Charging circuit, vehicle-mounted charging equipment and vehicle

Abstract

The embodiment of the invention provides a charging circuit, vehicle-mounted charging equipment and a vehicle. The charging circuit comprises a primary side conversion circuit, a secondary side first conversion circuit, a secondary side second conversion circuit and a transformer module, the first end of the transformer module is provided with a first winding, and the second end of the transformer module is provided with a second winding and a third winding; the first winding is connected with the primary side conversion circuit, the second winding is connected with the secondary side first conversion circuit, and the third winding is connected with the secondary side second conversion circuit; the secondary side second conversion circuit comprises a rectification module and is configured to independently adjust the output voltage based on the rectification module. The mutual influence of the voltage output by the secondary side second conversion circuit and the voltage output by the secondary side first conversion circuit can be avoided.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a charging circuit, an on-board charging device and a vehicle. Background Art

[0002] Currently, a magnetically integrated vehicle power supply circuit with dual output ports is widely used. This circuit integrates an onboard charger (OBC) and a direct current / direct current (DC / DC) converter, and the two share a transformer, thereby reducing the number of transformers and reducing the size and cost of the circuit.

[0003] Since the high-voltage port and low-voltage port of the magnetic integrated vehicle power circuit share a transformer, the energy of the two ports is coupled to each other, and the output of the high-voltage port will affect the output of the low-voltage port. For example, if the power battery of the high-voltage port requires a higher charging voltage, the operating frequency of the resonant circuit on the primary side of the transformer must be reduced. When the operating frequency of the resonant circuit is reduced, the output voltage of the low-voltage port will change. Summary of the invention

[0004] The embodiments of the present application provide a charging circuit, a vehicle-mounted charging device and a vehicle, which can decouple the voltage output by the second conversion circuit on the secondary side from the voltage output by the first conversion circuit on the secondary side, thereby avoiding the mutual influence between the voltage output by the second conversion circuit on the secondary side and the voltage output by the first conversion circuit on the secondary side.

[0005] A first aspect of an embodiment of the present application provides a charging circuit, including a primary conversion circuit, a secondary first conversion circuit, a secondary second conversion circuit and a transformer module; the first end of the transformer module has a first winding, and the second end of the transformer module has a second winding and a third winding; the first winding is connected to the primary conversion circuit, the second winding is connected to the secondary first conversion circuit, and the third winding is connected to the secondary second conversion circuit; the secondary second conversion circuit includes a rectifier module, and the secondary second conversion circuit is configured to independently adjust the output voltage based on the rectifier module.

[0006] Optionally, the secondary side second conversion circuit further includes an energy storage module connected to the rectification module, and the energy storage module and the rectification module cooperate to adjust the output voltage of the secondary side second conversion circuit.

[0007] Optionally, the rectifier module includes a first rectifier unit and a second rectifier unit; the first rectifier unit includes a first rectifier switch, and the second rectifier unit includes a second rectifier switch; or, the first rectifier unit includes at least two first rectifier switches connected in parallel, and the second rectifier unit includes at least two second rectifier switches connected in parallel; one end of the first rectifier switch and the second rectifier switch are connected to each other, and the other end is respectively connected to the energy storage module.

[0008] Optionally, a duty cycle of the first rectifier switch and a duty cycle of the second rectifier switch are both greater than 50%.

[0009] Optionally, the duty cycle of the first rectifier switch and the second rectifier switch are both greater than the duty cycle of the switch of the primary conversion circuit.

[0010] Optionally, the energy storage module includes a coupled inductor, the coupled inductor includes a first coil and a second coil, the first rectifier switch is connected to one end of the third winding through the first coil, and the second rectifier switch is connected to the other end of the third winding through the second coil.

[0011] Optionally, the energy storage module further includes a first inductor and a second inductor, the first coil is connected to one end of the third winding via the first inductor, and the second coil is connected to the other end of the third winding via the second inductor.

[0012] Optionally, the energy storage module includes a first inductor and a second inductor, the first rectifier switch is connected to one end of the third winding through the first inductor, and the second rectifier switch is connected to the other end of the third winding through the second inductor.

[0013] Optionally, the secondary side second conversion circuit also includes a first capacitor, one end of the first capacitor is connected to one end of the first rectifier switch and the second rectifier switch that are interconnected, and the other end is grounded; the two ends of the first capacitor are suitable for connecting to a voltage output port.

[0014] Optionally, within at least one switching cycle, the turn-off moment of the first rectifier switch lags behind the turn-off moment of the first power switch of the primary conversion circuit by a first time length; and / or, the turn-off moment of the second rectifier switch lags behind the turn-off moment of the second power switch of the primary conversion circuit by a first time length.

[0015] Optionally, the first duration is determined based on the output current, voltage waveform amplitude and inductance of the first inductor of the secondary side second conversion circuit.

[0016] Optionally, the first duration is obtained according to the following formula:

[0017] t1 = k*io2*L1 / (0.5*Vin);

[0018] Among them, t1 is the first time length, k is the control coefficient, io2 is the output current of the secondary side second conversion circuit, L1 is the inductance of the first inductor, and Vin is the voltage waveform amplitude of the transformer module input to the secondary side second conversion circuit.

[0019] Optionally, the primary side conversion circuit includes: the first power switch, the second power switch, the third power switch, the fourth power switch and a resonant circuit, the first end of the first power switch is connected to the first end of the second power switch and the positive pole of the DC power supply, the second end of the first power switch is connected to the first end of the third power switch and the first end of the resonant circuit, the second end of the second power switch is connected to the first end of the fourth power switch and the second end of the resonant circuit, and the second end of the third power switch is connected to the second end of the fourth power switch and the negative pole of the DC power supply.

[0020] Optionally, the charging circuit also includes a control module, which determines parameters of the first wave signal and the second wave signal based on the output voltage of the secondary side second conversion circuit and the output current of the secondary side second conversion circuit; the first wave signal is used to control the conduction or off-state of the first rectifier switch to control the conduction or off-state of the first current path, and / or the second wave signal is used to control the conduction or off-state of the second rectifier switch to control the conduction or off-state of the second current path.

[0021] Optionally, the control module determines parameters of a third wave signal, a fourth wave signal, a fifth wave signal, and a sixth wave signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit; the third wave signal is used to control the on or off of the first power switch, the fourth wave signal is used to control the on or off of the second power switch, the fifth wave signal is used to control the on or off of the third power switch, and the sixth wave signal is used to control the on or off of the fourth power switch; the parameters of the third wave signal are the same as the parameters of the sixth wave signal, and the parameters of the fourth wave signal are the same as the parameters of the fifth wave signal.

[0022] Optionally, the secondary side first conversion circuit includes: a fifth power switch, a sixth power switch, a seventh power switch and an eighth power switch, the first end of the fifth power switch is connected to the first end of the sixth power switch and the first output end of the secondary side first conversion circuit, the second end of the fifth power switch is connected to the first end of the seventh power switch, the second end of the sixth power switch is connected to the first end of the eighth power switch, and the second end of the seventh power switch is connected to the second end of the eighth power switch and the second output end of the secondary side first conversion circuit;

[0023] The control module determines parameters of a seventh transmission signal, an eighth transmission signal, a ninth transmission signal, and a tenth transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit; the seventh transmission signal is used to control the on or off of the fifth power switch, the eighth transmission signal is used to control the on or off of the sixth power switch, the ninth transmission signal is used to control the on or off of the seventh power switch, and the tenth transmission signal is used to control the on or off of the eighth power switch.

[0024] Optionally, the control module includes a first controller and a second controller;

[0025] The control module determines the parameters of the first waving signal and the second waving signal based on the output voltage of the secondary side second conversion circuit and the output current of the secondary side second conversion circuit, including:

[0026] The second controller determines the parameters of the first waving signal and the parameters of the second waving signal based on the output voltage of the secondary side second conversion circuit and the output current of the secondary side second conversion circuit;

[0027] The control module determines the parameters of the third wave transmission signal, the fourth wave transmission signal, the fifth wave transmission signal, and the sixth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit, including:

[0028] The first controller determines the parameters of the third wave transmission signal, the fourth wave transmission signal, the fifth wave transmission signal, and the sixth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit;

[0029] The control module determines the parameters of the seventh transmission signal, the eighth transmission signal, the ninth transmission signal, and the tenth transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit, including:

[0030] The first controller determines parameters of the seventh wave transmission signal, the eighth wave transmission signal, the ninth wave transmission signal, and the tenth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit.

[0031] Optionally, the first controller shares a common ground with the first conversion circuit on the secondary side, the second controller shares a common ground with the second conversion circuit on the secondary side, and the first controller and the second controller are time-synchronized via a synchronization signal.

[0032] Optionally, the inductance of the first inductor is equal to the inductance of the second inductor.

[0033] Optionally, the coupling coefficient of the coupled inductor is greater than a set threshold.

[0034] A second aspect of an embodiment of the present application provides a vehicle-mounted charging device, comprising a charging circuit as described in any one of the first aspect of an embodiment of the present application.

[0035] A third aspect of an embodiment of the present application provides a vehicle, comprising the on-board charging device described in the second aspect of an embodiment of the present application.

[0036] The charging circuit of the embodiment of the present application includes a primary side conversion circuit, a secondary side first conversion circuit, a secondary side second conversion circuit, and a transformer module connected to the above circuits; the secondary side second conversion circuit includes a rectifier module, and the secondary side second conversion circuit is configured to independently output a voltage based on the rectifier module. The secondary side second conversion circuit can independently output a voltage based on the rectifier module, so that the voltage output by the secondary side second conversion circuit is decoupled from the voltage output by the secondary side first conversion circuit, avoiding the voltage output by the secondary side second conversion circuit and the voltage output by the secondary side first conversion circuit from affecting each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] 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 those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 is a structural schematic diagram of a charging circuit provided in an embodiment of the present application;

[0039] Figure 2 is a structural schematic diagram of another charging circuit provided in an embodiment of the present application;

[0040] Figure 3a is a structural schematic diagram of another charging circuit provided in an embodiment of the present application;

[0041] Figure 3b is a structural schematic diagram of another charging circuit provided in an embodiment of the present application;

[0042] Figure 4 is a structural schematic diagram of another charging circuit provided in an embodiment of the present application;

[0043] Figure 5 is a structural schematic diagram of another charging circuit provided in an embodiment of the present application;

[0044] Figure 6 is a structural schematic diagram of another charging circuit provided in an embodiment of the present application;

[0045] Figure 7 is a schematic diagram of the structure of a coupled inductor provided in an embodiment of the present application;

[0046] Figure 8 is a schematic diagram of the control principle of a control module provided in an embodiment of the present application;

[0047] Fig. 9 is a schematic diagram of the control principle of another control module provided in an embodiment of the present application;

[0048] Fig.10 It is a timing diagram of a wave signal provided in an embodiment of the present application;

[0049] Fig.11 It is a schematic diagram of simulation waveforms of output voltage and output current of a secondary-side second conversion circuit provided in an embodiment of the present application;

[0050] Fig.12 It is a structural schematic diagram of a vehicle-mounted charging device provided in an embodiment of the present application;

[0051] Fig.13 It is a structural schematic diagram of a vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0052] 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 those skilled in the art without creative work are within the scope of protection of this application.

[0053] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, products or devices.

[0054] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0055] See also Figure 1 , Figure 1 is a schematic diagram of a charging circuit provided in an embodiment of the present application. Figure 1 As shown, the charging circuit includes a primary conversion circuit, a secondary first conversion circuit, a secondary second conversion circuit and a transformer module. The first end of the transformer module has a first winding W1, and the second end of the transformer module has a second winding W2 and a third winding W3; the first winding W1 is connected to the primary conversion circuit, the second winding W2 is connected to the secondary first conversion circuit, and the third winding W3 is connected to the secondary second conversion circuit; the secondary second conversion circuit includes a rectifier module, and the secondary second conversion circuit is configured to independently adjust the output voltage based on the rectifier module.

[0056] The output voltage of the secondary side first conversion circuit is Vo1, and the output current of the secondary side first conversion circuit is io1. The rectifier module can control the stability of the voltage output by the secondary side second conversion circuit, and can also enable the secondary side second conversion circuit to independently adjust the output voltage. The output voltage of the secondary side second conversion circuit is Vo2, and the output current of the secondary side second conversion circuit is io2.

[0057] In an embodiment of the present application, the secondary side first conversion circuit and the secondary side second conversion circuit share a transformer module. The secondary side first conversion circuit can supply power to load 1, for example, the secondary side first conversion circuit can output a high voltage to charge the vehicle's power battery (for example, a 400V power battery). The secondary side second conversion circuit can supply power to load 2, for example, the secondary side second conversion circuit can output a low voltage to supply power to the vehicle's battery (for example, a 14V battery) and a low-voltage load (for example, a load less than or equal to 14V). The primary side conversion circuit, the transformer module and the secondary side first conversion circuit can form an on-board charger (OBC); the primary side conversion circuit, the transformer module and the secondary side second conversion circuit can form a direct current / direct current (DC / DC) converter. The charging circuit can integrate the on-board charger (OBC) and the direct current / direct current (DC / DC) converter, and the two share a transformer module, thereby reducing the number of transformer modules and reducing the volume and cost of the circuit.

[0058] For example, Figure 1 As shown, the load 1 connected between the positive and negative electrodes of the output terminal of the secondary side second conversion circuit can be a power battery. The load 2 connected between the first output terminal and the second output terminal of the secondary side second conversion circuit can be a storage battery. Figure 1 As shown, the first output end of the secondary side second conversion circuit is a positive output end, and the second output end of the secondary side second conversion circuit is a negative output end.

[0059] In a possible embodiment, the first output terminal of the secondary-side second conversion circuit may be a negative output terminal, and the second output terminal of the secondary-side second conversion circuit may be a positive output terminal.

[0060] The load 1 connected between the positive and negative electrodes of the output end of the secondary side second conversion circuit may be a power battery.

[0061] The load 2 connected between the first output terminal and the second output terminal of the secondary side second conversion circuit may be at least one of a storage battery and an electrical device.

[0062] The output port of the secondary side first conversion circuit is a high voltage port, which can charge the high voltage battery (e.g., power battery) of the vehicle. The output port of the secondary side second conversion circuit is a low voltage port, which can power the low voltage battery (e.g., storage battery) and electrical equipment (e.g., air conditioner, lighting, audio-visual equipment, wiper, etc.) of the vehicle.

[0063] In an embodiment of the present application, the second conversion circuit on the secondary side can independently output a voltage based on the rectifier module, thereby decoupling the voltage output by the second conversion circuit on the secondary side from the voltage output by the first conversion circuit on the secondary side, thereby avoiding mutual influence between the voltage output by the second conversion circuit on the secondary side and the voltage output by the first conversion circuit on the secondary side.

[0064] like Figure 1 As shown, the transformer module includes a first winding W1, a second winding W2 and a third winding W3; the primary conversion circuit is connected to the first winding W1, the secondary first conversion circuit is connected to the second winding W2, and the secondary second conversion circuit is connected to the third winding W3.

[0065] See also Figure 2 , Figure 2 is a schematic diagram of another charging circuit provided in an embodiment of the present application. Figure 2 As shown, in Figure 1 On the basis of Figure 2 The secondary side second conversion circuit also includes an energy storage module connected to the rectification module, and the energy storage module and the rectification module cooperate to adjust the output voltage of the secondary side second conversion circuit.

[0066] In the embodiment of the present application, the energy storage module can play the role of energy storage, which can avoid drastic changes in the output current and output voltage of the secondary side second conversion circuit, thereby stabilizing the output current and output voltage of the secondary side second conversion circuit.

[0067] Optional, such as Figure 2 As shown, the energy storage module includes a coupled inductor, which includes a first coil N1 and a second coil N2. The first rectifier switch SR1 is connected to one end of the third winding W3 through the first coil N1, and the second rectifier switch SR2 is connected to the other end of the third winding W3 through the second coil N2.

[0068] In the embodiment of the present application, the coupled inductor can increase the output inductance of the second conversion circuit on the secondary side and reduce the ripple of the output current io2 of the second conversion circuit on the secondary side.

[0069] See also Figure 3a , Figure 3a It is a structural schematic diagram of another charging circuit provided in an embodiment of the present application. Figure 3a is Figure 2 Based on Figure 2 On the basis of Figure 3a The energy storage module further includes a first inductor L1 and a second inductor L2, the first coil N1 is connected to one end of the third winding W3 via the first inductor L1, and the second coil N2 is connected to the other end of the third winding W3 via the second inductor L2.

[0070] Optionally, the rectifier module includes a first rectifier unit and a second rectifier unit.

[0071] The first rectifier unit includes a first rectifier switch, and the second rectifier unit includes a second rectifier switch; or, the first rectifier unit includes at least two first rectifier switches connected in parallel, and the second rectifier unit includes at least two second rectifier switches connected in parallel; one end of the first rectifier switch and the second rectifier switch are connected to each other, and the other end is respectively connected to the energy storage module.

[0072] For example, Figure 3a As shown, the rectifier module includes a first rectifier switch SR1 and a second rectifier switch SR2. Each rectifier unit includes a rectifier switch, which can reduce the volume of the rectifier module and further reduce the volume of the secondary side second conversion circuit.

[0073] For example, Figure 3b As shown, the rectifier module includes a first rectifier unit and a second rectifier unit, the first rectifier unit includes three first rectifier switches connected in parallel, and the second rectifier unit includes three second rectifier switches connected in parallel. The rectifier unit includes at least two rectifier switches connected in parallel, which can reduce the current passing through each rectifier switch, and can use a rectifier switch with a lower current resistance, thereby reducing the cost of the rectifier switch. When one of the at least two rectifier switches connected in parallel is damaged, the other rectifier switches can continue to work, thereby improving the redundancy of the secondary side second conversion circuit. Each rectifier switch can independently control the fluctuation of the current outputted by it. By controlling the fluctuation of the output current of the secondary side second conversion circuit through at least two rectifier switches connected in parallel, the fluctuation of the output current of the secondary side second conversion circuit can be further reduced, thereby improving the rectification effect of the rectifier unit.

[0074] Optionally, the duty cycle of the first rectifier switch SR1 and the second rectifier switch SR2 are both greater than 50%.

[0075] In the embodiment of the present application, the duty cycle of the first rectifier switch SR1 and the second rectifier switch SR2 are both greater than 50%, so that the first rectifier switch SR1 and the second rectifier switch SR2 are turned on at the same time, which can reduce the fluctuation of the output current of the second conversion circuit on the secondary side. Figure 2 or Figure 3aFor example, when the first rectifier switch SR1 is switched on to the second rectifier switch SR2 is switched on, if at a certain moment the first rectifier switch SR1 is switched from on to off, and the second rectifier switch SR2 is switched from off to on, at this time the current on the first rectifier switch SR1 drops rapidly to 0, while the current on the second rectifier switch SR2 rises slowly, which will cause the output current io2 of the secondary side second conversion circuit to suddenly drop rapidly. In order to avoid a sudden change in the output current io2 of the secondary side second conversion circuit, there will be a period of time when there is current on both the first rectifier switch SR1 and the second rectifier switch SR2, and this period of time is called the commutation time.

[0076] The duty cycle of a switch refers to the ratio of the on-time of the switch to the switching cycle in a switching cycle. For example, the duty cycle of the first rectifier switch SR1 refers to the ratio of the on-time of the first rectifier switch SR1 to the switching cycle in a switching cycle. The duty cycle of the second rectifier switch SR2 refers to the ratio of the on-time of the second rectifier switch SR2 to the switching cycle in a switching cycle.

[0077] Optionally, the duty cycle of the first rectifier switch SR1 and the second rectifier switch SR2 are both greater than the duty cycle of the switch of the primary conversion circuit.

[0078] In the embodiment of the present application, the duty cycle of the first rectifier switch SR1 is greater than the duty cycle of the switch of the primary conversion circuit, and the on-time of the first rectifier switch SR1 in each cycle is greater than the on-time of the switch of the primary conversion circuit. After the switch of the primary conversion circuit is turned off, the first rectifier switch SR1 is still turned on. Although the current on the first rectifier switch SR1 has begun to decrease, the current on the first rectifier switch SR1 will not pass through the body diode of the first rectifier switch SR1, thereby not damaging the body diode of the first rectifier switch SR1. In addition, the current loss on the first rectifier switch is lower than the current loss of the body diode. The duty cycle of the first rectifier switch SR1 is greater than the duty cycle of the switch of the primary conversion circuit, which can also reduce the current loss.

[0079] Optionally, the energy storage module can also be two independent inductors. Figure 4 As shown, the energy storage module includes a first inductor L1 and a second inductor L2; the first rectifier switch SR1 is connected to one end of the third winding W3 through the first inductor L1, and the second rectifier switch SR2 is connected to the other end of the third winding W3 through the second inductor L2.

[0080] The first inductor L1 and the second inductor L2 of the embodiment of the present application can prevent the current from dropping too fast at the commutation time to cause a turn-off voltage spike. The commutation time refers to the time when the first rectifier switch SR1 and the second rectifier switch SR2 are both turned on and only one rectifier switch is turned on.

[0081] In addition, the energy storage module can also be integrated with the transformer module into a magnetic device, or some devices in the transformer module can be reused.

[0082] Optionally, within at least one switching cycle, the turn-off moment of the first rectifier switch lags behind the turn-off moment of the first power switch of the primary conversion circuit by a first time length; and / or, the turn-off moment of the second rectifier switch lags behind the turn-off moment of the second power switch of the primary conversion circuit by a first time length.

[0083] In the embodiment of the present application, the first rectifier switch SR1 is set to be turned off at a time lag behind the first power switch of the primary conversion circuit by a first time length, which can reduce losses. After the first rectifier switch SR1 is turned off, the current on the body diode of the first rectifier switch SR1 begins to decrease. If the turn-off time of the first rectifier switch SR1 is the same as the turn-off time of the first power switch, after the first rectifier switch SR1 is turned off, the body diode of the first rectifier switch SR1 is turned on. Since the conduction damage of the diode is greater than the conduction damage of the first rectifier switch SR1, the energy conversion efficiency is low.

[0084] Optional, such as Figure 5 As shown, the primary side conversion circuit includes: the first power switch Q1, the second power switch Q2, the third power switch Q3, the fourth power switch Q4 and a resonant circuit, wherein the first end of the first power switch Q1 is connected to the first end of the second power switch Q2 and the positive electrode of the DC power supply, the second end of the first power switch Q1 is connected to the first end of the third power switch Q3 and the first end of the resonant circuit, the second end of the second power switch Q2 is connected to the first end of the fourth power switch Q4 and the second end of the resonant circuit, and the second end of the third power switch Q3 is connected to the second end of the fourth power switch Q4 and the negative electrode of the DC power supply.

[0085] In the embodiment of the present application, the DC power supply, the primary side conversion circuit, the transformer module, and the secondary side first conversion circuit can constitute a vehicle charger. The DC power supply can be a pre-stage power factor correction (PFC) conversion circuit connected to the primary side conversion circuit. The secondary side first conversion circuit can be used to charge the vehicle's power battery, and the secondary side second conversion circuit can be used to supply power to other electrical appliances in the vehicle.

[0086] In the embodiment of the present application, the primary side conversion circuit includes two groups of power switch combinations, the first group of power switch combinations includes the first power switch Q1 and the fourth power switch Q4, and the second group of power switch combinations includes the second power switch Q2 and the third power switch Q3. The on-off actions of the two groups of power switch combinations are opposite.

[0087] The first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4 may be any one of a metal-oxide-semiconductor field-effect transistor (MOSFET) and an insulated-gate bipolar transistor (IGBT). For example, the first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4 may be an N-type metal-oxide-semiconductor field-effect transistor (NMOS for short).

[0088] The resonant circuit may include Figure 5 The resonant inductor L0, resonant capacitor C0 and excitation inductor L m .

[0089] Figure 5 In the embodiment, a second capacitor C2 can be added between the positive and negative electrodes of the load 1 of the secondary side first conversion circuit, and the load 2 of the secondary side second conversion circuit ( Figure 5 A first capacitor C1 can be added between the positive and negative electrodes of the load 2 (for example, a battery). The first capacitor C1 and the second capacitor C2 are both filter capacitors, which can be used to ensure the stability of the output voltage Vo2 of the secondary side second conversion circuit and the stability of the output voltage Vo1 of the secondary side first conversion circuit, respectively.

[0090] Optionally, the first duration is determined based on the output current, voltage waveform amplitude and inductance of the first inductor of the secondary side second conversion circuit.

[0091] In the embodiment of the present application, the first duration is positively correlated with the output current of the second conversion circuit on the secondary side, positively correlated with the inductance of the first inductor, and negatively correlated with the voltage waveform amplitude.

[0092] Optionally, the first duration is obtained according to the following formula:

[0093] t1 = k*io2*L1 / (0.5*Vin);

[0094] Among them, t1 is the first time length, k is the control coefficient, io2 is the output current of the secondary side second conversion circuit, L1 is the inductance of the first inductor, and Vin is the voltage waveform amplitude of the transformer module input to the secondary side second conversion circuit.

[0095] Among them, the value of k is between 0 and 1. The closer k is to 1, the smaller the turn-off current is, which is beneficial to reduce the turn-off loss, but it will increase the risk of voltage spikes. K can be reasonably determined according to actual conditions.

[0096] The above formula is essentially a calculation of the current drop rate. The larger the output current io2 of the secondary side second conversion circuit is, the larger the first time duration t1 can be set. The output current io2 of the secondary side second conversion circuit drops from a larger current, and the time for the output current io2 of the secondary side second conversion circuit to drop from a large current to 0 will be longer, so the first time duration t1 can be set longer. Vin is the rated amplitude of the square wave on W31 or W32. The larger the Vin is set, the faster the output current io2 of the secondary side second conversion circuit drops. Figure 5 As shown, W31 is a partial winding between the first end of the third winding W3 and the middle tap of the third winding W3, which can be understood as the upper half of the third winding W3. W32 is a partial winding between the second end of the third winding W3 and the middle tap of the third winding W3, which can be understood as the lower half of the third winding W3. The number of turns of W31 is the same as the number of turns of W32, and the square wave rated amplitude on W31 is the same as the square wave rated amplitude on W32.

[0097] It should be noted that the above formula is a possible calculation method of t1 provided in the embodiment of the present application. The calculation method of t1 is not unique.

[0098] See also Figure 6 , Figure 6 It is a structural schematic diagram of another charging circuit provided in an embodiment of the present application. Figure 6 exist Figure 5 The charging circuit further includes a control module, which determines the parameters of the first wave signal and the second wave signal based on the output voltage Vo2 of the secondary side second conversion circuit and the output current io2 of the secondary side second conversion circuit; the first wave signal is used to control the conduction or disconnection of the first rectifier switch SR1 to control the conduction or disconnection of the first current path, and the second wave signal is used to control the conduction or disconnection of the second rectifier switch SR2 to control the conduction or disconnection of the second current path.

[0099] Among them, the first current path includes the first end of the third winding W3, the first inductor L1, the first coil N1 of the coupled inductor, the first rectifier switch SR1 and the first output end of the secondary second conversion circuit; the second current path includes the second end of the third winding W3, the second inductor L2, the second coil N2 of the coupled inductor, the second rectifier switch SR2 and the first output end of the secondary second conversion circuit; the middle tap of the third winding W3 is connected to the second output end of the secondary second conversion circuit.

[0100] The control module determines the parameters of the first wave signal and the second wave signal based on the output voltage Vo2 of the secondary side second conversion circuit and the output current io2 of the secondary side second conversion circuit; the first wave signal is used to control the conduction or cutoff of the first rectifier switch SR1 to control the conduction or cutoff of the first current path, and the second wave signal is used to control the conduction or cutoff of the second rectifier switch SR2 to control the conduction or cutoff of the second current path.

[0101] The waving signal may be a pulse width modulation (PWM) signal, and the parameter of the waving signal may be at least one of the frequency and duty cycle of the PWM signal. Exemplarily, the parameter of the first waving signal may include the frequency and duty cycle of the first waving signal. The parameter of the second waving signal may include the frequency and duty cycle of the second waving signal.

[0102] Figure 6 In the embodiment, the first end of the third winding W3 is connected to the first end of the first inductor L1, the second end of the first inductor L1 is connected to the first end of the first coil N1 of the coupling inductor, the second end of the first coil N1 of the coupling inductor is connected to the first end of the first rectifier switch SR1, and the second end of the first rectifier switch SR1 is connected to the first output end of the secondary side second conversion circuit; the second end of the third winding W3 is connected to the first end of the second inductor L2, the second end of the second inductor L2 is connected to the first end of the second coil N2 of the coupling inductor, the second end of the second coil N2 of the coupling inductor is connected to the first end of the second rectifier switch SR2, and the second end of the second rectifier switch SR2 is connected to the first output end of the secondary side second conversion circuit.

[0103] Theoretically, when the rectifier module is working normally, the first rectifier switch SR1 and the second rectifier switch SR2 are alternately turned on. When the first rectifier switch SR1 is turned on, the second rectifier switch SR2 is turned off. At this time, there is current in the first current path, and there is no current in the second current path; when the second rectifier switch SR2 is turned on, the first rectifier switch SR1 is turned off. At this time, there is current in the second current path, and there is no current in the first current path. In actual work, when the first rectifier switch SR1 is switched to the second rectifier switch SR2, in order to avoid a sudden change in the output current io2 of the second conversion circuit on the secondary side, there will be a period of time when both current paths (the first current path and the second current path) have current. The time from the moment when both current paths have current to the moment when only one current path has current is called the commutation time. The commutation time is generally short. For example, the period of time when the current of the first current path decreases and the current of the second current path increases is the commutation time. During the commutation time, there is current in both the first rectifier switch SR1 and the second rectifier switch SR2.

[0104] The first inductor L1 and the second inductor L2 of the embodiment of the present application can prevent the current from dropping too fast at the commutation time and causing a turn-off voltage spike. The commutation time refers to the moment when the first rectifier switch SR1 and the second rectifier switch SR2 are both turned on and switched to the moment when only one rectifier power switch is turned on; or refers to the moment when there is current in both current paths and there is current in only one current path. Exemplarily, during the commutation time, if the current on the first current path rises and the current on the second current path drops, under normal circumstances, if the second rectifier switch SR2 is turned off in time, the second current path will be disconnected before the current on the second current path becomes a negative current, and the current on the second current path will not become a negative current. During commutation, if the current on the second current path drops very quickly, and the second rectifier switch SR2 is turned off after the current on the second current path becomes a negative current, the energy of the negative current in the second current path will become a large turn-off voltage spike, which is loaded on the second rectifier switch SR2 and may break down the second rectifier switch SR2. If the current in the second current path is a forward current (the direction of the current is the same as the conduction direction of the body diode of the second rectifier switch SR2 ) when the second rectifier switch SR2 is turned off, no turn-off voltage spike will be generated.

[0105] The embodiment of the present application increases the first inductor L1 and the second inductor L2, so as to reduce the falling speed of the current in the first current path or the second current path during the commutation time, thereby avoiding turning off the first rectifier switch SR1 after the current in the first current path becomes negative current or turning off the second rectifier switch SR2 after the current in the second current path becomes negative current, thereby avoiding the occurrence of a turn-off voltage spike and improving the safety of the circuit.

[0106] The first inductor L1 can limit the speed of change of the current flowing through the first inductor L1. At the commutation moment when switching from the first current path to the second current path, the current drop speed on the first current path at the commutation moment can be limited, thereby avoiding the generation of a turn-off voltage spike when the first rectifier switch SR1 is turned off. The second inductor L2 can limit the speed of change of the current flowing through the second inductor L2. At the commutation moment when switching from the second current path to the first current path, the current drop speed on the second current path at the commutation moment can be limited, thereby avoiding the generation of a turn-off voltage spike when the second rectifier switch SR2 is turned off.

[0107] The inductance values ​​(inductance) of the first inductor L1 and the second inductor L2 can be designed as required. The larger the inductance value, the slower the rising speed and falling speed of the current flowing through the inductor.

[0108] Optionally, the inductance of the first inductor L1 is equal to the inductance of the second inductor L2.

[0109] In the embodiment of the present application, the inductance of L1 and L2 is made equal. The inductance determines the speed at which the current rises and falls during the commutation time. The larger the inductance of the inductor, the slower it rises. If the inductance of L1 and L2 is very different, the speed at which the current rises and falls in the two current paths is inconsistent, and voltage spikes may be generated. Setting the inductance of the first inductor L1 to be equal to the inductance of the second inductor L2 can make the rising speed of the current in the first current path as close as possible to the rising speed of the current in the second current path, and make the falling speed of the current in the first current path as close as possible to the falling speed of the current in the second current path, thereby avoiding the generation of a turn-off voltage spike at the commutation moment.

[0110] The parameters of the first waving signal may include the frequency and duty cycle of the first waving signal. Similarly, the parameters of the second waving signal may include the frequency and duty cycle of the second waving signal. Both the first waving signal and the second waving signal may be PWM signals.

[0111] The control module determines the parameters of the first wave signal and the second wave signal based on the output voltage Vo2 of the secondary side second conversion circuit and the output current io2 of the secondary side second conversion circuit; the first wave signal is used to control the on or off of the first rectifier switch SR1 to control the on or off of the first current path, and the second wave signal is used to control the on or off of the second rectifier switch SR2 to control the on or off of the second current path. Exemplarily, during the high level period of the first wave signal, the first rectifier switch SR1 is turned on, and during the low level period of the first wave signal, the first rectifier switch SR1 is turned off. During the high level period of the second wave signal, the second rectifier switch SR2 is turned on, and during the low level period of the second wave signal, the second rectifier switch SR2 is turned off.

[0112] The first rectifier switch SR1 and the second rectifier switch SR2 may be any one of a metal-oxide-semiconductor field-effect transistor (MOSFET) and an insulated-gate bipolar transistor (IGBT). For example, the first rectifier switch SR1 and the second rectifier switch SR2 may be N-type metal-oxide-semiconductor field-effect transistor (NMOS for short).

[0113] The charging circuit of the embodiment of the present application does not need to add a voltage regulating circuit behind the rectifier module, nor does it need to detect the primary current zero-crossing detection signal. The control module can determine the parameters of the first wave signal and the second wave signal based on the output voltage Vo2 of the secondary side second conversion circuit and the output current io2 of the secondary side second conversion circuit, thereby realizing the control of the first rectifier switch SR1 and the second rectifier switch SR2, which can reduce the cost and control logic of the charging circuit.

[0114] When the first current path is turned on and the second current path is turned off, there is current in the partial winding between the first end of the third winding W3 and the middle tap of the third winding W3, while there is no current in the partial winding between the second end of the third winding W3 and the middle tap of the third winding W3.

[0115] When the second current path is turned on and the first current path is turned off, there is current in the partial winding between the second end of the third winding W3 and the middle tap of the third winding W3, while there is no current in the partial winding between the first end of the third winding W3 and the middle tap of the third winding W3.

[0116] In the embodiment of the present application, the coupled inductor can increase the output inductance after the commutation is completed, and slow down the output current io2 ripple of the second conversion circuit on the secondary side. During the commutation time, the coupled inductor is equivalent to a short circuit. After the commutation is completed, there is only one current path with current. At this time, the coupled inductor can play a role in slowing down the output current io2 ripple of the second conversion circuit on the secondary side. For example, only the current path of the first inductor L1 (i.e., the first current path) is working, and the actual inductance of the first current path is: the inductance of the first inductor L1 + the inductance of the coupled inductor. The inductance of the first current path becomes larger, and the current change speed on the first current path becomes slower, then the current ripple becomes smaller, so that the output current io2 of the second conversion circuit on the secondary side will not fluctuate greatly (for example, there will be no huge triangular wave current).

[0117] The coupled inductor may be a forward coupled inductor.

[0118] See also Figure 7 , Figure 7 Schematic diagram of a coupled inductor structure provided in an embodiment of the present application. Figure 7 As shown, the coupled inductor includes a magnetic core, a first coil N1 and a second coil N2 wound around the magnetic core. Figure 7 A winding method of a coupled inductor is shown, the shape of the magnetic core is in the positive direction, and the first coil N1 and the second coil N2 are respectively wound on both sides of the magnetic core. The number of turns of the first coil N1 and the second coil N2 can be the same.

[0119] Optionally, the coupling coefficient of the coupled inductor is greater than a set threshold.

[0120] The leakage inductance of a coupled inductor refers to the inductance that does not produce coupling in the coupled inductor, and the magnetic flux generated by the current flowing through one inductor (for example, the first coil or the second coil) is ignored by the other inductor (for example, the second coil or the first coil). The leakage inductance of a coupled inductor means that when there is coupling between two inductors, the current flowing through one inductor is not completely coupled when passing through the other inductor. This part of the inductance has an important influence on the performance of the coupled circuit. Usually, in an ideal state, the two inductors are completely coupled and the leakage inductance is zero. But in reality, leakage inductance is inevitable due to various reasons. Leakage inductance will cause the circuit gain to become low.

[0121] A part of the magnetic flux generated by the first coil N1 is used to verify the second coil N2 (i.e., a part is coupled by the second coil N2), and another part is not used to verify the second coil N2 (i.e., the other part is not coupled by the second coil N2), and the other part is the leakage inductance.

[0122] The threshold value may be set in advance. The threshold value is a positive number less than 1. For example, the threshold value may be set to 98%.

[0123] The shape of the magnetic core is not limited and can be any of rectangular, square, circular, polygonal, special-shaped, and irregular shapes.

[0124] The coupling coefficient can be set according to the needs of the actual scene. If the coupling coefficient is lower, the circuit gain will be lower. In some scenarios where high circuit gain is not required, a coupled inductor with a relatively low coupling coefficient can be used.

[0125] Figure 4 When coupling inductance is not included, Figure 4 The secondary side second conversion circuit is suitable for low power and low current scenarios. For example, the power demand of the load 2 at the output end of the secondary side second conversion circuit is less than 100 watts (W). Exemplarily, the output end of the secondary side second conversion circuit is connected to a mobile phone charger. Since the output current io2 of the secondary side second conversion circuit is low, there is no need to add a coupling inductor, and low power loads can also be powered.

[0126] Figure 2 , Figure 3a , Figure 3b , Figure 5 and Figure 6 The secondary side second conversion circuit including the coupled inductor is suitable for high power and high current scenarios. For example, if the power demand of the load 2 at the output end of the secondary side second conversion circuit exceeds 1000 watts, it is necessary to add the coupled inductor. For example, the load 2 can be a battery in the car, an electrical device, etc.

[0127] Optional, such as Figure 6 As shown, the control module determines the parameters of the third wave signal, the fourth wave signal, the fifth wave signal, and the sixth wave signal based on the output voltage Vo1 of the secondary side first conversion circuit and the output current io1 of the secondary side first conversion circuit; the third wave signal is used to control the on or off of the first power switch, the fourth wave signal is used to control the on or off of the second power switch, the fifth wave signal is used to control the on or off of the third power switch, and the sixth wave signal is used to control the on or off of the fourth power switch; the parameters of the third wave signal are the same as the parameters of the sixth wave signal, and the parameters of the fourth wave signal are the same as the parameters of the fifth wave signal.

[0128] Among them, the first wave signal has the same frequency as the third wave signal, and the second wave signal has the same frequency as the fourth wave signal; the turn-off time of the first wave signal lags behind the turn-off time of the third wave signal by a first time length, and the turn-off time of the second wave signal lags behind the turn-off time of the fourth wave signal by the first time length.

[0129] In the embodiment of the present application, the turn-off time of the first wave signal lags behind the turn-off time of the third wave signal by the first time length, and the turn-off time of the second wave signal lags behind the turn-off time of the fourth wave signal by the first time length. Losses can be reduced. After the first rectifier switch SR1 is turned off, the current on the first current path begins to decrease. If the turn-off time of the first wave signal is the same as the turn-off time of the third wave signal, after the first rectifier switch SR1 is turned off, the current on the first current path will pass through the body diode of the first rectifier switch SR1. Since the conduction damage of the diode is greater than the conduction damage of the first rectifier switch SR1, the energy conversion efficiency is low. The turn-off time of the first wave signal is set to lag behind the turn-off time of the third wave signal by the first time length, and the first time length is less than or equal to the time length required for the current on the first current path to decrease from the beginning to 0, and the first time length is less than or equal to the time length required for the current on the second current path to decrease from the beginning to 0.

[0130] The first duration can be adjusted in real time. The size of the first duration can be set. If the first duration is set too large, for example, the first duration is greater than the time required for the current in the first current path to decrease from the beginning to zero, when the first current switch is turned off, the current in the first current path becomes negative, and a voltage spike will appear.

[0131] Optionally, the first duration is obtained according to the following formula:

[0132] t1 = k*io2*L1 / (0.5*Vin);

[0133] Wherein, t1 is the first duration, k is the control coefficient, io2 is the output current io2 of the second conversion circuit on the secondary side, L1 is the inductance of the first inductor L1, and Vin is the waveform amplitude between the first end of the third winding W3 and the middle tap of the third winding W3 ( Figure 6 The square wave rated amplitude on W31 is shown in Figure 1. Figure 6 The square wave rated amplitude on W31 is the same as the square wave rated amplitude on W32 (the waveform amplitude between the second end of the third winding W3 and the center tap of the third winding W3).

[0134] Optional, such as Figure 5 or Figure 6As shown, the secondary side first conversion circuit includes: a fifth power switch Q5, a sixth power switch Q6, a seventh power switch Q7 and an eighth power switch Q8, the first end of the fifth power switch Q5 is connected to the first end of the sixth power switch Q6 and the first output end of the secondary side first conversion circuit, the second end of the fifth power switch Q5 is connected to the first end of the seventh power switch Q7 and the first end of the second winding W2, the second end of the sixth power switch Q6 is connected to the first end of the eighth power switch Q8 and the second end of the second winding W2, and the second end of the seventh power switch Q7 is connected to the second end of the eighth power switch Q8 and the second output end of the secondary side first conversion circuit.

[0135] The fifth power switch Q5, the sixth power switch Q6, the seventh power switch Q7 and the eighth power switch Q8 may be any one of a metal oxide semiconductor field effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) and an insulated gate bipolar transistor (Insulate-Gate Bipolar Transistor, IGBT). For example, the fifth power switch Q5, the sixth power switch Q6, the seventh power switch Q7 and the eighth power switch Q8 may all be N-type metal oxide semiconductor field effect transistors (abbreviated as: NMOS).

[0136] The control module determines parameters of the seventh transmission signal, the eighth transmission signal, the ninth transmission signal, and the tenth transmission signal based on the output voltage Vo1 of the secondary side first conversion circuit and the output current io1 of the secondary side first conversion circuit; the seventh transmission signal is used to control the conduction or shutoff of the fifth power switch, the eighth transmission signal is used to control the conduction or shutoff of the sixth power switch, the ninth transmission signal is used to control the conduction or shutoff of the seventh power switch, and the tenth transmission signal is used to control the conduction or shutoff of the eighth power switch.

[0137] See also Figure 8 , Figure 8 Schematic diagram of the control principle of a control module provided in an embodiment of the present application. Figure 8 As shown, the control module includes two proportional integral (PI) controllers (a first PI controller and a second PI controller) and a pulse width modulation (PWM) module. It should be noted that: Figure 8The PI controller can be replaced by a proportional integral differentiation (PID) controller or a proportional differentiation (PD) controller. The PI controller includes a voltage loop and a current loop. The PWM module is used to generate a PWM signal (a PWM signal is a wave signal). Figure 8 The PWM module can be used to generate a first wave signal, a second wave signal, a third wave signal, a fourth wave signal, a fifth wave signal, a sixth wave signal, a seventh wave signal, an eighth wave signal, a ninth wave signal, and a tenth wave signal, which are respectively used to control the first rectifier switch SR1, the second rectifier switch SR2, the first power switch Q1, the second power switch Q2, the third power switch Q3, the fourth power switch Q4, the fifth power switch Q5, the sixth power switch Q6, the seventh power switch Q7, and the eighth power switch Q8.

[0138] The control module performs a difference operation on the collected output voltage Vo1 of the secondary side first conversion circuit and the Vo1 reference voltage, obtains the difference between the two, and then performs loop compensation on the difference through the control algorithm of the first PI controller (which can be a PI control algorithm), performs a subtraction operation on the obtained compensation value and the io1 reference value preset in the current loop, and uses the smaller of the compensation value and the io1 reference value as the current loop reference value Iref1; performs a difference operation (using Iref1-io1) on the collected output current io1 of the secondary side first conversion circuit and the current loop reference value Iref1, obtains the difference between the two, and then performs loop compensation on the difference to obtain the switching frequency fs of the primary power switch (the first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4) (loop compensation can be performed on the first power switch Q1-fourth power switch Q4). The switching frequency of the power switch Q4 is adjusted, or the duty cycle of the first power switch Q1 to the fourth power switch Q4 is adjusted; or both the switching frequency of the first power switch Q1 to the fourth power switch Q4 is adjusted, and the duty cycle of the first power switch Q1 to the fourth power switch Q4 is adjusted) and the switching frequency fs of the power switches (fifth power switch Q5, sixth power switch Q6, seventh power switch Q7 and eighth power switch Q8) in the secondary side first conversion circuit (loop compensation can be performed to adjust the switching frequency of the fifth power switch Q5 to the eighth power switch Q8, or the duty cycle of the fifth power switch Q5 to the eighth power switch Q8; or both the switching frequency of the fifth power switch Q5 to the eighth power switch Q8 is adjusted, and the duty cycle of the fifth power switch Q5 to the eighth power switch Q8 is adjusted). The first group of power switches (the first power switch Q1 and the fourth power switch Q4) and the second group of power switches (the second power switch Q2 and the third power switch Q3) have opposite on-off actions; at the same time, the control module performs a difference operation on the collected output voltage Vo2 of the secondary side second conversion circuit and the Vo2 reference voltage, and after obtaining the difference between the two, loop compensation is performed on the difference through the control algorithm of the second PI controller (which can be a PI control algorithm), and the obtained compensation value is subtracted from the preset io2 reference value of the current loop, and the smaller of the compensation value and the current loop preset value is used as the current loop reference value Iref2; the collected output current io2 of the secondary side second conversion circuit is performed a difference operation (using Iref2-io2) with the voltage loop reference value Iref2, and after obtaining the difference between the two, the difference is loop compensated to obtain the duty cycle D of the first rectifier switch SR1 and the second rectifier switch SR2.

[0139] The duty ratios of the primary power switches (the first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4) can be set as needed. For example, the duty ratios of the first power switch Q1 to the fourth power switch Q4 are consistent, approximately 0.5.

[0140] By performing a smaller operation between the obtained compensation value and the io1 reference value preset in the current loop, the output current io1 of the first conversion circuit on the secondary side can be prevented from exceeding the io1 reference value, thereby improving the output stability of the first conversion circuit on the secondary side. Exemplarily, if the output of the voltage loop is very high, the compensation value for loop compensation based on the difference between the output voltage Vo1 of the first conversion circuit and the Vo1 reference voltage is relatively large, and the current loop has a limit on the current (for example, the io1 reference value preset in the current loop is 10A), and the compensation value is greater than the io1 reference value preset in the current loop. If the larger of the two is taken, the compensation value is used as the current loop reference value Iref1. Although the output requirement of the voltage loop can be met, the current of the current loop will be greater than 10A, which may cause the current to rise rapidly.

[0141] It should be noted that the first transmission signal has the same frequency as the third transmission signal, and the second transmission signal has the same frequency as the fourth transmission signal. When the switching frequencies of the primary power switches (the first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4) are the same, the switching frequencies of the first rectifier switch SR1, the second rectifier switch SR2, and the primary power switches (the first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4) are consistent. If the frequency of the primary power switch is adjusted, the frequencies of the first rectifier switch SR1 and the second rectifier switch SR2 must also be adjusted synchronously.

[0142] Generally speaking, the ground signal of the secondary first conversion circuit is different from the ground signal of the secondary second conversion circuit. The ground signal of the control module can be the same as the ground signal of the secondary first conversion circuit or the same as the ground signal of the secondary second conversion circuit. Figure 8 As shown, the ground signal of the first conversion circuit on the secondary side is GND1, and the ground signal of the second conversion circuit on the secondary side is GND2, that is, the ground signal of the voltage signal Vo1 is GND1, and the ground signal of the voltage signal Vo2 is GND2. If the ground signal of the control module is GND1, in order to avoid the inaccuracy of the voltage signal Vo2 collected by the control module due to the difference between the ground signal of the control module and the ground signal of the second conversion circuit on the secondary side, it is necessary to add an isolation module between the collected voltage signal Vo2 and the control module. Figure 8As shown, the voltage signal Vo1 reaches the control module after passing through the first sampling circuit and the first amplifier, and the voltage signal Vo2 reaches the control module after passing through the second sampling circuit, the isolation module (eg, isolation chip), and the second amplifier.

[0143] Optionally, the control module includes a first controller and a second controller;

[0144] The control module determines the parameters of the first waving signal and the second waving signal based on the output voltage of the secondary side second conversion circuit and the output current of the secondary side second conversion circuit, including:

[0145] The second controller determines the parameters of the first waving signal and the parameters of the second waving signal based on the output voltage of the secondary side second conversion circuit and the output current of the secondary side second conversion circuit;

[0146] The control module determines the parameters of the third wave transmission signal, the fourth wave transmission signal, the fifth wave transmission signal, and the sixth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit, including:

[0147] The first controller determines the parameters of the third wave transmission signal, the fourth wave transmission signal, the fifth wave transmission signal, and the sixth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit;

[0148] The control module determines the parameters of the seventh transmission signal, the eighth transmission signal, the ninth transmission signal, and the tenth transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit, including:

[0149] The first controller determines parameters of the seventh wave transmission signal, the eighth wave transmission signal, the ninth wave transmission signal, and the tenth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit.

[0150] See also Fig. 9 , Fig. 9 Schematic diagram of the control principle of another control module provided in the embodiment of the present application. Fig. 9As shown, the control module includes a first controller and a second controller. The first controller can determine the parameters of the third wave signal, the fourth wave signal, the fifth wave signal, the sixth wave signal, the seventh wave signal, the eighth wave signal, the ninth wave signal, and the tenth wave signal based on the output voltage Vo1 of the secondary side first conversion circuit and the output current io1 of the secondary side first conversion circuit, which are respectively used for the first power switch Q1, the second power switch Q2, the third power switch Q3, the fourth power switch Q4, the fifth power switch Q5, the sixth power switch Q6, the seventh power switch Q7, and the eighth power switch Q8.

[0151] The second controller can determine the parameters of the first wave transmission signal and the parameters of the second wave transmission signal based on the output voltage Vo2 of the secondary side second conversion circuit and the output current io2 of the secondary side second conversion circuit. The parameters of the first wave transmission signal and the parameters of the second wave transmission signal are used to control the first rectifier switch SR1 and the second rectifier switch SR2 respectively.

[0152] Optionally, the first controller shares a common ground with the first conversion circuit on the secondary side, the second controller shares a common ground with the second conversion circuit on the secondary side, and the first controller and the second controller are time-synchronized via a synchronization signal.

[0153] Generally speaking, the ground signal of the secondary first conversion circuit is different from the ground signal of the secondary second conversion circuit. The first controller shares a common ground with the secondary first conversion circuit, that is, the ground signal of the first controller is the same as the ground signal of the secondary first conversion circuit. The second controller shares a common ground with the secondary second conversion circuit, that is, the ground signal of the second controller can be the same as the ground signal of the secondary second conversion circuit. Fig. 9 As shown, the ground signal of the secondary side first conversion circuit is GND1, and the ground signal of the secondary side second conversion circuit is GND2, that is, the ground signal of the voltage signal Vo1 is GND1, the ground signal of the voltage signal Vo2 is GND2, the ground signal of the first controller is GND1, and the ground signal of the second controller is GND2. Fig. 9 As shown, the voltage signal Vo1 reaches the first controller after passing through the first sampling circuit and the first amplifier, and the voltage signal Vo2 reaches the second controller after passing through the second sampling circuit and the second amplifier.

[0154] In the embodiment of the present application, the ground signal of the first controller is the same as the ground signal of the first conversion circuit of the secondary side, and no isolation module is required between the first controller and the collected voltage signal Vo1, thereby reducing the cost of voltage collection. The ground signal of the second controller is the same as the ground signal of the second conversion circuit of the secondary side, and no isolation module is required between the second controller and the collected voltage signal Vo2, thereby reducing the cost of voltage collection.

[0155] Since the ground signal of the first controller is different from the ground signal of the second controller, in order to ensure the timing synchronization between the first controller and the second controller, the first controller and the second controller are synchronized with each other through a synchronization signal.

[0156] See also Fig.10 , Fig.10 is a timing diagram of a wave signal provided in an embodiment of the present application. Fig.10 As shown, from top to bottom are: the PWM waveform of the primary power switch, the PWM waveform of the first rectifier switch SR1, and the PWM waveform of the second rectifier switch SR1. Among them, the PWM waveform of the primary power switch includes the PWM waveforms of the first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4. The ripple period Ts of the ripple signal of the first rectifier switch SR1 and the second rectifier switch SR2 needs to be the same as the frequency of the primary power switch (the first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4). The turn-on time of the first rectifier switch SR1 and the second rectifier switch SR2 is D*Ts, where D is Figure 8 The duty cycle D of SR1-SR2 output by the second PI controller. The turn-off time of the first rectifier switch SR1 and the second rectifier switch SR2 is fixed relative to the primary PWM waveform: the turn-off of the first rectifier switch SR1 lags behind the turn-off time of the first power switch Q1 and the fourth power switch Q4 of the primary side by the first time length t1; the turn-off of the second rectifier switch SR2 lags behind the turn-off time of the second power switch Q2 and the third power switch Q3 of the primary side by the first time length t1. The driving waveform (i.e., the first wave signal) of the first rectifier switch SR1 can be generated according to the duty cycle D of the rectifier circuit generated by the control module. Fig.10 The wave signal is taken as an example of a square wave signal.

[0157] The wave transmission period Ts may be the above-mentioned switching period.

[0158] The charging circuit of the embodiment of the present application can achieve complete decoupling of the dual output ports, and the low-voltage side output can be independently controlled without being affected by the high-voltage side output. The charging circuit has fewer switching devices and sensors, simple control, low cost, and high reliability.

[0159] See also Fig.11 , Fig.11 It is a schematic diagram of simulation waveforms of output voltage and output current of a secondary side second conversion circuit provided in an embodiment of the present application. Fig.11 The charging circuit of the embodiment of the present application is used. When the output voltage Vo1 of the first conversion circuit on the secondary side jumps (such as Fig.11As shown in FIG. 1 , when the output voltage Vo1 of the secondary side first conversion circuit decreases from 600V to 400V, the simulation waveform of the output current io2 of the secondary side second conversion circuit and the simulation waveform of the output voltage Vo2 of the secondary side second conversion circuit are shown. Fig.11 As shown, at the moment when the output voltage Vo1 of the secondary side first conversion circuit jumps, the output voltage Vo2 of the secondary side second conversion circuit changes briefly by 0.1V (drops from 13.8V to 13.7V), and then returns to the predetermined 13.8V output. Fig.11 It can be seen that the output port of the first secondary conversion circuit and the output port of the second secondary conversion circuit in the embodiment of the present application can be decoupled and controlled (that is, the outputs of the output port of the first secondary conversion circuit and the output port of the second secondary conversion circuit do not interfere with each other). Fig.11 The output current io2 of the secondary side second conversion circuit varies greatly, which is mainly related to the load of the output port of the second conversion circuit. When the load is large, the output current io2 of the secondary side second conversion circuit decreases faster.

[0160] The embodiment of the present application may also provide a vehicle-mounted charging device, which may include: Figures 1 to 6 Any of the charging circuits. Fig.12 , Fig.12 Schematic diagram of the structure of a vehicle charging device provided in an embodiment of the present application. Fig.12 As shown, the vehicle-mounted charging device includes Figures 1 to 6 The charging circuit shown in FIG. This charging circuit is used to charge the power battery, and can also be used to charge the vehicle's electrical equipment and batteries ( Fig.12 ) is powered.

[0161] See also Fig.13 , Fig.13 Schematic diagram of a vehicle structure provided by an embodiment of the present application. Fig.13 As shown, the vehicle may include Fig.12 The on-board charging device shown.

[0162] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0163] In the several embodiments provided in the present application, it should be understood that the disclosed charging circuit and electric device can be implemented in other ways. For example, the charging circuit embodiments described above are only schematic, and the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

Claims

1. A charging circuit, characterized in that: It includes a primary conversion circuit, a secondary first conversion circuit, a secondary second conversion circuit and a transformer module; the first end of the transformer module has a first winding, and the second end of the transformer module has a second winding and a third winding; the first winding is connected to the primary conversion circuit, the second winding is connected to the secondary first conversion circuit, and the third winding is connected to the secondary second conversion circuit; the secondary second conversion circuit includes a rectifier module, and the secondary second conversion circuit is configured to independently adjust the output voltage based on the rectifier module.

2. The charging circuit according to claim 1, characterized in that: The secondary side second conversion circuit also includes an energy storage module connected to the rectification module, and the energy storage module and the rectification module cooperate to adjust the output voltage of the secondary side second conversion circuit.

3. The charging circuit according to claim 2, characterized in that: The rectifier module includes a first rectifier unit and a second rectifier unit; the first rectifier unit includes a first rectifier switch, and the second rectifier unit includes a second rectifier switch; or, the first rectifier unit includes at least two first rectifier switches connected in parallel, and the second rectifier unit includes at least two second rectifier switches connected in parallel; one end of the first rectifier switch and the second rectifier switch are connected to each other, and the other end is respectively connected to the energy storage module.

4. The charging circuit according to claim 3, characterized in that: The duty cycle of the first rectifier switch and the second rectifier switch are both greater than 50%.

5. The charging circuit according to claim 3, characterized in that: The duty cycle of the first rectifier switch and the second rectifier switch are both greater than the duty cycle of the switch of the primary conversion circuit.

6. The charging circuit according to claim 3, characterized in that: The energy storage module includes a coupled inductor, which includes a first coil and a second coil. The first rectifier switch is connected to one end of the third winding through the first coil, and the second rectifier switch is connected to the other end of the third winding through the second coil.

7. The charging circuit according to claim 6, characterized in that: The energy storage module further includes a first inductor and a second inductor. The first coil is connected to one end of the third winding via the first inductor, and the second coil is connected to the other end of the third winding via the second inductor.

8. The charging circuit according to claim 3, characterized in that: The energy storage module includes a first inductor and a second inductor. The first rectifier switch is connected to one end of the third winding through the first inductor, and the second rectifier switch is connected to the other end of the third winding through the second inductor.

9. The charging circuit according to claim 3, characterized in that: The secondary side second conversion circuit also includes a first capacitor, one end of which is connected to one end of the first rectifier switch and the second rectifier switch that are connected to each other, and the other end is grounded; the two ends of the first capacitor are suitable for connecting to the voltage output port.

10. The charging circuit according to claim 7 or 8, characterized in that: In at least one switching cycle, the turn-off time of the first rectifier switch lags behind the turn-off time of the first power switch of the primary conversion circuit by a first time length; and / or, the turn-off time of the second rectifier switch lags behind the turn-off time of the second power switch of the primary conversion circuit by a first time length.

11. The charging circuit according to claim 10, characterized in that: The first duration is determined based on the output current and voltage waveform amplitude of the secondary-side second conversion circuit and the inductance of the first inductor.

12. The charging circuit according to claim 11, characterized in that: The first duration is obtained according to the following formula: t1 = k*io2*L1 / (0.5*Vin); Among them, t1 is the first time length, k is the control coefficient, io2 is the output current of the secondary side second conversion circuit, L1 is the inductance of the first inductor, and Vin is the voltage waveform amplitude of the transformer module input to the secondary side second conversion circuit.

13. The charging circuit according to claim 10, characterized in that: The primary side conversion circuit includes: the first power switch, the second power switch, the third power switch, the fourth power switch and a resonant circuit, wherein the first end of the first power switch is connected to the first end of the second power switch and the positive pole of the DC power supply, the second end of the first power switch is connected to the first end of the third power switch and the first end of the resonant circuit, the second end of the second power switch is connected to the first end of the fourth power switch and the second end of the resonant circuit, and the second end of the third power switch is connected to the second end of the fourth power switch and the negative pole of the DC power supply.

14. The charging circuit according to claim 13, characterized in that: The charging circuit also includes a control module, which determines parameters of a first waving signal and a second waving signal based on an output voltage of the secondary side second conversion circuit and an output current of the secondary side second conversion circuit; the first waving signal is used to control the on or off of the first rectifier switch to control the on or off of the first current path, and / or the second waving signal is used to control the on or off of the second rectifier switch to control the on or off of the second current path.

15. The charging circuit according to claim 14, characterized in that: The control module determines parameters of a third wave signal, a fourth wave signal, a fifth wave signal, and a sixth wave signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit; the third wave signal is used to control the on or off of the first power switch, the fourth wave signal is used to control the on or off of the second power switch, the fifth wave signal is used to control the on or off of the third power switch, and the sixth wave signal is used to control the on or off of the fourth power switch; the parameters of the third wave signal are the same as the parameters of the sixth wave signal, and the parameters of the fourth wave signal are the same as the parameters of the fifth wave signal.

16. The charging circuit according to claim 15, characterized in that: The secondary side first conversion circuit comprises: a fifth power switch, a sixth power switch, a seventh power switch and an eighth power switch, wherein a first end of the fifth power switch is connected to a first end of the sixth power switch and a first output end of the secondary side first conversion circuit, a second end of the fifth power switch is connected to a first end of the seventh power switch, a second end of the sixth power switch is connected to a first end of the eighth power switch, and a second end of the seventh power switch is connected to a second end of the eighth power switch and a second output end of the secondary side first conversion circuit; The control module determines parameters of a seventh transmission signal, an eighth transmission signal, a ninth transmission signal, and a tenth transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit; the seventh transmission signal is used to control the on or off of the fifth power switch, the eighth transmission signal is used to control the on or off of the sixth power switch, the ninth transmission signal is used to control the on or off of the seventh power switch, and the tenth transmission signal is used to control the on or off of the eighth power switch.

17. The charging circuit according to claim 16, characterized in that: The control module includes a first controller and a second controller; The control module determines the parameters of the first waving signal and the second waving signal based on the output voltage of the secondary side second conversion circuit and the output current of the secondary side second conversion circuit, including: The second controller determines the parameters of the first waving signal and the parameters of the second waving signal based on the output voltage of the secondary side second conversion circuit and the output current of the secondary side second conversion circuit; The control module determines the parameters of the third wave transmission signal, the fourth wave transmission signal, the fifth wave transmission signal, and the sixth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit, including: The first controller determines the parameters of the third wave transmission signal, the fourth wave transmission signal, the fifth wave transmission signal, and the sixth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit; The control module determines the parameters of the seventh transmission signal, the eighth transmission signal, the ninth transmission signal, and the tenth transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit, including: The first controller determines parameters of the seventh wave transmission signal, the eighth wave transmission signal, the ninth wave transmission signal, and the tenth wave transmission signal based on the output voltage of the secondary side first conversion circuit and the output current of the secondary side first conversion circuit.

18. The charging circuit according to claim 17, characterized in that: The first controller shares a common ground with the secondary-side first conversion circuit, the second controller shares a common ground with the secondary-side second conversion circuit, and the first controller and the second controller are time-synchronized via a synchronization signal.

19. The charging circuit according to any one of claims 7 to 8, 10 to 18, characterized in that: The inductance of the first inductor is equal to the inductance of the second inductor.

20. The charging circuit according to claim 6 or 7, characterized in that: The coupling coefficient of the coupled inductor is greater than a set threshold.

21. A vehicle-mounted charging device, characterized in that: The charging circuit comprises the charging circuit as claimed in any one of claims 1 to 20.

22. A vehicle, characterized in that: Comprising the on-vehicle charging device as described in claim 21.

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