Power supply system, vehicle and power supply system control method
By employing a special connection method and control strategy for the full-bridge inverter switch and transformer, the problems of bidirectional energy flow and low-voltage high-current in the vehicle-mounted DC-DC circuit were solved, achieving a power supply system with low ripple current and high reliability, and reducing costs.
Patent Information
- Application Number
- CN202511421913.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-02-10
AI Technical Summary
Existing automotive DC-DC circuits cannot achieve bidirectional energy flow, and under high current conditions at the low voltage end, it is difficult to select DC blocking capacitors, resulting in high circuit cost, low reliability, and large output ripple current, which affects power quality and reliability.
The system employs a full-bridge inverter switch and transformer, combined with the connection methods of the first output half-bridge conversion arm, the second output half-bridge conversion arm, the bus capacitor, and the filter capacitor. Through the design of resonant inductors and center taps, the winding connection on the secondary side of the transformer is realized. A specific switching transistor control strategy is adopted, with complementary conduction at 50% duty cycle and phase difference control, to avoid transformer magnetization.
It reduces the ripple current of the output filter capacitor and bus capacitor, simplifies component selection, improves the output voltage quality, avoids transformer magnetization, and enhances the reliability and cost-effectiveness of the circuit.
Smart Images
Figure CN121508323A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power supply equipment technology, and in particular to a power supply system, a vehicle, and a power supply system control method. Background Technology
[0002] With the rapid development of the new energy vehicle industry, the requirements for on-board chargers and on-board DC-DC converters are becoming increasingly stringent. Currently, in addition to the general requirement that on-board chargers can operate bidirectionally, many automakers are further demanding that on-board DC-DC converters also operate bidirectionally. On the one hand, they should be able to obtain energy from the high-voltage power battery to charge the on-board low-voltage battery; on the other hand, when the vehicle starts, they should be able to obtain energy from the low-voltage battery to charge the bus capacitor connected to the high-voltage power battery, thus eliminating the need for a high-voltage pre-charging stage in the vehicle and reducing size and cost.
[0003] Currently, the mainstream topology for automotive DC-DC converters is a full-bridge converter (hard-switching full-bridge or soft-switching phase-shifting full-bridge) combined with a secondary-side synchronous rectification circuit. This circuit is essentially a unidirectional circuit, where energy can only flow from the high-voltage battery terminal to the low-voltage battery terminal, and it cannot achieve the reverse high-voltage pre-charge function. To achieve reverse operation of this circuit, a complex startup circuit must be added, increasing circuit costs and reducing system reliability. The dual active bridge (DAB) circuit is inherently a high-power bidirectional conversion circuit topology, and in recent years it has become the mainstream application topology for automotive chargers. Theoretically, it can also be used as an automotive DC-DC circuit topology to achieve bidirectional energy flow.
[0004] Mainstream DAB circuit topologies such as Figure 1 As shown, due to the discreteness of the components—namely, the different drive delays of the driver chips and the different switching speeds of the switching transistors—the time applied to the midpoints a and b, and c and d of the bridge arms cannot be perfectly symmetrical. When the voltage is the same but the application time is different, a small DC voltage component will inevitably exist on both the primary and secondary sides of the transformer. Although this DC voltage component is small, it will accumulate over time and cause… Figure 1 If the primary or secondary side of a transformer becomes magnetically biased or even saturated, it can introduce a large amount of extra current into the circuit, causing damage.
[0005] To prevent this from happening, a DC blocking capacitor is typically connected in series with the transformer winding to cancel out this DC voltage component, thereby ensuring that the volt-second product of the voltage applied to any winding of the transformer is zero and avoiding magnetic bias. For example Figure 1 The Cg1 connected in series on the primary side and the Cg2 connected in series on the secondary side of the transformer serve this purpose.
[0006] like Figure 1As shown, in mainstream DAB circuits, the current flowing through the DC blocking capacitor is equal to the primary or secondary current of the transformer. When both the input and output are at high voltage, such as in a vehicle OBC, the current flowing through the transformer's primary and secondary sides is relatively small, and correspondingly, the current flowing through the series-connected DC blocking capacitor is also relatively small, allowing this function to be achieved with a small number of capacitors. However, when the input or output voltage is very low, such as when the input of a vehicle DC-DC converter connected to the power battery is high, but the output voltage connected to the low-voltage battery is only a few tens of volts, the winding current of the low-voltage transformer is very large. Correspondingly, if a DC blocking capacitor is connected in series, the current flowing through it will also be very large; for example, if a DC blocking capacitor is connected in series on the low-voltage side of a vehicle DC-DC converter, the current can reach several hundred amperes. In this case, it is difficult to select a suitable device as the DC blocking capacitor, or a large number of capacitors need to be used in parallel, which seriously affects cost and reliability, making implementation almost impossible.
[0007] in addition, Figure 1 In traditional DAB circuits, if the output is low voltage and high current, the ripple current flowing through the output bus filter capacitor Co will also be very large. On the one hand, a large ripple current will make it difficult to select components; on the other hand, a large ripple current will also cause the output ripple voltage to be relatively large, which will seriously affect the output quality and reliability of the power supply. Summary of the Invention
[0008] The first objective of this invention is to provide a power supply system that solves the problem of transformer saturation without DC blocking capacitors.
[0009] A second objective of the present invention is to provide a vehicle having the aforementioned power system.
[0010] A third objective of this invention is to provide a control method applicable to the aforementioned power supply system.
[0011] To achieve the first objective of this invention, a power supply system is provided, comprising a full-bridge inverter switch and a transformer. The primary winding of the transformer is connected to the midpoint of the two arms of the full-bridge inverter switch. The power supply system further comprises a first output half-bridge conversion arm, a second output half-bridge conversion arm, a first output bus capacitor, a second output bus capacitor, an output filter inductor, and an output filter capacitor. The first end of the secondary winding of the transformer is connected to the midpoint of the arm of the first output half-bridge conversion arm, and the second end of the secondary winding of the transformer is connected to the midpoint of the arm of the second output half-bridge conversion arm. The center tap of the secondary winding of the transformer is connected to the first end of the output filter inductor, and the second end of the output filter inductor is connected to the positive terminal of the output filter capacitor. The low ends of the arms of both the first and second output half-bridge conversion arms are connected to the negative terminal of the output filter capacitor. The first output bus capacitor is connected between the high and low ends of the first output half-bridge conversion arm, and the second output bus capacitor is connected between the high and low ends of the second output half-bridge conversion arm.
[0012] A further proposed solution is to have a resonant inductor in the transformer, which is located on one side of the primary winding, one side of the secondary winding, or both sides of the primary and secondary windings.
[0013] A further proposed solution is to include an input DC blocking capacitor in the power supply system. The primary winding of the transformer has a resonant inductance, and the input DC blocking capacitor is connected in series between the resonant inductance and the midpoint of the bridge arm of the full-bridge inverter switch.
[0014] To achieve the first objective of this invention, a power supply system is provided, characterized in that it includes a first input half-bridge converter arm, a second input half-bridge converter arm, a first input bus capacitor, a second input bus capacitor, an input filter inductor, a transformer, a first output half-bridge converter arm, a second output half-bridge converter arm, a first output bus capacitor, a second output bus capacitor, an output filter inductor, and an output filter capacitor; the first end of the primary winding of the transformer is connected to the midpoint of the arm of the first input half-bridge converter arm, the second end of the primary winding of the transformer is connected to the midpoint of the arm of the second input half-bridge converter arm, the center tap of the primary winding of the transformer is connected to the first end of the input filter inductor, the second end of the input filter inductor is used to connect to the first polarity terminal of the DC power supply, and the low ends of the arms of the first and second input half-bridge converter arms are both used to connect to the second polarity terminal of the DC power supply. The first input bus capacitor is connected between the high and low ends of the first input half-bridge converter arm, and the second input bus capacitor is connected between the high and low ends of the second input half-bridge converter arm. The first end of the secondary winding of the transformer is connected to the midpoint of the first output half-bridge converter arm, the second end of the secondary winding of the transformer is connected to the midpoint of the second output half-bridge converter arm, the center tap of the secondary winding of the transformer is connected to the first end of the output filter inductor, the second end of the output filter inductor is connected to the positive terminal of the output filter capacitor, and the low ends of both the first and second output half-bridge converter arms are connected to the negative terminal of the output filter capacitor. The first output bus capacitor is connected between the high and low ends of the first output half-bridge converter arm, and the second output bus capacitor is connected between the high and low ends of the second output half-bridge converter arm.
[0015] A further proposed solution is to have a resonant inductor in the transformer, which is located on one side of the primary winding, one side of the secondary winding, or both sides of the primary and secondary windings.
[0016] To achieve the second objective of this invention, this invention provides a means of transportation that includes the power system described above.
[0017] To achieve the third objective of this invention, this invention provides a control method for a power supply system applied to the above-described scheme; The full-bridge inverter switch includes switch Q1, switch Q2, switch Q3 and switch Q4. Switch Q1 and switch Q2 form one bridge arm, switch Q3 and switch Q4 form another bridge arm, switch Q1 and switch Q4 are diagonal bridge arms, and switch Q2 and switch Q3 are diagonal bridge arms. The first output half-bridge conversion arm includes switch Q5 and switch Q6, and the second output half-bridge conversion arm includes switch Q7 and switch Q8. Switch Q5 and switch Q6 form one arm, and switch Q7 and switch Q8 form another arm. Switch Q5 and switch Q8 are diagonal arms to each other, and switch Q6 and switch Q7 are diagonal arms to each other. The control methods for power supply systems include: Switches Q1 and Q2 are turned on complementaryly with a 50% duty cycle, and switches Q3 and Q4 are turned on complementaryly with a 50% duty cycle. There is a phase difference α between switches Q1 and Q4. The bridge arm drive signal of switch Q1 leads the bridge arm drive signal of switch Q4. Switches Q5 and Q6 are turned on complementaryly with a 50% duty cycle, and switches Q7 and Q8 are turned on complementaryly with a 50% duty cycle. Switches Q8 and Q5 are in phase, and switches Q7 and Q6 are in phase. There is a phase difference φ between switches Q1 and Q5.
[0018] To achieve the third objective of this invention, this invention provides a control method for a power supply system as described in claim 7. The first input half-bridge conversion arm includes switch Q1 and switch Q2, and the second input half-bridge conversion arm includes switch Q3 and switch Q4. Switch Q1 and switch Q2 form one arm, and switch Q3 and switch Q4 form another arm. Switch Q1 and switch Q4 are diagonal arms to each other, and switch Q2 and switch Q3 are diagonal arms to each other. The first output half-bridge conversion arm includes switch Q5 and switch Q6, and the second output half-bridge conversion arm includes switch Q7 and switch Q8. Switch Q5 and switch Q6 form one arm, and switch Q7 and switch Q8 form another arm. Switch Q5 and switch Q8 are diagonal arms to each other, and switch Q6 and switch Q7 are diagonal arms to each other. The control methods for power supply systems include: Switches Q1 and Q2 are turned on complementaryly with a 50% duty cycle, and switches Q3 and Q4 are turned on complementaryly with a 50% duty cycle. Switches Q1 and Q4 are in phase, and switches Q2 and Q3 are in phase. Switches Q5 and Q6 are turned on complementaryly with a 50% duty cycle, and switches Q7 and Q8 are turned on complementaryly with a 50% duty cycle. Switches Q8 and Q5 are in phase, and switches Q7 and Q6 are in phase. There is a phase difference φ between switching transistors Q1 and Q5.
[0019] The beneficial effects of this invention are as follows: the secondary side of the transformer in this invention features a winding connection with a center tap. The center tap is connected to the output filter capacitor via an output filter inductor. This circuit is equivalent to a traditional DAB converter combined with an interleaved parallel Buck converter, with the operating duty cycle always maintained close to 50%. This is a circuit configuration shared by the output bridge arm of the DAB converter and the bridge arm of the Buck converter. Since the theoretical output ripple current of the interleaved parallel Buck converter operating at a 50% duty cycle is zero, the ripple current flowing through the output filter capacitor Co is almost zero. The selection of the filter capacitor is easy, and the number of parallel capacitors is small. Simultaneously, the output ripple voltage is also almost zero, resulting in excellent output voltage quality. Furthermore, by adding the bus capacitor of the bridge arm, the voltage increases while the current decreases, thus significantly reducing the ripple current flowing through the bus capacitor, making component selection easier.
[0020] In addition, a bus capacitor is connected to each bridge arm, allowing the voltage of the two independent bus capacitors to automatically adjust during circuit operation. This compensates for the DC component of the voltage between the bridge arm midpoints caused by other asymmetries, ensuring that the voltage between the bridge arm midpoints remains balanced in volt-second product. This effectively solves the problem of transformer winding bias or even saturation in this circuit. If the circuit components operate asymmetrically, causing the positive voltage VCC1 applied to the transformer terminal at bridge arm midpoint c for a longer time than the positive voltage VCC2 applied to the transformer terminal at bridge arm midpoint d, the circuit will adjust to decrease VCC1 and increase VCC2. This ensures that the product of the voltage and time applied to the midpoints of the first and second output half-bridge conversion arms is equal, thus balancing the volt-second product between the two midpoints and preventing bias in the transformer windings connecting the two midpoints. Attached Figure Description
[0021] Figure 1 This is a circuit diagram of a DAB circuit in the prior art.
[0022] Figure 2 This is a circuit diagram of the first embodiment of the power supply system of the present invention.
[0023] Figure 3 This is a circuit diagram of the second embodiment of the power supply system of the present invention.
[0024] Figure 4 This is a timing diagram of the drive signal of the switching transistor in the first and second embodiments of the power system control method of the present invention.
[0025] Figure 5 This is a circuit diagram of the third embodiment of the power supply system of the present invention.
[0026] Figure 6 This is a timing diagram of the drive signal of the switching transistor in the third embodiment of the power system control method of the present invention.
[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed Implementation
[0028] First embodiment of the power supply system: Reference Figure 2 The power supply system includes a full-bridge inverter switch, a first output half-bridge conversion arm, a second output half-bridge conversion arm, a transformer Tr, an input DC blocking capacitor Cg, an output filter inductor Lo, and an output filter capacitor Co. The primary winding of the transformer Tr is connected to the midpoints (a, b) of the two arms of the full-bridge inverter switch, and the two ends of the secondary winding of the transformer Tr are connected to the midpoints of the arms of the first output half-bridge conversion arm and the second output half-bridge conversion arm, respectively.
[0029] Specifically, the full-bridge inverter switch includes transistors Q1, Q2, Q3, and Q4. Transistors Q1 and Q2 form one input bridge arm, and transistors Q3 and Q4 form another input bridge arm. Transistors Q1 and Q4 are diagonal bridge arms, as are transistors Q2 and Q3. The high and low ends of each input bridge arm are connected to the input DC power supply Vin. One side of the primary winding of the transformer Tr has a resonant inductance Ls, and the input DC blocking capacitor Cg is connected in series between the resonant inductance Ls and the midpoint b of the input bridge arm of the full-bridge inverter switch.
[0030] The first output half-bridge converter arm includes switches Q5 and Q6, and the second output half-bridge converter arm includes switches Q7 and Q8. Switches Q5 and Q6 form one output bridge arm, and switches Q7 and Q8 form another output bridge arm. Switches Q5 and Q8 are diagonal bridge arms, and switches Q6 and Q7 are diagonal bridge arms.
[0031] The center tap of the secondary winding of transformer Tr is connected to the first terminal of the output filter inductor Lo. The second terminal of the output filter inductor Lo is connected to the positive terminal of the output filter capacitor Co. The low terminals of the first and second output half-bridge converter arms are both connected to the negative terminal of the output filter capacitor Co. The power supply system also includes a first output bus capacitor Cc1 and a second output bus capacitor Cc2. The first output bus capacitor Cc1 is connected between the high and low terminals of the first output half-bridge converter arm, and the second output bus capacitor Cc2 is connected between the high and low terminals of the second output half-bridge converter arm.
[0032] Second embodiment of the power supply system: Reference Figure 3Based on the first embodiment described above, the resonant inductor Ls can also be located on one side of the secondary winding of the transformer Tr. In this case, the resonant inductor is a coupled inductor with two windings, as shown in the attached figure. Figure 4 As shown, the DC blocking capacitor Cg is connected between the primary winding of the transformer Tr and the midpoint of the bridge arm of the full-bridge inverter switch.
[0033] In addition, the resonant inductor can be located on both the primary and secondary sides of the transformer at the same time, or it can be integrated into the transformer as a leakage inductor using magnetic integration.
[0034] First embodiment of power system control method: Reference Figure 4 The power system control method, applied to the first and second embodiments of the power system described above, includes switching transistors Q1 and Q2 being turned on complementaryly with a 50% duty cycle, switching transistors Q3 and Q4 being turned on complementaryly with a 50% duty cycle, a phase difference α (inner phase shift angle) between switching transistors Q1 and Q4, and the bridge arm drive signal of switching transistor Q1 being triggered ahead of the bridge arm drive signal of switching transistor Q4.
[0035] Switches Q5 and Q6 are turned on complementaryly with a 50% duty cycle, and switches Q7 and Q8 are turned on complementaryly with a 50% duty cycle. Switches Q8 and Q5 are in phase, and switches Q7 and Q6 are in phase. There is a phase difference φ (outer phase angle) between switches Q1 and Q5.
[0036] By controlling the outer and inner phase shift angles, precise control of the DC output voltage and current can be achieved. It should also be noted that phase shifting can be used between output bridge arms Q5 and Q6 and output bridge arms Q7 and Q8 to increase the flexibility of output voltage and current control, but this will increase the output ripple current, which is theoretically no longer zero. Therefore, although this control method can be used, it is not recommended.
[0037] Third embodiment of the power supply system: Reference Figure 5 In the third embodiment, both the input and output terminals are low-voltage and high-current, and it is a circuit form in which no DC blocking capacitor is connected in series. The power supply system includes a first input half-bridge converter arm, a second input half-bridge converter arm, a first output half-bridge converter arm, a second output half-bridge converter arm, a transformer Tr, an input filter inductor Lin, an output filter inductor Lo, and an output filter capacitor Co.
[0038] Specifically, the first input half-bridge conversion arm includes switch Q1 and switch Q2, and the second input half-bridge conversion arm includes switch Q3 and switch Q4. Switch Q1 and switch Q2 form one input arm, and switch Q3 and switch Q4 form another input arm. Switch Q1 and switch Q4 are diagonal arms to each other, and switch Q2 and switch Q3 are diagonal arms to each other.
[0039] The first end of the primary winding of transformer Tr is connected to the midpoint a of the first input half-bridge converter arm, and the second end of the primary winding of transformer Tr is connected to the midpoint b of the second input half-bridge converter arm. The center tap of the primary winding of transformer Tr is connected to the first polarity terminal of the DC power supply through the series input inductor Lin. The low ends of the first and second input half-bridge converter arms are both used to connect to the second polarity terminal of the DC power supply.
[0040] The first output half-bridge converter arm includes switches Q5 and Q6, and the second output half-bridge converter arm includes switches Q7 and Q8. Switches Q5 and Q6 form one output bridge arm, and switches Q7 and Q8 form another output bridge arm. Switches Q5 and Q8 are diagonal bridge arms, and switches Q6 and Q7 are diagonal bridge arms.
[0041] The structure on the output side is the same as in the first or second embodiment, and will not be described again hereafter. The power supply system also includes a first input bus capacitor Cc3 and a second input bus capacitor Cc4. The first input bus capacitor Cc3 is connected between the high end and the low end of the first input half-bridge converter arm, and the second input bus capacitor Cc4 is connected between the high end and the low end of the second input half-bridge converter arm.
[0042] As in the above embodiment, the resonant inductance Ls of the transformer is located on one side of the primary winding of the transformer Tr, on one side of the secondary winding of the transformer Tr, or simultaneously on both sides of the primary winding and the secondary winding of the transformer Tr.
[0043] Second embodiment of power system control method: Reference Figure 6 In the third embodiment of the power supply system described above, the control method of the power supply system includes: switching transistors Q1 and Q2 are turned on complementaryly with a 50% duty cycle; switching transistors Q3 and Q4 are turned on complementaryly with a 50% duty cycle; switching transistors Q1 and Q4 are in phase; and switching transistors Q2 and Q3 are in phase.
[0044] Switches Q5 and Q6 are turned on complementaryly with a 50% duty cycle, and switches Q7 and Q8 are turned on complementaryly with a 50% duty cycle. Switches Q8 and Q5 are in phase, and switches Q7 and Q6 are in phase.
[0045] There is a phase difference φ (outer phase shift angle) between switching transistors Q1 and Q5. By controlling the outer phase shift angle, precise control of the DC output voltage and current can be achieved. It should be noted that although the circuit can also use a triple phase shift control method, it is not recommended because it violates the condition of zero ripple current at the input and output terminals.
[0046] As can be seen from the above, the secondary side of the transformer in this case has a winding connection with a center tap. The center tap is connected to the output filter capacitor through the output filter inductor. The circuit in this case is equivalent to a traditional DAB converter combined with an interleaved parallel Buck converter, and the duty cycle is always kept close to 50%. This is a circuit form shared by the output bridge arm of the DAB converter and the bridge arm of the Buck converter. Since the theoretical output ripple current of the interleaved parallel Buck converter operating at a 50% duty cycle is zero, the ripple current flowing through the output filter capacitor Co is almost zero. The selection of the filter capacitor is easy and the number of parallel capacitors is small. At the same time, the output ripple voltage is also almost zero, and the output voltage quality is good.
Claims
1. A power supply system comprising a full-bridge inverter switch and a transformer, wherein the primary winding of the transformer is connected to the midpoint of the two arms of the full-bridge inverter switch; Its features are: The power supply system further includes a first output half-bridge converter arm, a second output half-bridge converter arm, a first output bus capacitor, a second output bus capacitor, an output filter inductor, and an output filter capacitor. The first end of the secondary winding of the transformer is connected to the midpoint of the arm of the first output half-bridge converter arm, the second end of the secondary winding of the transformer is connected to the midpoint of the arm of the second output half-bridge converter arm, the center tap of the secondary winding of the transformer is connected to the first end of the output filter inductor, the second end of the output filter inductor is connected to the positive terminal of the output filter capacitor, and the low ends of the arms of the first and second output half-bridge converter arms are both connected to the negative terminal of the output filter capacitor. The first output bus capacitor is connected between the high end and the low end of the first output half-bridge converter arm, and the second output bus capacitor is connected between the high end and the low end of the second output half-bridge converter arm.
2. The power supply system according to claim 1, characterized in that: The transformer has a resonant inductor located on one side of the primary winding, one side of the secondary winding, or simultaneously on both sides of the primary and secondary windings.
3. The power supply system according to claim 1, characterized in that: The power supply system also includes an input DC blocking capacitor. One side of the primary winding of the transformer has a resonant inductance, and the input DC blocking capacitor is connected in series between the resonant inductance and the midpoint of the bridge arm of the full-bridge inverter switch.
4. The power supply system according to any one of claims 1 to 3, characterized in that: The high-end and low-end of the bridge arm of the full-bridge inverter switch are used to connect to a DC power supply.
5. A power supply system, characterized in that, It includes a first input half-bridge converter arm, a second input half-bridge converter arm, a first input bus capacitor, a second input bus capacitor, an input filter inductor, a transformer, a first output half-bridge converter arm, a second output half-bridge converter arm, a first output bus capacitor, a second output bus capacitor, an output filter inductor, and an output filter capacitor; The first end of the primary winding of the transformer is connected to the midpoint of the arm of the first input half-bridge converter arm, the second end of the primary winding of the transformer is connected to the midpoint of the arm of the second input half-bridge converter arm, the center tap of the primary winding of the transformer is connected to the first end of the input filter inductor, the second end of the input filter inductor is used to connect to the first polarity terminal of the DC power supply, and the low ends of the arms of the first and second input half-bridge converter arms are both used to connect to the second polarity terminal of the DC power supply. The first input bus capacitor is connected between the high end and the low end of the first input half-bridge converter arm, and the second input bus capacitor is connected between the high end and the low end of the second input half-bridge converter arm. The first end of the secondary winding of the transformer is connected to the midpoint of the arm of the first output half-bridge converter arm, the second end of the secondary winding of the transformer is connected to the midpoint of the arm of the second output half-bridge converter arm, the center tap of the secondary winding of the transformer is connected to the first end of the output filter inductor, the second end of the output filter inductor is connected to the positive terminal of the output filter capacitor, and the low ends of the arms of the first and second output half-bridge converter arms are both connected to the negative terminal of the output filter capacitor. The first output bus capacitor is connected between the high end and the low end of the first output half-bridge converter arm, and the second output bus capacitor is connected between the high end and the low end of the second output half-bridge converter arm.
6. The power supply system according to claim 5, characterized in that: The transformer has a resonant inductor located on one side of the primary winding, one side of the secondary winding, or simultaneously on both sides of the primary and secondary windings.
7. A means of transport, characterized in that, The power supply system includes any one of claims 1 to 6.
8. A control method applied to the power supply system according to any one of claims 1 to 4, characterized in that: The full-bridge inverter switch includes switch Q1, switch Q2, switch Q3 and switch Q4. Switch Q1 and switch Q2 form one bridge arm, switch Q3 and switch Q4 form another bridge arm, switch Q1 and switch Q4 are diagonal bridge arms, and switch Q2 and switch Q3 are diagonal bridge arms. The first output half-bridge conversion arm includes switch Q5 and switch Q6, and the second output half-bridge conversion arm includes switch Q7 and switch Q8. Switch Q5 and switch Q6 form one arm, and switch Q7 and switch Q8 form another arm. Switch Q5 and switch Q8 are diagonal arms to each other, and switch Q6 and switch Q7 are diagonal arms to each other. The control method for the power supply system includes: The switching transistors Q1 and Q2 are turned on complementaryly with a 50% duty cycle, and the switching transistors Q3 and Q4 are turned on complementaryly with a 50% duty cycle. There is a phase difference α between the switching transistors Q1 and Q4. The bridge arm drive signal of the switching transistor Q1 is triggered ahead of the bridge arm drive signal of the switching transistor Q4. Switch Q5 and switch Q6 are turned on complementaryly with a 50% duty cycle, switch Q7 and switch Q8 are turned on complementaryly with a 50% duty cycle, switch Q8 and switch Q5 are in phase, switch Q7 and switch Q6 are in phase, and there is a phase difference φ between switch Q1 and switch Q5.
9. A control method applied to the power supply system described in claim 5 or 6, characterized in that: The first input half-bridge conversion arm includes switch Q1 and switch Q2, and the second input half-bridge conversion arm includes switch Q3 and switch Q4. Switch Q1 and switch Q2 form one arm, and switch Q3 and switch Q4 form another arm. Switch Q1 and switch Q4 are diagonal arms to each other, and switch Q2 and switch Q3 are diagonal arms to each other. The first output half-bridge conversion arm includes switch Q5 and switch Q6, and the second output half-bridge conversion arm includes switch Q7 and switch Q8. Switch Q5 and switch Q6 form one arm, and switch Q7 and switch Q8 form another arm. Switch Q5 and switch Q8 are diagonal arms to each other, and switch Q6 and switch Q7 are diagonal arms to each other. The control method for the power supply system includes: The switching transistors Q1 and Q2 are turned on complementaryly with a 50% duty cycle, and the switching transistors Q3 and Q4 are turned on complementaryly with a 50% duty cycle. The switching transistors Q1 and Q4 are in phase, and the switching transistors Q2 and Q3 are in phase. The switching transistors Q5 and Q6 are turned on complementaryly with a 50% duty cycle, the switching transistors Q7 and Q8 are turned on complementaryly with a 50% duty cycle, the switching transistors Q8 and Q5 are in phase, and the switching transistors Q7 and Q6 are in phase. There is a phase difference φ between the switching transistors Q1 and Q5.