A charging voltage series-parallel switching device, a loop control method and equipment thereof

Abstract

The application discloses a charging voltage series-parallel switching device and a loop control method and equipment thereof, relates to the technical field of electric vehicle direct-current charging piles, and comprises a series-parallel switching circuit and a voltage loop controller. The anti-backflow diode in the traditional series-parallel switching circuit is omitted in the series-parallel 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 simultaneously performs voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage, the short-circuit risk is avoided, and finally, the electric vehicle direct-current charging pile has a wide output voltage range in a low-cost mode.

Description

TECHNICAL FIELD

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

[0002] With the rapid development of electric vehicles, the battery pack voltage has generally crossed the high-voltage platform, and therefore, the demand for electric vehicle direct current charging piles with a wide output voltage range has significantly increased. The output voltage range of the traditional electric vehicle direct current charging pile is narrow, and a complex charging voltage series-parallel switching device needs to be installed at the output end of the electric vehicle direct current charging pile in order to achieve a wide output voltage range at a high cost. SUMMARY

[0003] The purpose of the present application is to provide a charging voltage series-parallel switching device, a loop control method and equipment thereof, which can simplify the charging voltage series-parallel switching device and enable the electric vehicle direct current charging pile to have a wide output voltage range at a low cost.

[0004] To achieve the above-mentioned purpose, the present 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.

[0006] The series-parallel switching circuit comprises a voltage input module, a first voltage output module, a second voltage output module and a switching module, the switching module comprising a switch; the output end of the voltage input module is connected to the input end of the first voltage output module and the input end of the second voltage output module respectively, 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 connected to the first end of the switch and the second output end of the second voltage output module respectively, the first output end of the second voltage output module is connected to the second end of the switch and the first output end of the first voltage output module respectively, and the second output end of the second voltage output module serves as the second output end of the series-parallel switching circuit.

[0007] The voltage loop controller is configured to sample the voltage at the first output end of the series-parallel switching circuit to obtain an output voltage, sample the voltage at the second end of the switch to obtain a midpoint voltage, and perform voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage.

[0008] Optionally, the voltage input module adopts an LLC resonant converter.

[0009] The voltage input module comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a resonant inductor, a resonant capacitor and an input winding of a transformer; a first end of the first switch tube is connected to a first input end of the voltage input module and a first end of the second switch tube respectively, a second end of the first switch tube is connected to a first end of the third switch tube and a first end of the resonant capacitor respectively, a second end of the second switch tube is connected to a first end of the fourth switch tube and a first end of the resonant inductor respectively, a second end of the third switch tube is connected to a second input end of the voltage input module and a second end of the fourth switch tube respectively, a second end of the resonant inductor is connected to a first end of the input winding, a second end of the resonant capacitor is connected to a second end of the input winding, and the input winding is an output end of the voltage input module;

[0010] 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 connected to the voltage loop controller, and the voltage loop controller is used for 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 based on the output voltage and the midpoint voltage, so as to perform voltage loop control on the series-parallel switching circuit.

[0011] Optionally, the first voltage output module and the second voltage output module are the same in structure.

[0012] The first voltage output module comprises 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 an input end of the first voltage output module; a first end of the output winding is connected to an anode of the first rectifier diode and a cathode of the third rectifier diode respectively, a second end of the output winding is connected to an anode of the second rectifier diode and a cathode of the fourth rectifier diode respectively, a cathode of the first rectifier diode is connected to a cathode of the second rectifier diode and a first end of the output electrolytic capacitor respectively, serving as a first output end of the first voltage output module, and an anode of the third rectifier diode is connected to an anode of the fourth rectifier diode and a second end of the output electrolytic capacitor respectively, serving as a second output end of the first voltage output module.

[0013] Optionally, the switching module further comprises a first anti-inrush diode, a second anti-inrush diode and a third anti-inrush diode; a cathode of the first anti-inrush diode is connected to a first output end of the first voltage output module, an anode of the first anti-inrush diode is connected to a second end of the switch and a first output end of the second voltage output module respectively, a first end of the switch is connected to an anode of the second anti-inrush diode, a cathode of the second anti-inrush diode is connected to a second output end of the first voltage output module and a cathode of the third anti-inrush diode respectively, and an anode of the third anti-inrush diode is connected to a second output end of the second voltage output module.

[0014] When the switch is closed, the first voltage output module and the second voltage output module are connected in series; and when the switch is opened, the first voltage output module and the second voltage output module are connected in parallel.

[0015] In a second aspect, the application provides a loop control method of the charging voltage series-parallel switching device, comprising:

[0016] obtaining an output voltage and a midpoint voltage obtained by voltage sampling on the series-parallel switching circuit;

[0017] controlling the series-parallel switching circuit based on the output voltage and the midpoint voltage.

[0018] Optionally, the controlling the series-parallel switching circuit based on the output voltage and the midpoint voltage specifically comprises:

[0019] 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.

[0020] judging whether the error voltage is less than a maximum error voltage to obtain a first judgment result;

[0021] if the first judgment result is yes, calculating a difference between a target voltage and the output voltage to obtain a voltage loop control error factor;

[0022] if the first judgment result is no, calculating a difference between the target voltage and the reference voltage to obtain a voltage loop control error factor;

[0023] controlling the series-parallel switching circuit based on the voltage loop control error factor.

[0024] Optionally, the voltage loop control error factor is subjected to PI operation to obtain a loop output value.

[0025] The voltage loop control error factor is subjected to PI operation to obtain a loop output value.

[0026] 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.

[0027] Optionally, the voltage loop control error factor is subjected to PI operation to obtain a loop output value, specifically including:

[0028] It is determined whether the voltage loop control error factor is less than an error factor minimum value to obtain a second determination result.

[0029] If the second determination result is yes, the error factor minimum value is taken as an adjusted voltage loop control error factor.

[0030] If the second determination result is no, it is determined whether the voltage loop control error factor is greater than an error factor maximum value to obtain a third determination result.

[0031] If the third determination result is yes, the error factor maximum value is taken as the adjusted voltage loop control error factor.

[0032] If the third determination result is no, the voltage loop control error factor is taken as the adjusted voltage loop control error factor.

[0033] The adjusted voltage loop control error factor is subjected to PI operation to obtain a loop output value.

[0034] Optionally, 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:

[0035] It is determined whether the loop output value is less than a loop output value minimum value to obtain a fourth determination result.

[0036] If the fourth determination result is yes, the loop output value minimum value is taken as an adjusted loop output value.

[0037] If the fourth determination result is no, it is determined whether the loop output value is greater than a loop output value maximum value to obtain a fifth determination result.

[0038] If the fifth determination result is yes, the loop output value maximum value is taken as the adjusted loop output value.

[0039] If the fifth determination result is no, the loop output value is taken as an adjusted loop output value.

[0040] The duty cycle and / or frequency of the first switch, the second switch, the third switch and the fourth switch in the series-parallel switching circuit are controlled based on the adjusted loop output value.

[0041] 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, and the processor executes the computer program to implement the loop control method of the charging voltage series-parallel switching device described above.

[0042] According to the specific embodiments provided by the present application, the present application has the following technical effects:

[0043] The present application provides a charging voltage series-parallel switching device and a loop control method and device thereof. In the traditional charging voltage series-parallel switching device, a first output end of the traditional series-parallel switching circuit is provided with an anti-backflow diode, and the traditional voltage loop controller only controls 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, at this time, the series-parallel switching circuit may have a short circuit risk. Therefore, the present application further improves the voltage loop control process, introduces a midpoint voltage, and the voltage loop controller controls the series-parallel switching circuit based on the output voltage and the midpoint voltage, thereby avoiding the short circuit risk. Finally, the electric vehicle direct current charging pile has a wide output voltage range in a low-cost manner. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0045] Figure 1 It is a circuit schematic diagram of the traditional series-parallel switching circuit with an anti-backflow diode D1.

[0046] Figure 2 It is a circuit schematic diagram of a series-parallel switching circuit provided by Embodiment 1 of the present application, which omits the anti-backflow diode D1.

[0047] Figure 3The working process schematic diagram of the series-parallel switching circuit provided in Embodiment 1 of the present application in the parallel state in the positive half cycle.

[0048] Figure 4 The working process schematic diagram of the series-parallel switching circuit provided in Embodiment 1 of the present application in the parallel state in the negative half cycle.

[0049] Figure 5 The working process schematic diagram of the series-parallel switching circuit provided in Embodiment 1 of the present application in the series state in the positive half cycle.

[0050] Figure 6 The working process schematic diagram of the series-parallel switching circuit provided in Embodiment 1 of the present application in the series state in the negative half cycle.

[0051] Figure 7 The principle schematic diagram of the loop control method of the charging voltage series-parallel switching device provided in Embodiment 1 of the present application.

[0052] Figure 8 The flow schematic diagram of the loop control method of the charging voltage series-parallel switching device provided in Embodiment 2 of the present application.

[0053] Figure 9 The structure schematic diagram of a computer device provided in Embodiment 3 of the present application. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without any creative work fall within the protection scope of the present application.

[0055] Embodiment 1.

[0056] Figure 1The traditional series-parallel switching circuit with anti-reflux diode D1 is shown, the transformer primary side is connected with the DC charging pile of electric vehicle, which is composed of 4 switching tubes Q1, Q2, Q3, Q4, 1 resonant inductor L1, 1 resonant capacitor C1 and 1 input winding T1-A, the switching tube can be MOS tube (which is the abbreviation of MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor)), by controlling the conduction and turn-off of the 4 switching tubes Q1, Q2, Q3, Q4, the DC power output by the rectifier circuit of the DC charging pile of electric vehicle is converted into AC power, when the switching tube Q1 and the switching tube Q4 are turned on, the switching tube Q2 and the switching tube Q3 are turned off, at this time the AC power is in the negative half cycle, when the switching tube Q1 and the switching tube Q4 are turned off, the switching tube Q2 and the switching tube Q3 are turned on, at this time the AC power is in the positive half cycle. The secondary side of the transformer includes 2 output windings T1-B, T1-C, the output end of the output winding T1-B has 4 rectifier diodes D2, D3, D4, D5, the 4 rectifier diodes D2, D3, D4, D5 convert the AC power output by the output winding T1-B into DC power, the output end of the 4 rectifier diodes D2, D3, D4, D5 has an output electrolytic capacitor C2, which is used for energy storage and filtering, the output end of the output winding T1-C has 4 rectifier diodes D6, D7, D8, D9, the 4 rectifier diodes D6, D7, D8, D9 convert the AC power output by the output winding T1-C into DC power, the output end of the 4 rectifier diodes D6, D7, D8, D9 has an output electrolytic capacitor C3, which is used for energy storage and filtering, the output winding T1-B, the 4 rectifier diodes D2, D3, D4, D5 and the output electrolytic capacitor C2 constitute the first voltage output, the output winding T1-C, the 4 rectifier diodes D6, D7, D8, D9 and the output electrolytic capacitor C3 constitute the second voltage output, the first voltage output and the second voltage output realize voltage series output or parallel output through the switch K1 and the 3 anti-reflux diodes D10, D11, D12, when the switch K1 is open, parallel output is realized, when the switch K1 is closed, series output is realized, the switch K1 can be a contactor, the anti-reflux 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 (which can also be called output voltage sampling value) is obtained by sampling, the output voltage is the voltage between the output end VOUT_DC+ and VOUT_DC-, the subsequent voltage loop controller controls the 4 switching tubes Q1, Q2, Q3, Q4 based on the output voltage to realize voltage loop control, so that the output voltage is as close to the target voltage as possible.

[0057] Obviously, the traditional series-parallel switching circuit has an anti-backflow diode D1, and has a complex structure and high cost. In order to solve the problem of wide range output of the output voltage of the direct current charging pile of the electric vehicle and control cost, the embodiment provides a novel charging voltage series-parallel switching device, and the anti-backflow diode D1 on the secondary side of the transformer is omitted. At this time, a short circuit risk may be caused in the module parallel operation mode (i.e. in parallel). In order to solve the problem of the short circuit risk, the output voltage VOUT and the midpoint voltage VMID are used to participate in the voltage loop control, so as to realize the loop control process of the series-parallel switching circuit, and the stable output between 200V-1000V can be realized. Meanwhile, the anti-backflow diode D1 on the secondary side of the traditional transformer can be omitted, the simplicity of the charging voltage series-parallel switching device is improved under the premise of ensuring the reliability of the charging voltage series-parallel switching device, the size of the whole charging pile system is reduced, and the volume power density is improved.

[0058] Figure 2 The novel series-parallel switching circuit after omitting the anti-backflow diode D1 is shown, and the VMID is the midpoint of the two-way output, i.e. the midpoint voltage sampling point, and the midpoint voltage VMID (which can also be referred to as the midpoint voltage sampling value) is sampled. Specifically, the embodiment provides a charging voltage series-parallel switching device, which comprises a series-parallel switching circuit and a voltage loop controller.

[0059] The series-parallel switching circuit comprises a voltage input module, a first voltage output module, a second voltage output module and a switching module, and the switching module comprises a switch. The output end of the voltage input module is connected to the input end of the first voltage output module and the input end of the second voltage output module respectively, the first output end of the first voltage output module is used as the first output end of the series-parallel switching circuit, the second output end of the first voltage output module is connected to the first end of the switch and the second output end of the second voltage output module respectively, the first output end of the second voltage output module is connected to the second end of the switch and the first output end of the first voltage output module respectively, and the second output end of the second voltage output module is used as the second output end of the series-parallel switching circuit.

[0060] The voltage loop controller is used for sampling the voltage at the first output end of the series-parallel switching circuit to obtain the output voltage, sampling the voltage at the second end of the switch to obtain the midpoint voltage, and performing voltage loop control on the series-parallel switching circuit based on the output voltage and the midpoint voltage.

[0061] The embodiment provides a charging voltage series-parallel switching device, which realizes wide voltage range output by controlling the on-off of the switch, uses the control method that the output voltage sampling and the midpoint voltage sampling participate in the loop regulation together, omits the anti-backflow diode D1 on the secondary side of the transformer, reduces the device cost, reduces the overall size of the whole machine, and improves the volume power density.

[0062] AsFigure 2 As shown in the figure, the voltage input module adopts an LLC resonant converter. The voltage input module includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, a resonant inductor L1, a resonant capacitor C1, and an input winding T1-A of a transformer. The first end of the first switch Q1 is connected to the first input end of the voltage input module and the first end of the second switch Q2, respectively; the second end of the first switch Q1 is connected to the first end of the third switch Q3 and the first end of the resonant capacitor C1, respectively; the second end of the second switch Q2 is connected to the first end of the fourth switch Q4 and the first end of the resonant inductor L1, respectively; the second end of the third switch Q3 is connected to the second input end of the voltage input module and the second end of the fourth switch Q4, respectively; the first input end of the voltage input module and the second input end of the voltage input module are connected to the output end of the DC charging pile of the electric vehicle; the second end of the resonant inductor L1 is connected to the first end of the input winding T1-A; the second end of the resonant capacitor C1 is connected to the second end of the input winding T1-A; and the input winding T1-A is the output end of the voltage input module.

[0063] The control end of the first switch Q1, the control end of the second switch Q2, the control end of the third switch Q3, and the control end of the fourth switch Q4 are connected to a voltage loop controller, which is configured to control the duty ratio and / or frequency of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 based on the output voltage and the midpoint voltage, so as to perform voltage loop control on the series-parallel switching circuit.

[0064] As shown in the figure, the first voltage output module and the second voltage output module have the same structure. Figure 2 As shown in the figure, the first voltage output module and the second voltage output module have the same structure.

[0065] The first voltage output module includes an output winding T1-B of a transformer, 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 end of the first voltage output module; the first end of the output winding T1-B is connected to the anode of the first rectifier diode D2 and the cathode of the third rectifier diode D4, respectively; the second end of the output winding T1-B is connected to the anode of the second rectifier diode D3 and the cathode of the fourth rectifier diode D5, respectively; the cathode of the first rectifier diode D2 is connected to the cathode of the second rectifier diode D3 and the first end of the output electrolytic capacitor C2, respectively; the anode of the third rectifier diode D4 is connected to the anode of the fourth rectifier diode D5 and the second end of the output electrolytic capacitor C2, respectively; and the first end of the output electrolytic capacitor C2 is the first output end of the first voltage output module, and the second end of the output electrolytic capacitor C2 is the second output end of the first voltage output module.

[0066] The second voltage output module comprises an output winding T1-C of the transformer, 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 is the input end 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 respectively, serving as the first output end of the second voltage output module, and 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 respectively, serving as the second output end of the second voltage output module.

[0067] As shown in Figure 2 The switching module further comprises a first anti-inrush diode D10, a second anti-inrush diode D11 and a third anti-inrush diode D12, the cathode of the first anti-inrush diode D10 is connected to the first output end of the first voltage output module, the anode of the first anti-inrush diode D10 is connected to the second end of the switch K1 and the first output end of the second voltage output module respectively, the first end of the switch K1 is connected to the anode of the second anti-inrush diode D11, the cathode of the second anti-inrush diode D11 is connected to the second output end of the first voltage output module and the cathode of the third anti-inrush diode D12 respectively, and the anode of the third anti-inrush diode D12 is connected to the second output end of the second voltage output module.

[0068] 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 opened, the first voltage output module and the second voltage output module are connected in parallel.

[0069] The embodiment designs a series-parallel switching circuit, when low voltage below 500V needs to be output, the switch is controlled to be opened to make the two output paths on the secondary side connected in parallel, when high voltage above 500V needs to be output, the switch is controlled to be closed to make the two output paths on the secondary side connected in series, of course, other values can also be selected as the demarcation line of series connection and parallel connection according to user demand.

[0070] Figure 3 And Figure 4 The working process diagram when the switch K1 is opened and the output is in parallel is shown, 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 working process diagram when the switch K1 is closed and the output is in series is shown, at this time, the midpoint voltage is equal to half of the output voltage, that is, the output voltage VOUT=2 midpoint voltage VMID.

[0071] Figure 1 D1 is an anti-inrush diode at the output end, which prevents the outside voltage from flowing into the secondary side of the transformer, and which may affect the output voltage VOUT, possibly causing a short circuit risk in the module parallel operation mode. Due to the particularity of the series-parallel switching circuit and the voltage loop controller in the embodiment, D10, D11, and D12 can prevent the outside voltage from flowing into the secondary side of the transformer, and the control method of flexibly switching the loop control object avoids the short circuit risk caused by the influence of the output voltage VOUT, so the anti-inrush diode D1 can be omitted.

[0072] Since the secondary side output anti-inrush 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, and then affect the voltage loop control output. Therefore, in the embodiment, the midpoint voltage and the output voltage are both taken as the loop control objects to participate in the voltage loop control, that is, when the corresponding relationship between the output voltage and the midpoint voltage within the normal error range is detected, the output voltage is taken as the voltage loop control object; when the corresponding relationship between the output voltage and the midpoint voltage deviates from the normal error range is detected, the midpoint voltage is taken as the voltage loop control object.

[0073] Specifically, Figure 7 The principle of the loop control method is shown, and the specific steps are as follows.

[0074] (1) When the output voltage is below 503V, the switch K1 is opened to make the two outputs on the secondary side parallel, at which time the output voltage VOUT is theoretically equal to the midpoint voltage VMID, and the error voltage AV = |VOUT-VMID| is calculated. When the error voltage AV 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, where Vreq is the given value of the output voltage, i.e. the target voltage; when the error voltage AV 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.

[0075] (2) When the output voltage is above 503V, the switch K1 is closed to make the two outputs on the secondary side series, at which time the output voltage VOUT is theoretically equal to twice the midpoint voltage VMID, and the error voltage AV = |VOUT-2VMID| is calculated. When the error voltage AV 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 AV is greater than or equal to the maximum allowable error voltage Vmax, the voltage loop control object is twice the midpoint voltage VMID, and the voltage loop control error factor Δε = Vreq-2VMID. ​VMID, voltage loop control error factor Δε = Vreq - 2 VMID.

[0076] (3) 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, to obtain the adjusted voltage loop control error factor Δε1, and the adjusted voltage loop control error factor Δε1 is subjected to PI (Proportional-Integral) operation, u = Kp Δε1+ Ki Δε1, u is the loop output value, which is the control adjustment variable of the output voltage, Kp is the proportional operation coefficient of the PI controller, and Ki is the integral operation coefficient of the PI controller. The loop output value u is limited to the minimum value of the loop output value Umin and the maximum value of the loop output value Umax to obtain the adjusted loop output value u1. The adjusted loop output value u1 is converted into the duty ratio and / or frequency of the control switch tube, and the output voltage is dynamically adjusted under negative feedback regulation to complete closed-loop control.

[0077] The working process of the charging voltage series-parallel switching device of the embodiment will be described in detail below.

[0078] As shown in Figure 3 and Figure 4 , when the output voltage is below 503V, the control switch K1 is turned off, at this time, the T1-C winding same-phase terminal voltage is output to the VOUT_DC+ pole through the D10 diode, returns to the VOUT_DC- pole and then reaches the T1-C winding opposite-phase terminal, the T1-B winding same-phase terminal voltage is output to the VOUT_DC+ pole, returns to the VOUT_DC- pole and then returns to the T1-B winding opposite-phase terminal through the D12 diode, that is, the T1-B winding and the T1-C winding are in parallel output, realizing the secondary side parallel output, at this time, the output voltage VOUT is theoretically equal to the midpoint voltage VMID, the circuit working graph of the positive half cycle is as shown in Figure 3 , and the circuit working graph of the negative half cycle is as shown in Figure 4The error voltage AV = |VOUT-VMID| 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 AV 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 to the minimum voltage loop control error factor εmin and the maximum voltage loop control error factor εmax to obtain the adjusted voltage loop control error factor Δε1, which is subjected to PI operation, u = Kp Δε1+Ki Δε1, the loop output value u is limited to the minimum loop output value Umin and the maximum loop output value Umax to obtain the adjusted loop output value u1, which is converted into the duty ratio and / or frequency of the control switch tube, and the output voltage is dynamically adjusted under negative feedback regulation to complete closed-loop control.

[0079] As shown in Figure 5 and Figure 6 When the output voltage is above 503V, the control switch K1 is closed, at this time, the T1-C winding same-phase terminal voltage returns to the T1-B winding opposite-phase terminal through the D11 diode, and is output to the VOUT_DC+ pole through the T1-B winding same-phase terminal, and returns to the VOUT_DC- pole and reaches the T1-C winding opposite-phase terminal, the T1-B winding same-phase terminal voltage is output to the VOUT_DC+ pole, and returns to the VOUT_DC- pole through the T1-C winding opposite-phase terminal and reaches the T1-C winding same-phase terminal, and returns to the T1-B winding opposite-phase terminal through the D11 diode, that is, the T1-B winding and the T1-C winding are connected in series to realize 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 working graph of the positive half cycle is as shown in Figure 5 , and the circuit working graph of the negative half cycle is as shown in Figure 6 In fact, the output voltage and 2 times the midpoint voltage exist a certain error voltage AV, the error voltage AV = |VOUT-2 VMID, error voltage ΔV is less than the maximum allowable error voltage Vmax, it belongs to normal stable state, so when the error voltage ΔV is less than the maximum allowable error voltage Vmax, the voltage loop control object is 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, the voltage loop control error factor Δε = Vreq-2 VMID. After calculating the voltage loop control error factor Δε, it is limited to the minimum voltage loop control error factor εmin and the maximum voltage loop control error factor εmax, to obtain the adjusted voltage loop control error factor Δε1, and the adjusted voltage loop control error factor Δε1 is subjected to PI operation, u = Kp Δε1+Ki Δε1, the loop output value u is limited to the minimum loop output value Umin and the maximum loop output value Umax, to obtain the adjusted loop output value u1, and the adjusted loop output value u1 is converted into the duty cycle and / or frequency of the control switch tube, and the output voltage is dynamically adjusted under negative feedback regulation to complete closed-loop control.

[0080] In the module parallel operation mode, that is, the two voltage output module VOUT_DC+ and VOUT_DC- are connected in parallel, since the output voltage VOUT may come from other parallel modules, and the sampling value is higher than the output voltage given value of itself, the voltage loop control of itself will be reduced under the action of negative feedback regulation PWM (Pulse Width Modulation, pulse width modulation) duty cycle output, and finally the PWM duty cycle is reduced to 0, which will cause the midpoint voltage VMID to be 0, at this time the output electrolytic capacitor is approximately short-circuited, and at this time the module is in the state of starting, and the output voltage soft start process has been completed. If VOUT_DC+, VOUT_DC- suddenly adds heavy load at this time, the output voltage VOUT will drop in an instant, which will cause the voltage loop control of itself to issue a large duty cycle PWM under the action of negative feedback regulation, the heavier the added load, the larger the instantaneous PWM duty cycle will be, which will cause the risk of short circuit of the transformer secondary side without voltage soft start. Therefore, without the anti-backflow diode D1, the midpoint voltage VMID is essential as a voltage loop control object, which is also conducive to the stable regulation and operation of the system, so as to realize Figure 1 the traditional series-parallel switching circuit with anti-backflow diode D1 shown in the figure is changed to Figure 2 the new series-parallel switching circuit without anti-backflow diode D1 shown in the figure.

[0081] The embodiment uses a charging voltage series-parallel switching device and a voltage loop control method to realize 200V-1000V wide voltage range output, adapt to the high-voltage platform charging demand of electric vehicles, and also compatible with traditional low-voltage platform vehicles. The circuit is simple, and the boost function is realized with the least devices to reduce the cost. By changing the voltage loop control object for flexible regulation and control, reducing the use of secondary side anti-backflow diode D1, both avoiding the risk brought by parallel operation and reducing the size of the whole machine, further reducing the cost of devices through software control method, and improving the power density of the whole machine.

[0082] Embodiment 2.

[0083] The embodiment provides a loop control method of the charging voltage series-parallel switching device described in embodiment 1, as shown in Figure 8 , comprising the following steps.

[0084] S1: obtaining the output voltage and the midpoint voltage obtained by voltage sampling of the series-parallel switching circuit.

[0085] S2: based on the output voltage and the midpoint voltage, the voltage loop control of the series-parallel switching circuit is carried out.

[0086] In S2, based on the output voltage and the midpoint voltage, the voltage loop control of the series-parallel switching circuit is carried out, 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 in series, the reference voltage is twice the midpoint voltage, when the first voltage output module and the second voltage output module in the series-parallel switching circuit are 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 control of the series-parallel switching circuit is carried out.

[0087] Among them, based on the voltage loop control error factor, the voltage loop control of the series-parallel switching circuit is carried out, specifically including the following steps.

[0088] (1) PI operation is carried out on the voltage loop control error factor to obtain a loop output value.

[0089] The PI operation is performed on the voltage loop control error factor to obtain the loop output value, specifically including: judging whether the voltage loop control error factor is less than the error factor minimum value to obtain a second judgment result; if the second judgment result is yes, taking the error factor minimum 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 the error factor maximum value to obtain a third judgment result; if the third judgment result is yes, taking the error factor maximum value as the adjusted voltage loop control error factor; if the third judgment result is no, taking the voltage loop control error factor as the adjusted voltage loop control error factor; and performing the PI operation on the adjusted voltage loop control error factor to obtain the loop output value.

[0090] (2) 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 to perform voltage loop control on the series-parallel switching circuit.

[0091] 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 including: judging whether the loop output value is less than the loop output value minimum value to obtain a fourth judgment result; if the fourth judgment result is yes, taking the loop output value minimum value as the adjusted loop output value; if the fourth judgment result is no, judging whether the loop output value is greater than the loop output value maximum value to obtain a fifth judgment result; if the fifth judgment result is yes, taking the loop output value maximum 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; 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.

[0092] Embodiment 3.

[0093] In an exemplary embodiment, a computer device, which can be a server or a terminal, is provided, and an internal structure diagram of the computer device can be as shown in FIG. 1. Figure 9As shown in the figure. The computer device includes a processor, a memory, an Input / Output (I / O) interface and a communication interface. Among them, the processor, the memory and the input / output interface are connected through the system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capability. 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 the 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 the external device. The communication interface of the computer device is used to communicate with the terminal outside through the network connection. The computer program is executed by the processor to realize a loop control method of a charging voltage series-parallel switching device.

[0094] Those skilled in the art can understand that, Figure 9 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0095] In an exemplary embodiment, a computer device is provided, comprising a memory and a processor, the memory storing a computer program, and the processor executing the computer program to realize the loop control method of the charging voltage series-parallel switching device in embodiment 2.

[0096] Embodiment 4.

[0097] In an exemplary embodiment, a computer readable storage medium is provided, storing a computer program, the computer program being executed by a processor to realize the loop control method of the charging voltage series-parallel switching device in embodiment 2.

[0098] It should be noted that the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or authorized by all parties, and the collection, use and processing of related data need to comply with relevant regulations.

[0099] The technical features of the above embodiments can be combined in any way. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0100] The principles and implementations of the present application are described in detail with specific examples in this paper, and the above examples are only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation and application range will be changed. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A charging voltage series-parallel switching device, characterized by, include: Series-parallel switching circuits and voltage loop controllers; 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 terminal of the voltage input module is connected to the input terminal of the first voltage output module and the input terminal of the second voltage output module. The first output terminal of the first voltage output module serves as the first output terminal of the series-parallel switching circuit. The second output terminal of the first voltage output module is connected to the first terminal of the switch and the second output terminal of the second voltage output module. The first output terminal of the second voltage output module is connected to the second terminal of the switch and the first output terminal of the first voltage output module. The second output terminal of the second voltage output module serves as the second output terminal of the series-parallel switching circuit. The voltage loop controller is used to sample the voltage at the first output terminal of the series-parallel switching circuit to obtain the output voltage, sample the voltage at the second terminal 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. The voltage input module employs an LLC resonant converter; The voltage input module includes a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a resonant inductor, a resonant capacitor, and an input winding of a transformer. The first terminal of the first switching transistor is connected to the first input terminal of the voltage input module and the first terminal of the second switching transistor. The second terminal of the first switching transistor is connected to the first terminal of the third switching transistor and the first terminal of the resonant capacitor. The second terminal of the second switching transistor is connected to the first terminal of the fourth switching transistor and the first terminal of the resonant inductor. The second terminal of the third switching transistor is connected to the second input terminal of the voltage input module and the second terminal of the fourth switching transistor. The second terminal of the resonant inductor is connected to the first terminal of the input winding. The second terminal of the resonant capacitor is connected to the second terminal of the input winding. The input winding is the output terminal of the voltage input module. The control terminals of the first switch, the second switch, the third switch, and the fourth switch 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, the second switch, the third switch, and the fourth switch based on the output voltage and the midpoint voltage, so as to perform voltage loop control on the series-parallel switching circuit. The first voltage output module and the second voltage output module have the same structure; The first voltage output module comprises 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 connected to the anode of the first rectifier diode and the cathode of the third rectifier diode respectively, the second end of the output winding is connected to the anode of the second rectifier diode and the cathode of the fourth rectifier diode respectively, the cathode of the first rectifier diode is connected to the cathode of the second rectifier diode and the first end of the output electrolytic capacitor respectively, serving as the first output end of the first voltage output module, and the anode of the third rectifier diode is connected to the anode of the fourth rectifier diode and the second end of the output electrolytic capacitor respectively, serving as the second output end of the first voltage output module.

2. The charging voltage series-parallel switching device according to claim 1, characterized by The switching module further comprises a first anti-inrush diode, a second anti-inrush diode and a third anti-inrush diode; the cathode of the first anti-inrush diode is connected to the first output end of the first voltage output module, the anode of the first anti-inrush diode is connected to the second end of the switch and the first output end of the second voltage output module respectively, the first end of the switch is connected to the anode of the second anti-inrush diode, the cathode of the second anti-inrush diode is connected to the second output end of the first voltage output module and the cathode of the third anti-inrush diode respectively, and the anode of the third anti-inrush 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 opened, the first voltage output module and the second voltage output module are connected in parallel.

3. A loop control method of the charging voltage series-parallel switching device according to any one of claims 1 to 2, characterized by, It comprises: acquiring an output voltage and a midpoint voltage obtained by voltage sampling on the series-parallel switching circuit; controlling the series-parallel switching circuit based on the output voltage and the midpoint voltage.

4. The loop control method of a charging voltage series-parallel switching device according to claim 3, characterized by, controlling the series-parallel switching circuit based on the output voltage and the midpoint voltage, specifically comprising: calculating the absolute value of the 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; judging whether the error voltage is less than a maximum error voltage to obtain a first judgment result; if the first judgment result is yes, calculating the difference between a 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; controlling the series-parallel switching circuit based on the voltage loop control error factor.

5. The loop control method of a charging voltage series-parallel switching device according to claim 4, characterized by, controlling the series-parallel switching circuit based on the voltage loop control error factor, specifically comprising: performing PI operation on the voltage loop control error factor to obtain a loop output value; controlling duty cycles and / or frequencies of the first switch, the second switch, the third switch and the fourth switch in the series-parallel switching circuit based on the loop output value to perform voltage loop control on the series-parallel switching circuit.

6. The loop control method of a charging voltage series-parallel switching device according to claim 5, characterized by, performing PI operation on the voltage loop control error factor to obtain a loop output value, specifically comprising: determining whether the voltage loop control error factor is less than an error factor minimum value to obtain a second determination result; if the second determination result is yes, taking the error factor minimum value as an adjusted voltage loop control error factor; if the second determination result is no, determining whether the voltage loop control error factor is greater than an error factor maximum value to obtain a third determination result; if the third determination result is yes, taking the error factor maximum value as the adjusted voltage loop control error factor; if the third determination result is no, taking the voltage loop control error factor as the adjusted voltage loop control error factor; performing PI operation on the adjusted voltage loop control error factor to obtain a loop output value.

7. The loop control method of a charging voltage series-parallel switching device according to claim 5, characterized by, controlling duty cycles and / or frequencies of the first switch, the second switch, the third switch and the fourth switch in the series-parallel switching circuit based on the loop output value, specifically comprising: determining whether the loop output value is less than a loop output value minimum value to obtain a fourth determination result; if the fourth determination result is yes, taking the loop output value minimum value as an adjusted loop output value; if the fourth determination result is no, determining whether the loop output value is greater than a loop output value maximum value to obtain a fifth determination result; if the fifth determination result is yes, taking the loop output value maximum value as the adjusted loop output value; if the fifth determination result is no, taking the loop output value as the adjusted loop output value; controlling duty cycles and / or frequencies of the first switch, the second switch, the third switch and the fourth switch in the series-parallel switching circuit based on the adjusted loop output value.

8. 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 3-7.

Images