Charging voltage series-parallel switching device and loop control method and equipment thereof

Abstract

The invention discloses a charging voltage series-parallel connection switching device and a loop control method and equipment thereof, and relates to the technical field of electric vehicle direct current charging piles, the device comprises a series-parallel connection switching circuit and a voltage loop controller, an anti-backflow diode in a traditional series-parallel connection switching circuit is omitted in the series-parallel connection switching circuit, and the voltage loop controller is connected with the series-parallel connection switching circuit. The charging voltage series-parallel switching device can be simplified, the voltage loop control process is further improved, the midpoint voltage is introduced, the voltage loop controller carries out voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage at the same time, the risk of short circuit is avoided, and the reliability is improved. Finally, the direct-current charging pile of the electric vehicle has a wide output voltage range in a low-cost mode.

Description

Technical Field

[0001] The present application relates to the technical field of DC charging piles for electric vehicles, and in particular to a charging voltage series-parallel switching device and a loop control method and equipment thereof. Background Art

[0002] With the rapid development of electric vehicles, battery pack voltages have generally shifted towards higher voltages. Consequently, demand for DC charging stations with a wide output voltage range has increased significantly. Traditional DC charging stations for electric vehicles have a narrow output voltage range, requiring complex series-parallel switching devices at the output terminals to achieve this wide output voltage range at a high cost. Summary of the Invention

[0003] The purpose of this application is to provide a charging voltage series-parallel switching device and its loop control method and equipment, which can simplify the charging voltage series-parallel switching device and enable electric vehicle DC charging piles to have a wide output voltage range in a low-cost manner.

[0004] To achieve the above objectives, this application provides the following solutions.

[0005] In a first aspect, the present application provides a charging voltage series-parallel switching device, comprising: a series-parallel switching circuit and a voltage loop controller; The series-parallel switching circuit includes a voltage input module, a first voltage output module, a second voltage output module, and a switching module, wherein the switching module includes a switch; the output end of the voltage input module is respectively connected to the input end of the first voltage output module and the input end of the second voltage output module, the first output end of the first voltage output module serves as the first output end of the series-parallel switching circuit, the second output end of the first voltage output module is respectively connected to the first end of the switch and the second output end of the second voltage output module, the first output end of the second voltage output module is respectively connected to the second end of the switch and the first output end of the first voltage output module, and the second output end of the second voltage output module serves as the second output end of the series-parallel switching circuit; The voltage loop controller is used to sample the voltage at the first output end of the series-parallel switching circuit to obtain the output voltage, sample the voltage at the second end of the switch to obtain the midpoint voltage, and perform voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage.

[0006] Optionally, the voltage input module adopts an LLC resonant converter; The voltage input module includes a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a resonant inductor, a resonant capacitor and an input winding of a transformer; the first end of the first switching tube is respectively connected to the first input end of the voltage input module and the first end of the second switching tube, the second end of the first switching tube is respectively connected to the first end of the third switching tube and the first end of the resonant capacitor, the second end of the second switching tube is respectively connected to the first end of the fourth switching tube and the first end of the resonant inductor, the second end of the third switching tube is respectively connected to the second input end of the voltage input module and the second end of the fourth switching tube, the second end of the resonant inductor is connected to the first end of the input winding, the second end of the resonant capacitor is connected to the second end of the input winding, and the input winding is the output end of the voltage input module; The control end of the first switch tube, the control end of the second switch tube, the control end of the third switch tube and the control end of the fourth switch tube are all connected to the voltage loop controller. The voltage loop controller is used to control the duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube based on the output voltage and the midpoint voltage, so as to perform voltage loop control on the series-parallel switching circuit.

[0007] Optionally, the first voltage output module and the second voltage output module have the same structure; The first voltage output module includes an output winding of a transformer, a first rectifier diode, a second rectifier diode, a third rectifier diode, a fourth rectifier diode and an output electrolytic capacitor; the output winding is the input end of the first voltage output module; the first end of the output winding is respectively connected to the anode of the first rectifier diode and the cathode of the third rectifier diode, the second end of the output winding is respectively connected to the anode of the second rectifier diode and the cathode of the fourth rectifier diode, the cathode of the first rectifier diode is respectively connected to the cathode of the second rectifier diode and the first end of the output electrolytic capacitor, serving as the first output end of the first voltage output module, the anode of the third rectifier diode is respectively connected to the anode of the fourth rectifier diode and the second end of the output electrolytic capacitor, serving as the second output end of the first voltage output module.

[0008] Optionally, the switching module further includes a first anti-backflow diode, a second anti-backflow diode, and a third anti-backflow diode; the cathode of the first anti-backflow diode is connected to the first output end of the first voltage output module, the anode of the first anti-backflow diode is respectively connected to the second end of the switch and the first output end of the second voltage output module, the first end of the switch is connected to the anode of the second anti-backflow diode, the cathode of the second anti-backflow diode is respectively connected to the second output end of the first voltage output module and the cathode of the third anti-backflow diode, and the anode of the third anti-backflow diode is connected to the second output end of the second voltage output module; When the switch is closed, the first voltage output module and the second voltage output module are connected in series; when the switch is open, the first voltage output module and the second voltage output module are connected in parallel.

[0009] In a second aspect, the present application provides a loop control method for the above-mentioned charging voltage series-parallel switching device, comprising: Obtaining an output voltage and a midpoint voltage obtained by voltage sampling the series-parallel switching circuit; Based on the output voltage and the midpoint voltage, a voltage loop control is performed on the series-parallel switching circuit.

[0010] Optionally, performing voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage specifically includes: calculating an absolute value of a difference between the output voltage and a reference voltage to obtain an error voltage; when the first voltage output module and the second voltage output module in the series-parallel switching circuit are connected in series, the reference voltage is twice the midpoint voltage; and when the first voltage output module and the second voltage output module in the series-parallel switching circuit are connected in parallel, the reference voltage is the midpoint voltage; Determine whether the error voltage is less than a maximum error voltage value to obtain a first determination result; If the first judgment result is yes, calculating the difference between the target voltage and the output voltage to obtain a voltage loop control error factor; If the first judgment result is no, calculating the difference between the target voltage and the reference voltage to obtain a voltage loop control error factor; Based on the voltage loop control error factor, voltage loop control is performed on the series-parallel switching circuit.

[0011] Optionally, performing voltage loop control on the series-parallel switching circuit based on the voltage loop control error factor specifically includes: Performing a PI operation on the voltage loop control error factor to obtain a loop output value; The duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in the series-parallel switching circuit are controlled based on the loop output value to perform voltage loop control on the series-parallel switching circuit.

[0012] Optionally, performing a PI operation on the voltage loop control error factor to obtain a loop output value specifically includes: Determining whether the voltage loop control error factor is less than a minimum error factor value to obtain a second determination result; If the second judgment result is yes, then using the minimum value of the error factor as the adjusted voltage loop control error factor; If the second judgment result is no, determining whether the voltage loop control error factor is greater than the maximum error factor, and obtaining a third judgment result; If the third judgment result is yes, taking the maximum value of the error factor as the adjusted voltage loop control error factor; If the third judgment result is no, using the voltage loop control error factor as the adjusted voltage loop control error factor; A PI operation is performed on the adjusted voltage loop control error factor to obtain a loop output value.

[0013] Optionally, controlling the duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube in the series-parallel switching circuit based on the loop output value specifically includes: Determine whether the loop output value is less than a minimum loop output value, to obtain a fourth determination result; If the fourth judgment result is yes, the minimum value of the loop output value is used as the adjusted loop output value; If the fourth judgment result is no, determining whether the loop output value is greater than the maximum loop output value to obtain a fifth judgment result; If the fifth judgment result is yes, taking the maximum value of the loop output value as the adjusted loop output value; If the fifth judgment result is no, taking the loop output value as the adjusted loop output value; The duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in the series-parallel switching circuit are controlled based on the adjusted loop output value.

[0014] In a third aspect, the present application provides a computer device comprising: a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the computer program to implement the loop control method of the above-mentioned charging voltage series-parallel switching device.

[0015] According to the specific embodiments provided in this application, this application has the following technical effects: The present application provides a charging voltage series-parallel switching device and its loop control method and equipment. In the traditional charging voltage series-parallel switching device, the first output end of the traditional series-parallel switching circuit is installed with an anti-backflow diode, and the traditional voltage loop controller only performs voltage loop control on the traditional series-parallel switching circuit based on the output voltage. However, the traditional charging voltage series-parallel switching device has a complex structure and high cost. In order to solve this problem, the present application omits the anti-backflow diode in the traditional series-parallel switching circuit, which can simplify the charging voltage series-parallel switching device. However, this will cause the series-parallel switching circuit to have a short-circuit risk. Therefore, the present application further improves the voltage loop control process and introduces the midpoint voltage. The voltage loop controller performs voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage at the same time, avoiding the short-circuit risk, and ultimately enabling the electric vehicle DC charging pile to have a wide output voltage range in a low-cost manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 FIG. 1 is a circuit diagram of a traditional series-parallel switching circuit with an anti-backfeed diode D1.

[0018] Figure 2 This is a circuit diagram of a series-parallel switching circuit provided in Example 1 of the present application, in which the anti-backflow diode D1 is omitted.

[0019] Figure 3 This is a schematic diagram of the working process of the series-parallel switching circuit provided in Example 1 of the present application in the parallel state in the positive half cycle.

[0020] Figure 4 This is a schematic diagram of the working process of the series-parallel switching circuit provided in Example 1 of the present application in the parallel state in the negative half cycle.

[0021] Figure 5 This is a schematic diagram of the working process of the series-parallel switching circuit provided in Example 1 of the present application in the series state in the positive half cycle.

[0022] Figure 6 This is a schematic diagram of the working process of the series-parallel switching circuit provided in Example 1 of the present application in the series state in the negative half cycle.

[0023] Figure 7This is a schematic diagram of the principle of the loop control method of the charging voltage series-parallel switching device provided in Example 1 of the present application.

[0024] Figure 8 This is a flow chart of the loop control method of the charging voltage series-parallel switching device provided in Example 2 of the present application.

[0025] Figure 9 A schematic diagram of the structure of a computer device provided in Example 3 of the present application. DETAILED DESCRIPTION

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

[0027] Example 1.

[0028] Figure 1The traditional series-parallel switching circuit with an anti-backfeed diode D1 is demonstrated. The primary side of the transformer is connected to the electric vehicle DC charging pile. It consists of four switching tubes Q1, Q2, Q3, Q4, a resonant inductor L1, a resonant capacitor C1 and an input winding T1-A. The switching tubes can be MOS tubes (which is the abbreviation of MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor)). By controlling the conduction and shutdown of the four switching tubes Q1, Q2, Q3, and Q4, the DC power output by the rectifier circuit of the electric vehicle DC charging pile is converted into AC power. When the switching tubes Q1 and Q4 are turned on, the switching tubes Q2 and Q3 are turned off. At this time, the AC power is in the negative half-cycle. When the switching tubes Q1 and Q4 are turned off, the switching tubes Q2 and Q3 are turned on. At this time, the AC power is in the positive half-cycle. The secondary side of the transformer includes two output windings T1-B and T1-C. The output end of the output winding T1-B has four rectifier diodes D2, D3, D4, and D5. The four rectifier diodes D2, D3, D4, and D5 convert the AC power output by the output winding T1-B into DC power. The output ends of the four rectifier diodes D2, D3, D4, and D5 have an output electrolytic capacitor C2. The output electrolytic capacitor C2 is used for energy storage and filtering. There are 4 rectifier diodes D6, D7, D8, and D9 at the output end of C. The 4 rectifier diodes D6, D7, D8, and D9 convert the AC power output by the output winding T1-C into DC power. There is an output electrolytic capacitor C3 at the output end of the 4 rectifier diodes D6, D7, D8, and D9. The output electrolytic capacitor C3 is used to store energy and filter. The output winding T1-B, 4 rectifier diodes D2, D3, D4, and D5, and the output electrolytic capacitor C2 are composed The first voltage output, the output winding T1-C, four rectifier diodes D6, D7, D8, D9, and the output electrolytic capacitor C3 constitute the second voltage output. The first and second voltage outputs are connected in series or in parallel through the switch K1 and three anti-backflow diodes D10, D11, and D12. When the switch K1 is disconnected, the parallel output is realized, and when the switch K1 is closed, the series output is realized. The switch K1 can be a contactor. The anti-backflow diode D1 is used to prevent current from flowing from the load to the power supply. VOUT is the output voltage sampling point. The total output voltage VOUT (also called the output voltage sampling value) is sampled. The output voltage is the voltage between the output terminals VOUT_DC+ and VOUT_DC-. The subsequent voltage loop controller controls the four switches Q1, Q2, Q3, and Q4 based on the output voltage to perform voltage loop control so that the output voltage is as close to the target voltage as possible.

[0029] Obviously, the traditional series-parallel switching circuit has an anti-backflow diode D1, which has a complex structure and high cost. In order to solve the problem of wide-range output of the output voltage of the DC charging pile of electric vehicles and control the cost, this embodiment provides a new charging voltage series-parallel switching device, which eliminates the anti-backflow diode D1 on the secondary side of the transformer. At this time, it may bring a short circuit risk in the module parallel working mode (i.e., parallel connection). In order to solve the problem of short circuit risk, the output voltage VOUT and the midpoint voltage VMID are simultaneously involved in the voltage loop control to perform the loop control process of the series-parallel switching circuit, which can achieve a stable output between 200V and 1000V. At the same time, the anti-backflow diode D1 on the secondary side of the traditional transformer can be eliminated. While ensuring the reliability of the charging voltage series-parallel switching device, the simplicity of the charging voltage series-parallel switching device is improved, the volume of the entire charging pile system is reduced, and the volume power density is improved.

[0030] Figure 2 This embodiment demonstrates a novel series-parallel switching circuit that eliminates the backfeed diode D1. VMID represents the midpoint between the two outputs, i.e., the midpoint voltage sampling point. The midpoint voltage VMID (also referred to as the midpoint voltage sampling value) is sampled and obtained. Specifically, this embodiment provides a charging voltage series-parallel switching device, comprising a series-parallel switching circuit and a voltage loop controller.

[0031] The series-parallel switching circuit includes a voltage input module, a first voltage output module, a second voltage output module, and a switching module. The switching module includes a switch. The output end of the voltage input module is respectively connected to the input end of the first voltage output module and the input end of the second voltage output module. The first output end of the first voltage output module serves as the first output end of the series-parallel switching circuit. The second output end of the first voltage output module is respectively connected to the first end of the switch and the second output end of the second voltage output module. The first output end of the second voltage output module is respectively connected to the second end of the switch and the first output end of the first voltage output module. The second output end of the second voltage output module serves as the second output end of the series-parallel switching circuit.

[0032] The voltage loop controller is used to sample the voltage at the first output end of the series-parallel switching circuit to obtain the output voltage, sample the voltage at the second end of the switch to obtain the midpoint voltage, and perform voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage.

[0033] This embodiment provides a charging voltage series-parallel switching device that achieves a wide voltage range output by controlling the on-off of switches. A control method using output voltage sampling and midpoint voltage sampling to jointly participate in loop regulation eliminates the anti-backfeed diode D1 on the secondary side of the transformer, reduces device costs, reduces the overall size of the device, and improves volume power density.

[0034] like Figure 2 As shown, the voltage input module uses an LLC resonant converter. The voltage input module includes a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, a fourth switching transistor Q4, a resonant inductor L1, a resonant capacitor C1, and a transformer input winding T1-A. The first end of the first switching transistor Q1 is connected to the first input of the voltage input module and the first end of the second switching transistor Q2, respectively. The second end of the first switching transistor Q1 is connected to the first end of the third switching transistor Q3 and the first end of the resonant capacitor C1, respectively. The second end of the second switching transistor Q2 is connected to the first end of the fourth switching transistor Q4 and the first end of the resonant inductor L1, respectively. The second end of the third switching transistor Q3 is connected to the second input of the voltage input module and the second end of the fourth switching transistor Q4, respectively. The first and second inputs of the voltage input module are connected to the output of the electric vehicle DC charging station. The second end of the resonant inductor L1 is connected to the first end of the input winding T1-A, and the second end of the resonant capacitor C1 is connected to the second end of the input winding T1-A. The input winding T1-A serves as the output of the voltage input module.

[0035] The control ends of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 are all connected to a voltage loop controller. The voltage loop controller is used to control the duty cycle and / or frequency of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 based on the output voltage and the midpoint voltage, so as to perform voltage loop control on the series-parallel switching circuit.

[0036] like Figure 2 As shown, the first voltage output module and the second voltage output module have the same structure.

[0037] The first voltage output module includes a transformer output winding T1-B, a first rectifier diode D2, a second rectifier diode D3, a third rectifier diode D4, a fourth rectifier diode D5, and an output electrolytic capacitor C2. The output winding T1-B is the input terminal of the first voltage output module. The first end of the output winding T1-B is respectively connected to the anode of the first rectifier diode D2 and the cathode of the third rectifier diode D4. The second end of the output winding T1-B is respectively connected to the anode of the second rectifier diode D3 and the cathode of the fourth rectifier diode D5. The cathode of the first rectifier diode D2 is respectively connected to the cathode of the second rectifier diode D3 and the first end of the output electrolytic capacitor C2, serving as the first output terminal of the first voltage output module. The anode of the third rectifier diode D4 is respectively connected to the anode of the fourth rectifier diode D5 and the second end of the output electrolytic capacitor C2, serving as the second output terminal of the first voltage output module.

[0038] The second voltage output module includes a transformer output winding T1-C, a first rectifier diode D6, a second rectifier diode D7, a third rectifier diode D8, a fourth rectifier diode D9, and an output electrolytic capacitor C3. The output winding T1-C serves as the input of the second voltage output module. The first end of the output winding T1-C is connected to the anode of the first rectifier diode D6 and the cathode of the third rectifier diode D8, respectively. The second end of the output winding T1-C is connected to the anode of the second rectifier diode D7 and the cathode of the fourth rectifier diode D9, respectively. The cathode of the first rectifier diode D6 is connected to the cathode of the second rectifier diode D7 and the first end of the output electrolytic capacitor C3, serving as the first output of the second voltage output module. The anode of the third rectifier diode D8 is connected to the anode of the fourth rectifier diode D9 and the second end of the output electrolytic capacitor C3, serving as the second output of the second voltage output module.

[0039] like Figure 2 As shown, the switching module also includes a first anti-backflow diode D10, a second anti-backflow diode D11 and a third anti-backflow diode D12. The cathode of the first anti-backflow diode D10 is connected to the first output end of the first voltage output module, and the anode of the first anti-backflow diode D10 is respectively connected to the second end of the switch K1 and the first output end of the second voltage output module. The first end of the switch K1 is connected to the anode of the second anti-backflow diode D11, and the cathode of the second anti-backflow diode D11 is respectively connected to the second output end of the first voltage output module and the cathode of the third anti-backflow diode D12. The anode of the third anti-backflow diode D12 is connected to the second output end of the second voltage output module.

[0040] When the switch K1 is closed, the first voltage output module and the second voltage output module are connected in series; when the switch K1 is open, the first voltage output module and the second voltage output module are connected in parallel.

[0041] This embodiment designs a series-parallel switching circuit. When a low voltage below 500V is required to be output, the control switch is opened to connect the two outputs on the secondary side in parallel. When a high voltage above 500V is required to be output, the control switch is closed to connect the two outputs on the secondary side in series. Of course, other values ​​can also be selected as the dividing line between series and parallel according to user needs.

[0042] Figure 3 and Figure 4 The diagram shows the working process when the switch K1 is disconnected and in the parallel output state. At this time, the midpoint voltage is equal to the output voltage, that is, the output voltage VOUT = midpoint voltage VMID. Figure 5 and Figure 6 The diagram shows the working process when switch K1 is closed in the series output state. At this time, the midpoint voltage is equal to half of the output voltage, that is, the output voltage VOUT=2 Midpoint voltage VMID.

[0043] Figure 1 D1 is the anti-backflow diode at the output end, which prevents the external voltage from flowing back into the secondary side of the transformer and affecting the output voltage VOUT. This may cause a short-circuit risk in the parallel operation mode of the modules. Due to the particularity of the series-parallel switching circuit and the voltage loop controller of this embodiment, D10, D11, and D12 can prevent the external voltage from flowing back into the secondary side of the transformer. At the same time, the control method of flexibly switching the loop control object avoids the short-circuit risk caused by the output voltage VOUT being affected, and the anti-backflow diode D1 can be omitted.

[0044] Since the secondary-side output anti-backfeed diode D1 is omitted, when the output sides of two or more voltage output modules are connected in parallel, the sampling of the output voltage point will be affected by the output voltage of the parallel module, thereby affecting the voltage loop control output. Therefore, in this embodiment, the midpoint voltage and the output voltage are simultaneously used as loop control objects to participate in the voltage loop control. That is, when the corresponding relationship between the output voltage and the midpoint voltage is detected to be within the normal error range, the output voltage is used as the voltage loop control object; when the corresponding relationship between the output voltage and the midpoint voltage is detected to deviate from the normal error range, the midpoint voltage is used as the voltage loop control object.

[0045] Specifically, Figure 7 The principle of the loop control method is demonstrated, and the specific steps are as follows.

[0046] (1) When the output voltage is below 503V, switch K1 is disconnected, connecting the two secondary outputs in parallel. At this point, the output voltage VOUT is theoretically equal to the midpoint voltage VMID, and the error voltage ΔV is calculated as |VOUT-VMID|. When the error voltage ΔV is less than the maximum allowable error voltage Vmax, the voltage loop controls the output voltage VOUT, and the voltage loop control error factor Δε=Vreq-VOUT, where Vreq is the output voltage setpoint, i.e., the target voltage. When the error voltage ΔV is greater than or equal to the maximum allowable error voltage Vmax, the voltage loop controls the midpoint voltage VMID, and the voltage loop control error factor Δε=Vreq-VMID.

[0047] (2) When the output voltage is above 503V, switch K1 is closed to connect the two outputs of the secondary side in series. At this time, the output voltage VOUT is theoretically equal to twice the midpoint voltage VMID. The error voltage ΔV is calculated as |VOUT-2 VMID|. When the error voltage ΔV is less than the maximum allowable error voltage Vmax, the voltage loop control object is the output voltage VOUT, and the voltage loop control error factor Δε=Vreq-VOUT; when the error voltage ΔV is greater than or equal to the maximum allowable error voltage Vmax, the voltage loop control object is 2 VMID, voltage loop control error factor Δε=Vreq-2 VMID.

[0048] (3) After the voltage loop control error factor Δε is calculated, it is limited. The minimum is the minimum value of the voltage loop control error factor εmin, and the maximum is the maximum value of the voltage loop control error factor εmax. The adjusted voltage loop control error factor Δε1 is obtained. The PI (Proportional-Integral) operation is performed on the adjusted voltage loop control error factor Δε1, u= Kp Δε1+Ki Δε1, u is the loop output value, which is the control variable for the output voltage. Kp is the proportional coefficient of the PI controller, and Ki is the integral coefficient of the PI controller. The loop output value u is clipped, with the minimum value (Umin) and the maximum value (Umax) being the loop output value, to obtain the adjusted loop output value u1. This adjusted loop output value u1 is converted into the duty cycle and / or frequency of the control switch. The output voltage is dynamically adjusted under negative feedback to complete closed-loop control.

[0049] The following is a detailed description of the working process of the charging voltage series-parallel switching device of this embodiment.

[0050] like Figure 3 and Figure 4 As shown in the figure, when the output voltage is below 503V, the control switch K1 is disconnected. At this time, the voltage at the in-phase end of the T1-C winding is output to the VOUT_DC+ pole through the D10 diode, and then returns to the VOUT_DC- pole to reach the inverting end of the T1-C winding. The voltage at the in-phase end of the T1-B winding is output to the VOUT_DC+ pole, and then returns to the VOUT_DC- pole through the D12 diode to return to the inverting end of the T1-B winding. That is, the T1-B winding and the T1-C winding are output in parallel, realizing the parallel output of the secondary side. At this time, the output voltage VOUT is theoretically equal to the midpoint voltage VMID. The circuit working diagram of the positive half cycle is shown in the figure. Figure 3 As shown, the circuit working diagram of the negative half cycle is as follows Figure 4As shown. In fact, there is a certain sampling and calculation error voltage ΔV between the output voltage and the midpoint voltage. The error voltage ΔV=|VOUT-VMID|. When the error voltage ΔV is less than the maximum allowable error voltage Vmax, it is in a normal stable state. Therefore, when the error voltage ΔV is less than the maximum allowable error voltage Vmax, the voltage loop control object is the output voltage VOUT, and the voltage loop control error factor Δε=Vreq-VOUT; when the error voltage ΔV is greater than or equal to the maximum allowable error voltage Vmax, the voltage loop control object is the midpoint voltage VMID, and the voltage loop control error factor Δε=Vreq-VMID. After the voltage loop control error factor Δε is calculated, it is limited. The minimum is the minimum value of the voltage loop control error factor εmin, and the maximum is the maximum value of the voltage loop control error factor εmax. The adjusted voltage loop control error factor Δε1 is obtained. The adjusted voltage loop control error factor Δε1 is subjected to PI operation, u=Kp Δε1+Ki Δε1 limits the loop output value u, the minimum is the minimum loop output value Umin, and the maximum is the maximum loop output value Umax, to obtain the adjusted loop output value u1, and convert the adjusted loop output value u1 into the duty cycle and / or frequency of the control switch tube, and dynamically adjust the output voltage under negative feedback regulation to complete closed-loop control.

[0051] like Figure 5 and Figure 6 As shown in the figure, when the output voltage is above 503V, the control switch K1 is closed. At this time, the voltage at the in-phase end of the T1-C winding returns to the inverting end of the T1-B winding through the D11 diode, and is output to the VOUT_DC+ pole through the in-phase end of the T1-B winding. After returning to the VOUT_DC- pole, it reaches the inverting end of the T1-C winding. The voltage at the in-phase end of the T1-B winding is output to the VOUT_DC+ pole, returns to the VOUT_DC- pole, passes through the inverting end of the T1-C winding to the inverting end of the T1-C winding, and returns to the inverting end of the T1-B winding through the D11 diode. That is, the T1-B winding and the T1-C winding are output in series, realizing the secondary side series output. At this time, the output voltage VOUT is theoretically equal to 2 times the midpoint voltage 2 VMID, the circuit operation diagram of the positive half cycle is as follows Figure 5 As shown, the circuit working diagram of the negative half cycle is as follows Figure 6 In fact, there is a certain sampling error voltage ΔV between the output voltage and 2 times the midpoint voltage. The error voltage ΔV=|VOUT-2 VMID|, when the error voltage ΔV is less than the maximum allowable error voltage Vmax, it is in a normal stable state. Therefore, when the error voltage ΔV is less than the maximum allowable error voltage Vmax, the voltage loop control object is the output voltage VOUT, and the voltage loop control error factor Δε=Vreq-VOUT; when the error voltage ΔV is greater than or equal to the maximum allowable error voltage Vmax, the voltage loop control object is 2 VMID, voltage loop control error factor Δε=Vreq-2 VMID. After calculating the voltage loop control error factor Δε, it is limited to the minimum value of the voltage loop control error factor εmin and the maximum value of the voltage loop control error factor εmax. The adjusted voltage loop control error factor Δε1 is obtained. The PI operation is performed on the adjusted voltage loop control error factor Δε1, u=Kp Δε1+Ki Δε1 limits the loop output value u, the minimum is the minimum loop output value Umin, and the maximum is the maximum loop output value Umax, to obtain the adjusted loop output value u1, and convert the adjusted loop output value u1 into the duty cycle and / or frequency of the control switch tube, and dynamically adjust the output voltage under negative feedback regulation to complete closed-loop control.

[0052] In parallel operation, with two voltage output modules (VOUT_DC+ and VOUT_DC-) connected in parallel, the output voltage (VOUT) of the module itself may be derived from other parallel modules, and the sampled value may be higher than the set output voltage. This causes the voltage loop to reduce the PWM (Pulse Width Modulation) duty cycle under negative feedback. Eventually, the PWM duty cycle drops to zero, causing the midpoint voltage (VMID) to reach zero. At this point, the output electrolytic capacitors are effectively short-circuited, and the module is powered on, completing the output voltage soft-start process. If a heavy load is suddenly added to VOUT_DC+ and VOUT_DC-, the moment the output voltage (VOUT) drops, the voltage loop will generate a high-duty-cycle PWM signal under negative feedback. The heavier the load, the greater the instantaneous PWM duty cycle, leading to the risk of a short circuit on the transformer secondary side without voltage soft-start. Therefore, in the absence of anti-backfeed diode D1, it is crucial to include the midpoint voltage (VMID) in the voltage loop control. This also facilitates stable system operation, thereby achieving a stable output voltage. Figure 1 The traditional series-parallel switching circuit with anti-backflow diode D1 is transformed into Figure 2 The novel series-parallel switching circuit shown here omits the anti-backflow diode D1.

[0053] This embodiment utilizes a series-parallel charging voltage switching device and its voltage loop control method to achieve a wide voltage output range of 200V-1000V. This adapts to the charging requirements of electric vehicles with high-voltage platforms while also being compatible with traditional low-voltage platforms. The circuit is simple, achieving a voltage boost function with minimal components, thus reducing costs. By changing the voltage loop control object for flexible regulation, the use of secondary-side anti-backfeed diode D1 is reduced, thus avoiding the risks associated with parallel operation and reducing the overall size of the system. Furthermore, software control methods are used to reduce component costs and increase overall power density.

[0054] Example 2.

[0055] This embodiment provides a loop control method for the charging voltage series-parallel switching device described in Embodiment 1, such as Figure 8 As shown, the following steps are included.

[0056] S1: Obtain the output voltage and midpoint voltage obtained by voltage sampling the series-parallel switching circuit.

[0057] S2: Based on the output voltage and the midpoint voltage, perform voltage loop control on the series-parallel switching circuit.

[0058] In S2, based on the output voltage and the midpoint voltage, the voltage loop of the series-parallel switching circuit is controlled, specifically including: calculating the absolute value of the difference between the output voltage and the reference voltage to obtain the error voltage, when the first voltage output module and the second voltage output module in the series-parallel switching circuit are connected in series, the reference voltage is twice the midpoint voltage, and when the first voltage output module and the second voltage output module in the series-parallel switching circuit are connected in parallel, the reference voltage is the midpoint voltage; judging whether the error voltage is less than the maximum error voltage to obtain a first judgment result; if the first judgment result is yes, calculating the difference between the target voltage and the output voltage to obtain a voltage loop control error factor; if the first judgment result is no, calculating the difference between the target voltage and the reference voltage to obtain a voltage loop control error factor; based on the voltage loop control error factor, the voltage loop of the series-parallel switching circuit is controlled.

[0059] The voltage loop control of the series-parallel switching circuit is performed based on the voltage loop control error factor, which specifically includes the following steps.

[0060] (1) Perform PI operation on the voltage loop control error factor to obtain the loop output value.

[0061] Performing a PI operation on the voltage loop control error factor to obtain a loop output value, specifically including: judging whether the voltage loop control error factor is less than a minimum error factor value to obtain a second judgment result; if the second judgment result is yes, using the minimum error factor value as the adjusted voltage loop control error factor; if the second judgment result is no, judging whether the voltage loop control error factor is greater than a maximum error factor value to obtain a third judgment result; if the third judgment result is yes, using the maximum error factor value as the adjusted voltage loop control error factor; if the third judgment result is no, using the voltage loop control error factor as the adjusted voltage loop control error factor; performing a PI operation on the adjusted voltage loop control error factor to obtain a loop output value.

[0062] (2) Based on the loop output value, the duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube in the series-parallel switching circuit are controlled to perform voltage loop control on the series-parallel switching circuit.

[0063] The duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in the series-parallel switching circuit are controlled based on the loop output value, specifically including: judging whether the loop output value is less than the minimum loop output value to obtain a fourth judgment result; if the fourth judgment result is yes, using the minimum loop output value as the adjusted loop output value; if the fourth judgment result is no, judging whether the loop output value is greater than the maximum loop output value to obtain a fifth judgment result; if the fifth judgment result is yes, using the maximum loop output value as the adjusted loop output value; if the fifth judgment result is no, using the loop output value as the adjusted loop output value; and controlling the duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in the series-parallel switching circuit based on the adjusted loop output value.

[0064] Example 3.

[0065] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 9As shown. The computer device includes a processor, a memory, an input / output interface (I / O) and a communication interface. The processor, memory and input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store data. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a loop control method for a charging voltage series-parallel switching device is implemented.

[0066] Those skilled in the art will understand that Figure 9 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0067] In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the loop control method of the charging voltage series-parallel switching device in embodiment 2 is implemented.

[0068] Example 4.

[0069] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, which, when executed by a processor, implements the loop control method of the charging voltage series-parallel switching device in embodiment 2.

[0070] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0071] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A charging voltage series-parallel switching device, characterized in that: include: Series-parallel switching circuit and voltage loop controller; The series-parallel switching circuit includes a voltage input module, a first voltage output module, a second voltage output module, and a switching module, wherein the switching module includes a switch; the output end of the voltage input module is respectively connected to the input end of the first voltage output module and the input end of the second voltage output module, the first output end of the first voltage output module serves as the first output end of the series-parallel switching circuit, the second output end of the first voltage output module is respectively connected to the first end of the switch and the second output end of the second voltage output module, the first output end of the second voltage output module is respectively connected to the second end of the switch and the first output end of the first voltage output module, and the second output end of the second voltage output module serves as the second output end of the series-parallel switching circuit; The voltage loop controller is used to sample the voltage at the first output end of the series-parallel switching circuit to obtain the output voltage, sample the voltage at the second end of the switch to obtain the midpoint voltage, and perform voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage.

2. The charging voltage series-parallel switching device according to claim 1, characterized in that: The voltage input module adopts LLC resonant converter; The voltage input module includes a first switching tube, a second switching tube, a third switching tube, a fourth switching tube, a resonant inductor, a resonant capacitor and an input winding of a transformer; the first end of the first switching tube is respectively connected to the first input end of the voltage input module and the first end of the second switching tube, the second end of the first switching tube is respectively connected to the first end of the third switching tube and the first end of the resonant capacitor, the second end of the second switching tube is respectively connected to the first end of the fourth switching tube and the first end of the resonant inductor, the second end of the third switching tube is respectively connected to the second input end of the voltage input module and the second end of the fourth switching tube, the second end of the resonant inductor is connected to the first end of the input winding, the second end of the resonant capacitor is connected to the second end of the input winding, and the input winding is the output end of the voltage input module; The control end of the first switch tube, the control end of the second switch tube, the control end of the third switch tube and the control end of the fourth switch tube are all connected to the voltage loop controller. The voltage loop controller is used to control the duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube based on the output voltage and the midpoint voltage, so as to perform voltage loop control on the series-parallel switching circuit.

3. The charging voltage series-parallel switching device according to claim 1, characterized in that: The first voltage output module and the second voltage output module have the same structure; The first voltage output module includes an output winding of a transformer, a first rectifier diode, a second rectifier diode, a third rectifier diode, a fourth rectifier diode and an output electrolytic capacitor; the output winding is the input end of the first voltage output module; the first end of the output winding is respectively connected to the anode of the first rectifier diode and the cathode of the third rectifier diode, the second end of the output winding is respectively connected to the anode of the second rectifier diode and the cathode of the fourth rectifier diode, the cathode of the first rectifier diode is respectively connected to the cathode of the second rectifier diode and the first end of the output electrolytic capacitor, serving as the first output end of the first voltage output module, the anode of the third rectifier diode is respectively connected to the anode of the fourth rectifier diode and the second end of the output electrolytic capacitor, serving as the second output end of the first voltage output module.

4. The charging voltage series-parallel switching device according to claim 1, characterized in that: The switching module also includes a first anti-backflow diode, a second anti-backflow diode and a third anti-backflow diode; the cathode of the first anti-backflow diode is connected to the first output end of the first voltage output module, the anode of the first anti-backflow diode is respectively connected to the second end of the switch and the first output end of the second voltage output module, the first end of the switch is connected to the anode of the second anti-backflow diode, the cathode of the second anti-backflow diode is respectively connected to the second output end of the first voltage output module and the cathode of the third anti-backflow diode, and the anode of the third anti-backflow diode is connected to the second output end of the second voltage output module; When the switch is closed, the first voltage output module and the second voltage output module are connected in series; when the switch is open, the first voltage output module and the second voltage output module are connected in parallel.

5. A loop control method for a charging voltage series-parallel switching device according to any one of claims 1 to 4, characterized in that: include: Obtaining an output voltage and a midpoint voltage obtained by voltage sampling the series-parallel switching circuit; Based on the output voltage and the midpoint voltage, a voltage loop control is performed on the series-parallel switching circuit.

6. The loop control method of the charging voltage series-parallel switching device according to claim 5, characterized in that: Based on the output voltage and the midpoint voltage, voltage loop control is performed on the series-parallel switching circuit, specifically including: calculating an absolute value of a difference between the output voltage and a reference voltage to obtain an error voltage; when the first voltage output module and the second voltage output module in the series-parallel switching circuit are connected in series, the reference voltage is twice the midpoint voltage; and when the first voltage output module and the second voltage output module in the series-parallel switching circuit are connected in parallel, the reference voltage is the midpoint voltage; Determine whether the error voltage is less than a maximum error voltage value to obtain a first determination result; If the first judgment result is yes, calculating the difference between the target voltage and the output voltage to obtain a voltage loop control error factor; If the first judgment result is no, calculating the difference between the target voltage and the reference voltage to obtain a voltage loop control error factor; Based on the voltage loop control error factor, voltage loop control is performed on the series-parallel switching circuit.

7. The loop control method of the charging voltage series-parallel switching device according to claim 6, characterized in that: Based on the voltage loop control error factor, voltage loop control is performed on the series-parallel switching circuit, specifically including: Performing a PI operation on the voltage loop control error factor to obtain a loop output value; The duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in the series-parallel switching circuit are controlled based on the loop output value to perform voltage loop control on the series-parallel switching circuit.

8. The loop control method of the charging voltage series-parallel switching device according to claim 7, characterized in that: Performing a PI operation on the voltage loop control error factor to obtain a loop output value specifically includes: Determining whether the voltage loop control error factor is less than a minimum error factor value to obtain a second determination result; If the second judgment result is yes, then using the minimum value of the error factor as the adjusted voltage loop control error factor; If the second judgment result is no, determining whether the voltage loop control error factor is greater than the maximum error factor, and obtaining a third judgment result; If the third judgment result is yes, taking the maximum value of the error factor as the adjusted voltage loop control error factor; If the third judgment result is no, using the voltage loop control error factor as the adjusted voltage loop control error factor; A PI operation is performed on the adjusted voltage loop control error factor to obtain a loop output value.

9. The loop control method of the charging voltage series-parallel switching device according to claim 7, characterized in that: Controlling the duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube in the series-parallel switching circuit based on the loop output value specifically includes: Determine whether the loop output value is less than a minimum loop output value, to obtain a fourth determination result; If the fourth judgment result is yes, the minimum value of the loop output value is used as the adjusted loop output value; If the fourth judgment result is no, determining whether the loop output value is greater than the maximum loop output value to obtain a fifth judgment result; If the fifth judgment result is yes, taking the maximum value of the loop output value as the adjusted loop output value; If the fifth judgment result is no, taking the loop output value as the adjusted loop output value; The duty cycle and / or frequency of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube in the series-parallel switching circuit are controlled based on the adjusted loop output value.

10. A computer device comprising: A memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that the processor executes the computer program to implement the loop control method of the charging voltage series-parallel switching device according to any one of claims 5-9.

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