectively connected to the two ends of the low-voltage secondary winding; when the power battery connected to the high-voltage conversion circuit changes from charging to charging completion, the high-voltage conversion circuit is controlled not to work, and the steps of controlling the primary conversion circuit and the low-voltage conversion circuit to work include: controlling the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the first rectifier switch tube, and the second rectifier switch tube to work, controlling the first step-down switch tube to be normally open, and controlling the second step-down switch tube to be turned off.

[0012] According to any of the aforementioned embodiments of the first aspect of the present application, the step of controlling the operation of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the first rectifier switch tube, and the second rectifier switch tube includes: controlling the operation of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the first rectifier switch tube, and the second rectifier switch tube with a pulse width modulation signal, so that the first switch tube and the fourth switch tube are turned on and off at the same time and are complementary to the first rectifier switch tube, and the second switch tube and the third switch tube are turned on and off at the same time and are complementary to the second rectifier switch tube.

[0013] According to any of the aforementioned embodiments of the first aspect of the present application, the control method of the conversion circuit also includes: when the power battery connected to the high-voltage conversion circuit is in charging, controlling the primary conversion circuit, the high-voltage conversion circuit and the low-voltage conversion circuit to operate, so that the conversion circuit supplies power to the power battery and the low-voltage electrical devices from the AC power supply device.

[0014] In a second aspect, an embodiment of the present application provides a control device for a conversion circuit, wherein the conversion circuit includes a transformer, a primary conversion circuit connected to the primary winding of the transformer, a high-voltage conversion circuit connected to the high-voltage secondary winding of the transformer, and a low-voltage conversion circuit connected to the low-voltage secondary winding of the transformer, wherein the high-voltage conversion circuit is used to connect a power battery, the primary conversion circuit can be connected to an AC power supply device, and the low-voltage conversion circuit can be connected to a low-voltage electrical device. The control device for the conversion circuit includes: a charging completion control module, which is used to control the high-voltage conversion circuit to not work, and control the primary conversion circuit and the low-voltage conversion circuit to work when the power battery connected to the high-voltage conversion circuit changes from charging to charging completion; a duty cycle control module, which is used to control the switch tube of the primary conversion circuit to work at a preset duty cycle, so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device.

[0015] In a third aspect, an embodiment of the present application provides a controller for a conversion circuit, wherein the controller is electrically connected to multiple switching tubes of the conversion circuit, and the controller includes a memory and at least one processor, wherein the memory is electrically connected to the at least one processor, and instructions are stored in the memory, and the at least one processor calls the instructions in the memory so that the controller executes a control method for the conversion circuit according to any of the aforementioned embodiments of the first aspect of the present application.

[0016] In a fourth aspect, an embodiment of the present application provides a vehicle-mounted power supply system, which includes a conversion circuit and a controller of the conversion circuit according to any of the foregoing embodiments of the third aspect of the present application.

[0017] In a fifth aspect, an embodiment of the present application provides a vehicle, comprising a conversion circuit and a controller of the conversion circuit according to any of the foregoing embodiments of the third aspect of the present application.

[0018] According to the control method of the conversion circuit of the embodiment of the present application, when the power battery is fully charged and still connected to the external AC power supply device, some low-voltage electrical devices need to be powered. For example, when the power battery is fully charged and the charging gun is still connected to the electric vehicle, some low-voltage electrical devices on the electric vehicle still need to be powered, such as the indicator light at the charging interface. When the power battery connected to the high-voltage conversion circuit changes from charging to charging completion, the low-voltage electrical devices on the electric vehicle that need to be powered are connected to the low-voltage conversion circuit of the conversion circuit, the high-voltage conversion circuit is controlled not to work, the primary conversion circuit and the low-voltage conversion circuit are controlled to work, and the power supply from the AC power supply device to the power battery is stopped. At the same time, the primary conversion circuit and the low-voltage conversion circuit form a hard-switching full-bridge circuit, so that the conversion circuit outputs electrical energy from the AC power supply device to the low-voltage electrical devices. By controlling the switch tube of the primary conversion circuit to work at a preset duty cycle, the conversion circuit reduces the DC bus voltage of the primary conversion circuit to a target voltage that matches the low-voltage electrical devices, thereby ensuring the power demand of the low-voltage electrical devices. In the above scheme, when the power battery is fully charged and is still connected to the external AC power supply device, the external AC power supply device is used to assist in powering the low-voltage electrical components. For example, when the power battery is fully charged and the charging gun is still connected to the electric vehicle, the external AC power supply device is used to assist in powering the low-voltage electrical components on the electric vehicle, and the power battery is no longer needed for power supply, thereby avoiding power feeding from the fully charged power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0020] Figure 1 A circuit diagram of an embodiment of a conversion circuit of the present application;

[0021] Figure 2 A circuit diagram of an alternative embodiment of the conversion circuit of the present application;

[0022] Figure 3 A flow chart of an embodiment of a control method of a conversion circuit of the present application;

[0023] Figure 4 This is a timing diagram of multiple switch tubes after the power battery connected to the high-voltage conversion circuit is converted to a charging completion in an embodiment of the control method of the conversion circuit of the present application;

[0024] Figure 5 A schematic structural diagram of an embodiment of a control device for a conversion circuit of the present application;

[0025] Figure 6 This is a schematic diagram of the hardware structure of an embodiment of the controller of the present application. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0027] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0029] An embodiment of the present application provides a control method for a conversion circuit, which can be used in a conversion circuit of a vehicle.

[0030] Figure 1 This is a circuit diagram of an embodiment of the conversion circuit of the present application. The conversion circuit includes a transformer 110, a primary conversion circuit 120 connected to the primary winding Np of the transformer 110, a high-voltage conversion circuit 130 connected to the high-voltage secondary winding Ns1 of the transformer 110, and a low-voltage conversion circuit 140 connected to the low-voltage secondary winding Ns2 of the transformer 110. The high-voltage conversion circuit 130 is used to connect a power battery. The primary conversion circuit 120 can be connected to an AC power supply device. The low-voltage conversion circuit 140 can be connected to low-voltage electrical devices. When the conversion circuit is a conversion circuit of an electric vehicle, the AC power supply device is, for example, an AC power grid, and the low-voltage electrical devices are low-voltage electrical devices of the electric vehicle.

[0031] In the embodiments of the present application, high voltage and low voltage are relative, and are determined according to actual applications, and are not limited here. For example, "high voltage" refers to a voltage in the range of 200V to 480V, and "low voltage" refers to a voltage in the range of 9V to 16V.

[0032] like Figure 1 Specifically, in this embodiment, the transformer 110 is a three-winding transformer, including a primary winding Np, a high-voltage secondary winding Ns1, and a low-voltage secondary winding Ns2. The excitation inductor is integrated in the primary winding Np of the transformer 110. The turns ratio of the primary winding Np, the high-voltage secondary winding Ns1, and the low-voltage secondary winding Ns2 of the transformer 110 is n1:n2:n3, which is determined according to actual conditions and is not limited here.

[0033] The primary conversion circuit 120 may include a full-bridge conversion circuit. Exemplarily, the primary conversion circuit 120 may include a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, and a DC blocking capacitor Cb. The first switch tube Q1 and the second switch tube Q2 are connected as a first bridge arm, the third switch tube Q3 and the fourth switch tube Q4 are connected as a second bridge arm, and the midpoint of the first bridge arm and the midpoint of the second bridge arm are connected in series to the primary winding Np and the DC blocking capacitor Cb. The power supply terminal VB of the primary conversion circuit 120 can be connected to an external AC power supply device or an external AC power-consuming device. The primary conversion circuit 120 may also include a first capacitor C1, which is connected between the positive and negative electrodes of the power supply terminal VB.

[0034] In some embodiments, the primary conversion circuit 120 includes a DC bus.

[0035] The high-voltage conversion circuit 130 may include a full-bridge conversion circuit. Exemplarily, the high-voltage conversion circuit 130 may include a fifth switch tube Q5, a sixth switch tube Q6, a seventh switch tube Q7, an eighth switch tube Q8, a resonant capacitor Cr, and a resonant inductor Lr. The fifth switch tube Q5 and the sixth switch tube Q6 are connected as a third bridge arm, and the seventh switch tube Q7 and the eighth switch tube Q8 are connected as a fourth bridge arm. The midpoint of the third bridge arm and the midpoint of the fourth bridge arm are connected in series with the resonant capacitor Cr, the high-voltage secondary winding Ns1 of the transformer 110, and the resonant inductor Lr. The high-voltage power supply terminal VH of the high-voltage conversion circuit 130 is connected to a power battery. The high-voltage conversion circuit 130 may also include a second capacitor C2, which is connected between the positive and negative electrodes of the high-voltage power supply terminal VH.

[0036] The low voltage conversion circuit 140 may include a half-bridge conversion circuit. Exemplarily, the low voltage conversion circuit 140 may include a synchronous rectification circuit 141 and a buck circuit 142. The synchronous rectification circuit 141 may include a first rectifier switch tube Q9 and a second rectifier switch tube Q10. The buck circuit 142 may include a first buck switch tube Q11 and a second buck switch tube Q12, a buck inductor L and a third capacitor C3. One end of the first buck switch tube Q11 is connected to the center tap of the low voltage secondary winding Ns2, the source of the first rectifier switch tube Q9 and the source of the second rectifier switch tube Q10 are connected to one end of the second buck switch tube Q12, and the drain of the first rectifier switch tube Q9 and the drain of the second rectifier switch tube Q10 are respectively connected to the two ends of the low voltage secondary winding Ns2. The other end of the first buck switch tube Q11 and the other end of the second buck switch tube Q12 are both connected to one end of the buck inductor L, and the other end of the buck inductor L is connected to the low-voltage power supply terminal VL of the low-voltage conversion circuit 140. The low-voltage power supply terminal VL of the low-voltage conversion circuit 140 can be connected to a low-voltage electrical device, such as an indicator light at the charging interface. The third capacitor C3 is connected between the positive electrode and the negative electrode of the low-voltage power supply terminal VL.

[0037] Figure 2 A circuit diagram of an alternative embodiment of the conversion circuit of the present application. In an alternative embodiment, the conversion circuit further includes a power factor correction (PFC) circuit 150 connected to the primary conversion circuit 120, and the primary conversion circuit 120 can be connected to an external AC power supply device through the PFC circuit 150.

[0038] Figure 3 This is a flow chart of an embodiment of a control method for a conversion circuit of the present application. The control method for a conversion circuit includes step S150 and step S160.

[0039] In step S150 , when the power battery connected to the high-voltage conversion circuit 130 changes from being charged to being fully charged, the high-voltage conversion circuit 130 is controlled not to operate, and the primary conversion circuit 120 and the low-voltage conversion circuit 140 are controlled to operate.

[0040] In step S160, the switch tube of the primary conversion circuit 120 is controlled to operate at a preset duty cycle, so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device.

[0041] According to the control method of the conversion circuit of the embodiment of the present application, when the power battery is fully charged and still connected to the external AC power supply device, some low-voltage electrical devices need to be powered. For example, when the power battery is fully charged and the charging gun is still connected to the electric vehicle, some low-voltage electrical devices on the electric vehicle still need to be powered, such as the indicator light at the charging interface. When the power battery connected to the high-voltage conversion circuit 130 changes from charging to charging completion, the low-voltage electrical devices on the electric vehicle that need to be powered are connected to the low-voltage conversion circuit 140 of the conversion circuit, the high-voltage conversion circuit 130 is controlled not to work, the primary conversion circuit 120 and the low-voltage conversion circuit 140 are controlled to work, and the power supply from the AC power supply device to the power battery is stopped. At the same time, the primary conversion circuit 120 and the low-voltage conversion circuit 140 form a hard-switched full-bridge circuit, so that the conversion circuit outputs electrical energy from the AC power supply device to the low-voltage electrical devices. By controlling the switch tube of the primary conversion circuit 120 to operate at a preset duty cycle, the conversion circuit steps down the DC bus voltage of the primary conversion circuit 120 to a target voltage that matches the low-voltage electrical device, thereby ensuring the power demand of the low-voltage electrical device. In the above scheme, when the power battery is fully charged and still connected to the external AC power supply device, the external AC power supply device is used to assist in powering the low-voltage electrical device. For example, when the power battery is fully charged and the charging gun is still connected to the electric vehicle, the external AC power supply device is used to assist in powering the low-voltage electrical device on the electric vehicle, and the power battery is no longer needed to supply power, thereby avoiding the power battery that has been fully charged from feeding.

[0042] As described above, in some embodiments, the primary conversion circuit 120 may include a full-bridge conversion circuit, and the primary conversion circuit 120 may include a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, and a DC blocking capacitor Cb. The first switch tube Q1 and the second switch tube Q2 are connected to form a first bridge arm, the third switch tube Q3 and the fourth switch tube Q4 are connected to form a second bridge arm, and the midpoint of the first bridge arm and the midpoint of the second bridge arm are connected in series to the primary winding Np and the DC blocking capacitor Cb. The low-voltage conversion circuit 140 may include a synchronous rectification circuit 141 and a buck circuit 142. The synchronous rectification circuit 141 includes a first rectification switch tube Q9 and a second rectification switch tube Q10. The buck circuit 142 includes a first buck switch tube Q11 and a second buck switch tube Q12. The first step-down switch tube Q11 is connected to the center tap of the low-voltage secondary winding Ns2, the source of the first rectifier switch tube Q9 and the source of the second rectifier switch tube Q10 are connected to the second step-down switch tube Q12, and the drain of the first rectifier switch tube Q9 and the drain of the second rectifier switch tube Q10 are respectively connected to the two ends of the low-voltage secondary winding Ns2.

[0043] In some embodiments, when the power battery connected to the high-voltage conversion circuit 130 changes from charging to charging completion, the high-voltage conversion circuit 130 is controlled not to work, and the step S150 of controlling the primary conversion circuit 120 and the low-voltage conversion circuit 140 to work may include: controlling the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the first rectifier switch tube Q9, and the second rectifier switch tube Q10 to work, controlling the first buck switch tube Q11 to be normally open, and controlling the second buck switch tube Q12 to be turned off.

[0044] Figure 4 This is a timing diagram of multiple switch tubes after the power battery connected to the high-voltage conversion circuit is converted to a charging completed power battery in an embodiment of the control method of the conversion circuit of the present application. Figure 4 Further, the step of controlling the operation of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the first rectifier switch tube Q9, and the second rectifier switch tube Q10 may include: controlling the operation of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the first rectifier switch tube Q9, and the second rectifier switch tube Q10 with a pulse width modulation signal, so that the first switch tube Q1 and the fourth switch tube Q4 are turned on and off at the same time and are complementary to the first rectifier switch tube Q9, and the second switch tube Q2 and the third switch tube Q3 are turned on and off at the same time and are complementary to the second rectifier switch tube Q10.

[0045] like Figure 3 In some embodiments, before step S160, the control method of the conversion circuit further includes step S130 and step S140. The primary side conversion circuit 120 may include a DC bus.

[0046] In step S130 , the DC bus voltage of the primary conversion circuit 120 and the target voltage output by the low voltage conversion circuit 140 are obtained.

[0047] As mentioned above, in some embodiments, the conversion circuit further includes a power factor correction circuit 150 connected to the primary conversion circuit 120. At this time, the step S130 of obtaining the DC bus voltage of the primary conversion circuit 120 and the target voltage output by the low voltage conversion circuit 140 includes: controlling the DC bus voltage through the power factor correction circuit 150. In one example, the DC bus voltage is controlled to be 350V through the power factor correction circuit 150.

[0048] In step S140 , a preset duty cycle is calculated based on the DC bus voltage, the target voltage, and the winding turns ratio of the transformer 110 .

[0049] As mentioned above, in some embodiments, the turns ratio of the primary winding Np, the high-voltage secondary winding Ns1, and the low-voltage secondary winding Ns2 of the transformer 110 is n1:n2:n3. At this time, based on the DC bus voltage, the target voltage, and the winding turns ratio of the transformer 110, the step S140 of calculating the preset duty cycle includes: calculating the preset duty cycle according to the following formula:

[0050] D=VLV×n1 / (2×n3×VBUS); where D is the preset duty cycle; VLV is the target voltage; VBUS is the DC bus voltage. In one example, the DC bus voltage VBUS is 350V, the target voltage VLV is 12V, the turns ratio of the primary winding Np to the low-voltage secondary winding Ns2 is n1 / n3=20, and accordingly, the preset duty cycle D is 0.343.

[0051] In some embodiments, the control method of the conversion circuit further includes: when the power battery connected to the high-voltage conversion circuit 130 is being charged, controlling the primary conversion circuit 120, the high-voltage conversion circuit 130 and the low-voltage conversion circuit 140 to operate, so that the conversion circuit supplies power to the power battery and the low-voltage electrical device from the AC power supply device. That is, before charging is completed, each switch tube of the primary conversion circuit 120, the high-voltage conversion circuit 130 and the low-voltage conversion circuit 140 is in operation.

[0052] According to the control method of the conversion circuit of the embodiment of the present application, it can be used in the conversion circuit of an electric vehicle. When the power battery is fully charged and the charging gun is still connected to the electric vehicle, an external AC power supply device is used to auxiliary power the low-voltage electrical components on the electric vehicle, and the power battery is no longer needed for power supply, thereby avoiding power feeding from a fully charged power battery.

[0053] The present application also provides a control device for a conversion circuit. Figure 1 or Figure 2 The conversion circuit includes a transformer 110, a primary conversion circuit 120 connected to the primary winding Np of the transformer 110, a high-voltage conversion circuit 130 connected to the high-voltage secondary winding Ns1 of the transformer 110, and a low-voltage conversion circuit 140 connected to the low-voltage secondary winding Ns2 of the transformer 110. The high-voltage conversion circuit 130 is used to connect a power battery. The primary conversion circuit 120 can be connected to an AC power supply device. The low-voltage conversion circuit 140 can be connected to low-voltage electrical devices. When the conversion circuit is a conversion circuit of an electric vehicle, the AC power supply device is, for example, an AC power grid, and the low-voltage electrical devices are low-voltage electrical devices of the electric vehicle.

[0054] Figure 5 8 is a schematic diagram of the structure of an embodiment of a control device for a conversion circuit of the present application. The control device for the conversion circuit includes a charging completion control module 850 and a duty cycle control module 860 .

[0055] The charging completion control module 850 is used to control the high-voltage conversion circuit to stop working and control the primary side conversion circuit and the low-voltage conversion circuit to work when the power battery connected to the high-voltage conversion circuit changes from charging to charging completion.

[0056] The duty cycle control module 860 is used to control the switch tube of the primary conversion circuit to operate at a preset duty cycle, so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device.

[0057] In some embodiments, the control device of the conversion circuit further includes a voltage acquisition module 830 and a duty cycle calculation module 840. The voltage acquisition module 830 is used to obtain the DC bus voltage of the primary conversion circuit 120 and the target voltage output by the low voltage conversion circuit 140. The duty cycle calculation module 840 is used to calculate a preset duty cycle based on the DC bus voltage, the target voltage and the winding turns ratio of the transformer 110.

[0058] According to the control device of the conversion circuit of the embodiment of the present application, when the power battery is fully charged and still connected to the external AC power supply device, some low-voltage electrical devices need to be powered. For example, when the power battery is fully charged and the charging gun is still connected to the electric vehicle, some low-voltage electrical devices on the electric vehicle still need to be powered, such as the indicator light at the charging interface. When the power battery connected to the high-voltage conversion circuit 130 changes from charging to charging completion, the low-voltage electrical devices on the electric vehicle that need to be powered are connected to the low-voltage conversion circuit 140 of the conversion circuit, and the charging completion control module 850 controls the high-voltage conversion circuit 130 not to work, controls the primary conversion circuit 120 and the low-voltage conversion circuit 140 to work, and stops supplying power from the AC power supply device to the power battery. At the same time, the primary conversion circuit 120 and the low-voltage conversion circuit 140 form a hard-switching full-bridge circuit, so that the conversion circuit outputs electrical energy from the AC power supply device to the low-voltage electrical devices. The duty cycle control module 860 controls the switch tube of the primary conversion circuit 120 to operate at a preset duty cycle, so that the conversion circuit steps down the DC bus voltage of the primary conversion circuit 120 to a target voltage that matches the low-voltage electrical device, thereby ensuring the power demand of the low-voltage electrical device. In the above scheme, when the power battery is fully charged and is still connected to the external AC power supply device, the external AC power supply device is used to assist in powering the low-voltage electrical device. For example, when the power battery is fully charged and the charging gun is still connected to the electric vehicle, the external AC power supply device is used to assist in powering the low-voltage electrical devices on the electric vehicle, and the power battery is no longer needed to supply power, thereby avoiding the power battery that has been fully charged from feeding.

[0059] The embodiment of the present application also provides a controller of a conversion circuit. Figure 6This is a hardware structure diagram of an embodiment of the controller of the present application. The controller is electrically connected to multiple switch tubes of the conversion circuit. The controller includes a memory 910 and at least one processor 920, the memory 910 is electrically connected to the at least one processor 920, the memory 910 stores instructions, and the at least one processor 920 calls the instructions in the memory 910, so that the controller executes the control method of the conversion circuit according to any of the aforementioned embodiments of the present application.

[0060] The conversion circuit includes a transformer, a primary conversion circuit connected to the primary winding of the transformer, a high-voltage conversion circuit connected to the high-voltage secondary winding of the transformer, and a low-voltage conversion circuit connected to the low-voltage secondary winding of the transformer. The high-voltage conversion circuit is used to connect to the power battery, the primary conversion circuit can be connected to the AC power supply device, and the low-voltage conversion circuit can be connected to the low-voltage electrical devices.

[0061] The control method of the conversion circuit includes: when the power battery connected to the high-voltage conversion circuit changes from charging to charging completion, controlling the high-voltage conversion circuit not to work, controlling the primary conversion circuit and the low-voltage conversion circuit to work; controlling the switch tube of the primary conversion circuit to work at a preset duty cycle, so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device.

[0062] Specifically, the processor 920 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0063] The memory 910 may include a large capacity memory 910 for data or instructions. By way of example and not limitation, the memory 910 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a tape, or a universal serial bus (USB) drive, or a combination of two or more of these. In appropriate cases, the memory 910 may include a removable or non-removable (or fixed) medium. In appropriate cases, the memory 910 may be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 910 is a non-volatile solid-state memory. In a specific embodiment, the memory 910 includes a read-only memory (ROM). In appropriate cases, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM), or a flash memory, or a combination of two or more of these.

[0064] In one example, the control device may further include a communication interface 930 and a bus 940. The processor 920, the memory 910, and the communication interface 930 are connected via the bus 940 and communicate with each other.

[0065] The communication interface 930 is mainly used to implement communication between various modules, devices, units and / or equipment in the embodiments of the present application.

[0066] Bus 940 includes hardware, software or both, and the parts of online data flow billing equipment are coupled to each other. For example, but not limitation, bus may include accelerated graphics port (AGP) or other graphics bus, enhanced industrial standard architecture (EISA) bus, front-end bus (FSB), hypertransport (HT) interconnection, industrial standard architecture (ISA) bus, infinite bandwidth interconnection, low pin count (LPC) bus, memory 910 bus, micro channel architecture (MCA) bus, peripheral component interconnection (PCI) bus, PCI-Express (PCI-X) bus, serial advanced technology attachment (SATA) bus, video electronics standard association local (VLB) bus or other suitable bus or two or more of these combinations. In appropriate cases, bus 940 may include one or more buses. Although the present application embodiment describes and shows a specific bus, the application considers any suitable bus or interconnection.

[0067] In addition, in combination with the control method of the conversion circuit in the above embodiments, the embodiment of the present application can provide a computer-readable storage medium for implementation. The computer-readable storage medium stores instructions, and when the instructions are executed by the processor, the control method of the conversion circuit in any of the above embodiments is implemented.

[0068] The conversion circuit includes a transformer, a primary conversion circuit connected to the primary winding of the transformer, a high-voltage conversion circuit connected to the high-voltage secondary winding of the transformer, and a low-voltage conversion circuit connected to the low-voltage secondary winding of the transformer. The high-voltage conversion circuit is used to connect to the power battery, the primary conversion circuit can be connected to the AC power supply device, and the low-voltage conversion circuit can be connected to the low-voltage electrical devices.

[0069] The control method of the conversion circuit includes: when the power battery connected to the high-voltage conversion circuit changes from charging to charging completion, controlling the high-voltage conversion circuit not to work, controlling the primary conversion circuit and the low-voltage conversion circuit to work; controlling the switch tube of the primary conversion circuit to work at a preset duty cycle, so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device.

[0070] The embodiment of the present application also provides a vehicle-mounted power supply system, which includes a conversion circuit and a controller of the conversion circuit of any of the above-mentioned embodiments. The controller can implement the control method of the conversion circuit of any of the above-mentioned embodiments.

[0071] The embodiment of the present application also provides a vehicle, which includes a conversion circuit and a controller of the conversion circuit of any of the above embodiments. The controller can implement the control method of the conversion circuit of any of the above embodiments.

[0072] According to the vehicle power supply system and vehicle of the embodiment of the present application, when the power battery is fully charged and the charging gun is still connected to the vehicle, some low-voltage electrical devices on the vehicle still need to be powered, such as the indicator light at the charging interface. When the power battery connected to the high-voltage conversion circuit 130 changes from charging to charging completion, the low-voltage electrical devices on the vehicle that need to be powered are connected to the low-voltage conversion circuit 140 of the conversion circuit, and the high-voltage conversion circuit 130 is controlled not to work, and the primary conversion circuit 120 and the low-voltage conversion circuit 140 are controlled to work. While stopping the power supply from the AC power supply device to the power battery, the primary conversion circuit 120 and the low-voltage conversion circuit 140 form a hard-switching full-bridge circuit, so that the conversion circuit outputs electrical energy from the AC power supply device to the low-voltage electrical devices. By controlling the switch tube of the primary conversion circuit 120 to work at a preset duty cycle, the conversion circuit steps down the DC bus voltage of the primary conversion circuit 120 to match the target voltage of the low-voltage electrical devices, thereby ensuring the power demand of the low-voltage electrical devices. In the above scheme, when the power battery is fully charged and the charging gun is still connected to the vehicle, an external AC power supply device is used to auxiliary power the low-voltage electrical components on the vehicle, and the power battery is no longer needed to supply power, thereby avoiding the need to feed power from a fully charged power battery.

[0073] The present application is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known methods is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present application is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present application.

[0074] The functional blocks shown in the above block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present application are programs or code segments that are used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segment can be downloaded via a computer network such as the Internet, an intranet, etc.

[0075] It should also be noted that the exemplary embodiments mentioned in this application describe some methods or systems based on a series of steps or devices. However, this application is not limited to the order of the above steps, that is, the steps can be performed in the order mentioned in the embodiment, or in a different order from the embodiment, or several steps can be performed simultaneously.

[0076] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

Claims

1. A control method for a conversion circuit, characterized in that: The conversion circuit includes a transformer, a primary conversion circuit connected to the primary winding of the transformer, a high-voltage conversion circuit connected to the high-voltage secondary winding of the transformer, and a low-voltage conversion circuit connected to the low-voltage secondary winding of the transformer. The high-voltage conversion circuit is used to connect to a power battery, the primary conversion circuit can be connected to an AC power supply device, and the low-voltage conversion circuit can be connected to a low-voltage electrical device. The control method of the conversion circuit comprises: When the power battery connected to the high-voltage conversion circuit changes from being charged to being fully charged, the high-voltage conversion circuit is controlled not to work, and the primary side conversion circuit and the low-voltage conversion circuit are controlled to work; The switch tube of the primary conversion circuit is controlled to operate at a preset duty cycle, so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device.

2. The control method of the conversion circuit according to claim 1, characterized in that: The primary side conversion circuit includes a DC bus; Before the step of controlling the switch tube of the primary conversion circuit to operate at a preset duty cycle so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device, the control method of the conversion circuit further includes: Obtaining a DC bus voltage of the primary conversion circuit and a target voltage output by the low-voltage conversion circuit; The preset duty cycle is calculated based on the DC bus voltage, the target voltage and the winding turns ratio of the transformer.

3. The control method of the conversion circuit according to claim 2, characterized in that: The conversion circuit also includes a power factor correction circuit connected to the primary side conversion circuit; The step of obtaining the DC bus voltage of the primary conversion circuit and the target voltage output by the low voltage conversion circuit comprises: The DC bus voltage is controlled by the power factor correction circuit.

4. The control method of the conversion circuit according to claim 2, characterized in that: The turns ratio of the primary winding, the high-voltage secondary winding, and the low-voltage secondary winding of the transformer is n1:n2:n3; The step of calculating the preset duty cycle based on the DC bus voltage, the target voltage and the winding turns ratio of the transformer comprises: The preset duty cycle is calculated according to the following formula: D = VLV × n1 / (2 × n3 × VBUS); Wherein, D is the preset duty cycle; VLV is the target voltage; VBUS is the DC bus voltage.

5. The control method of the conversion circuit according to claim 1, characterized in that: The primary side conversion circuit comprises a full-bridge conversion circuit, the primary side conversion circuit comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, and a DC blocking capacitor, the first switch tube and the second switch tube are connected to form a first bridge arm, the third switch tube and the fourth switch tube are connected to form a second bridge arm, and the midpoint of the first bridge arm and the midpoint of the second bridge arm are connected in series to the primary winding and the DC blocking capacitor; The low-voltage conversion circuit includes a synchronous rectification circuit and a step-down circuit. The synchronous rectification circuit includes a first rectification switch tube and a second rectification switch tube. The step-down circuit includes a first step-down switch tube and a second step-down switch tube. The first step-down switch tube is connected to the center tap of the low-voltage secondary winding. The source of the first rectification switch tube and the source of the second rectification switch tube are connected to the second step-down switch tube. The drain of the first rectification switch tube and the drain of the second rectification switch tube are respectively connected to the two ends of the low-voltage secondary winding. When the power battery connected to the high-voltage conversion circuit changes from being charged to being fully charged, the step of controlling the high-voltage conversion circuit to not work and controlling the primary side conversion circuit and the low-voltage conversion circuit to work comprises: The first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the first rectifier switch tube, and the second rectifier switch tube are controlled to operate, the first buck switch tube is controlled to be normally open, and the second buck switch tube is controlled to be turned off.

6. The control method of the conversion circuit according to claim 5, characterized in that: The step of controlling the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the first rectifier switch tube, and the second rectifier switch tube to work comprises: The first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the first rectifier switch tube, and the second rectifier switch tube are controlled to operate by a pulse width modulation signal, so that the first switch tube and the fourth switch tube are turned on and off at the same time and complement the first rectifier switch tube, and the second switch tube and the third switch tube are turned on and off at the same time and complement the second rectifier switch tube.

7. The control method of the conversion circuit according to claim 5, characterized in that: The control method of the conversion circuit also includes: When the power battery connected to the high-voltage conversion circuit is in charging, the primary conversion circuit, the high-voltage conversion circuit and the low-voltage conversion circuit are controlled to operate so that the conversion circuit supplies power from the AC power supply device to the power battery and the low-voltage electrical components.

8. A control device for a conversion circuit, characterized in that: The conversion circuit includes a transformer, a primary conversion circuit connected to the primary winding of the transformer, a high-voltage conversion circuit connected to the high-voltage secondary winding of the transformer, and a low-voltage conversion circuit connected to the low-voltage secondary winding of the transformer. The high-voltage conversion circuit is used to connect to a power battery, the primary conversion circuit can be connected to an AC power supply device, and the low-voltage conversion circuit can be connected to a low-voltage electrical device. The control device of the conversion circuit comprises: A charging completion control module, used to control the high-voltage conversion circuit to stop working and control the primary side conversion circuit and the low-voltage conversion circuit to work when the power battery connected to the high-voltage conversion circuit changes from being charged to being charged; The duty cycle control module is used to control the switch tube of the primary conversion circuit to operate at a preset duty cycle, so that the conversion circuit outputs a target voltage from the AC power supply device to the low-voltage electrical device.

9. A controller for a conversion circuit, characterized in that: The controller is electrically connected to a plurality of switch tubes of the conversion circuit, and the controller includes a memory and at least one processor, the memory is electrically connected to the at least one processor, and the memory stores instructions. The at least one processor calls the instruction in the memory, so that the controller executes the control method of the conversion circuit according to any one of claims 1 to 7.

10. A vehicle-mounted power supply system, characterized in that: The invention comprises a conversion circuit and a controller of the conversion circuit as claimed in claim 9.

11. A vehicle, characterized in that: The invention comprises a conversion circuit and a controller of the conversion circuit as claimed in claim 9.

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