Topology of isolated rectifier power converter, and power factor control method

Abstract

Topology of an isolated rectifier power converter, and a power factor control method, which belong to the technical field of power electronics. The topology comprises a voltage source, a rectifier circuit, a power conversion unit and a drive control circuit. The power conversion unit comprises n power conversion circuits connected in parallel. Each power conversion circuit comprises a clamping transistor, a transformer, a primary-side switching transistor and a secondary-side switching transistor, wherein a clamping transistor of an ith power conversion circuit is an active clamping transistor, and clamping transistors of the remaining (n-1) power conversion circuits are passive clamping transistors. The drive control circuit is used for determining a target on-time and target duty cycle of each primary-side switching transistor within one switching cycle, and generating, on the basis of the target on-time and the target duty cycle, a drive control signal for controlling each primary-side switching transistor, wherein under the action of the drive control signal, the waveform of an input alternating current flowing through the voltage source is consistent with the waveform of an alternating voltage.

Description

Topology of isolated rectifier power converter and power factor control method

[0001] Related Applications

[0002] The present application claims priority to Chinese Patent Application No. 202411048139.3, filed on July 31, 2024, and incorporates by reference the entire disclosure of the aforementioned patent application as part of the present application. TECHNICAL FIELD

[0003] The present application belongs to the technical field of power electronics, and specifically relates to a topology of an isolated rectifier power converter and a power factor control method. BACKGROUND

[0004] A common isolated rectifier power conversion topology generally consists of a two-stage power conversion circuit as shown in FIG. 1, where the first stage is a power factor corrector for controlling the total harmonic component of the AC input current, and the second stage is a DC-DC conversion for electrical isolation and adjusting the control output voltage and current. The common topology of the first-stage power factor corrector is a Boost circuit as shown in FIG. 2A and a bridgeless totem pole boost circuit as shown in FIG. 2B; the common topology of the second-stage DC-DC conversion is a half-bridge LLC circuit as shown in FIG. 3A and a full-bridge LLC circuit as shown in FIG. 3B.

[0005] Most rectifier power converter products on the market currently use the above topology. However, with the development of the power electronics market, people have increasingly high pursuit of higher energy conversion efficiency and lower product cost. The current rectifier power converter products have the disadvantages of low energy conversion efficiency and high product cost, and a new type of isolated rectifier power converter is urgently needed. SUMMARY

[0006] To solve the above problems, the present application provides a topology of an isolated rectifier power converter and a power factor control method, which can simplify the circuit structure, realize harmonic suppression of input current, and achieve single-stage power conversion.

[0007] An embodiment of the present application provides a topology of an isolated rectifier power converter, which comprises a voltage source, a rectifier circuit, a power conversion unit, and a drive control circuit, wherein:

[0008] The power conversion unit comprises n parallel power conversion circuits, each of which comprises a clamping tube, a transformer, a primary side switch tube and a secondary side switch tube, wherein the clamping tube of the ith power conversion circuit is an active clamping tube, and the clamping tubes of the remaining (n-1) power conversion circuits are passive clamping tubes, n is a natural number greater than 1, and 1≤i≤n;

[0009] The power conversion unit is connected with the rectifier circuit, the rectifier circuit is connected with the voltage source, and the drive control circuit is connected with the rectifier circuit and the power conversion unit. The voltage source is used for inputting an alternating voltage.

[0010] The drive control circuit is used for determining the target conduction time and target duty cycle of each primary side switch tube in a switching cycle, and generating a drive control signal for controlling each primary side switch tube based on the target conduction time and target duty cycle, wherein under the action of the drive control signal, the waveform of the input alternating current flowing through the voltage source is consistent with the waveform of the alternating voltage.

[0011] Another embodiment of the present application provides a power factor control method using the foregoing topology, which comprises:

[0012] Determining the target conduction time and target duty cycle of each primary side switch tube in a switching cycle;

[0013] Generating a drive control signal for controlling each primary side switch tube based on the target conduction time and target duty cycle, wherein the phase difference between the drive control signals of two adjacent primary side switch tubes is 360° / n, so that the power factor of the topology is 1 under the action of the drive control signal.

[0014] The present application has the advantages of low cost, high efficiency, simple circuit and simple control, and realizes power factor correction, primary and secondary electrical isolation, and adjustment and control of output voltage and current.

[0015] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments thereof, with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0017] FIG. 1 is a schematic diagram of a two-stage power conversion circuit.

[0018] FIG. 2A is one of the commonly used topologies of a front-stage power factor corrector.

[0019] Fig. 2B is another common topology of the front stage power factor corrector.

[0020] Fig. 3A is one of the common topologies of the DC-DC conversion of the back stage.

[0021] Fig. 3B is another common topology of the DC-DC conversion of the back stage.

[0022] Fig. 4 is one of the topologies of the isolated rectifier power converter according to an embodiment of the present application.

[0023] Fig. 5 is a schematic diagram of a two-stage power conversion circuit according to an embodiment of the present application.

[0024] Fig. 6 is a schematic diagram of the current waveform in one switching period according to an embodiment of the present application.

[0025] Fig. 7 is another topology of the isolated rectifier power converter according to an embodiment of the present application.

[0026] Fig. 8 is a schematic flowchart of the power factor control method according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps set forth in the embodiments, as well as the numerical expressions and values, are not limitations on the scope of the present application, unless otherwise specifically stated.

[0028] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the scope of the application, its application, or uses.

[0029] Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail herein. However, where appropriate, such techniques, methods, and devices can be viewed as part of the specification.

[0030] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary, and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0031] As shown in Fig. 4, one embodiment of the present application provides a topology of an isolated rectifier power converter, which includes:

[0032] a voltage source Uin, a rectifier circuit 1, a power conversion unit 2, and a driving control circuit 3, wherein:

[0033] The power conversion unit 2 comprises n parallel power conversion circuits, each of which comprises a clamping tube, a transformer, a primary side switch tube and a secondary side switch tube, wherein the clamping tube of the i-th power conversion circuit is an active clamping tube, and the clamping tubes of the remaining (n-1) power conversion circuits are passive clamping tubes, n is a natural number greater than 1, and 1≤i≤n;

[0034] The power conversion unit 2 is connected with the rectifier circuit 1, the rectifier circuit 1 is connected with the voltage source Uin, and the drive control circuit 3 is connected with the rectifier circuit 1 and the power conversion unit 2;

[0035] The drive control circuit 3 is used to determine the target conduction time and target duty cycle of each primary side switch tube in a switching cycle, and generate a drive control signal for controlling each primary side switch tube based on the target conduction time and target duty cycle, wherein under the action of the drive control signal, the waveform of the input alternating current flowing through the voltage source Uin is consistent with the waveform of the alternating voltage.

[0036] It should be noted that the above isolation type rectifier power converter topology proposed in the present application is a single-stage power conversion circuit, as shown in FIG. 5, the present application can simultaneously realize power factor correction, primary and secondary side electrical isolation, and adjustment control output voltage and current functions by using a single-stage power conversion circuit, which has the advantages of low cost, high efficiency, simple circuit and simple control.

[0037] In the present application, the single-stage power conversion topology has the following advantages: (1) The complexity of the circuit is greatly reduced, the use of power devices is reduced, thereby reducing the cost; (2) Energy is only transformed once, which theoretically reduces the energy conversion loss and improves the energy conversion efficiency.

[0038] In some optional modes of the present embodiment, as shown in FIG. 4, an absorption circuit 4 and an output circuit 5 are further included, wherein:

[0039] The absorption circuit 4 is connected with the power conversion unit 2 and the rectifier circuit 1, and the output circuit 5 is connected with the power conversion unit 2;

[0040] The absorption circuit 4 is used to absorb the leakage energy of the n transformers, and release the leakage energy of the n transformers to the output circuit 5 through the active clamping tube;

[0041] In some optional modes of the present embodiment, the rectifier circuit 1 comprises a first diode d1, a second diode d2, a third diode d3 and a fourth diode d4, wherein:

[0042] The anode of the first diode d1 is connected with the anode of the voltage source Uin and the cathode of the second diode d2, and the cathode of the first diode d1 is connected with the cathode of the third diode d3;

[0043] The anode of the second diode d2 is connected with the anode of the fourth diode d4.

[0044] The cathode of the third diode d3 is connected with the absorption circuit 4, and the anode of the third diode d3 is connected with the cathode of the voltage source Uin and the cathode of the fourth diode d4.

[0045] The anode of the fourth diode d4 is connected with the power conversion unit 2.

[0046] In some optional manners of the embodiment, as shown in FIG. 4, the i th power conversion circuit 2i includes an active clamp Va tube, an i th transformer Ti, an i th primary side switch tube Qi and an i th secondary side switch tube Di, wherein:

[0047] The same name end of the primary side winding of the i th transformer is connected with the absorption circuit.

[0048] The non-same name end of the primary side winding of the i th transformer is connected with the source of the active clamp tube and the drain of the i th primary side switch tube.

[0049] The non-same name end of the secondary side winding of the i th transformer is connected with the anode of the i th secondary side switch tube.

[0050] The same name end of the secondary side winding of the i th transformer, the cathode of the i th secondary side switch tube is connected with the output circuit.

[0051] The drain of the active clamp tube is connected with the absorption circuit, and the gate of the active clamp tube is used for inputting a clamp control signal, wherein the clamp control signal is used for controlling the conduction and the closing of the active clamp tube.

[0052] The source of the i th primary side switch tube is connected with the anode of the fourth diode, and the gate of the i th primary side switch tube is used for inputting an i th driving control signal, wherein the i th driving control signal is generated by the driving control circuit, and the i th driving control signal is used for controlling the conduction time of the i th primary side switch tube in a switching period to be the target conduction time and the duty cycle to be the target duty cycle.

[0053] In some optional manners of the embodiment, the circuit connection relationship and the circuit structure of the remaining (n-1) power conversion circuits are the same, wherein the m th power conversion circuit 2m includes an m th passive clamp tube Vpm, an m th transformer Tm, an m th primary side switch tube Qm and an m th secondary side switch tube Dm, wherein:

[0054] the same name end of the primary winding of the mth transformer is connected with the positive pole of the voltage source;

[0055] the non-same name end of the primary winding of the mth transformer is connected with the positive pole of the mth passive clamp tube and the drain of the mth primary switch tube;

[0056] the non-same name end of the secondary winding of the mth transformer is connected with the positive pole of the mth secondary switch tube;

[0057] the same name end of the secondary winding of the mth transformer and the negative pole of the mth secondary switch tube are connected with the output circuit;

[0058] the negative pole of the mth passive clamp tube is connected with the absorption circuit;

[0059] the source of the mth primary switch tube is connected with the positive pole of the fourth diode, and the gate of the mth primary switch tube is used for inputting the mth drive control signal, wherein the mth drive control signal is generated by the drive control circuit, the mth drive control signal is used for controlling the conduction time of the mth primary switch tube in a switching period to be the target conduction time and the duty cycle to be the target duty cycle, wherein 1≤m≤n and m≠i.

[0060] In some optional manners of the embodiment, as shown in FIG. 4, the absorption circuit includes a clamp capacitor C1 and a clamp resistor R1, wherein:

[0061] the absorption circuit is used for absorbing the leakage energy of the n transformers through the clamp capacitor, and releasing the leakage energy of the n transformers to the output circuit through the active clamp tube.

[0062] In the embodiment, one clamp capacitor is shared by the plurality of parallel power conversion circuits, so that the number of power switch tubes of the present application is greatly reduced relative to the topology architecture of the conventional multi-channel interleaved parallel active clamp flyback converter, effectively reducing the cost problem caused by the large number of switch tubes in the prior art; at the same time, the active clamp tube (active clamp) can recover all the leakage energy of the transformer, reducing the energy loss caused by the leakage inductance of the transformer, thereby further improving the energy conversion efficiency of the flyback converter while reducing the cost.

[0063] The n parallel power circuits share one clamp capacitor C1, and the clamp capacitor C1 can absorb the leakage energy of the corresponding transformer when each power circuit is turned on, and release the absorbed leakage energy of the transformer to the output circuit through the active clamp tube when the active clamp tube is turned on.

[0064] It should be noted that the active clamp tube is turned on after the i-th primary side switch tube is turned off, and the remaining (n-1) primary side switch tubes are turned on staggered before the i-th primary side switch tube is turned off, that is, before the i-th primary side switch tube is turned off, the clamp capacitor can absorb all the leakage energy of the transformer, and when the active clamp tube is turned on, the absorbed leakage energy of the transformer is released to the output circuit through the active clamp tube, thereby improving the energy conversion efficiency of the interleaved parallel flyback converter.

[0065] In some optional modes of the embodiment, the first end of the clamp capacitor C1 is connected with the common end of the primary winding of the n transformers, the negative electrode of the third diode, and the first end of the clamp resistor, and the second end of the clamp capacitor is connected with the drain electrode of the active clamp tube, the negative electrodes of all passive clamp tubes, and the second end of the clamp resistor.

[0066] In some optional modes of the embodiment, as shown in FIG. 4, the output circuit includes an output capacitor C0, and the output circuit 5 is further connected with an output load R0, wherein:

[0067] The first end of the output capacitor is connected with the negative electrodes of all secondary side switch tubes;

[0068] The second end of the output capacitor is connected with the common end of the secondary winding of all transformers.

[0069] In the present application, power factor correction (PFC) is a technology aimed at improving the power factor of the power grid and improving the utilization rate of electricity. The power factor refers to the ratio of effective power to total power consumption (apparent power), which reflects the degree of effective use of electricity. The larger the power factor value, the higher the power utilization rate. PFC adjusts the input current waveform of the electronic device to be as consistent as possible with the voltage waveform, thereby approaching 1, to improve the power factor.

[0070] At present, the most commonly used topology structure for power factor correction in the industry is the Boost circuit as shown in FIG. 2A. However, the Boost circuit cannot achieve electrical isolation, so it is not suitable for single-stage power conversion topology. The flyback converter (power conversion unit) based on the embodiment of the present application shown in FIG. 4 can achieve electrical isolation, and through PWM control of the primary side switch tube, the input current waveform and the input voltage waveform can be made consistent, thereby making the power factor approach 1.

[0071] In the present application, the power factor correction is realized based on the principle of current critical continuous, and the specific implementation method is as follows: for the flyback converter, the so-called current critical continuous refers to that, as shown in FIG. 6, in each switching period, the switch tube (for example, the i-th primary side switch tube Qi) is turned on in the Ton time, and in this conduction time, the current in the primary side winding (coil) of the transformer (for example, the i-th transformer) increases linearly from 0 to the peak value I p_pk at the switch-off moment of the switch tube (for example, the i-th primary side switch tube Qi), the transformer starts to feed energy to the secondary side, as shown in FIG. 6, the current in the secondary side winding of the transformer decreases linearly from the peak value until the current decreases to 0 (see formula (2)), and then the next switch tube (for example, the i+1-th primary side switch tube) is turned on to start the next switching period.

[0072] In the formula, I p_pk is the peak value of the current flowing through the primary side coil of the transformer in a switching period; V ac is the effective value of the input alternating voltage Uin, the input alternating voltage is a sinusoidal voltage, and the formula is L P is the inductance of the primary side coil of the transformer; V o is the DC output voltage; T on is the conduction time of the primary side switch tube in the switching period; T off is the switch-off time of the primary side switch tube in the switching period; and n is the turn ratio of the transformer.

[0073] FIG. 6 is a current waveform diagram in a switching period, and the average current I in_Ave of the input current in the switching period can be calculated by combining formula (1) and formula (2).

[0074] In the formula, Duty is the duty ratio, and it can be known from formula (3) that if the product of the turn-on time and the duty ratio of each switching period is fixed, that is, the control realizes (T on × Duty) is a constant value, the power factor correction can be realized, the input current is the same as the input voltage, that is, a sinusoidal shape, so that the power factor is 1.

[0075] Therefore, in some optional modes of the present embodiment, as shown in FIG. 4, the drive control circuit includes an input voltage sampling sub-circuit, an output voltage sampling sub-circuit, a duty ratio calculation module, a feedback voltage generation sub-circuit, a conduction time calculation module, and a drive control signal generator (that is, the PWM generator in FIG. 4), wherein:

[0076] The input voltage sampling sub-circuit is configured to sample a voltage between a negative electrode of the third diode d3 and a first terminal of the clamping capacitor C1 to obtain an input voltage Vin, where Vin is an input voltage of a rectified voltage source Uin, and Vin satisfies

[0077] The output voltage sampling sub-circuit is configured to sample a voltage across the output capacitor to obtain a direct current output voltage Vo.

[0078] The duty cycle calculation module is configured to calculate a target duty cycle Duty of each of the primary side switch tubes in a switching cycle according to the input voltage Vin and the direct current output voltage Vo.

[0079] In this embodiment, according to formula (4), the value of Duty can be calculated according to the input voltage Vin and the direct current output voltage Vo. In a specific example, the duty cycle calculation module includes a multiplier, an adder and a first divider to realize the calculation of the target duty cycle in formula (4).

[0080] The feedback voltage generation sub-circuit is configured to determine a feedback voltage VFB according to the direct current output voltage Vo and a preset reference voltage Vref, and use the feedback voltage VFB as a constant value of (T on ×Duty); specifically, the feedback voltage generation sub-circuit includes a feedback compensation network, an opto-coupler and a comparator, where a positive input terminal of the comparator is configured to input the reference voltage, a negative input terminal of the comparator is configured to input the direct current output voltage, and the comparator is configured to compare the reference voltage and the direct current output voltage; the feedback compensation network and the opto-coupler are configured to generate the feedback voltage VFB according to the comparison result.

[0081] The on-time calculation module is configured to calculate a target on-time T on of each of the primary side switch tubes in a switching cycle according to the feedback voltage VFB and the target duty cycle Duty.

[0082] In this embodiment, since the feedback voltage VFB is used as a constant value of (T on ×Duty), after the feedback voltage VFB and the target duty cycle Duty are determined, a second divider can be used to obtain the target on-time T on of the primary side switch tube.

[0083] Further, after the target on-time T on and the target duty cycle Duty are determined, the drive control signal generation sub-circuit is configured to generate a drive control signal according to the target on-time T onand the target duty ratio Duty, to generate a drive control signal for controlling each of the primary side switch tubes.

[0084] It should be noted that, in order to achieve interleaving parallel connection between the power circuits, so that the input and output currents are continuous, in the embodiment, the phase difference between the drive control signals of the adjacent two primary side switch tubes is 360° / n. That is, the phase difference between the adjacent two drive control signals among the first drive control signal, the second drive control signal, the third drive control signal,..., and the nth drive control signal is 360° / n. According to the above target conduction time T on and the target duty ratio Duty, to generate a drive control signal for controlling the first primary side switch tube, and then the drive control signals of the remaining primary side switch tubes can be determined by delaying according to the phase difference, which will not be described herein.

[0085] In some optional manners of the embodiment, the transistor type of the active clamp tube is a silicon MOSFET, a silicon carbide MOSFET, or a gallium nitride device;

[0086] The transistor type of the passive clamp tube is a silicon diode or a silicon carbide diode;

[0087] The transistor type of the primary side switch tube is a silicon MOSFET, a silicon carbide MOSFET, or a gallium nitride device;

[0088] The transistor type of the secondary side switch tube is a silicon diode, a silicon carbide diode, or a MOSFET.

[0089] Next, as shown in FIG. 7, the power factor control method of the topology structure of the isolation type rectification power converter of the application is described by taking the example of a 1-way flyback converter power module, wherein:

[0090] The AC input passes through a rectification unit (usually a diode rectification bridge) and is then connected to a power conversion unit, which is composed of a 1-way flyback converter power module, wherein the flyback converter power module adopts an active clamp topology architecture, and the clamp tube is an active switch tube (which can be a silicon MOSFET, a silicon carbide MOSFET, or a gallium nitride device).

[0091] The DC output voltage Vo is set by a voltage reference Vref. After sampling the DC output voltage and comparing it with the reference voltage, a feedback voltage VFB is formed through a feedback compensation network and an optocoupler isolator. As can be seen from formula (3) and formula (4), for a specific output power, as long as the control (T on × Duty) is a constant value, power factor correction can be achieved, that is, the input current shape and the output voltage shape are consistent and are sine waves.

[0092] Specifically, the feedback voltage VFB is used as a constant value of (T on ×Duty), and since

[0093] Thus, the value of Duty can be calculated from the input voltage and the output voltage, and the on time of the switch tube can be obtained through a divider. According to the on time and the duty cycle, a drive control signal for controlling the switch tube is generated, thereby realizing the control of the power factor correction. Similarly, for the case of staggered parallel connection of n parallel flyback converter power modules, only the calculated drive control signal needs to be provided to other switch tubes after being uniformly phase-shifted by 360° / n, and the present application will not be described here.

[0094] On the basis of the topology structure proposed in the foregoing embodiments, as shown in FIG. 8, another embodiment of the present application provides a power factor control method using the topology structure of the foregoing embodiments, comprising:

[0095] Step 10, determining the target on time and the target duty cycle of each primary side switch tube in a switching cycle;

[0096] Step 20, generating a drive control signal for controlling each primary side switch tube based on the target on time and the target duty cycle, wherein the phase difference between the drive control signals of two adjacent primary side switch tubes is 360° / n, so that the power factor of the topology structure is 1 under the action of the drive control signal.

[0097] Specifically, the power factor correction control method proposed in the present application comprises: forming a feedback voltage VFB through DC output voltage Vo feedback control; the feedback voltage is used as a constant value of (T on ×Duty) ; calculating the Duty value in real time through detection of the DC output voltage Vo and the input voltage Vin; calculating the Ton time through the values of VFB and Duty; and forming a PWM signal through the setting of the Ton time. For the case of staggered parallel connection of n parallel flyback converter power modules, only the PWM signal of Q1 needs to be provided to other switch tubes after being uniformly phase-shifted by 360° / n.

[0098] In the present application, the target on time and the target duty cycle are calculated in advance to ensure that the product of the on time and the duty cycle of each switching cycle is fixed, so that the input current is also sinusoidal as the input voltage, thereby realizing a power factor of 1.

[0099] It can be understood that the above examples are only examples listed for better understanding of the technical solutions of the embodiments of the present application, and are not the only limitation of the embodiments of the present application.

[0100] It should be noted that, in the description of the present application, the terms "upper", "lower", and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0101] It should also be noted that, in the description of the present application, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element.

[0102] In the embodiments of the present application, the singular form "a", "the" and the like includes the plural form and should be broadly understood as "one" or "a kind" rather than the meaning of "one"; in addition, the term "said" should be understood to include both singular and plural forms, unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least partially according to", and the term "based on" should be understood as "at least partially based on", unless the context clearly indicates otherwise.

[0103] It should be understood that the various forms of flow shown above can be reordered, added or deleted. For example, the steps described in the present disclosure can be executed in parallel, sequentially or in different order, as long as the desired results of the technical solutions of the present disclosure can be achieved, which is not limited herein.

[0104] The above detailed description does not constitute a limitation on the protection scope of the present disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

[0105] While certain embodiments of the application have been described by way of example with specific reference to the drawings, it will be appreciated that the application is not limited by any of the examples described. It will be further appreciated that modifications can be made to the described embodiments without departing from the scope and spirit of the application. The scope of the application is defined in the claims that follow.

Claims

1. A topology for an isolated rectifying power converter, comprising: The voltage source, the rectifier circuit, the power conversion unit and the drive control circuit, wherein: The power conversion unit comprises n parallel power conversion circuits, each of which comprises a clamping tube, a transformer, a primary side switch tube and a secondary side switch tube, wherein the clamping tube of the i th power conversion circuit is an active clamping tube, and the clamping tubes of the remaining (n-1) power conversion circuits are passive clamping tubes, n is a natural number greater than 1, and 1≤i≤n; The power conversion unit is connected with the rectifier circuit, the rectifier circuit is connected with the voltage source, the drive control circuit is connected with the rectifier circuit and the power conversion unit, and the voltage source is used for inputting alternating voltage; The drive control circuit is used for determining the target conduction time and the target duty cycle of each primary side switch tube in a switching cycle, and generating a drive control signal for controlling each primary side switch tube based on the target conduction time and the target duty cycle, wherein under the action of the drive control signal, the waveform of the input alternating current flowing through the voltage source is consistent with the waveform of the alternating voltage.

2. The topology of claim 1, further comprising an absorption circuit and an output circuit, wherein: The absorption circuit is connected with the power conversion unit and the rectifier circuit, and the output circuit is connected with the power conversion unit; The absorption circuit is used for absorbing the leakage energy of the n transformers, and releasing the leakage energy of the n transformers to the output circuit through the active clamping tube.

3. The topology of claim 2, wherein, The rectifier circuit comprises a first diode, a second diode, a third diode and a fourth diode, wherein: The anode of the first diode is connected with the anode of the voltage source and the cathode of the second diode, and the cathode of the first diode is connected with the cathode of the third diode; The anode of the second diode is connected with the anode of the fourth diode; The cathode of the third diode is connected with the absorption circuit, and the anode of the third diode is connected with the cathode of the voltage source and the cathode of the fourth diode; The anode of the fourth diode is connected with the power conversion unit.

4. The topology of claim 3, wherein, The i th power conversion circuit comprises an active clamping tube, an i th transformer, an i th primary side switch tube and an i th secondary side switch tube, wherein: The same name end of the primary side winding of the i th transformer is connected with the absorption circuit; The non-same name end of the primary side winding of the i th transformer is connected with the source of the active clamping tube and the drain of the i th primary side switch tube; The non-same name end of the secondary side winding of the i th transformer is connected with the anode of the i th secondary side switch tube; The same name end of the secondary side winding of the i th transformer, the cathode of the i th secondary side switch tube and the output circuit are connected; The drain of the active clamping tube is connected with the absorption circuit, and the gate of the active clamping tube is used for inputting a clamping control signal, wherein the clamping control signal is used for controlling the conduction and the closing of the active clamping tube. The source of the ith primary switch is connected with the anode of the fourth diode, and the gate of the ith primary switch is used for inputting an ith drive control signal, wherein the ith drive control signal is generated by the drive control circuit, and the ith drive control signal is used for controlling the conduction time of the ith primary switch in a switching cycle to be the target conduction time and the duty cycle to be the target duty cycle.

5. The topology of claim 3, wherein, The circuit connection relationship and the circuit structure of the remaining (n-1) power conversion circuits are the same, wherein the mth power conversion circuit comprises an mth passive clamp, an mth transformer, an mth primary switch and an mth secondary switch, wherein: The same end of the primary winding of the mth transformer is connected with the anode of the voltage source; The non-same end of the primary winding of the mth transformer is connected with the anode of the mth passive clamp and the drain of the mth primary switch; The non-same end of the secondary winding of the mth transformer is connected with the anode of the mth secondary switch; The same end of the secondary winding of the mth transformer, the cathode of the mth secondary switch and the output circuit are connected; The cathode of the mth passive clamp is connected with the absorption circuit; The source of the mth primary switch is connected with the anode of the fourth diode, and the gate of the mth primary switch is used for inputting an mth drive control signal, wherein the mth drive control signal is generated by the drive control circuit, and the mth drive control signal is used for controlling the conduction time of the mth primary switch in a switching cycle to be the target conduction time and the duty cycle to be the target duty cycle, wherein 1≤m≤n and m≠i.

6. The topology of claim 3, wherein, The absorption circuit comprises a clamping capacitor and a clamping resistor, wherein: The absorption circuit is used for absorbing the leakage energy of the n transformers through the clamping capacitor, and releasing the leakage energy of the n transformers to the output circuit through the active clamp.

7. The topology of claim 6, wherein, The first end of the clamping capacitor is connected with the same end of the primary winding of the n transformers, the cathode of the third diode and the first end of the clamping resistor, and the second end of the clamping capacitor is connected with the drain of the active clamp, the cathodes of all passive clamps and the second end of the clamping resistor.

8. The topology of claim 6, wherein, The output circuit comprises an output capacitor, wherein: The first end of the output capacitor is connected with the cathodes of all secondary switches; The second end of the output capacitor is connected with the same end of the secondary winding of all transformers.

9. The topology of claim 8, wherein, The drive control circuit comprises an input voltage sampling sub-circuit, an output voltage sampling sub-circuit, a duty cycle calculation module, a feedback voltage generation sub-circuit, a conduction time calculation module and a drive control signal generator, wherein: The input voltage sampling sub-circuit is used for sampling the voltage between the cathode of the third diode and the first end of the clamping capacitor to obtain an input voltage; The output voltage sampling sub-circuit is used for sampling the voltage across the output capacitor to obtain a direct current output voltage; The duty cycle calculation module is used for calculating the target duty cycle of each primary switch in a switching cycle according to the input voltage and the direct current output voltage; The feedback voltage generation sub-circuit is configured to determine a feedback voltage according to the DC output voltage and a preset reference voltage; The on-time calculation module is configured to calculate a target on-time of each of the primary-side switch tubes in a switching cycle according to the feedback voltage and the target duty cycle; The drive control signal generation sub-circuit is configured to generate drive control signals for controlling the primary-side switch tubes according to the target on-time and the target duty cycle, wherein the phases of the drive control signals of adjacent two primary-side switch tubes are different by 360° / n.

10. The topology of claim 9, wherein, The feedback voltage generation sub-circuit comprises a feedback compensation network, an opto-coupler and a comparator, wherein: a positive input terminal of the comparator is configured to input a reference voltage, a negative input terminal of the comparator is configured to input the DC output voltage, and the comparator is configured to compare the reference voltage and the DC output voltage; and the feedback compensation network and the opto-coupler are configured to generate the feedback voltage according to a comparison result. The duty cycle calculation module comprises a multiplier, an adder and a first divider. The on-time calculation module comprises a second divider.

11. The topology of claim 1, wherein, The transistor type of the active clamp tube is silicon MOSFET, silicon carbide MOSFET or gallium nitride device; The transistor type of the passive clamp tube is silicon diode or silicon carbide diode; The transistor type of the primary-side switch tube is silicon MOSFET, silicon carbide MOSFET or gallium nitride device; The transistor type of the secondary-side switch tube is silicon diode, silicon carbide diode or MOSFET.

12. A power factor control method using the topology of any one of claims 1-11, comprising: determining a target on-time and a target duty cycle of each of the primary-side switch tubes in a switching cycle; generating drive control signals for controlling the primary-side switch tubes based on the target on-time and the target duty cycle, wherein the phases of the drive control signals of adjacent two primary-side switch tubes are different by 360° / n, so that the power factor of the topology is 1 under the action of the drive control signals.

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