On-board charger and control method thereof

Abstract

In the control method for an on-board charger, the transformer side of the AC / AC conversion circuit (30) is connected to the AC side of the AC / DC conversion circuit (40) via the transformer (10), the on-board charger has a single-stage structure, and since the instantaneous sampling value of the grid-side current in a stable state is equal to its instantaneous reference value, the instantaneous reference value of the grid-side current is determined by the phase of the instantaneous sampling value of the grid-side voltage and the reference peak value of the grid-side current. The on-board charger has a PFC function, and indirectly controls the battery-side charging power by controlling the grid-side current, thereby giving the on-board charger a battery-side voltage / current control function, and also realizes soft switching of the power devices in the two conversion circuits by performing phase shift control on the two conversion circuits. The single-stage structure reduces the number of devices through which current flows, improving efficiency, and thus the single-stage structure can be used to efficiently realize the PFC and battery-side voltage / current control functions of the two-stage isolation type on-board charger. Further, an on-board charger is disclosed.

Description

[Technical field]

[0001] This application claims priority to a Chinese patent application bearing application number 202211460016.1 and entitled "On-board charger and control method thereof" filed with the State Intellectual Property Office of the People's Republic of China on November 16, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of power electronics technology, and in particular to an on-board charger and a control method thereof. [Background technology]

[0003] Currently, two-stage isolation type on-board chargers are commonly used on the market, also known as a two-stage structure, and its specific structure can be seen in Figure 1. The two-stage isolation type includes a PFC (Power Factor Correction) circuit and an isolated DC / DC conversion circuit. The PFC circuit is responsible for correcting the power factor of the power grid current and maintaining the stability of the bipolar voltage of the DC bus Cbus, and the isolated DC / DC conversion circuit controls the battery side voltage or battery side current of the on-board charger to complete the battery charging process.

[0004] Normally, a two-stage isolation type on-board charger requires more power devices, which increases the overall cost of the on-board charger. To reduce the overall cost of the on-board charger, a single-stage isolation type on-board charger (also called a one-stage structure) can be adopted.

[0005] Therefore, how to efficiently realize the PFC function and battery side voltage / current control function of a two-stage isolation type on-board charger by using a single-stage isolation type on-board charger is a technical problem that needs to be solved as soon as possible. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of this, the present invention provides an on-board charger and a control method thereof for efficiently realizing the PFC function and battery side voltage / current control function of a two-stage isolation type on-board charger by using a single-stage isolation type on-board charger. [Means for solving the problem]

[0007] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions. One aspect of the present application provides a control method for an on-board charger, the control method comprising: adjusting a reference peak value of a grid-side current of the on-board charger based on a deviation of the sampled value of the battery-side voltage from a reference value of the battery-side voltage; converting the reference peak value of the grid-side current into an instantaneous reference value of the grid-side current based on a phase of the obtained instantaneous sampling value of the grid-side voltage of the on-board charger; performing phase shift control on two conversion circuits based on an instantaneous reference value of the grid-side current, an instantaneous sampled value of the grid-side voltage, and a sampled value of the battery-side voltage, the phase shift control causing power devices in the two conversion circuits to realize soft switching; and correcting the phase shift control based on a deviation of the instantaneous sampled value of the grid-side current from an instantaneous reference value of the grid-side current.

[0008] Preferably, the phase shift control comprises: determining a phase shift angle of a transformer-side output voltage of the AC / AC conversion circuit and a phase shift angle of an AC-side output voltage of the AC / DC conversion circuit based on a combination of an instantaneous reference value of the grid-side current, an instantaneous sampled value of the grid-side voltage, a sampled value of the battery-side voltage, a switching frequency of the on-board charger, and an equivalent total reactance (i.e., a sum of equivalent reactances) of all passive elements in the on-board charger; generating drive signals for two conversion circuits based on the two phase shift angles respectively; and driving each conversion circuit based on a drive signal for each conversion circuit to perform power conversion.

[0009] Preferably, the step of determining a phase shift angle of a transformer side output voltage of the AC / AC conversion circuit and a phase shift angle of an AC side output voltage of the AC / DC conversion circuit includes: determining a phase shift angle of a transformer side output voltage of the AC / AC conversion circuit and a relationship between two phase shift angles based on a combination of an instantaneous reference value of the grid-side current, an instantaneous sampled value of the grid-side voltage, a sampled value of the battery-side voltage, a switching frequency of the on-board charger, and an equivalent total reactance of all passive elements in the on-board charger, wherein the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit is within a range of values ​​that can realize soft switching of power devices in two conversion circuits; and determining a phase shift angle of an AC side output voltage of the AC / DC conversion circuit based on the phase shift angle of a transformer side output voltage of the AC / AC conversion circuit and a relationship between the two phase shift angles.

[0010] Preferably, the step of correcting the phase shift control based on a deviation of an instantaneous sampled value of the grid side current from an instantaneous reference value of the grid side current comprises: The method includes the step of correcting at least one phase shift angle in the phase shift control.

[0011] Preferably, the reference value of the battery side voltage is equal to a charging voltage in a constant voltage trickle charging state of a battery connected to the on-board charger.

[0012] Preferably, the step of adjusting a reference peak value of a grid-side current of the on-board charger based on a deviation of a sampled value of the battery-side voltage from a reference value of the battery-side voltage further comprises: adjusting the reference value of the battery side current based on a deviation of the sampled value of the battery side voltage from the reference value of the battery side voltage; and adjusting the reference peak value of the grid-side current based on a deviation of the sampled value of the battery-side current from a reference value of the battery-side current.

[0013] Preferably, the reference value of the battery side current is equal to or less than a charging current in a constant current charging state of a battery connected to the on-board charger.

[0014] Preferably, the charging current in the constant current charging state of the battery is determined according to an operating state of the on-board charger and a user instruction.

[0015] Another aspect of the present application provides an on-board charger, the on-board charger including: a controller; a transformer; at least one passive element; a bridge-type controllable AC / AC conversion circuit; and an AC / DC conversion circuit; a transformer side of the AC / AC conversion circuit is connected to an AC side of the AC / DC conversion circuit via the transformer, a grid side of the AC / AC conversion circuit serves as a grid side of the on-board charger, and a DC side of the AC / DC conversion circuit serves as a battery side of the on-board charger, The passive elements are provided on a primary side and / or a secondary side of the transformer, and each of the passive elements includes at least an inductor; Both the AC / AC conversion circuit and the AC / DC conversion circuit are controlled by a controller for executing the control method for an on-board charger according to any one of the aspects of the present application.

[0016] Preferably, the AC / AC conversion circuit is a half-bridge topology or a full-bridge topology; The AC / DC conversion circuit is a half-bridge or full-bridge topology.

[0017] Preferably, the passive element includes an inductor branch, the inductor branch including at least one inductor; When the number of the inductors is greater than one, the inductors are connected in series, in parallel, or in series-parallel.

[0018] Preferably, the passive element further includes a capacitor branch (a capacitor branch circuit) connected in series or in parallel with the inductor branch, the capacitor branch includes at least one capacitor; When the number of the capacitors is greater than one, the capacitors are connected in series, in parallel, or in series-parallel.

[0019] Preferably, the switching frequency of the on-board charger is greater than a resonant frequency of a resonant cavity in the on-board charger.

[0020] Preferably, the filter further comprises two filters: One of the filters is installed on the grid side of the AC / AC conversion circuit, and the other filter is installed on the DC side of the AC / DC conversion circuit.

[0021] As is clear from the above technical proposal, the present invention provides a control method for an on-board charger. In this control method for an on-board charger, the transformer side of the AC / AC conversion circuit is connected to the AC side of the AC / DC conversion circuit via a transformer, so that the on-board charger is a single-stage isolation type on-board charger. In addition, the instantaneous sampling value of the grid-side current in a stable state is equal to its instantaneous reference value, and the instantaneous reference value of the grid-side current is determined by the phase of the instantaneous sampling value of the grid-side voltage and the reference peak value of the grid-side current, so that the on-board charger has a PFC function. In addition, the battery-side charging power can be indirectly controlled by controlling the grid-side current, so that the on-board charger has a battery-side voltage / current control function. In addition, phase shift control is performed on the two conversion circuits, and the phase shift control enables soft switching of the power devices in the two conversion circuits to be realized, and the single-stage isolation type on-board charger reduces the number of devices through which current flows, so that the efficiency of the on-board charger can be improved. As described above, this control method can efficiently realize the PFC function and battery side voltage / current control function of a two-stage isolation type on-board charger by utilizing a single-stage isolation type on-board charger. In order to more clearly describe the technical solutions in the embodiments of the present application or the prior art, the drawings used in the description of the embodiments or the prior art are briefly described below. Obviously, the drawings in the following description are some embodiments of the present application. Those skilled in the art can obtain other drawings from these drawings without creative efforts. [Brief description of the drawings]

[0022] [Figure 1] Schematic diagram of a conventional two-stage isolation type on-board charger [Diagram 2] FIG. 1 is a schematic diagram showing the configuration of an embodiment of an on-board charger provided by an embodiment of the present application. [Diagram 3] 1 is a flowchart of an embodiment of a control method for an on-board charger provided by an embodiment of the present application. [Figure 4]1 is a flowchart illustrating another embodiment of a method for controlling an on-board charger according to an embodiment of the present application. [Diagram 5] Schematic of an embodiment of an on-board charger control loop [Figure 6] Equivalent circuit of the fundamental wave of the on-board charger provided by the embodiment of the present application [Figure 7] Power transmission vector diagram in Figure 6 [Figure 8a] Schematic diagram of grid side voltage simulation test results [Figure 8b] Schematic diagram of grid-side current simulation test results [Figure 8c] Schematic diagram of battery side voltage simulation test results [Figure 8d] Schematic diagram of battery side current simulation test results [Figure 9] 1 is a flow chart of a specific embodiment of the phase shift control provided by the present application. [Figure 10] Schematic diagram of another embodiment of an on-board charger control loop; [Figure 11a] Schematic diagram of the drive signals for the two conversion circuits in one embodiment of the on-board charger during a positive half-cycle of the power grid. [Figure 11b] Schematic diagram of the drive signals of the two conversion circuits of one embodiment of the on-board charger during the negative half-cycle of the power grid. [Figure 12a] 1 is a schematic diagram of the drive signals of the two conversion circuits in another embodiment of the on-board charger during a positive half-cycle of the power grid; [Figure 12b] 1 is a schematic diagram of the drive signals of the two conversion circuits in another embodiment of the on-board charger during a negative half-cycle of the power grid; [Figure 13a] Half-bridge frequency conversion circuit configuration diagram [Figure 13b] Full-bridge frequency conversion circuit configuration schematic [Figure 13c] Half-bridge rectifier circuit configuration diagram [Figure 13d] Full-bridge rectifier circuit configuration diagram [Figure 14]1 is a flow chart of another specific embodiment of the phase shift control provided by the present application. [Figure 15] FIG. 1 is a schematic diagram showing another embodiment of an on-board charger provided by an embodiment of the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, and are not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0024] In this application, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that such an actual relationship or order exists between these entities or operations. And the terms "comprise", "have" and any variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, product or device that includes a set of elements further includes not only those elements, but also other elements not expressly listed or inherent to the process, method, product or device. In the absence of further limitations, an element defined by the phrase "including a" does not exclude the presence of other identical elements in the process, method, product or device that includes the element.

[0025] In order to improve the efficiency of the single-stage isolation type on-board charger and provide the single-stage isolation type on-board charger with a PFC function, an embodiment of the present application provides a control method for the on-board charger.

[0026] 2, the on-board charger includes a transformer 10, an AC / AC conversion circuit 30, and an AC / DC conversion circuit 40. The transformer side of the AC / AC conversion circuit 30 is connected to the AC side of the AC / DC conversion circuit 40 via the transformer 10, and passive elements 20 are provided on the primary side and / or secondary side of the transformer 10, each of the passive elements 20 including at least an inductor, and both the AC / AC conversion circuit 30 and the AC / DC conversion circuit 40 are of a bridge-type controllable topology.

[0027] As shown in FIG. 3, the flow of the control method for the on-board charger specifically includes the following steps.

[0028] In S110, the reference peak value of the grid-side current of the vehicle-mounted charger is adjusted based on the deviation of the sampled value of the battery-side voltage from the reference value of the battery-side voltage.

[0029] The reference peak value of the grid-side current is the reference value of the peak value of the grid-side current, and the reference value of the battery-side voltage is equal to the charging voltage of the battery connected to the on-board charger in a constant voltage trickle charging state. Note that the charging voltage is not usually adjusted.

[0030] In practical application, as shown in FIG. 4, a specific embodiment of step S110 includes the following steps:

[0031] In S210, the reference value of the battery side current is adjusted based on the deviation of the sampled value of the battery side voltage from the reference value of the battery side voltage.

[0032] The reference value of the battery side current is equal to or less than the charging current of the battery connected to the on-board charger in a constant current charging state. In practical application, the charging current is determined by the operating state and user command of the on-board charger, so that the charging current can be adjusted according to the operating state and user command of the on-board charger.

[0033] In practical application, the control loop corresponding to step S210 specifically includes a first PI controller and a limiter, as shown by reference numeral 01 in Fig. 5, and the limit value of the limiter is the charging current in the constant current charging state, where Vdc_ref is the reference value of the battery side voltage, Vdc is the sampling value of the battery side voltage, and Idc_ref is the reference value of the battery side current.

[0034] In S220, the reference peak value of the grid-side current is adjusted based on the deviation of the sampled value of the battery-side current from the reference value of the grid-side current.

[0035] In practical application, the control loop corresponding to step S220 specifically includes a second PI controller, as shown in FIG. 5 by reference numeral 02, where Idc is the sampled value of the battery side current, and Ig_ref is the reference peak value of the grid side current.

[0036] As can be seen from steps S210 and S220, in the initial stage of charging, the battery has a large power loss and the battery end voltage is low, so the sampling value of the battery side voltage is always much smaller than the reference value of the battery side voltage, and the reference value of the battery side current after adjustment is always equal to the charging current in the constant current charging state of the battery, and the battery is in a constant current charging state. As the battery is gradually filled, the battery end voltage continues to rise and becomes slightly larger than the reference value of the battery side voltage, and the reference value of the battery side current after adjustment begins to be smaller than the charging current in the constant current charging state, and gradually decreases, and finally the sampling value of the battery side voltage is stabilized to the reference value of the battery side voltage, so that the battery is in a constant voltage trickle charging state.

[0037] In S120, the reference peak value of the grid-side current is converted into an instantaneous reference value of the grid-side current based on the phase of the obtained instantaneous sampling value of the grid-side voltage of the vehicle-mounted charger.

[0038] However, the instantaneous reference value of the grid side current is a reference value of the instantaneous value of the grid side current.

[0039] In practical application, the control loop corresponding to step S120 specifically includes a PLL (Phase Locked Loop) and a parameter conversion link, as shown by reference numeral 03 in Fig. 5, where vg is the instantaneous sampling value of the grid side voltage, θ is the phase of the instantaneous sampling value of the grid side voltage, sinθ is the transfer function of the parameter conversion part, and ig_ref is the instantaneous reference value of the grid side current.

[0040] In S130, phase shift control is performed on the two conversion circuits based on the instantaneous reference value of the grid side current, the instantaneous sampled value of the grid side voltage, and the sampled value of the battery side voltage.

[0041] The phase shift control adjusts the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit and the phase shift angle of the AC side output voltage of the AC / DC conversion circuit, that is, adjusts the phase difference between the two output voltages, thereby controlling the power transmission of the on-board charger. In addition, in the above adjustment procedure, the power devices in the two conversion circuits can realize soft switching. In the following embodiment, the phase shift control will be described in detail, but will not be described again here.

[0042] In practical application, the control loop corresponding to step S130 is shown as reference numeral 04 in FIG. 5, and the specific control procedure of this control loop will be described in detail in the following embodiment, but will not be described again here.

[0043] Controlling the power transmission of the on-board charger using the above two phase differences will be described in detail below.

[0044] By performing a fundamental wave equivalent analysis on the on-board charger, an equivalent circuit like that shown in Figure 6 is obtained. In Figure 6, the output voltage of the AC / AC conversion circuit transformer side Fundamental component of TIFF2025515923000002.tif1118 TIFF2025515923000003.tif1115 characterizes the AC / AC conversion circuit transformer side output voltage and the AC / DC conversion circuit AC side output voltage Fundamental component of TIFF2025515923000004.tif1118 TIFF2025515923000005.tif1014 characterizes the AC side output voltage of the AC / DC conversion circuit. In practical applications, TIFF2025515923000006.tif1377, TIFF2025515923000007.tif1249, where β / 2 is the fundamental component TIFF2025515923000008.tif1115, α is the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit, and β is the phase shift angle of the AC side output voltage of the AC / DC conversion circuit.

[0045] Also, in FIG. TIFF2025515923000009.tif1213 is the equivalent total reactance of all passive elements, specifically, The file is TIFF2025515923000010.tif1153. TIFF2025515923000011.tif1020 shows the current in the equivalent total reactance above, i.e. the current in the transformer.

[0046] According to the above equivalent circuit, the power transfer vector diagram shown in Figure 7 can be drawn. As can be seen from Figure 7, with the change of α and β, the voltage across the above equivalent total reactance The mode and declination of TIFF2025515923000012.tif1243 change, The mode and argument of TIFF2025515923000013.tif1020 are changed. Therefore, by adjusting α and β, the magnitude and direction of the current in the equivalent total reactance can be controlled, and thus the direction and magnitude of the transmission power of the on-board charger, i.e., the power transmission of the on-board charger, can be controlled.

[0047] When the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit is defined as positive, it indicates that the phase after the phase shift of the transformer side output voltage of the AC / AC conversion circuit leads the phase when the phase shift angle is zero, and conversely, it indicates that the phase after the phase shift of the transformer side output voltage of the AC / AC conversion circuit lags the phase when the phase shift angle is zero. When the phase shift angle of the AC side output voltage of the AC / DC conversion circuit is negative, it indicates that the phase after the phase shift of the AC side output voltage of the AC / DC conversion circuit lags the phase when the phase shift angle is zero, and conversely, it indicates that the phase after the phase shift of the AC side output voltage of the AC / DC conversion circuit leads the phase when the phase shift angle is zero.

[0048] In S140, the phase shift control is corrected based on the deviation of the instantaneous sampled value of the grid side current from the instantaneous reference value of the grid side current.

[0049] In practical application, the control loop corresponding to step S140 specifically includes a resonant PI controller, as shown in FIG. 5 at reference numeral 05, where ig is the instantaneous sampling value of the grid-side current.

[0050] In practical applications, the correction of the phase shift control may be correcting the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit, or may be correcting the phase shift angle of the AC side output voltage of the AC / DC conversion circuit, or may be simultaneously correcting the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit and the phase shift angle of the AC side output voltage of the AC / DC conversion circuit; this is not specifically limited here and is determined according to specific circumstances.

[0051] In this on-board charger control method, the transformer side of the AC / AC conversion circuit is connected to the AC side of the AC / DC conversion circuit via a transformer, so that the on-board charger is a single-stage isolated on-board charger. In addition, when the on-board charger reaches a steady state, the instantaneous sampling value of the grid-side current is equal to the instantaneous reference value of the grid-side current, and the instantaneous reference value of the grid-side current is determined by the phase of the instantaneous sampling value of the grid-side voltage and the reference peak value of the grid-side current, so that the grid-side current is in phase with the grid-side voltage, that is, this on-board charger has a PFC function. In addition, phase shift control is performed on the two conversion circuits, and the power devices in the two conversion circuits can realize soft switching through the phase shift control. Furthermore, the single-stage isolated on-board charger reduces the number of devices through which current flows, so that the efficiency of the on-board charger can be improved. As described above, this control method can efficiently realize the PFC function and the battery-side voltage / current control function of the two-stage isolated on-board charger by using the single-stage isolated on-board charger.

[0052] In order to verify the effectiveness of the control method of the on-board charger provided by the present application, a simulation test of the on-board charger is performed using this control method, and the test results are shown in Figures 8a, 8b, 8c, and 8d. As can be seen from Figures 8a and 8b, the grid side voltage and grid side current are inverted, so that grid side power factor and current control can be realized. As can be seen from Figures 8c and 8d, the on-board charger can complete the charging function to the battery according to the preset battery side voltage and battery side current.

[0053] It should be noted that the simulated THD (Total Harmonic Distortion) in FIGS. 8a and 8b is 2%.

[0054] This on-board charger includes a transformer and a bridge-type controllable AC / AC conversion circuit and an AC / DC conversion circuit, and the transformer side of the AC / AC conversion circuit is connected to the AC side of the AC / DC conversion circuit via the transformer, so that the number of power devices included in this on-board charger is reduced, thereby reducing the overall cost of the on-board charger. In addition, because the number of power devices included in this on-board charger is reduced, the number of control inputs is also reduced accordingly, and the control cost of the on-board charger is reduced. In addition, since this on-board charger does not require a busbar electrolytic capacitor, the overall cost of the on-board charger can be further reduced, and the overall volume of the on-board charger can be reduced, thereby extending the service life of the on-board charger.

[0055] Another embodiment of the present application describes in detail the specific procedure of phase shift output control, the flow of which, as shown in FIG. 9, specifically includes the following steps:

[0056] In S310, a phase shift angle of the transformer side output voltage of the AC / AC conversion circuit and a phase shift angle of the AC side output voltage of the AC / DC conversion circuit are determined based on a combination of an instantaneous reference value of the grid side current, an instantaneous sampled value of the grid side voltage, a sampled value of the battery side voltage, a switching frequency of the on-board charger, and an equivalent total reactance of all passive elements in the on-board charger.

[0057] The switching frequency of the on-board charger is the operating frequency of the switching tubes of the two conversion circuits in the on-board charger.

[0058] In practical application, the control loop corresponding to step S310 is shown as calculation part 06 in FIG. 10, where f is the switching frequency of the on-board charger, Z is the equivalent total reactance, α is the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit, and β is the phase shift angle of the AC side output voltage of the AC / DC conversion circuit.

[0059] In S320, drive signals for the two conversion circuits are generated based on the two phase shift angles, and the conversion circuits are driven based on the drive signals for each conversion circuit to perform power conversion.

[0060] When the AC / AC conversion circuit has a half-bridge topology as shown in FIG. 13a, for example, the driving signals of Sp1 to Sp4 are as shown in FIG. 11a, FIG. 11b, FIG. 12a, and FIG. 12b. In the positive half cycle of the power grid, Sp1 and Sp3 operate at high frequency, and Sp2 and Sp4 are always conductive, as shown in FIG. 11a and FIG. 12a (FIG. 11a and FIG. 12a are both shown as examples of the driving signals of the switching tubes Sp1 to Sp4 in the circuit shown in FIG. 13a). In the negative half cycle of the power grid, Sp2 and Sp4 operate at high frequency, and Sp1 and Sp3 are always conductive, as shown in FIG. 11b and FIG. 12b (FIG. 11b and FIG. 12b are both shown as examples of the driving signals of the switching tubes Sp1 to Sp4 in the circuit shown in FIG. 13a).

[0061] When the AC / AC conversion circuit is, for example, a full-bridge topology as shown in FIG. 13b, the drive of the half-bridge topology can be extended according to the logic of adopting the same drive signal to the opposite semiconductor devices of the two bridge arms (i.e., the upper side of one bridge arm and the lower side of the other bridge arm).

[0062] When the AC / DC conversion circuit has a half-bridge topology as shown in Figure 13c, for example, the drive signals of Ss1 and Ss3 are alternately conductive as shown in Figure 12a or Figure 12b (Figures 12a and 12b are shown as an example of drive signals of switching tubes Ss1 and Ss3 in the circuit shown in Figure 13c).

[0063] When the AC / DC conversion circuit has a full-bridge topology as shown in FIG. 13d, for example, the drive signals of Ss1 to Ss4 are as shown in FIG. 11a or FIG. 11b (FIG. 11a or FIG. 11b is shown as an example of drive signals of switching tubes Ss1 to Ss4 in the circuit shown in FIG. 13d), so that the two groups of Ss1 and Ss4, and Ss2 and Ss3, are alternately conductive, with Ss1 conducting before Ss4 and Ss3 conducting before Ss2.

[0064] In practical application, the control loop corresponding to step S330 is like the PWM generator 07 in FIG. 10, and Kpwm is the transfer function of the PWM generator.

[0065] This embodiment also describes in detail the specific procedure of step S310, and the flow thereof, as shown in FIG. 14, specifically includes the following steps:

[0066] In S410, a phase shift angle of the transformer side output voltage of the AC / AC conversion circuit and a relationship between the two phase shift angles are determined based on a combination of an instantaneous reference value of the grid side current, an instantaneous sampled value of the grid side voltage, a sampled value of the battery side voltage, a switching frequency of the on-board charger, and an equivalent total reactance of all passive elements in the on-board charger.

[0067] The phase shift angle of the transformer-side output voltage of the AC / AC conversion circuit is within a range of values ​​that realizes soft switching of the power devices in the two conversion circuits.

[0068] In S420, the phase shift angle of the AC side output voltage of the AC / DC conversion circuit is determined based on the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit and the relationship between the two phase shift angles.

[0069] Another embodiment of the present application provides an on-board charger, the specific configuration of which, as shown in FIG. 2, specifically includes a controller (for simplicity, the controller is not shown in FIG. 2), a transformer 10, at least one passive element 20 (only two passive elements 20 are shown in FIG. 2 as an example), a bridge-type controllable AC / AC conversion circuit 30 and an AC / DC conversion circuit 40, and the connection relationship of each device is as follows:

[0070] The transformer side of the AC / AC conversion circuit 30 is connected to the AC side of the AC / DC conversion circuit 40 via the transformer 10, the grid side of the AC / AC conversion circuit 30 is the grid side of the on-board charger and is connected to a power source, usually connected to a power grid, and the DC side of the AC / DC conversion circuit 40 is the battery side of the on-board charger and is connected to the charging interface of the vehicle.

[0071] Passive elements 20 are installed on the primary side and / or secondary side of the transformer 10, and each passive element 20 includes at least an inductor, and both the AC / AC conversion circuit 30 and the AC / DC conversion circuit 40 are controlled by a controller that executes the control method for the vehicle charger provided by the above embodiment.

[0072] Preferably, the bridge-type controllable AC / AC conversion circuit 30 may be a half-bridge topology such as the circuit shown in Figure 13a, or a full-bridge topology such as the circuit shown in Figure 13b, which is not specifically limited here, and both are within the scope of protection of the present application. The bridge-type controllable AC / DC conversion circuit 40 may be a half-bridge topology such as the circuit shown in Figure 13c, or a full-bridge topology such as the circuit shown in Figure 13d, which is not specifically limited here, and both are within the scope of protection of the present application.

[0073] In practical application, the bridge-type controllable AC / AC conversion circuit 30 is preferably a half-bridge frequency conversion circuit or a full-bridge frequency conversion circuit, and in practical application, it is not limited thereto. However, there is no specific limitation here, and it can be determined according to specific circumstances, and either one is within the scope of protection of the present application.

[0074] In practical applications, the bridge-type controllable AC / DC conversion circuit 40 is preferably a half-bridge rectifier circuit or a full-bridge rectifier circuit, and is not limited thereto in practical applications. However, no specific limitation is given here, and it can be determined according to specific circumstances, and any of them is within the scope of protection of the present application.

[0075] This embodiment provides an embodiment of the passive element 20, specifically including an inductor branch, where the inductor branch includes at least one inductor, and when the number of inductors is greater than one, the inductors are connected in series, parallel, or series-parallel.

[0076] This embodiment provides another embodiment of the passive element 20, the configuration of which, in addition to the above embodiment, further includes a capacitor branch connected in series or parallel to the inductor branch, as shown in FIG. 2 (FIG. 2 shows an example of only one capacitor and one inductor for each passive element 20), and the capacitor branch includes at least one capacitor, and when the number of capacitors is greater than one, the capacitors are connected in series, parallel, or series-parallel.

[0077] In practical applications, when the passive element 20 includes both an inductor and a capacitor, i.e., when the on-board charger is capable of resonance, the switching frequency of the on-board charger is preferentially set to be higher than the resonant frequency of the resonant cavity in the on-board charger, so as to further realize soft switching of each switching tube in the AC / AC conversion circuit 30 and the AC / DC conversion circuit 40.

[0078] This embodiment further provides another embodiment of the on-board charger, the specific configuration of which, in addition to the above embodiment, further includes two filters, one filter being installed on the grid side of the AC / AC conversion circuit 30, and the other filter being installed on the DC side of the AC / DC conversion circuit 40, as shown in FIG. 15 .

[0079] With respect to the above description of the disclosed embodiments, the features described in each embodiment in this specification may be substituted or combined with each other so that a person skilled in the art can realize or use the present application. The above is only a preferred embodiment of the present invention, and does not limit the present invention in any way. Although the present invention is disclosed in a preferred embodiment as above, it is not used to limit the present invention. Those skilled in the art can make many possible changes and modifications to the technical solution of the present invention using the above disclosed method and technical content without departing from the technical scope of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention all fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for controlling an on-board charger, comprising: In the on-board charger, a transformer side of the bridge-type controllable AC / AC conversion circuit is connected to an AC side of a bridge-type controllable AC / DC conversion circuit via a transformer; The method for controlling the on-board charger includes: adjusting a reference peak value of a grid-side current of the on-board charger based on a deviation of the sampled value of the battery-side voltage from a reference value of the battery-side voltage; converting the reference peak value of the grid-side current into an instantaneous reference value of the grid-side current based on a phase of the obtained instantaneous sampling value of the grid-side voltage of the on-board charger; a step of performing phase shift control on two conversion circuits based on an instantaneous reference value of the grid-side current, an instantaneous sampled value of the grid-side voltage, and a sampled value of the battery-side voltage, the phase shift control causing power devices in the two conversion circuits to realize soft switching; correcting the phase shift control based on a deviation of an instantaneous sampled value of the grid side current from an instantaneous reference value of the grid side current; The method according to claim 1, further comprising:

2. The phase shift control includes: determining a phase shift angle of a transformer-side output voltage of the AC / AC conversion circuit and a phase shift angle of an AC-side output voltage of the AC / DC conversion circuit based on a combination of an instantaneous reference value of the grid-side current, an instantaneous sampled value of the grid-side voltage, a sampled value of the battery-side voltage, a switching frequency of the on-board charger, and an equivalent total reactance of all passive elements in the on-board charger; generating drive signals for two conversion circuits based on the two phase shift angles respectively; driving each conversion circuit based on a drive signal of each conversion circuit to perform power conversion; The method for controlling an on-board charger according to claim 1, further comprising:

3. The step of determining a phase shift angle of a transformer side output voltage of the AC / AC conversion circuit and a phase shift angle of an AC side output voltage of the AC / DC conversion circuit includes: determining a phase shift angle of a transformer side output voltage of the AC / AC conversion circuit and a relationship between two phase shift angles based on a combination of an instantaneous reference value of the grid-side current, an instantaneous sampled value of the grid-side voltage, a sampled value of the battery-side voltage, a switching frequency of the on-board charger, and an equivalent total reactance of all passive elements in the on-board charger, wherein the phase shift angle of the transformer side output voltage of the AC / AC conversion circuit is within a range of values ​​that can realize soft switching of power devices in the two conversion circuits; determining a phase shift angle of an AC side output voltage of the AC / DC conversion circuit based on a phase shift angle of a transformer side output voltage of the AC / AC conversion circuit and a relationship between two phase shift angles; 3. The method for controlling an on-board charger according to claim 2, further comprising:

4. correcting the phase shift control based on a deviation of an instantaneous sampled value of the grid side current from an instantaneous reference value of the grid side current, correcting at least one phase shift angle in the phase shift control; The method for controlling an on-board charger according to claim 1, further comprising:

5. The reference value of the battery side voltage is equal to a charging voltage in a constant voltage trickle charging state of the battery connected to the on-board charger. The method for controlling an on-board charger according to any one of claims 1 to 4.

6. The step of adjusting a reference peak value of a grid-side current of the vehicle-mounted charger based on a deviation of a sampled value of the battery-side voltage from a reference value of the battery-side voltage includes: adjusting the reference value of the battery side current based on a deviation of the sampled value of the battery side voltage from the reference value of the battery side voltage; adjusting a reference peak value of the grid-side current based on a deviation of the sampled value of the battery-side current from a reference value of the battery-side current; The method for controlling an on-board charger according to any one of claims 1 to 4, further comprising:

7. The reference value of the battery side current is equal to or less than a charging current in a constant current charging state of the battery connected to the on-board charger. The method for controlling an on-board charger according to claim 6 .

8. The charging current in the constant current charging state of the battery is determined according to the operating state of the on-board charger and a user instruction. The method for controlling an on-board charger according to claim 7 .

9. An on-board charger, The power supply includes a controller, a transformer, at least one passive element, and a bridge-type controllable AC / AC conversion circuit and an AC / DC conversion circuit; a transformer side of the AC / AC conversion circuit is connected to an AC side of the AC / DC conversion circuit via the transformer, a grid side of the AC / AC conversion circuit serves as a grid side of the on-board charger, and a DC side of the AC / DC conversion circuit serves as a battery side of the on-board charger, The passive elements are provided on a primary side and / or a secondary side of the transformer, and each of the passive elements includes at least an inductor; The AC / AC conversion circuit and the AC / DC conversion circuit are controlled by a controller that executes the control method for an on-board charger according to any one of claims 1 to 8. An on-board charger characterized by:

10. The AC / AC conversion circuit is a half-bridge topology or a full-bridge topology, The AC / DC conversion circuit is a half-bridge topology or a full-bridge topology.

10. The vehicle charger according to claim 9.

11. the passive element includes an inductor branch, the inductor branch including at least one inductor; When the number of the inductors is greater than one, the inductors are connected in series, in parallel, or in series-parallel.

10. The vehicle charger according to claim 9.

12. the passive element further includes a capacitor branch connected in series or parallel with the inductor branch; the capacitor branch includes at least one capacitor; When the number of the capacitors is greater than one, the capacitors are connected in series, in parallel, or in series-parallel. The vehicle charger according to claim 11 .

13. The switching frequency of the on-board charger is greater than the resonant frequency of a resonant cavity in the on-board charger. The vehicle-mounted charger according to any one of claims 9 to 12.

14. Further comprising two filters: One of the filters is installed on a grid side of the AC / AC conversion circuit, and the other filter is installed on a DC side of the AC / DC conversion circuit. The vehicle-mounted charger according to any one of claims 9 to 12.

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