Power conversion device, control method thereof and power system
By setting a buffer circuit in the conversion circuit of the switching power supply to absorb the leakage inductance energy on the secondary side of the transformer, the energy loss problem of the switching device during hard switching is solved, and efficient energy utilization and power supply efficiency are achieved.
Patent Information
- Application Number
- CN202511296385.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-11
- Publication Date
- 2025-12-05
AI Technical Summary
The switching devices in a switching power supply suffer significant energy loss during hard switching, especially when power is scarce, leading to insufficient power supply.
A buffer circuit consisting of a buffer capacitor, a buffer inductor, and an auxiliary switching transistor is set between the rectifier side and the load side of the converter circuit to absorb the leakage inductance energy of the transformer secondary side. The buffer circuit absorbs and stores energy within one cycle, thereby reducing the switching losses of the switching devices.
It reduces the energy loss of the switching power supply, improves the efficiency of the power supply, enhances the stability and reliability of the system, simplifies the complexity of the absorption circuit, and reduces the system cost.
Smart Images
Figure CN121077253A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of power supply, and particularly relates to a power conversion device, a control method thereof and a power supply system, in particular to a conversion circuit based on absorbing leakage energy of a transformer at a secondary side of the transformer, a control method thereof and a power supply system. BACKGROUND
[0002] In the modern scientific and technological information era, higher requirements are put forward for the stability and quality of power supply in various fields. Especially in unmanned environments, long-term efficient and stable power supply has become the focus of power electronics research. Switching power supply, as a kind of power supply, can provide long-term efficient and stable power supply.
[0003] Switching power supply, also known as switching mode power supply (SMPS) or switching converter, is a kind of high-frequency power conversion device. The function of switching power supply is to convert a voltage of one level into a voltage or current required by the user end through different forms of architecture. The input of switching power supply is mostly alternating current power (such as mains) or direct current power, and the output is mostly devices requiring direct current power, such as personal computers, and switching power supply converts voltage and current between the two.
[0004] However, in the related scheme, the switching device in the switching power supply has significant energy loss (i.e. switching loss) in the hard switching process, especially in extreme environments where the power is relatively scarce, and the switching loss may cause insufficient power supply.
[0005] The above content is only used to assist in understanding the technical solutions of the present application, and does not represent the acknowledgement of the above content as prior art. SUMMARY
[0006] The purpose of the present application is to provide a power conversion device, a control method thereof and a power supply system, to solve the problem of energy loss (i.e. switching loss) of the switching device in the switching power supply in the hard switching process in the related scheme, which may cause insufficient power supply in the case of relatively scarce power. By setting a buffer circuit between the rectifier side and the load side of the conversion circuit, the leakage energy of the secondary side of the transformer (such as high-frequency transformer Tr) can be absorbed, which not only reduces the switching loss of the switching device at the inverter side, but also improves the power efficiency.
[0007] The application provides a power conversion device, comprising: a conversion unit and a buffer unit; wherein the conversion unit comprises: an inverter module, a voltage conversion module and a rectifier module; the inverter module is arranged on the primary side of the voltage conversion module, and the rectifier module is arranged on the secondary side of the inverter module; an external DC power supply supplies power to the load side through the inverter module, the voltage conversion module and the rectifier module; the buffer unit is arranged between the rectifier module and the load side, and is used for absorbing the leakage energy of the secondary side of the voltage conversion module and supplying power to the load side when the conversion unit is working.
[0008] In some embodiments, the buffer unit comprises: a buffer capacitor module, a buffer inductor module and an auxiliary switch tube module; wherein the rectifier module has a first connection end and a second connection end; the first connection end of the buffer inductor module is connected to the first connection end of the rectifier module; the second connection end of the buffer inductor module is connected to the second connection end of the rectifier module; the first connection end of the buffer capacitor module is connected to the second connection end of the rectifier module; the second connection end of the buffer capacitor module can be connected to the second connection end of the buffer inductor module; the first connection end of the auxiliary switch tube module can be connected to the second connection end of the buffer capacitor module; and the second connection end of the auxiliary switch tube module is connected to the second connection end of the rectifier module.
[0009] In some embodiments, the buffer unit further comprises: a first buffer diode module; wherein the first connection end of the auxiliary switch tube module is connected to the anode of the first buffer diode module; and the second connection end of the buffer capacitor module is connected to the cathode of the first buffer diode module.
[0010] In some embodiments, the buffer unit further comprises: a second buffer diode module; wherein the second connection end of the buffer capacitor module is connected to the anode of the second buffer diode module; and the second connection end of the buffer inductor module is connected to the cathode of the second buffer diode module.
[0011] In some embodiments, the buffer unit further comprises: a first buffer diode module and a second buffer diode module; wherein the first connection end of the auxiliary switch tube module is connected to the anode of the first buffer diode module; the second connection end of the buffer capacitor module is connected to the cathode of the first buffer diode module; the second connection end of the buffer capacitor module is connected to the anode of the second buffer diode module; and the second connection end of the buffer inductor module is connected to the cathode of the second buffer diode module.
[0012] In some embodiments, the rectifier module comprises: a first rectifier diode module, a second rectifier diode module, a third rectifier diode module and a fourth rectifier diode module; wherein the cathode of the first rectifier diode module is connected to the cathode of the second rectifier diode module, and serves as a first connection end of the rectifier unit; the anode of the first rectifier diode module is connected to the cathode of the third rectifier diode module, and the anode of the second rectifier diode module is connected to the cathode of the fourth rectifier diode module; the anode of the third rectifier diode module is connected to the anode of the fourth rectifier diode module, and serves as a second connection end of the rectifier unit; the first connection end of the winding of the secondary side of the transformer unit is connected to the anode of the third rectifier diode module; and the second connection end of the winding of the secondary side of the transformer unit is connected to the anode of the fourth rectifier diode module.
[0013] In some embodiments, the load side has an anti-parallel diode module, a smoothing reactor module and a voltage stabilizing capacitor module; wherein the first connection end of the buffer inductor module is connected to the cathode of the anti-parallel diode module; the cathode of the anti-parallel diode module is connected to the anode of the anti-parallel diode module via the smoothing reactor module and the voltage stabilizing capacitor module; and the first connection end of the auxiliary switch tube module is connected to the anode of the anti-parallel diode module.
[0014] In some embodiments, the inverter module comprises any one of a full-bridge inverter circuit, a half-bridge inverter circuit and a push-pull inverter circuit; and / or at least one of the switching devices in the inverter unit and the auxiliary switch tube module in the buffer unit adopts a MOS tube with GaN or SiC or an IGBT tube with GaN or SiC; and / or the number of the secondary sides of the transformer unit is more than one, and the number of the buffer units is the same as the number of the secondary sides of the transformer unit.
[0015] In another aspect, the present application provides a power supply system, which is matched with the above-mentioned device and comprises the above-mentioned power supply conversion device.
[0016] In conjunction with the aforementioned device, the present invention further provides a control method for a power conversion device, comprising: acquiring the number of loads of the conversion unit, and / or acquiring the input voltage and load demand voltage of the conversion unit; adjusting the switching frequency of the auxiliary switching transistor module in the buffer unit according to the input voltage and load demand voltage of the conversion unit; and / or adjusting the parameters of the buffer capacitor module and / or the parameters of the buffer inductor module in the buffer unit; and / or, when the number of secondary sides of the transformer unit is one or more, distributing the energy of different secondary sides of one or more secondary sides of the transformer unit to different loads according to the number of loads of the conversion unit and / or the load demand voltage of the conversion unit.
[0017] Therefore, the present invention addresses a converter circuit that supplies power to the load side after DC power is inverted by an inverter (such as a full-bridge inverter circuit or a half-bridge inverter circuit composed of switching devices), transformed by a high-frequency transformer (such as a high-frequency transformer Tr), and rectified by a rectifier bridge (such as a rectifier circuit composed of rectifier diodes). A buffer circuit (i.e., a discharge circuit) is provided between the rectifier bridge and the load, consisting of at least a capacitor (i.e., a buffer capacitor Cs), an inductor (i.e., a buffer inductor Ls), and a switching transistor (i.e., an auxiliary switching device Ts). In one cycle, the auxiliary switching device Ts turns off the buffer capacitor Cs to charge it, absorbing the leakage inductance energy of the high-frequency transformer Tr. Then, the auxiliary switching device Ts turns on the buffer capacitor Cs to discharge the energy stored in the buffer inductor Ls, discharging it to the load to utilize the leakage inductance energy of the high-frequency transformer Tr. Thus, by providing a buffer circuit between the rectifier side and the load side of the converter circuit, the leakage inductance energy of the secondary side of the transformer (such as the high-frequency transformer Tr) can be absorbed, which not only reduces the switching losses of the inverter-side switching devices but also improves power efficiency.
[0018] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention.
[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of the power conversion device of the present invention;
[0021] Figure 2 This is a schematic diagram of the overall design circuit principle of a conversion circuit based on the absorption of leakage inductance energy from the secondary side of a self-transformer.
[0022] Figure 3Waveform diagram of the conduction state of the switch device T1, the switch device T2, the switch device T3 and the switch device T4 and the auxiliary switch device Ts in the inverter in a cycle;
[0023] Figure 4 Equivalent circuit schematic diagram of the capacitor charging process in the t0-t1 period;
[0024] Figure 5 Equivalent circuit schematic diagram of the capacitor charging process in the t0-t1 period;
[0025] Figure 6 Equivalent circuit schematic diagram of the capacitor charging process in the t0-t1 period;
[0026] Figure 7 Equivalent circuit schematic diagram of the capacitor charging process in the t0-t1 period;
[0027] Figure 8 Equivalent circuit schematic diagram of the capacitor charging process in the t0-t1 period;
[0028] Figure 9 Equivalent circuit schematic diagram of the capacitor charging process in the t0-t1 period;
[0029] Figure 10 Flowchart of an embodiment of the control method of the power conversion device;
[0030] Figure 11 Current direction schematic diagram of the buffer circuit. DETAILED DESCRIPTION
[0031] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described below in connection with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.
[0032] It is considered that in the related scheme, the switch device in the switching power supply has energy loss (i.e. switching loss) in the hard switching process, and in the case of relatively tight power supply, such switching loss will cause insufficient power supply. The switch device in the switching power supply is hard switched, which means that in the switching power supply, the switch device is switched when voltage and current exist at the same time, resulting in large switching loss and low efficiency.
[0033] In some schemes, an absorption circuit is arranged for the switching power supply, which is a protection circuit designed to suppress voltage spikes and oscillations generated by the switching device (such as MOSFET, IGBT) in the hard switching process of the switching power supply. The absorption circuit in some schemes usually corresponds to the switching device in the switching power supply one by one, but in the switching power supply, too many absorption circuits will increase the complexity, economic cost of the system, and reduce the stability of the system. Therefore, there is an urgent need for a conversion circuit that can reduce switching loss and efficiently utilize energy to meet the demand for power stability and efficiency in unmanned environments.
[0034] Therefore, the scheme of the present application proposes a power conversion device, specifically a conversion circuit based on self-transformer secondary side absorption transformer leakage energy, which sets up a discharge circuit composed of a capacitor (i.e. buffer capacitor Cs), an inductor (i.e. buffer inductor Ls) and a switching tube (i.e. auxiliary switching device Ts), which can absorb the leakage energy of the transformer from the secondary side of the transformer, solve the energy loss problem of the switching device in the hard switching process of the switching power supply, and reduce the switching loss and improve the power efficiency. The circuit composed of the capacitor (i.e. buffer capacitor Cs), the inductor (i.e. buffer inductor Ls) and the switching tube (i.e. auxiliary switching device Ts) in the scheme of the present application is different from the circuit implementation of the related scheme, the series-parallel connection mode is different, and the device topology used is different.
[0035] According to the embodiment of the present application, a power conversion device is provided. Referring to Figure 1 The structure diagram of an embodiment of the device of the present application is shown. The power conversion device can include a conversion unit such as a conversion circuit and a buffer unit such as a buffer circuit; of course, the power conversion device also includes a load side.
[0036] The conversion unit includes an inverter module, a transformer module and a rectifier module, the inverter module is an inverter, the transformer module is a high-frequency transformer Tr, and the rectifier module is a rectifier bridge; the inverter module is arranged on the primary side of the transformer module, and the rectifier module is arranged on the secondary side of the inverter module; an external DC power supply supplies power to the load side through the inverter module, the transformer module and the rectifier module.
[0037] The buffer unit is arranged between the rectifier module and the load side, and is used to absorb the leakage energy of the secondary side of the transformer module and supply power to the load side in a cycle when the conversion unit is working.
[0038] The scheme of the present application sets a buffer circuit between the rectifier circuit and the load side, can absorb the leakage energy of the transformer from the secondary side of the transformer, store and utilize the energy, generally solves the energy loss problem of the switching device in the hard switching process in the switching power supply, can reduce the switching loss and improve the power supply efficiency.
[0039] In some embodiments, the buffer unit comprises a buffer capacitor module, a buffer inductor module and an auxiliary switch tube module, the buffer capacitor module is like a buffer capacitor Cs, the buffer inductor module is like a buffer inductor Ls, and the auxiliary switch tube module is like an auxiliary switch device Ts.
[0040] The rectifier module has a first connection end and a second connection end; the first connection end of the rectifier module is like the cathode of a rectifier diode D6, and the second connection end of the rectifier module is like the anode of a rectifier diode D8. The buffer inductor module is connected in parallel between the first connection end of the rectifier module and the second connection end of the rectifier module; specifically, the first connection end of the buffer inductor module is connected to the first connection end of the rectifier module, and the second connection end of the buffer inductor module is connected to the second connection end of the rectifier module.
[0041] The buffer capacitor module is connected in series between the second connection end of the rectifier module and the second connection end of the buffer inductor module; specifically, the first connection end of the buffer capacitor module is connected to the second connection end of the rectifier module, and the second connection end of the buffer capacitor module can be connected to the second connection end of the buffer inductor module.
[0042] The first connection end of the auxiliary switch tube module can be connected to the second connection end of the buffer capacitor module, and the second connection end of the auxiliary switch tube module is connected to the second connection end of the rectifier module. In the case where the auxiliary switch tube module comprises a MOS tube, the first connection end of the auxiliary switch tube module is the drain of the MOS tube, and the second connection end of the auxiliary switch tube module is the source of the MOS tube.
[0043] The scheme of the present application sets a discharge circuit (i.e. a buffer circuit) composed of a capacitor (i.e. a buffer capacitor Cs), an inductor (i.e. a buffer inductor Ls) and a switch tube (i.e. an auxiliary switch device Ts), can absorb the leakage energy of the transformer from the secondary side of the transformer, store and utilize the energy by limiting the current change through the inductor, and realize the conversion of high voltage through a high-frequency transformer, generally solves the energy loss problem of the switching device in the hard switching process in the switching power supply, can reduce the switching loss and improve the power supply efficiency.
[0044] In some embodiments, the buffer unit further comprises a first buffer diode module, the first buffer diode module is like a buffer branch diode D s1.
[0045] The first connecting end of the auxiliary switch tube module is connected with the anode of the first buffer diode module; and the second connecting end of the buffer capacitor module is connected with the cathode of the first buffer diode module.
[0046] In the scheme of the present application, the complexity of the absorption circuit in the related scheme is solved by using the conversion circuit capable of absorbing the leakage energy of the transformer from the secondary side of the transformer, thereby reducing the system cost, improving the reliability and anti-disturbance ability of the system.
[0047] In some embodiments, the buffer unit further comprises a second buffer diode module, the second buffer diode module being a buffer branch diode D s2 .
[0048] The second connecting end of the buffer capacitor module is connected with the anode of the second buffer diode module; and the second connecting end of the buffer inductor module is connected with the cathode of the second buffer diode module.
[0049] In the scheme of the present application, in view of the high switching loss problem of the hard switching of the switching device in the switching power supply, the switching loss of the existing circuit structure is reduced by increasing the buffer capacitor Cs and the buffer inductor Ls and switching the loop through the switching device.
[0050] In some embodiments, the buffer unit further comprises a first buffer diode module and a second buffer diode module, the first buffer diode module being a buffer branch diode D s1 , and the second buffer diode module being a buffer branch diode D s2 .
[0051] The first connecting end of the auxiliary switch tube module is connected with the anode of the first buffer diode module; and the second connecting end of the buffer capacitor module is connected with the cathode of the first buffer diode module.
[0052] The second connecting end of the buffer capacitor module is connected with the anode of the second buffer diode module; and the second connecting end of the buffer inductor module is connected with the cathode of the second buffer diode module.
[0053] The scheme of the present application can significantly reduce the switching loss: by transferring the leakage energy in the first half cycle, the energy loss of the switching device in the hard switching process is reduced, and the power supply efficiency is improved. The scheme of the present application can enhance the stability of the system: the complexity of the absorption circuit is simplified, the system cost is reduced, and the reliability and anti-disturbance ability of the system are improved.
[0054] In some embodiments, the rectifier module comprises: a first rectifier diode module, a second rectifier diode module, a third rectifier diode module and a fourth rectifier diode module, the first rectifier diode module is like rectifier diode D5, the second rectifier diode module is like rectifier diode D6, the third rectifier diode module is like rectifier diode D7, and the fourth rectifier diode module is like rectifier diode D8.
[0055] The cathode of the first rectifier diode module is connected with the cathode of the second rectifier diode module, and serves as a first connection end of the rectifier unit; the anode of the first rectifier diode module is connected with the cathode of the third rectifier diode module, and the anode of the second rectifier diode module is connected with the cathode of the fourth rectifier diode module.
[0056] The anode of the third rectifier diode module is connected with the anode of the fourth rectifier diode module, and serves as a second connection end of the rectifier unit; a first connection end of the winding of the secondary side of the transformer unit is connected with the anode of the third rectifier diode module; and a second connection end of the winding of the secondary side of the transformer unit is connected with the anode of the fourth rectifier diode module.
[0057] In the scheme of the present application, in order to solve the problem of low energy utilization rate caused by high switching loss of the switching device in the switching power supply, the buffer inductor Ls stores energy, provides a path for the load, avoids the energy from being consumed on the load, and thus improves the energy utilization rate.
[0058] In some embodiments, the load side has an anti-parallel diode module, a smoothing reactor module and a voltage stabilizing capacitor module, the anti-parallel diode module is like anti-parallel diode D0, the smoothing reactor module is like smoothing reactor L0, and the voltage stabilizing capacitor module is like voltage stabilizing capacitor C0.
[0059] The first connection end of the buffer inductor module is connected with the cathode of the anti-parallel diode module; the cathode of the anti-parallel diode module is connected with the anode of the anti-parallel diode module through the smoothing reactor module and the voltage stabilizing capacitor module.
[0060] The first connection end of the auxiliary switch tube module is connected with the anode of the anti-parallel diode module.
[0061] The switching device conduction and turn-off timing in the transformation circuit based on self-transformer secondary side absorbing transformer leakage energy is exemplarily explained as follows. The switching device conduction and turn-off timing in the transformation circuit based on self-transformer secondary side absorbing transformer leakage energy is exemplarily explained as follows.
[0062] Figure 2 It is a general design circuit schematic diagram of a conversion circuit based on self-transformer secondary side absorption transformer leakage energy. The general circuit schematic diagram of the conversion circuit based on self-transformer secondary side absorption transformer leakage energy provided in the scheme of the present application is as follows:Figure 2 As shown, the entire circuit consists of six parts: DC power supply Us, full-bridge inverter circuit T1-T4 (D1-D4 are freewheeling diodes), high-frequency transformer Tr, uncontrolled rectifier circuit D5-D8, transformer secondary side buffer circuit, and load circuit.
[0063] The full-bridge inverter circuit includes: switching devices T1, T2, T3, and T4, as well as freewheeling diodes D1 and D2 for T1, D3 and D4 for T3, and D4 for T4. For example, when all four switching devices are IGBTs, the collector of T1 is connected to the cathode of freewheeling diode D1, and the emitter of T1 is connected to the anode of D1; the collector of T2 is connected to the cathode of freewheeling diode D2, and the emitter of T2 is connected to the anode of D2; the collector of T3 is connected to the cathode of freewheeling diode D3, and the emitter of T3 is connected to the anode of D3; and the collector of T4 is connected to the cathode of freewheeling diode D4, and the emitter of T4 is connected to the anode of D4.
[0064] The uncontrolled rectifier circuit includes: rectifier diodes D5, D6, D7, and D8. The transformer secondary side snubber circuit includes: auxiliary switching device Ts, snubber capacitor Cs, snubber inductor Ls, and snubber branch diode D. s1 D s2 Auxiliary switching device Ts, buffer capacitor Cs, and buffer inductor Ls are necessary components, along with buffer branch diode D. s1 D s2 As a preferred component, the load circuit includes: an anti-parallel diode D0, a smoothing reactor L0, a voltage stabilizing capacitor C0, and a load R. L During the time period t0-t1, the switching device Ts is in the off state, such as... Figure 3 This process charges Cs.
[0065] exist Figure 2 In the example shown, the positive terminal of the DC power supply Us is connected to the collectors of switching devices T1 and T2, respectively; the emitter of switching device T1 is connected to the collector of switching device T3, and the emitter of switching device T2 is connected to the collector of switching device T4; the negative terminal of the DC power supply Us is connected to the emitters of switching devices T3 and T4, respectively. The emitter of switching device T1 is also connected to the first connection terminal of the primary winding of the high-frequency transformer Tr, and the collector of switching device T4 is also connected to the second connection terminal of the primary winding of the high-frequency transformer Tr.
[0066] The cathodes of rectifier diodes D5 and D6 are connected, the anode of D5 is connected to the cathode of D7, the anode of D6 is connected to the cathode of D8, and the anodes of D7 and D8 are connected. The first terminal of the secondary winding of the high-frequency transformer Tr is connected to the anode of rectifier diode D5, and the second terminal of the secondary winding of the high-frequency transformer Tr is connected to the cathode of rectifier diode D8.
[0067] The cathode of rectifier diode D6, after passing through buffer inductor Ls, connects to the buffer branch diode D. s2 The cathodes are connected, and the buffer branch diode D is connected. s2 Anode and buffer branch diode D s1 The cathode of rectifier diode D8 is connected to the cathode; the anode of rectifier diode D8 is connected to the buffer branch diode D after passing through buffer capacitor Cs. s1 The cathode is connected. For example, when the auxiliary switching device Ts is a MOSFET, the buffer branch diode D... s1 The anode of the rectifier diode D8 is connected to the source of the auxiliary switching device Ts, and the drain of the auxiliary switching device Ts is connected to the anode of the rectifier diode D8.
[0068] The cathode of rectifier diode D6, after passing through smoothing reactor L0 and voltage stabilizing capacitor C0, connects to the buffer branch diode D. s1 The anode is connected; the load R L It is connected in parallel to the output terminal of the voltage regulator capacitor C0.
[0069] Figure 2 The entire process of the conversion circuit shown, which is based on the absorption of leakage inductance energy from the secondary side of the self-transformer, is explained by... Figures 4 to 9 Each process in the example shown constitutes a specific example; for details, please refer to [link / reference needed]. Figures 4 to 9 Related explanations.
[0070] The solution of the present invention can achieve efficient energy transfer: through a discharge circuit composed of a capacitor (i.e., buffer capacitor Cs), an inductor (i.e., buffer inductor Ls) and a switching transistor (i.e., auxiliary switching device Ts), the inductor (i.e., buffer inductor Ls) limits the change of current and stores energy for utilization, and the high voltage conversion is achieved through a high-frequency transformer.
[0071] Figure 3 This is a waveform diagram showing the conduction status of switching devices T1, T2, T3, and T4, as well as auxiliary switching device Ts, in the inverter during one cycle. Figure 3The timing diagram for the on and off of the switching device, according to the timing diagram analysis circuit, in a cycle, can be divided into four parts: t0-t1 time period, t1-t2 time period, t2-t3 time period, t3-t4 time period. Among them, t0 moment, as shown in the timing diagram, is t0 moment in a cycle. Figure 2 The timing diagram for the on and off of the switching device, according to the timing diagram analysis circuit, in a cycle, can be divided into four parts: t0-t1 time period, t1-t2 time period, t2-t3 time period, t3-t4 time period. Among them, t0 moment, as shown in the timing diagram, is t0 moment in a cycle.
[0072] The switching device conduction and turn-off timing in the transformation circuit based on self-transformer secondary side absorbing transformer leakage energy is exemplarily explained as follows.
[0073] Figure 4 The equivalent circuit schematic diagram for the capacitor charging process in t0-t1 time period. As shown in the figure, Figure 4 t0 moment, auxiliary switch Ts is off, the current path is changed to buffer branch diode D s1 , the current path is: current through the first connection end of the secondary winding of high frequency transformer Tr, through rectifier diode D5, smoothing reactor L0, load R L , buffer branch diode D s1 , buffer capacitor Cs, rectifier diode D8, and then flows to the second connection end of the secondary winding of high frequency transformer Tr; the buffer capacitor Cs of the secondary winding of high frequency transformer Tr starts to charge, the energy stored in the leakage inductance of the secondary winding of high frequency transformer Tr is transferred to the buffer capacitor Cs, and the current in the smoothing reactor L0 can be approximately constant in a short time. The advantage of such setting is that the leakage inductance energy of the secondary winding of high frequency transformer Tr can be utilized, and the leakage inductance energy of the secondary winding of high frequency transformer Tr is avoided.
[0074] Figure 5 The equivalent circuit schematic diagram for the capacitor charging process in t0-t1 time period. As shown in the figure, Figure 5 when the buffer capacitor Cs is charged to the voltage of the secondary winding of high frequency transformer Tr, the freewheeling diode D0 (i.e. anti-parallel diode D0) is forward biased. At t1 moment, the current of the load R L forms a loop only with the anti-parallel diode D0, the secondary side current of the high frequency transformer Tr decreases to 0, and only a small magnetizing current passes through the primary side of the high frequency transformer Tr. In this way, zero current turn-off of the switching device (such as switching device T1, switching device T2, switching device T3, switching device T4) can be formed, and the switching loss of the switching device (such as switching device T1, switching device T2, switching device T3, switching device T4) is reduced. Among them, the freewheeling diode D0: the parallel diode as the freewheeling diode provides a discharge path for the inductor current.
[0075] The switching device conduction and turn-off timing in the transformation circuit based on self-transformer secondary side absorbing transformer leakage energy is exemplarily explained as follows.
[0076] Figure 6 The equivalent circuit schematic diagram for the topology in t1-t2 time period. As shown in the figure, Figure 6As shown, starting at time t1, the auxiliary switch Ts is turned on, and a discharge path is formed between the buffer capacitor Cs, the buffer inductor Ls, and the auxiliary switch Ts. Specifically, the electrical energy stored in the buffer capacitor Cs passes through the buffer branch diode D. s2 Buffer inductor Ls, smoothing reactor L0, load R L When the auxiliary switch Ts is released, the buffer capacitor Cs and the buffer inductor Ls begin to discharge in a resonant manner. The current change is limited by the buffer inductor Ls, which can reduce the sudden current change during the discharge process, thereby reducing the voltage spike during the discharge process.
[0077] During the time interval t1-t2, the buffer capacitor Cs is completely discharged, and the discharge energy is stored in the buffer inductor Ls, and then passes through the buffer branch diode D. s1 and the buffer branch diode D s2 To load R L Discharge. Until time t2, the buffer capacitor Cs is fully discharged, and the energy stored in the circuit is released to the load R. L This allows for the load R to be placed on the side. L Provides a continuous energy supply.
[0078] The switching device conduction and turn-off timing in the transformation circuit based on self-transformer secondary side absorbing transformer leakage energy is exemplarily explained as follows.
[0079] Figure 7 The equivalent circuit diagram for the stray capacitance charging process during the time interval t2-t3 is shown. Figure 8 This is a schematic diagram of the equivalent circuit principle for inverter commutation during the time period t2-t3. (Example) Figure 7 , Figure 8 As shown, the time period t2-t3 is the dead time of the inverter switching control signal. During the dead time, there is still only a very small magnetizing current in the circuit. In the first conduction circuit of the inverter, the internal parallel capacitors of switching devices T1 and T4 (such as the internal parallel capacitor Coss1 of switching device T1 and the internal parallel capacitor Coss4 of switching device T4) are charged to the input voltage Us. In the second conduction circuit, the internal parallel capacitors of switching devices T2 and T3 (such as the internal parallel capacitor Coss2 of switching device T2 and the internal parallel capacitor Coss3 of switching device T3) begin to discharge to zero. Then, the freewheeling diodes D2 and D3 are forward biased to provide a path for the magnetizing current, providing a circuit for the magnetic reset of the high-frequency transformer Tr and preventing the high-frequency transformer Tr from saturating.
[0080] The switching device conduction and turn-off timing in the transformation circuit based on self-transformer secondary side absorbing transformer leakage energy is exemplarily explained as follows.
[0081] Figure 9The equivalent circuit schematic diagram of the conduction stage of the switch device T2 and the switch device T3 in the inverter in the t3-t4 time period is shown in detail. L s1 s2 The D and D form a loop, and the current direction is shown in the example of Figure 11
[0082] As shown in Figure 9 , the t3-t4 time period is the conduction stage of the switch device T2 and the switch device T3 in the inverter, and in this working state, the switch device T2, the switch device T3 and the auxiliary switch tube Ts in the second conduction loop are simultaneously turned on, and the entire circuit enters the energy transmission state. L The direct current side Us is transmitted to the load R through the inversion and high-frequency transformation of the inverter and the high-frequency transformer Tr, the energy transmission efficiency is improved, and the loss is reduced.
[0083] The scheme has an energy transfer mechanism: in the first half cycle, the leakage energy of the transformer is absorbed by the buffer capacitor; and in the second half cycle, the energy in the buffer capacitor is transferred to the buffer inductor through the switch device switching circuit, so that the energy is used efficiently. The energy absorption and transmission mechanism is exemplarily explained as follows.
[0084] In the t1-t2 time period, the buffer capacitor Cs absorbs the leakage energy of the high-frequency transformer Tr, so as to avoid energy loss. In the t3-t4 time period, the buffer inductor Ls releases the stored energy to the load side, so as to further improve the energy utilization rate. The high-frequency transformer Tr is used to realize efficient isolation and transformation of voltage, and meet the needs of different loads.
[0085] In some embodiments, the inverter module comprises any one of a full-bridge inverter circuit, a half-bridge inverter circuit and a push-pull inverter circuit.
[0086] Application of different topologies: in addition to the full-bridge inverter circuit, the buffer circuit (i.e., the discharge circuit) in the scheme can also be applied to the half-bridge or the push-pull inverter circuit, so as to further widen the application range.
[0087] In some embodiments, at least one of the switch device in the inverter unit and the auxiliary switch tube module in the buffer unit adopts a MOS tube with GaN or SiC or an IGBT tube with GaN or SiC.
[0088] The application has the application of a new power electronic device: using GaN (gallium nitride) or SiC (silicon carbide) devices, significantly improving the switching speed of the circuit, reducing switching loss, and improving power efficiency. The use of new power electronic devices: using GaN or SiC devices as switching devices has the following advantages: high switching speed: significantly improves the switching speed of the circuit, reduces switching loss; low on-resistance: reduces conduction loss and improves power efficiency; high voltage resistance: adapts to high voltage application scenarios and improves system reliability. Selection of different switching devices: according to specific needs, different switching devices (such as MOSFET, IGBT, etc.) can be selected to optimize circuit performance, and different switching devices can be directly replaced.
[0089] In some embodiments, the number of secondary sides of the voltage transformation unit is more than one, and the number of the buffer units is the same as the number of the secondary sides of the voltage transformation unit.
[0090] The application has flexible scalability: in the case of multiple output requirements, the transformer can be expanded to multiple secondary coils to meet various voltage requirements. Multi-secondary transformer design: in the case of multiple output requirements, the transformer can be expanded to multiple secondary coils, each corresponding to an independent buffer circuit and load circuit. If applied to multiple output voltages, an additional buffer circuit (i.e. discharge circuit) and load circuit described in the embodiment can be added to each secondary coil.
[0091] By using the technical scheme of the application, for a conversion circuit for supplying power to a load side after a direct current power supply is inverted by an inverter (such as a full-bridge inverter circuit or a half-bridge inverter circuit composed of switching devices), high-frequency transformer (such as a high-frequency transformer Tr) transformation, and rectifier bridge (such as a rectifier circuit composed of rectifier diodes), at least one buffer circuit (i.e. discharge circuit) composed of a capacitor (i.e. buffer capacitor Cs), an inductor (i.e. buffer inductor Ls), and a switching tube (i.e. auxiliary switching device Ts) is arranged between the rectifier bridge and the load. In a cycle, the auxiliary switching device Ts is turned off to charge the buffer capacitor Cs to absorb the leakage energy of the high-frequency transformer Tr, and then the auxiliary switching device Ts is turned on to discharge the buffer capacitor Cs to store energy in the buffer inductor Ls to discharge to the load to utilize the leakage energy of the high-frequency transformer Tr. Thus, by arranging a buffer circuit between the rectifier side of the conversion circuit and the load side, the leakage energy of the transformer (such as the high-frequency transformer Tr) secondary side can be absorbed, not only reducing the switching loss of the inverter side switching device, but also improving the power efficiency.
[0092] According to the embodiments of the application, a power supply system corresponding to the power supply conversion device is also provided. The power supply system can include the power supply conversion device described above.
[0093] The process and functions realized by the power supply system of the embodiment are basically corresponding to the embodiments, principles and examples of the device, so the description of the embodiment will not be described in detail, and the related description in the foregoing embodiments can be referred to, and will not be described here.
[0094] According to the embodiments of the present application, a control method of a power conversion device corresponding to the power conversion device is also provided, as shown in the flowchart of an embodiment of the method of the present application. The control method of the power conversion device can include step S110, and can also include at least one of steps S120, S130 and S140. Figure 10
[0095] At step S110, the number of loads of the conversion unit is obtained, and / or the input voltage of the conversion unit and the load demand voltage are obtained, specifically, the number of loads on the load side of the conversion unit is obtained, the input voltage of the input side DC power supply of the conversion unit is obtained, and the load demand voltage on the load side of the conversion unit is obtained.
[0096] At step S120, for the auxiliary switch tube module in the buffer unit, the switching frequency of the auxiliary switch tube module is adjusted according to the input voltage of the conversion unit and the load demand voltage of the conversion unit, so as to optimize the energy transmission efficiency of the power conversion device.
[0097] At step S120, for the buffer capacitor module and the buffer inductor module in the buffer unit, the parameters of the buffer capacitor module and / or the parameters of the buffer inductor module are adjusted, so as to improve the working efficiency of the buffer unit.
[0098] At step S130, in the case that the number of secondary sides of the voltage conversion unit is more than one, specifically in the case that the number of secondary sides of the voltage conversion unit is more than two, the energy of different secondary sides of the more than one secondary sides of the voltage conversion unit is distributed to different loads according to the number of loads of the conversion unit and / or the load demand voltage of the conversion unit.
[0099] The scheme of the present application has an intelligent control algorithm: real-time adjustment of circuit parameters, optimization of energy transmission process, and improvement of efficiency. The role of the intelligent control algorithm is exemplarily explained as follows.
[0100] The intelligent control module (ICM) dynamically adjusts the following parameters by real-time monitoring of circuit parameters (such as voltage, current, temperature, etc.):
[0101] Switching frequency of auxiliary switching device Ts: Adjust the switching frequency of auxiliary switching device Ts in real time according to load requirements and input voltage, optimize energy transmission efficiency. Load requirements and input voltage are designed according to customer requirements, and specific requirements are designed according to actual conditions. By monitoring Vin and Iout in real time, the switching frequency of Ts is dynamically adjusted to keep the resonant circuit in the best working state; For example, when the output current Iout<1A, the Ts frequency can be reduced, the resonant time is prolonged, and the switching loss is reduced; When the output current Iout≥1A, the Ts frequency can be increased, the resonant time is shortened, and the saturation of the magnetic element is avoided.
[0102] Magnetic element parameters: dynamically adjust the parameters of buffer capacitor Cs and buffer inductor Ls according to the working state to improve the working efficiency. The parameters of the magnetic element, including the magnetic permeability of the inductor magnetic core and the like, are mainly adjusted according to the output load requirements, input requirements, and parasitic parameters of the specific circuit. By dynamically adjusting the parameters of the buffer capacitor and inductor, the magnetic element can maintain optimal efficiency under different load conditions. For example, Cs and Ls are reduced to reduce loss under light load, and the parameters are increased to suppress spikes under heavy load.
[0103] Energy distribution: In the case of multiple output, intelligently distribute energy to different loads to ensure stable operation of the system. According to the load requirements, such as different currents required by different paths, power distribution is carried out according to different currents. In the case of multiple output, the transformer can be expanded to multiple secondary coils, and each secondary coil corresponds to an independent buffer circuit and load circuit.
[0104] The core of the scheme of the present application is to set a transformation circuit based on the leakage energy absorption transformer on the secondary side of the transformer, combined with the application of intelligent control algorithm and new power electronic devices, to realize efficient energy transmission and reduce switching loss.
[0105] The circuit advantages of the scheme of the present application: high efficiency: the buffer circuit realizes efficient absorption and transmission of energy, significantly reducing switching loss. Stability: the intelligent control module adjusts the circuit parameters in real time, improving the stability and anti-disturbance ability of the system. Flexibility: support multiple output expansion, adapt to various application scenarios. Reliability: use new power electronic devices to improve the voltage withstand capability and service life of the system.
[0106] Since the processing and functions realized by the method of the present embodiment are basically corresponding to the foregoing embodiments, principles and examples of the power conversion device, the description of the present embodiment will not be described in detail, and the relevant description in the foregoing embodiments can be referred to.
[0107] In summary, those skilled in the art can easily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict.
[0108] The above description is only the preferred embodiment of the application, and is not intended to limit the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall fall within the scope of the claims of the application.
Claims
1. A power conversion device, characterized by comprising: The application relates to a variable unit and a buffer unit; wherein, The variable unit comprises an inversion module, a voltage conversion module and a rectification module; the inversion module is arranged on the primary side of the voltage conversion module, the rectification module is arranged on the secondary side of the inversion module; an external direct-current power supply supplies power to a load side through the inversion module, the voltage conversion module and the rectification module; The buffer unit is arranged between the rectification module and the load side and is used for absorbing leakage energy of the secondary side of the voltage conversion module and supplying power to the load side when the variable unit works. The buffer unit comprises a buffer capacitor module, a buffer inductor module and an auxiliary switch tube module; wherein, 2. The power conversion device of claim 1, wherein The rectification module has a first connecting end and a second connecting end; the first connecting end of the buffer inductor module is connected with the first connecting end of the rectification module; the second connecting end of the buffer inductor module is connected with the second connecting end of the rectification module; The first connecting end of the buffer capacitor module is connected with the second connecting end of the rectification module; the second connecting end of the buffer capacitor module can be connected with the second connecting end of the buffer inductor module; The first connecting end of the auxiliary switch tube module can be connected with the second connecting end of the buffer capacitor module; the second connecting end of the auxiliary switch tube module is connected with the second connecting end of the rectification module. The buffer unit further comprises a first buffer diode module; wherein, 3. The power conversion device of claim 2, wherein The first connecting end of the auxiliary switch tube module is connected with the anode of the first buffer diode module; the second connecting end of the buffer capacitor module is connected with the cathode of the first buffer diode module. The buffer unit further comprises a second buffer diode module; wherein, 4. The power conversion device of claim 2, wherein The second connecting end of the buffer capacitor module is connected with the anode of the second buffer diode module; the second connecting end of the buffer inductor module is connected with the cathode of the second buffer diode module. The buffer unit further comprises a first buffer diode module and a second buffer diode module; wherein, 5. The power conversion device of claim 2, wherein The first connecting end of the auxiliary switch tube module is connected with the anode of the first buffer diode module; the second connecting end of the buffer capacitor module is connected with the cathode of the first buffer diode module; The second connecting end of the buffer capacitor module is connected with the anode of the second buffer diode module; the second connecting end of the buffer inductor module is connected with the cathode of the second buffer diode module. The rectification module comprises a first rectification diode module, a second rectification diode module, a third rectification diode module and a fourth rectification diode module; wherein, 6. The power conversion device according to any one of claims 2 to 5, characterized by The cathode of the first rectification diode module is connected with the cathode of the second rectification diode module and serves as the first connecting end of the rectification unit; the anode of the first rectification diode module is connected with the cathode of the third rectification diode module, the anode of the second rectification diode module is connected with the cathode of the fourth rectification diode module; The anode of the third rectifier diode module is connected with the anode of the fourth rectifier diode module, and serves as a second connection end of the rectifier unit; a first connection end of the winding of the secondary side of the voltage transformation unit is connected to the anode of the third rectifier diode module; and a second connection end of the winding of the secondary side of the voltage transformation unit is connected to the anode of the fourth rectifier diode module.
7. The power conversion device according to any one of claims 2 to 6, characterized by The load side has an anti-parallel diode module, a smoothing reactor module and a voltage stabilizing capacitor module; wherein, A first connection end of the buffer inductor module is connected to the cathode of the anti-parallel diode module; the cathode of the anti-parallel diode module is connected to the anode of the anti-parallel diode module via the smoothing reactor module and the voltage stabilizing capacitor module; A first connection end of the auxiliary switch tube module is connected to the anode of the anti-parallel diode module.
8. The power conversion device according to any one of claims 2 to 7, characterized by, Wherein, The inverter module includes any one of a full-bridge inverter circuit, a half-bridge inverter circuit and a push-pull inverter circuit; And / or, At least one of the switching devices in the inverter unit and the auxiliary switch tube module in the buffer unit adopts a MOS tube with GaN or SiC or an IGBT tube with GaN or SiC; And / or, The number of the secondary sides of the voltage transformation unit is more than one, and the number of the buffer units is the same as the number of the secondary sides of the voltage transformation unit.
9. A power supply system characterized by comprising: The power conversion device comprises: The power conversion device according to any one of claims 1 to 8.
10. A control method of the power conversion device according to any one of claims 1 to 8, characterized by, The power conversion device comprises: The number of loads of the conversion unit is obtained, and / or the input voltage of the conversion unit and the load demand voltage are obtained; For the auxiliary switch tube module in the buffer unit, the switching frequency of the auxiliary switch tube module is adjusted according to the input voltage of the conversion unit and the load demand voltage of the conversion unit; And / or, for the buffer capacitor module and the buffer inductor module in the buffer unit, the parameters of the buffer capacitor module and / or the parameters of the buffer inductor module are adjusted; And / or, in the case where the number of the secondary sides of the voltage transformation unit is more than one, the energy of different secondary sides of the more than one secondary sides of the voltage transformation unit is distributed to different loads according to the number of loads of the conversion unit and / or the load demand voltage of the conversion unit.