Charging circuit, vehicle-mounted charging device, and vehicle

Abstract

Embodiments of the present application provide a charging circuit, a vehicle-mounted charging device, 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. A first end of the transformer module is provided with a first winding, and a second end of the transformer module is provided with a second winding and a third winding. The first winding is connected to the primary-side conversion circuit, the second winding is connected to the secondary-side first conversion circuit, and the third winding is connected to the secondary-side second conversion circuit. The secondary-side second conversion circuit comprises a rectifier module, and the secondary-side second conversion circuit is configured to independently regulate an output voltage on the basis of the rectifier module. The voltage outputted by the secondary-side second conversion circuit and a voltage outputted by the secondary-side first conversion circuit can be prevented from interacting with each other.

Description

Charging circuits, on-board charging equipment and vehicles

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411049328.2, filed on July 31, 2024, entitled "Charging Circuit, On-board Charging Equipment and Vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of electronic circuit technology, specifically to a charging circuit, an on-board charging device, and a vehicle. Background Technology

[0004] Currently, dual-output port magnetic integrated vehicle power supply circuits are widely used. This circuit integrates the on-board charger (OBC) and the direct current to direct current (DC / DC) converter into one circuit, with both sharing a single transformer. This reduces the number of transformers and lowers the size and cost of the circuit.

[0005] Because the high-voltage and low-voltage ports of the magnetically integrated vehicle power supply circuit share a single 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 at 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 decreases, the voltage output at the low-voltage port will change. Summary of the Invention

[0006] This application provides a charging circuit, an on-board charging device, and a vehicle, which can decouple the voltage output by the secondary-side second conversion circuit from the voltage output by the secondary-side first conversion circuit, thereby preventing the voltage output by the secondary-side second conversion circuit from interfering with each other.

[0007] A first aspect of this application provides a charging circuit, including a primary-side conversion circuit, a secondary-side first conversion circuit, a secondary-side second conversion circuit, and a transformer module; the transformer module has a first winding at a first end, and a second winding and a third winding at a second end; the first winding is connected to the primary-side conversion circuit, the second winding is connected to the secondary-side first conversion circuit, and the third winding is connected to the secondary-side second conversion circuit; the secondary-side second conversion circuit includes a rectifier module, and the secondary-side second conversion circuit is configured to independently adjust the output voltage based on the rectifier module.

[0008] Optionally, the secondary-side second conversion circuit further includes an energy storage module connected to the rectifier module, wherein the energy storage module and the rectifier module cooperate to adjust the output voltage of the secondary-side second conversion circuit.

[0009] 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.

[0010] Optionally, the duty cycles of both the first rectifier switch and the second rectifier switch are greater than 50%.

[0011] Optionally, the duty cycles of both the first rectifier switch and the second rectifier switch are greater than the duty cycle of the primary-side switching circuit.

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

[0013] Optionally, the energy storage module further includes a first inductor and a second inductor, wherein the first coil is connected to one end of the third winding through the first inductor, and the second coil is connected to the other end of the third winding through the second inductor.

[0014] 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.

[0015] Optionally, the secondary-side second conversion circuit further includes a first capacitor, one end of which is connected to one end of the interconnection between the first rectifier switch and the second rectifier switch, and the other end is grounded; the two ends of the first capacitor are adapted to be connected to a voltage output port.

[0016] Optionally, during 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-side conversion circuit by a first duration; 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-side conversion circuit by a first duration.

[0017] Optionally, 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.

[0018] Optionally, the first duration is obtained according to the following formula: t1=k*io2*L1 / (0.5*Vin);

[0019] Where t1 is the first duration, 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 input from the transformer module to the secondary-side second conversion circuit.

[0020] Optionally, the primary-side conversion circuit includes: a first power switch, a second power switch, a third power switch, a fourth power switch, and a resonant circuit. The first terminal of the first power switch is connected to the first terminal of the second power switch and the positive terminal of the DC power supply. The second terminal of the first power switch is connected to the first terminal of the third power switch and the first terminal of the resonant circuit. The second terminal of the second power switch is connected to the first terminal of the fourth power switch and the second terminal of the resonant circuit. The second terminal of the third power switch is connected to the second terminal of the fourth power switch and the negative terminal of the DC power supply.

[0021] Optionally, the charging circuit further includes a control module, which determines the parameters of the first wave signal and the parameters of the second wave signal based on the output voltage and output current of the secondary-side second conversion circuit; the first wave signal is used to control the first rectifier switch to turn on or off, thereby controlling the first current path to turn on or off, and / or the second wave signal is used to control the second rectifier switch to turn on or off, thereby controlling the second current path to turn on or off.

[0022] Optionally, the control module determines the parameters of the third, fourth, fifth, and sixth wave signals based on the output voltage and output current of the secondary-side first conversion circuit. The third wave signal is used to control the first power switch to turn on or off, the fourth wave signal is used to control the second power switch to turn on or off, the fifth wave signal is used to control the third power switch to turn on or off, and the sixth wave signal is used to control the fourth power switch to turn on or off. The parameters of the third wave signal and the sixth wave signal are the same, and the parameters of the fourth wave signal and the fifth wave signal are the same.

[0023] 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 terminal of the fifth power switch is connected to the first terminal of the sixth power switch and the first output terminal of the secondary-side first conversion circuit. The second terminal of the fifth power switch is connected to the first terminal of the seventh power switch. The second terminal of the sixth power switch is connected to the first terminal of the eighth power switch. The second terminal of the seventh power switch is connected to the second terminal of the eighth power switch and the second output terminal of the secondary-side first conversion circuit.

[0024] The control module determines the parameters of the seventh, eighth, ninth, and tenth wave signals based on the output voltage and output current of the secondary-side first conversion circuit. The seventh wave signal is used to control the on or off of the fifth power switch, the eighth wave signal is used to control the on or off of the sixth power switch, the ninth wave signal is used to control the on or off of the seventh power switch, and the tenth wave signal is used to control the on or off of the eighth power switch.

[0025] Optionally, the control module includes a first controller and a second controller;

[0026] The control module determines the parameters of the first and second transmitted signals based on the output voltage and output current of the secondary-side second conversion circuit, including:

[0027] The second controller determines the parameters of the first transmitted signal and the parameters of the second transmitted signal based on the output voltage and the output current of the secondary-side second conversion circuit.

[0028] The control module determines the parameters of the third, fourth, fifth, and sixth transmitted signals based on the output voltage and output current of the secondary-side first conversion circuit, including:

[0029] The first controller determines the parameters of the third, fourth, fifth, and sixth transmitted signals based on the output voltage and output current of the secondary-side first conversion circuit.

[0030] The control module determines the parameters of the seventh, eighth, ninth, and tenth transmitted signals based on the output voltage and output current of the secondary-side first conversion circuit, including:

[0031] The first controller determines the parameters of the seventh, eighth, ninth, and tenth wave signals based on the output voltage and output current of the secondary-side first conversion circuit.

[0032] Optionally, the first controller shares a common ground with the secondary first conversion circuit, and the second controller shares a common ground with the secondary second conversion circuit. The first controller and the second controller are synchronized in time through a synchronization signal.

[0033] Optionally, the inductance of the first inductor is equal to the inductance of the second inductor.

[0034] Optionally, the coupling coefficient of the coupled inductor is greater than a set threshold.

[0035] A second aspect of this application provides an on-board charging device, including the charging circuit described in any of the first aspects of this application.

[0036] A third aspect of this application provides a vehicle that includes the on-board charging device described in the second aspect of this application.

[0037] The charging circuit of this embodiment includes a primary-side conversion circuit, a secondary-side first conversion circuit, a secondary-side second conversion circuit, and a transformer module connecting the above circuits. The secondary-side second conversion circuit includes a rectifier module and is configured to output voltage independently based on the rectifier module. The secondary-side second conversion circuit can output voltage independently based on the rectifier module, thereby decoupling the voltage output by the secondary-side second conversion circuit from the voltage output by the secondary-side first conversion circuit, and preventing mutual interference between the two voltages. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 is a schematic diagram of a charging circuit provided in an embodiment of this application;

[0040] Figure 2 is a schematic diagram of another charging circuit provided in an embodiment of this application;

[0041] Figure 3a is a schematic diagram of another charging circuit provided in an embodiment of this application;

[0042] Figure 3b is a schematic diagram of another charging circuit provided in an embodiment of this application;

[0043] Figure 4 is a schematic diagram of another charging circuit provided in an embodiment of this application;

[0044] Figure 5 is a schematic diagram of another charging circuit provided in an embodiment of this application;

[0045] Figure 6 is a schematic diagram of another charging circuit provided in an embodiment of this application;

[0046] Figure 7 is a schematic diagram of a coupled inductor provided in an embodiment of this application;

[0047] Figure 8 is a schematic diagram of the control principle of a control module provided in an embodiment of this application;

[0048] Figure 9 is a schematic diagram of the control principle of another control module provided in an embodiment of this application;

[0049] Figure 10 is a timing diagram of a wave transmission signal provided in an embodiment of this application;

[0050] Figure 11 is a schematic diagram of the simulated output voltage and output current of a secondary-side second conversion circuit provided in an embodiment of this application;

[0051] Figure 12 is a structural schematic diagram of an on-board charging device provided in an embodiment of this application;

[0052] Figure 13 is a structural schematic diagram of a vehicle provided in an embodiment of this application.

[0053] Explanation of reference numerals in the attached diagram: 100 - Charging circuit; 1 - Primary-side conversion circuit; Q1 - First power switch; Q2 - Second power switch; Q3 - Third power switch; Q4 - Fourth power switch; 15 - Resonant circuit; 2 - Secondary-side first conversion circuit; C1 - First capacitor; Q5 - Fifth power switch; Q6 - Sixth power switch; Q7 - Seventh power switch; Q8 - Eighth power switch; 3 - Secondary-side second conversion circuit; 31 - Rectifier module; 311 - First rectifier unit; SR1 - First rectifier switch; 312 - Second rectifier unit; SR2 - Second rectifier switch; 32 - Energy storage module; 321 - Coupled inductor; N1 - First coil; N2 - Second coil; 3211 - Magnetic core; L1 - First inductor; L2 - Second inductor; C2 - Second capacitor; 4 - Transformer module; W1 - First winding; W2 - Second winding; W3 - Third winding; 5 - Control module; 51 - First controller; 52 - Second controller; 6 - DC power supply; 200 - On-board charging equipment; 300 - Vehicle. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, system, product, or apparatus that comprises a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, products, or apparatuses.

[0056] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0057] Please refer to Figure 1, which is a schematic diagram of a charging circuit 100 provided in an embodiment of this application. As shown in Figure 1, the charging circuit 100 includes a primary-side conversion circuit 1, a secondary-side first conversion circuit 2, a secondary-side second conversion circuit 3, and a transformer module 4. The first end of the transformer module 4 has a first winding W1, and the second end of the transformer module 4 has a second winding W2 and a third winding W3. The first winding W1 is connected to the primary-side conversion circuit 1, the second winding W2 is connected to the secondary-side first conversion circuit 2, and the third winding W3 is connected to the secondary-side second conversion circuit 3. The secondary-side second conversion circuit 3 includes a rectifier module 31, and the secondary-side second conversion circuit 3 is configured to independently adjust the output voltage based on the rectifier module 31.

[0058] The output voltage of the secondary-side first conversion circuit 2 is Vo1, and the output current of the secondary-side first conversion circuit 2 is io1. The rectifier module 31 can control the stability of the output voltage of the secondary-side second conversion circuit 3, and also allows the secondary-side second conversion circuit 3 to independently adjust its output voltage. The output voltage of the secondary-side second conversion circuit 3 is Vo2, and the output current of the secondary-side second conversion circuit 3 is io2.

[0059] In this embodiment, the secondary-side first conversion circuit 2 and the secondary-side second conversion circuit 3 share a transformer module 4. The secondary-side first conversion circuit 2 can supply power to the load 1; for example, it can output a high voltage to charge the vehicle 300's power battery (e.g., a 400V power battery). The secondary-side second conversion circuit 3 can supply power to the load 2; for example, it can output a low voltage to supply power to the vehicle 300's storage battery (e.g., a 14V storage battery) and low-voltage loads (e.g., loads less than or equal to 14V). The primary-side conversion circuit 1, the transformer module 4, and the secondary-side first conversion circuit 2 can form an on-board charger (OBC); the primary-side conversion circuit 1, the transformer module 4, and the secondary-side second conversion circuit 3 can form a direct current to direct current (DC / DC) converter. The charging circuit 100 can integrate the on-board charger (OBC) and the direct current to direct current (DC / DC) converter into one unit, which shares a single transformer module 4, thereby reducing the number of transformer modules 4 and lowering the size and cost of the circuit.

[0060] For example, as shown in Figure 1, the load 1 connected between the positive and negative terminals of the output terminal of the secondary-side second conversion circuit 3 can be a power battery. The load 2 connected between the first and second output terminals of the secondary-side second conversion circuit 3 can be a storage battery. As shown in Figure 1, the first output terminal of the secondary-side second conversion circuit 3 is the positive output terminal, and the second output terminal of the secondary-side second conversion circuit 3 is the negative output terminal.

[0061] In one possible embodiment, the first output terminal of the secondary-side second conversion circuit 3 can be a negative output terminal, and the second output terminal of the secondary-side second conversion circuit 3 can be a positive output terminal.

[0062] The load 1 connected between the positive and negative terminals of the output of the secondary conversion circuit 3 can be a power battery.

[0063] The load 2 connected between the first and second output terminals of the secondary-side second conversion circuit 3 can be at least one of a storage battery or an electrical device.

[0064] The output port of the secondary-side first conversion circuit 2 is a high-voltage port, which can charge the high-voltage battery (e.g., power battery) of the vehicle 300. The output port of the secondary-side second conversion circuit 3 is a low-voltage port, which can supply power to the low-voltage battery (e.g., storage battery) of the vehicle 300 and electrical equipment (e.g., air conditioner, lights, audio-visual equipment, windshield wipers, etc.).

[0065] In this embodiment, the secondary-side second conversion circuit 3 can output voltage independently based on the rectifier module 31, thereby decoupling the voltage output by the secondary-side second conversion circuit 3 from the voltage output by the secondary-side first conversion circuit 2, and avoiding mutual interference between the voltage output by the secondary-side second conversion circuit 3 and the voltage output by the secondary-side first conversion circuit 2.

[0066] As shown in Figure 1, the transformer module 4 includes a first winding W1, a second winding W2, and a third winding W3; the primary-side conversion circuit 1 is connected to the first winding W1, the secondary-side first conversion circuit 2 is connected to the second winding W2, and the secondary-side second conversion circuit 3 is connected to the third winding W3.

[0067] Please refer to Figure 2, which is a schematic diagram of another charging circuit 100 provided in an embodiment of this application. As shown in Figure 2, based on Figure 1, the secondary-side second conversion circuit 3 in Figure 2 further includes an energy storage module 32 connected to the rectifier module 31. The energy storage module 32 and the rectifier module 31 cooperate to adjust the output voltage of the secondary-side second conversion circuit 3.

[0068] In this embodiment, the energy storage module 32 can store energy and prevent drastic changes in the output current and output voltage of the secondary-side second conversion circuit 3, thereby stabilizing the output current and output voltage of the secondary-side second conversion circuit 3.

[0069] Optionally, as shown in Figure 2, the energy storage module 32 includes a coupling inductor 321, which includes a first coil N1 and a second coil N2. A first rectifier switch SR1 is connected to one end of a third winding W3 through the first coil N1, and a second rectifier switch SR2 is connected to the other end of the third winding W3 through the second coil N2.

[0070] In this embodiment, the coupling inductor 321 can increase the output inductance of the secondary-side second conversion circuit 3 and reduce the ripple of the output current io2 of the secondary-side second conversion circuit 3.

[0071] Please refer to Figure 3a, which is a schematic diagram of another charging circuit 100 provided in an embodiment of this application. Figure 3a is based on Figure 2. Based on Figure 2, the energy storage module 32 of Figure 3a 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 through the first inductor L1, and the second coil N2 is connected to the other end of the third winding W3 through the second inductor L2.

[0072] Optionally, the rectifier module 31 includes a first rectifier unit 311 and a second rectifier unit 312.

[0073] The first rectifier unit 311 includes a first rectifier switch, and the second rectifier unit 312 includes a second rectifier switch; or, the first rectifier unit 311 includes at least two first rectifier switches connected in parallel, and the second rectifier unit 312 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 32.

[0074] For example, as shown in FIG3a, the rectifier module 31 includes a first rectifier switch SR1 and a second rectifier switch SR2. Each rectifier unit includes a rectifier switch, which can reduce the size of the rectifier module 31 and thus reduce the size of the secondary-side second conversion circuit 3.

[0075] For example, as shown in Figure 3b, the rectifier module 31 includes a first rectifier unit 311 and a second rectifier unit 312. The first rectifier unit 311 includes three first rectifier switches connected in parallel, and the second rectifier unit 312 includes three second rectifier switches connected in parallel. The rectifier unit includes at least two parallel rectifier switches, which can reduce the current passing through each rectifier switch. Rectifier switches with lower current tolerance can be used, reducing the cost of the rectifier switches. If one of the at least two parallel rectifier switches fails, the other rectifier switches can continue to operate, thereby improving the redundancy of the secondary-side second conversion circuit 3. Each rectifier switch can individually control the fluctuation of its output current. By controlling the fluctuation of the output current of the secondary-side second conversion circuit 3 through at least two parallel rectifier switches, the fluctuation of the output current of the secondary-side second conversion circuit 3 can be further reduced, thereby improving the rectification effect of the rectifier unit.

[0076] Optionally, the duty cycles of both the first rectifier switch SR1 and the second rectifier switch SR2 are greater than 50%.

[0077] In this embodiment, the duty cycles of both the first rectifier switch SR1 and the second rectifier switch SR2 are greater than 50%, allowing both switches to be turned on simultaneously. This reduces fluctuations in the output current of the secondary-side second conversion circuit 3. For example, taking Figure 2 or Figure 3a as an example, when switching from the first rectifier switch SR1 to the second rectifier switch SR2, if at a certain moment the first rectifier switch SR1 switches from on to off, and the second rectifier switch SR2 switches from off to on, the current on the first rectifier switch SR1 will rapidly drop to 0, while the current on the second rectifier switch SR2 will slowly rise. This will cause a sudden and rapid decrease in the output current io2 of the secondary-side second conversion circuit 3. To avoid this sudden change in the output current io2, there will be a period of time during which both the first rectifier switch SR1 and the second rectifier switch SR2 will have current flowing through them; this period is called the commutation time.

[0078] The duty cycle of a switch refers to the ratio of the on-time of the switch to the duration of the switching cycle within one switching period. For example, the duty cycle of the first rectifier switch SR1 is the ratio of the on-time of the first rectifier switch SR1 to the duration of the switching cycle within one switching period. The duty cycle of the second rectifier switch SR2 is the ratio of the on-time of the second rectifier switch SR2 to the duration of the switching cycle within one switching period.

[0079] Optionally, the duty cycles of the first rectifier switch SR1 and the second rectifier switch SR2 are both greater than the duty cycle of the primary-side switching circuit 1.

[0080] In this embodiment, the duty cycle of the first rectifier switch SR1 is greater than the duty cycle of the primary-side switching circuit 1. The conduction duration of the first rectifier switch SR1 in each cycle is greater than the conduction duration of the primary-side switching circuit 1. After the primary-side switching circuit 1 is turned off, the first rectifier switch SR1 remains on. Although the current on the first rectifier switch SR1 begins to decrease, the current on the first rectifier switch SR1 will not pass through the body diode of the first rectifier switch SR1, thus preventing damage to the body diode. Furthermore, the current loss on the first rectifier switch is lower than the current loss of the body diode. The fact that the duty cycle of the first rectifier switch SR1 is greater than the duty cycle of the primary-side switching circuit 1 further reduces current loss.

[0081] Optionally, the energy storage module 32 can also be two independent inductors. As shown in Figure 4, the energy storage module 32 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.

[0082] The first inductor L1 and the second inductor L2 in this embodiment can prevent the current from dropping too quickly during the commutation time, thus preventing a turn-off voltage spike. The commutation time refers to the moment when both the first rectifier switch SR1 and the second rectifier switch SR2 are turned on, and then switching to only one rectifier switch being turned on.

[0083] In addition, the energy storage module 32 can also be integrated with the transformer module 4 into a magnetic device, or some of the components in the transformer module 4 can be reused.

[0084] Optionally, during 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-side conversion circuit 1 by a first duration; 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-side conversion circuit 1 by a first duration.

[0085] In this embodiment, setting the turn-off time of the first rectifier switch SR1 to lag behind the turn-off time of the first power switch in the primary-side conversion circuit 1 by a first duration can reduce losses. After the first rectifier switch SR1 is turned off, the current in 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, then after the first rectifier switch SR1 is turned off, the body diode of the first rectifier switch SR1 will conduct. Since the conduction failure of the diode is greater than that of the first rectifier switch SR1, the energy conversion efficiency is low.

[0086] Optionally, as shown in Figure 5, the primary-side conversion circuit 1 includes: a first power switch Q1, a second power switch Q2, a third power switch Q3, a fourth power switch Q4, and a resonant circuit 15. The first end of the first power switch Q1 is connected to the first end of the second power switch Q2 and the positive terminal of the DC power supply 6. 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 15. 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 15. The second end of the third power switch Q3 is connected to the second end of the fourth power switch Q4 and the negative terminal of the DC power supply 6.

[0087] In this embodiment, the DC power supply 6, the primary-side conversion circuit 1, the transformer module 4, and the secondary-side first conversion circuit 2 can form an on-board charger. The DC power supply 6 can be a front-end power factor correction (PFC) conversion circuit connected to the primary-side conversion circuit 1. The secondary-side first conversion circuit 2 can be used to charge the power battery of the vehicle 300, and the secondary-side second conversion circuit 3 can be used to supply power to other electrical appliances in the vehicle.

[0088] In this embodiment, the primary-side conversion circuit 1 includes two sets of power switch combinations. The first set of power switch combinations includes a first power switch Q1 and a fourth power switch Q4. The second set of power switch combinations includes a second power switch Q2 and a third power switch Q3. The switching operations of the two sets of power switch combinations are opposite.

[0089] The first power switch Q1, the second power switch Q2, the third power switch Q3, and the fourth power switch Q4 can be any of a metal-oxide-semiconductor field-effect transistor (MOSFET) or 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 can be an N-type metal-oxide-semiconductor field-effect transistor (NMOS).

[0090] The resonant circuit 15 may include the resonant inductor L0, resonant capacitor C0 and magnetizing inductor Lm shown in FIG5.

[0091] In Figure 5, a second capacitor C2 can be added between the positive and negative terminals of the load 1 in the secondary-side first conversion circuit 2, and a first capacitor C1 can be added between the positive and negative terminals of the load 2 (in Figure 5, the load 2 is a battery) in the secondary-side second conversion circuit 3. Both the first capacitor C1 and the second capacitor C2 are filter capacitors, which can be used to ensure the stability of the output voltage Vo2 of the secondary-side second conversion circuit 3 and the output voltage Vo1 of the secondary-side first conversion circuit 2, respectively.

[0092] Optionally, the first duration is determined based on the output current and voltage waveform amplitude of the secondary-side second conversion circuit 3 and the inductance of the first inductor.

[0093] In this embodiment, the first duration is positively correlated with the output current of the secondary-side second conversion circuit 3, positively correlated with the inductance of the first inductor, and negatively correlated with the voltage waveform amplitude.

[0094] Optionally, the first duration is obtained according to the following formula:

[0095] t1 = k * io2 * L1 / (0.5 * Vin);

[0096] Where t1 is the first duration, k is the control coefficient, io2 is the output current of the secondary-side second conversion circuit 3, L1 is the inductance of the first inductor, and Vin is the voltage waveform amplitude input from the transformer module 4 to the secondary-side second conversion circuit 3.

[0097] The value of k ranges from 0 to 1. The closer k is to 1, the smaller the turn-off current, which helps reduce turn-off losses, but it increases the risk of voltage spikes. K can be chosen reasonably according to the actual situation.

[0098] The above formula essentially calculates the rate of current decrease. The larger the output current io2 of the secondary-side second conversion circuit 3, the larger the first duration t1 can be set. Since the output current io2 of the secondary-side second conversion circuit 3 decreases from a larger current, the time it takes for the output current io2 of the secondary-side second conversion circuit 3 to decrease from a large current to 0 will be relatively long; therefore, the first duration t1 can be set longer. Vin is the rated amplitude of the square wave on W31 or W32. The larger Vin is set, the faster the rate of decrease of the output current io2 of the secondary-side second conversion circuit 3. As shown in Figure 5, W31 is the portion of the 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 the portion of the 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 in W31 is the same as the number of turns in W32, and the rated amplitude of the square wave on W31 is the same as the rated amplitude of the square wave on W32.

[0099] It should be noted that the above formula is one possible method for calculating t1 provided in the embodiments of this application. The method for calculating t1 is not unique.

[0100] Please refer to Figure 6, which is a schematic diagram of another charging circuit 100 provided in this embodiment of the application. Figure 6 adds a control module 5 to Figure 5. The charging circuit 100 also includes a control module 5, which determines the parameters of the first wave signal and the second wave signal based on the output voltage Vo2 and the output current io2 of the secondary side second conversion circuit 3. The first wave signal is used to control the first rectifier switch SR1 to turn on or off, thereby controlling the conduction or disconnection of the first current path. The second wave signal is used to control the second rectifier switch SR2 to turn on or off, thereby controlling the conduction or disconnection of the second current path.

[0101] The first current path includes the first end of the third winding W3, the first inductor L1, the first coil N1 of the coupling inductor 321, the first rectifier switch SR1, and the first output terminal of the secondary-side second conversion circuit 3. The second current path includes the second end of the third winding W3, the second inductor L2, the second coil N2 of the coupling inductor 321, the second rectifier switch SR2, and the first output terminal of the secondary-side second conversion circuit 3. The middle tap of the third winding W3 is connected to the second output terminal of the secondary-side second conversion circuit 3.

[0102] The control module 5 determines the parameters of the first wave signal and the parameters of the second wave signal based on the output voltage Vo2 and the output current io2 of the secondary side second conversion circuit 3. The first wave signal is used to control the first rectifier switch SR1 to turn on or off, so as to control the first current path to turn on or off. The second wave signal is used to control the second rectifier switch SR2 to turn on or off, so as to control the second current path to turn on or off.

[0103] The transmitted signal can be a pulse width modulation (PWM) signal, and its parameters can be at least one of the frequency and duty cycle of the PWM signal. For example, the parameters of the first transmitted signal can include its frequency and duty cycle. The parameters of the second transmitted signal can include its frequency and duty cycle.

[0104] In Figure 6, 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 321, the second end of the first coil N1 of the coupling inductor 321 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 terminal of the secondary-side second conversion circuit 3; 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 321, the second end of the second coil N2 of the coupling inductor 321 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 terminal of the secondary-side second conversion circuit 3.

[0105] Theoretically, during normal operation of the rectifier module 31, the first rectifier switch SR1 and the second rectifier switch SR2 are alternately turned on. When the first rectifier switch SR1 is on, the second rectifier switch SR2 is off. At this time, there is current in the first current path and no current in the second current path. When the second rectifier switch SR2 is on, the first rectifier switch SR1 is off. At this time, there is current in the second current path and no current in the first current path. In actual operation, when switching from the first rectifier switch SR1 to the second rectifier switch SR2, in order to avoid a sudden change in the output current io2 of the secondary second conversion circuit 3, there will be current in both current paths (the first current path and the second current path) for a period of time. The time from the moment when there is current in both current paths to the moment when there is current in only one current path is called the commutation time. The commutation time is generally relatively short. For example, the period of time during which the current in the first current path decreases and the current in 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.

[0106] The first inductor L1 and the second inductor L2 in this embodiment can prevent a rapid current drop during the commutation time, which could cause a turn-off voltage spike. The commutation time refers to the moment when both the first rectifier switch SR1 and the second rectifier switch SR2 are turned on, and only one rectifier power switch is turned on; or it refers to the moment when current flows through both current paths, and only one current path has current. For example, during the commutation time, if the current in the first current path increases and the current in the second current path decreases, normally, if the second rectifier switch SR2 is turned off in time, the second current path will be disconnected before the current in the second current path becomes negative, preventing the current in the second current path from becoming negative. However, if the current in the second current path decreases rapidly during commutation, and the second rectifier switch SR2 is turned off after the current in the second current path becomes negative, the energy of the negative current in the second current path will become a large turn-off voltage spike. This turn-off voltage spike, loaded on the second rectifier switch SR2, may break down the second rectifier switch SR2. If the current in the second current path is a forward current (the current direction 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.

[0107] By adding a first inductor L1 and a second inductor L2, the current drop rate in the first or second current path can be reduced during the commutation time. This avoids turning off the first rectifier switch SR1 after the current in the first current path becomes negative or turning off the second rectifier switch SR2 after the current in the second current path becomes negative, thereby avoiding turn-off voltage spikes and improving circuit safety.

[0108] The first inductor L1 limits the rate of change of the current flowing through it. During the commutation process from the first current path to the second current path, it limits the rate of current decrease in the first current path, thus preventing a turn-off voltage spike when the first rectifier switch SR1 is turned off. Similarly, the second inductor L2 limits the rate of change of the current flowing through it. During the commutation process from the second current path to the first current path, it limits the rate of current decrease in the second current path, thus preventing a turn-off voltage spike when the second rectifier switch SR2 is turned off.

[0109] The inductance values ​​(inductance values) of the first inductor L1 and the second inductor L2 can be designed as needed. The larger the inductance value, the slower the rise and fall rates of the current flowing through the inductor.

[0110] Optionally, the inductance of the first inductor L1 is equal to the inductance of the second inductor L2.

[0111] In this embodiment, the inductances of L1 and L2 are made equal. The inductance determines the rate at which the current rises and falls during the commutation time. The larger the inductance, the slower the current rises. If the inductances of L1 and L2 differ significantly, the rates of current rise and fall in the two current paths will be inconsistent, potentially causing voltage spikes. Setting the inductance of the first inductor L1 to be equal to that of the second inductor L2 ensures that the rate of current rise in the first current path is as close as possible to the rate of current rise in the second current path, and that the rate of current fall in the first current path is as close as possible to the rate of current fall in the second current path, thereby avoiding turn-off voltage spikes during commutation.

[0112] The parameters of the first transmitted signal can include its frequency and duty cycle. Similarly, the parameters of the second transmitted signal can include its frequency and duty cycle. Both the first and second transmitted signals can be PWM signals.

[0113] The control module 5 determines the parameters of the first and second transmitted signals based on the output voltage Vo2 and output current io2 of the secondary-side second conversion circuit 3. The first transmitted signal controls the on / off state of the first rectifier switch SR1 to control the on / off state of the first current path, and the second transmitted signal controls the on / off state of the second rectifier switch SR2 to control the on / off state of the second current path. For example, during the high-level period of the first transmitted signal, the first rectifier switch SR1 is on, and during the low-level period of the first transmitted signal, the first rectifier switch SR1 is off. During the high-level period of the second transmitted signal, the second rectifier switch SR2 is on, and during the low-level period of the second transmitted signal, the second rectifier switch SR2 is off.

[0114] The first rectifier switch SR1 and the second rectifier switch SR2 can be either a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-gate bipolar transistor (IGBT). For example, both the first rectifier switch SR1 and the second rectifier switch SR2 can be N-type metal-oxide-semiconductor field-effect transistors (NMOS).

[0115] The charging circuit 100 of this embodiment does not require adding a voltage regulation circuit after the rectifier module 31, nor does it require detecting the zero-crossing detection signal of the primary current. The control module 5 can determine the parameters of the first wave signal and the second wave signal based on the output voltage Vo2 and the output current io2 of the secondary second conversion circuit 3, thereby controlling the first rectifier switch SR1 and the second rectifier switch SR2. This can reduce the cost and control logic of the charging circuit 100.

[0116] When the first current path is open and the second current path is closed, there is current in the portion of the 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 portion of the winding between the second end of the third winding W3 and the middle tap of the third winding W3.

[0117] When the second current path is open and the first current path is closed, there is current in the part of the 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 part of the winding between the first end of the third winding W3 and the middle tap of the third winding W3.

[0118] In this embodiment, the coupling inductor 321 can increase the output inductance after commutation is completed, thereby reducing the output current io2 ripple of the secondary-side second conversion circuit 3. During the commutation time, the coupling inductor 321 is equivalent to a short circuit. After commutation is completed, there is current in only one current path. At this time, the coupling inductor 321 can reduce the output current io2 ripple of the secondary-side second conversion circuit 3. For example, only the first inductor L1 (i.e., the first current path) is working. The actual inductance of the first current path is: the inductance of the first inductor L1 + the inductance of the coupling inductor 321. As the inductance of the first current path increases, the rate of change of current in the first current path slows down, thus reducing the current ripple and preventing large fluctuations in the output current io2 of the secondary-side second conversion circuit 3 (e.g., preventing a huge triangular wave current).

[0119] Among them, the coupling inductor 321 can be a positive coupling inductor 321.

[0120] Please refer to Figure 7, which is a schematic diagram of a coupled inductor 321 provided in an embodiment of this application. As shown in Figure 7, the coupled inductor 321 includes a magnetic core, a first coil N1, and a second coil N2 wound around the magnetic core. Figure 7 illustrates a winding method of the coupled inductor 321, with the magnetic core oriented in the positive direction, and the first coil N1 and the second coil N2 wound around both sides of the magnetic core, respectively. The first coil N1 and the second coil N2 may have the same number of turns.

[0121] Optionally, the coupling coefficient of the coupling inductor 321 is greater than a set threshold.

[0122] The leakage inductance of coupled inductor 321 refers to the portion of inductance in the coupled inductor 321 where no coupling occurs, and the magnetic flux generated by the current flowing through one inductor (e.g., the first coil N1 or the second coil N2) is negligible by the other inductor (e.g., the second coil N1 or the first coil N2). In essence, the leakage inductance of coupled inductor 321 represents the portion of inductance left when the current flowing through one inductor is not fully coupled as it passes through the other inductor, indicating a coupling effect. This portion of inductance has a significant impact on the performance of coupled circuits. Ideally, the two inductors are fully coupled, resulting in zero leakage inductance. However, in reality, leakage inductance is unavoidable due to various reasons. Leakage inductance reduces circuit gain.

[0123] The magnetic flux generated by the first coil N1 is partly used to verify the second coil N2 (i.e., part of it is coupled by the second coil N2), and part of it is not used to verify the second coil N2 (i.e., part of it is not coupled by the second coil N2). The other part is the leakage inductance.

[0124] A threshold can be set in advance. The threshold is a positive number less than 1. For example, the threshold can be set to 98%.

[0125] The shape of the magnetic core is not limited; it can be any of the following: rectangular, symmetrical, circular, polygonal, irregular, or non-circular.

[0126] The coupling coefficient can be set according to the needs of the actual scenario. A lower coupling coefficient will result in lower circuit gain. In some scenarios where high circuit gain is not required, a coupling inductor 321 with a relatively low coupling coefficient can be used.

[0127] Without the coupling inductor 321, the secondary-side second conversion circuit 3 in Figure 4 is suitable for low-power, low-current scenarios. For example, the power requirement of the load 2 at the output of the secondary-side second conversion circuit 3 is less than 100 watts (W). For instance, the output of the secondary-side second conversion circuit 3 is connected to a mobile phone charger. Because the output current io2 of the secondary-side second conversion circuit 3 is low, it is not necessary to add the coupling inductor 321 to power a low-power load.

[0128] The secondary-side second conversion circuit 3, including the coupling inductor 321, as shown in Figures 2, 3a, 3b, 5, and 6, is suitable for high-power, high-current scenarios. For example, if the power requirement of the load 2 at the output of the secondary-side second conversion circuit 3 exceeds 1000 watts, then the coupling inductor 321 needs to be added. For example, the load 2 could be a vehicle battery, electrical equipment, etc.

[0129] Optionally, as shown in Figure 6, the control module 5 determines the parameters of the third, fourth, fifth, and sixth wave signals based on the output voltage Vo1 and the output current io1 of the secondary-side first conversion circuit 2. The third wave signal is used to control the first power switch to turn on or off, the fourth wave signal is used to control the second power switch to turn on or off, the fifth wave signal is used to control the third power switch to turn on or off, and the sixth wave signal is used to control the fourth power switch to turn on or off. The parameters of the third wave signal are the same as those of the sixth wave signal, and the parameters of the fourth wave signal are the same as those of the fifth wave signal.

[0130] Wherein, the first transmitted signal has the same frequency as the third transmitted signal, and the second transmitted signal has the same frequency as the fourth transmitted signal; the turn-off time of the first transmitted signal lags behind the turn-off time of the third transmitted signal by a first duration, and the turn-off time of the second transmitted signal lags behind the turn-off time of the fourth transmitted signal by the first duration.

[0131] In this embodiment, the turn-off time of the first transmitted signal lags behind the turn-off time of the third transmitted signal by a first duration, and the turn-off time of the second transmitted signal lags behind the turn-off time of the fourth transmitted signal by a first duration. This reduces losses. After the first rectifier switch SR1 is turned off, the current in the first current path begins to decrease. If the turn-off time of the first transmitted signal is the same as the turn-off time of the third transmitted signal, the current in the first current path will pass through the body diode of the first rectifier switch SR1 after the first rectifier switch SR1 is turned off. Since the conduction failure of the diode is greater than that of the first rectifier switch SR1, the energy conversion efficiency is low. By setting the turn-off time of the first transmitted signal to lag behind the turn-off time of the third transmitted signal by a first duration, the first duration is less than or equal to the time required for the current in the first current path to decrease from the beginning to zero, and the first duration is less than or equal to the time required for the current in the second current path to decrease from the beginning to zero.

[0132] The first duration can be adjusted in real time. The value of the first duration can be set. If the first duration is set too large, for example, if the first duration is greater than the time required for the current in the first current path to decrease from the beginning to zero, then when the first current switch is turned off, the current in the first current path will become negative, resulting in a voltage spike.

[0133] Optionally, the first duration is obtained according to the following formula: t1=k*io2*L1 / (0.5*Vin);

[0134] Where t1 is the first duration, k is the control coefficient, io2 is the output current io2 of the secondary side second conversion circuit 3, 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 (the rated amplitude of the square wave on W31 in Figure 6). It should be noted that the rated amplitude of the square wave on W31 in Figure 6 is the same as the rated amplitude of the square wave on W32 (the waveform amplitude between the second end of the third winding W3 and the middle tap of the third winding W3).

[0135] Optionally, as shown in Figure 5 or Figure 6, the secondary-side first conversion circuit 2 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 2. 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. 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 2.

[0136] The fifth power switch Q5, the sixth power switch Q6, the seventh power switch Q7, and the eighth power switch Q8 can be any of a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-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 can all be N-type metal-oxide-semiconductor field-effect transistors (NMOS).

[0137] The control module 5 determines the parameters of the seventh, eighth, ninth, and tenth wave signals based on the output voltage Vo1 and the output current io1 of the secondary-side first conversion circuit 2. The seventh wave signal is used to control the on or off of the fifth power switch, the eighth wave signal is used to control the on or off of the sixth power switch, the ninth wave signal is used to control the on or off of the seventh power switch, and the tenth wave signal is used to control the on or off of the eighth power switch.

[0138] Please refer to Figure 8, which is a schematic diagram of the control principle of a control module 5 provided in an embodiment of this application. As shown in Figure 8, the control module 5 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 the PI controllers in Figure 8 can be replaced with a proportional-integral-derivative (PID) controller or a proportional-derivative (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 waveform signal). The PWM module in Figure 8 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 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, respectively.

[0139] The control module 5 calculates the difference between the acquired output voltage Vo1 of the secondary-side first conversion circuit 2 and the Vo1 reference voltage. The difference is then used by the control algorithm of the first PI controller (which can be a PI control algorithm) to perform loop compensation. The resulting compensation value is then compared with the pre-set io1 reference value of the current loop, and the smaller of the two is taken as the current loop reference value Iref1. The control module 5 also calculates the difference between the acquired output current io1 of the secondary-side first conversion circuit 2 and the current loop reference value Iref1 (using Iref1-io1). The difference is then used for loop compensation to determine the switching frequency fs of the primary-side power switches (first power switch Q1, second power switch Q2, third power switch Q3, and fourth power switch Q4). The switching frequency of 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 frequencies of the first power switch Q1 to the fourth power switch Q4 and the duty cycle of the first power switch Q1 to the fourth power switch Q4 are adjusted. The switching frequency fs of the power switches (the fifth power switch Q5, the sixth power switch Q6, the seventh power switch Q7 and the eighth power switch Q8) in the secondary first conversion circuit 2 can be adjusted by loop compensation. The first set of power switches (first power switch Q1, fourth power switch Q4) and the second set of power switches (second power switch Q2, third power switch Q3) have opposite switching operations. Simultaneously, the control module 5 calculates the difference between the acquired output voltage Vo2 of the secondary-side second conversion circuit 3 and the Vo2 reference voltage. The difference is then used by the control algorithm of the second PI controller (which can be a PI control algorithm) to perform loop compensation. The resulting compensation value is then compared with a pre-set current loop reference value io2, and the smaller of the compensation value and the pre-set current loop value is used as the current loop reference value Iref2. The acquired output current io2 of the secondary-side second conversion circuit 3 is then compared with the voltage loop reference value Iref2 (using Iref2-io2). The difference is then used for loop compensation to determine the duty cycle D of the first rectifier switch SR1 and the second rectifier switch SR2.

[0140] The duty cycles of the power switches on the primary side (first power switch Q1, second power switch Q2, third power switch Q3, and fourth power switch Q4) can be set as needed. For example, the duty cycles of the first power switch Q1 through the fourth power switch Q4 are the same, approximately 0.5.

[0141] By taking the smaller value between the obtained compensation value and the pre-set io1 reference value of the current loop, the output current io1 of the secondary-side first conversion circuit 2 can be prevented from exceeding the io1 reference value, thus improving the output stability of the secondary-side first conversion circuit 2. For example, if the output of the voltage loop is very high, the compensation value of the loop compensation based on the difference between the output voltage Vo1 of the first conversion circuit and the Vo1 reference voltage is relatively large. However, the current loop has a current limit (for example, the pre-set io1 reference value of the current loop is 10A). This compensation value is greater than the pre-set io1 reference value of the current loop. If the larger of the two is taken, and this compensation value is used as the reference value Iref1 of the current loop, although it can meet the output requirements of the voltage loop, it will cause the current of the current loop to be greater than 10A, which may cause the current to rise rapidly.

[0142] It should be noted that the first transmitted signal and the third transmitted signal have the same frequency, and the second transmitted signal and the fourth transmitted signal have the same frequency. When the switching frequencies of the power switches on the primary side (first power switch Q1, second power switch Q2, third power switch Q3, and fourth power switch Q4) are the same, the switching frequencies of the first rectifier switch SR1, the second rectifier switch SR2, and the power switches on the primary side (first power switch Q1, second power switch Q2, third power switch Q3, and fourth power switch Q4) must be consistent. If the frequency of the power switches on the primary side is adjusted, the frequencies of the first rectifier switch SR1 and the second rectifier switch SR2 must also be adjusted synchronously.

[0143] Generally, the ground signal of the secondary-side first conversion circuit 2 is different from the ground signal of the secondary-side second conversion circuit 3. The ground signal of the control module 5 can be the same as the ground signal of the secondary-side first conversion circuit 2 or the same as the ground signal of the secondary-side second conversion circuit 3. As shown in Figure 8, the ground signal of the secondary-side first conversion circuit 2 is GND1, and the ground signal of the secondary-side second conversion circuit 3 is GND2. That is, the ground signal of voltage signal Vo1 is GND1, and the ground signal of voltage signal Vo2 is GND2. If the ground signal of the control module 5 is GND1, in order to avoid the voltage signal Vo2 collected by the control module 5 being inaccurate due to the difference between the ground signal of the control module 5 and the ground signal of the secondary-side second conversion circuit 3, an isolation module needs to be added between the collected voltage signal Vo2 and the control module 5. As shown in Figure 8, the voltage signal Vo1 reaches the control module 5 after passing through the first sampling circuit and the first amplifier, and the voltage signal Vo2 reaches the control module 5 after passing through the second sampling circuit, the isolation module (e.g., the isolation chip), and the second amplifier.

[0144] Optionally, the control module 5 includes a first controller 51 and a second controller 52;

[0145] The control module 5 determines the parameters of the first and second transmitted signals based on the output voltage and output current of the secondary-side second conversion circuit 3, including:

[0146] The second controller 52 determines the parameters of the first transmitted signal and the parameters of the second transmitted signal based on the output voltage and the output current of the secondary-side second conversion circuit 3.

[0147] The control module 5 determines the parameters of the third, fourth, fifth, and sixth transmitted signals based on the output voltage and output current of the secondary-side first conversion circuit 2, including:

[0148] The first controller 51 determines the parameters of the third, fourth, fifth, and sixth transmitted signals based on the output voltage and output current of the secondary first conversion circuit 2.

[0149] The control module 5 determines the parameters of the seventh, eighth, ninth, and tenth transmitted signals based on the output voltage and output current of the secondary-side first conversion circuit 2, including:

[0150] The first controller 51 determines the parameters of the seventh wave signal, the eighth wave signal, the ninth wave signal, and the tenth wave signal based on the output voltage and the output current of the secondary first conversion circuit 2.

[0151] Please refer to Figure 9, which is a schematic diagram of the control principle of another control module 5 provided in an embodiment of this application. As shown in Figure 9, the control module 5 includes a first controller 51 and a second controller 52. The first controller 51 can determine the parameters of the third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth wave signals based on the output voltage Vo1 and the output current io1 of the secondary first conversion circuit 2, respectively, and use them 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.

[0152] The second controller 52 can determine the parameters of the first wave signal and the parameters of the second wave signal based on the output voltage Vo2 of the secondary side second conversion circuit 3 and the output current io2 of the secondary side second conversion circuit 3. The parameters of the first wave signal and the parameters of the second wave signal are used to control the first rectifier switch SR1 and the second rectifier switch SR2, respectively.

[0153] Optionally, the first controller 51 shares a common ground with the secondary first conversion circuit 2, and the second controller 52 shares a common ground with the secondary second conversion circuit 3. The first controller 51 and the second controller 52 are synchronized in time through a synchronization signal.

[0154] Generally, the ground signal of the secondary-side first conversion circuit 2 is different from the ground signal of the secondary-side second conversion circuit 3. The first controller 51 shares a common ground with the secondary-side first conversion circuit 2, meaning the ground signal of the first controller 51 is the same as the ground signal of the secondary-side first conversion circuit 2. The second controller 52 shares a common ground with the secondary-side second conversion circuit 3, meaning the ground signal of the second controller 52 can be the same as the ground signal of the secondary-side second conversion circuit 3. As shown in Figure 9, the ground signal of the secondary-side first conversion circuit 2 is GND1, and the ground signal of the secondary-side second conversion circuit 3 is GND2. That is, the ground signal of voltage signal Vo1 is GND1, the ground signal of voltage signal Vo2 is GND2, the ground signal of the first controller 51 is GND1, and the ground signal of the second controller 52 is GND2. As shown in Figure 9, the voltage signal Vo1 reaches the first controller 51 after passing through the first sampling circuit and the first amplifier, and the voltage signal Vo2 reaches the second controller 52 after passing through the second sampling circuit and the second amplifier.

[0155] In this embodiment, the ground signal of the first controller 51 is the same as the ground signal of the secondary first conversion circuit 2. No isolation module is needed between the first controller 51 and the acquired voltage signal Vo1, thereby reducing the cost of voltage acquisition. Similarly, the ground signal of the second controller 52 is the same as the ground signal of the secondary second conversion circuit 3. No isolation module is needed between the second controller 52 and the acquired voltage signal Vo2, further reducing the cost of voltage acquisition.

[0156] Since the grounding signal of the first controller 51 and the grounding signal of the second controller 52 are different, in order to ensure the timing synchronization between the first controller 51 and the second controller 52, the first controller 51 and the second controller 52 are synchronized through a synchronization signal.

[0157] Please refer to Figure 10, which is a timing diagram of a waveform signal provided in an embodiment of this application. As shown in Figure 10, from top to bottom, the waveforms are: the PWM waveform of the primary-side power switch, the PWM waveform of the first rectifier switch SR1, and the PWM waveform of the second rectifier switch SR1. The PWM waveforms of the primary-side power switches include 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 waveform period Ts of the waveform signals of the first rectifier switch SR1 and the second rectifier switch SR2 needs to be the same as the frequency of the primary-side power switches (first power switch Q1, second power switch Q2, third power switch Q3, and fourth power switch Q4). The on-time of the first rectifier switch SR1 and the second rectifier switch SR2 is D*Ts, where D is the duty cycle D of SR1-SR2 output by the second PI controller in Figure 8. The turn-off times of the first rectifier switch SR1 and the second rectifier switch SR2 are fixed relative to the primary-side PWM waveform: the turn-off of the first rectifier switch SR1 lags behind the turn-off times of the first power switch Q1 and the fourth power switch Q4 on the primary side by a first duration t1; the turn-off of the second rectifier switch SR2 lags behind the turn-off times of the second power switch Q2 and the third power switch Q3 on the primary side by a first duration 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 5. The wave signal in Figure 10 uses a square wave signal as an example.

[0158] The wave generation period Ts can be the switching period mentioned above.

[0159] The charging circuit 100 of this application embodiment can achieve complete decoupling of the two output ports, and the low-voltage side output can be controlled independently without being affected by the high-voltage side output. The charging circuit 100 has fewer switching devices and fewer sensors, is simple to control, low in cost, and highly reliable.

[0160] Please refer to Figure 11, which is a schematic diagram of the simulated output voltage and output current of a secondary-side second conversion circuit 3 provided in an embodiment of this application. Figure 11 shows the simulated waveforms of the output current io2 and the output voltage Vo2 of the secondary-side second conversion circuit 3 when the output voltage Vo1 of the secondary-side first conversion circuit 2 changes (as shown in Figure 11, when the output voltage Vo1 of the secondary-side first conversion circuit 2 decreases from 600V to 400V). As shown in Figure 11, at the instant the output voltage Vo1 of the secondary-side first conversion circuit 2 changes, the output voltage Vo2 of the secondary-side second conversion circuit 3 experiences a brief change of 0.1V (from 13.8V to 13.7V), and then returns to the predetermined output of 13.8V. As can be seen from Figure 11, in this embodiment of the application, the output ports of the secondary-side first conversion circuit 2 and the secondary-side second conversion circuit 3 can be decoupled (i.e., the outputs of the secondary-side first conversion circuit 2 and the secondary-side second conversion circuit 3 do not interfere with each other). The output current io2 of the secondary-side second conversion circuit 3 in Figure 11 varies greatly, mainly because it is related to the load at the output port of the second conversion circuit. When the load is large, the output current io2 of the secondary-side second conversion circuit 3 decreases faster.

[0161] This application embodiment can also provide an on-board charging device 200, which may include any of the charging circuits 100 shown in Figures 1 to 6. Please refer to Figure 12, which is a structural schematic diagram of an on-board charging device 200 provided in this application embodiment. As shown in Figure 12, the on-board charging device 200 includes the charging circuits 100 shown in Figures 1 to 6. The charging circuit 100 is used to charge the power battery and can also be used to supply power to the electrical devices and the battery (not shown in Figure 12) of the vehicle 300.

[0162] Please refer to Figure 13, which is a structural schematic diagram of a vehicle 300 provided in an embodiment of this application. As shown in Figure 13, the vehicle 300 may include an on-board charging device 200 as shown in Figure 12.

[0163] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0164] In the several embodiments provided in this application, it should be understood that the disclosed charging circuit 100 and electric device can be implemented in other ways. For example, the charging circuit 100 embodiments described above are merely illustrative. For instance, the division of the units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

Claims

1. A charging circuit, wherein, The system includes a primary-side conversion circuit (1), a secondary-side first conversion circuit (2), a secondary-side second conversion circuit (3), and a transformer module (4). The transformer module (4) has a first winding (W1) at its first end and a second winding (W2) and a third winding (W3) at its second end. The first winding (W1) is connected to the primary-side conversion circuit (1), the second winding (W2) is connected to the secondary-side first conversion circuit (2), and the third winding (W3) is connected to the secondary-side second conversion circuit (3). The secondary-side second conversion circuit (3) includes a rectifier module (31) and is configured to independently adjust the output voltage based on the rectifier module (31).

2. The charging circuit according to claim 1, wherein, The secondary-side second conversion circuit (3) also includes an energy storage module (32) connected to the rectifier module (31). The energy storage module (32) and the rectifier module (31) cooperate to adjust the output voltage of the secondary-side second conversion circuit (3).

3. The charging circuit according to claim 2, wherein, The rectifier module (31) includes a first rectifier unit (311) and a second rectifier unit (312); the first rectifier unit (311) includes a first rectifier switch (SR1), and the second rectifier unit (312) includes a second rectifier switch (SR2); or, the first rectifier unit (311) includes at least two first rectifier switches (SR1) connected in parallel, and the second rectifier unit (312) includes at least two second rectifier switches (SR2) connected in parallel; one end of the first rectifier switch (SR1) and the second rectifier switch (SR2) are connected to each other, and the other end is respectively connected to the energy storage module (32).

4. The charging circuit according to claim 3, wherein, The duty cycles of both the first rectifier switch (SR1) and the second rectifier switch (SR2) are greater than 50%.

5. The charging circuit according to claim 3, wherein, The duty cycles of the first rectifier switch (SR1) and the second rectifier switch (SR2) are both greater than the duty cycle of the primary-side switching circuit (1).

6. The charging circuit according to claim 3, wherein, The energy storage module (32) includes a coupling inductor (321), 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).

7. The charging circuit according to claim 6, wherein, The energy storage module (32) 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) through the first inductor (L1), and the second coil (N2) is connected to the other end of the third winding (W3) through the second inductor (L2).

8. The charging circuit according to claim 3, wherein, The energy storage module (32) 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).

9. The charging circuit according to claim 3, wherein, The secondary-side second conversion circuit (3) further includes a first capacitor (C1), one end of which is connected to the interconnection of the first rectifier switch (SR1) and the second rectifier switch (SR2), and the other end is grounded; the two ends of the first capacitor (C1) are adapted to be connected to the voltage output port.

10. The charging circuit according to claim 7 or 8, wherein, During at least one switching cycle, the turn-off time of the first rectifier switch (SR1) lags behind the turn-off time of the first power switch (Q1) of the primary-side switching circuit (1) by a first duration; and / or, the turn-off time of the second rectifier switch (SR2) lags behind the turn-off time of the second power switch (Q2) of the primary-side switching circuit (1) by a first duration.

11. The charging circuit according to claim 10, wherein, The first duration is determined based on the output current and voltage waveform amplitude of the secondary side second conversion circuit (3) and the inductance of the first inductor (L1).

12. The charging circuit according to claim 11, wherein, The first duration is obtained according to the following formula: t1=k*io2*L1 / (0.5*Vin); Wherein, t1 is the first duration, k is the control coefficient, io2 is the output current of the secondary side second conversion circuit (3), L1 is the inductance of the first inductor (L1), and Vin is the voltage waveform amplitude input from the transformer module (4) to the secondary side second conversion circuit (3).

13. The charging circuit according to claim 10, wherein, The primary-side conversion circuit (1) includes: a first power switch (Q1), a second power switch (Q2), a third power switch (Q3), a fourth power switch (Q4), and a resonant circuit (15). The first end of the first power switch (Q1) is connected to the first end of the second power switch (Q2) and the positive terminal of the DC power supply (6). 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 (15). 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 (15). The second end of the third power switch (Q3) is connected to the second end of the fourth power switch (Q4) and the negative terminal of the DC power supply (6).

14. The charging circuit according to claim 13, wherein, The charging circuit (100) further includes a control module (5), which determines the parameters of the first wave signal and the parameters of the second wave signal based on the output voltage of the secondary second conversion circuit (3) and the output current of the secondary second conversion circuit (3); the first wave signal is used to control the first rectifier switch (SR1) to turn on or off, so as to control the first current path to turn on or off, and / or the second wave signal is used to control the second rectifier switch (SR2) to turn on or off, so as to control the second current path to turn on or off.

15. The charging circuit according to claim 14, wherein, The control module (5) determines the parameters of the third, fourth, fifth, and sixth wave signals based on the output voltage and output current of the secondary first conversion circuit (2). The third wave signal is used to control the first power switch (Q1) to turn on or off, the fourth wave signal is used to control the second power switch (Q2) to turn on or off, the fifth wave signal is used to control the third power switch (Q3) to turn on or off, and the sixth wave signal is used to control the fourth power switch (Q4) to turn on or off. The parameters of the third wave signal are the same as those of the sixth wave signal, and the parameters of the fourth wave signal are the same as those of the fifth wave signal.

16. The charging circuit according to claim 15, wherein, The secondary-side first conversion circuit (2) 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 (2). The second end of the fifth power switch (Q5) is connected to the first end of the seventh power switch (Q7). The second end of the sixth power switch (Q6) is connected to the first end of the eighth power switch (Q8). 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 (2). The control module (5) determines the parameters of the seventh wave signal, the eighth wave signal, the ninth wave signal, and the tenth wave signal based on the output voltage and output current of the secondary first conversion circuit (2). The seventh wave signal is used to control the conduction or de-conduction of the fifth power switch (Q5), the eighth wave signal is used to control the conduction or de-conduction of the sixth power switch (Q6), the ninth wave signal is used to control the conduction or de-conduction of the seventh power switch (Q7), and the tenth wave signal is used to control the conduction or de-conduction of the eighth power switch (Q8).

17. The charging circuit according to claim 16, wherein, The control module (5) includes a first controller (51) and a second controller (52); The control module (5) determines the parameters of the first and second transmitted signals based on the output voltage and output current of the secondary-side second conversion circuit (3), including: The second controller (52) determines the parameters of the first wave signal and the parameters of the second wave signal based on the output voltage of the secondary side second conversion circuit (3) and the output current of the secondary side second conversion circuit (3); The control module (5) determines the parameters of the third, fourth, fifth, and sixth transmitted signals based on the output voltage and output current of the secondary-side first conversion circuit (2), including: The first controller (51) 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 of the secondary first conversion circuit (2) and the output current of the secondary first conversion circuit (2). The control module (5) determines the parameters of the seventh, eighth, ninth, and tenth wave signals based on the output voltage and output current of the secondary-side first conversion circuit (2), including: The first controller (51) determines the parameters of the seventh wave signal, the eighth wave signal, the ninth wave signal, and the tenth wave signal based on the output voltage of the secondary first conversion circuit (2) and the output current of the secondary first conversion circuit (2).

18. The charging circuit according to claim 17, wherein, The first controller (51) shares a common ground with the secondary first conversion circuit (2), and the second controller (52) shares a common ground with the secondary second conversion circuit (3). The first controller (51) and the second controller (52) are synchronized in time through a synchronization signal.

19. The charging circuit according to any one of claims 7-8 and 10-18, wherein, The inductance of the first inductor (L1) is equal to the inductance of the second inductor (L2).

20. The charging circuit according to claim 6 or 7, wherein, The coupling coefficient of the coupled inductor (321) is greater than a set threshold.

21. An on-board charging device, wherein, Includes the charging circuit (100) as described in any one of claims 1 to 20.

22. A vehicle, wherein, Includes the on-board charging device (200) as described in claim 21.

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