A turn ratio optimization method for integrated three-phase boost-llc topology

Abstract

The application discloses a turn ratio optimization method of integrated three-phase Boost-LLC topology, comprising the following steps: obtaining a positive peak value and a negative peak value of a Boost chopper inductance current; obtaining an effective value of the chopper inductance current according to the positive peak value and the negative peak value; obtaining resonance current peak values of a Boost primary side and a secondary side; obtaining resonance current effective values of the primary side and the secondary side according to the resonance current peak values; calculating inductance values under different turn ratios when an output voltage is fixed; and obtaining a turn ratio with minimum loss according to the effective value of the chopper inductance current, the resonance current effective values and the inductance values under different turn ratios. The application solves the problem that the turn ratio in the integrated three-phase Boost-LLC topology is difficult to be scientifically and efficiently designed.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of isolated DC-DC converters, and particularly relates to a method for optimizing the turns ratio of an integrated three-phase Boost-LLC topology. BACKGROUND

[0002] To improve the power density of a system, the switching frequency of a device can be increased to reduce the size of passive components, but the higher the switching frequency, the greater the switching loss. To achieve high-efficiency high-power-density conversion, LLC is used because it can achieve soft switching of the primary and secondary devices. To improve power capacity and reduce current ripple, three-phase interleaved LLC is widely used. Meanwhile, to broaden the voltage regulation range and simplify synchronous rectification, an integrated three-phase Boost-LLC topology is proposed, but the turns ratio of the transformer will affect the various performances of the converter, and there is no scientific and reasonable specification for the design of the turns ratio. Therefore, there is an urgent need for a method for optimizing the turns ratio of an integrated three-phase Boost-LLC topology. SUMMARY

[0003] To solve the above technical problems, the application provides a method for optimizing the turns ratio of an integrated three-phase Boost-LLC topology, which can solve the problem of difficult scientific and efficient design of the turns ratio in an integrated three-phase Boost-LLC topology.

[0004] To achieve the above object, the application provides a method for optimizing the turns ratio of an integrated three-phase Boost-LLC topology, comprising:

[0005] obtaining a positive peak value and a negative peak value of a Boost chopper inductance current;

[0006] obtaining an effective value of the chopper inductance current according to the positive peak value and the negative peak value;

[0007] obtaining a resonance current peak value of the Boost primary side and the secondary side;

[0008] obtaining resonance current effective values of the primary side and the secondary side according to the resonance current peak value;

[0009] calculating inductance values under different turns ratios when the output voltage is fixed;

[0010] obtaining a turns ratio with minimum loss according to the effective value of the chopper inductance current, the resonance current effective values, and the inductance values under different turns ratios.

[0011] Optionally, the method for obtaining the positive peak value of the Boost chopper inductance current comprises:

[0012]

[0013] wherein, I L_p is the positive peak value of the Boost chopper inductance current, Vin f is the input voltage, r f is the resonant frequency, D is the duty cycle, and P is the input power;

[0014] The method for obtaining the negative peak value of the Boost chopper inductor current is:

[0015]

[0016] wherein I L_n is the negative peak value of the Boost chopper inductor current.

[0017] Optionally, the method for obtaining the effective value of the chopper inductor current is:

[0018]

[0019] wherein I L_rms is the effective value of the Boost chopper inductor current.

[0020] Optionally, the method for obtaining the resonant current peak value of the Boost secondary side is:

[0021]

[0022] wherein I s_pk is the resonant current peak value of the secondary side Y connection, and I o is the output current, D is the duty cycle, and x is the integral variable.

[0023] The method for obtaining the resonant current peak value of the Boost primary side is:

[0024] I p_pk = I s_pk / n

[0025] wherein I p_pk is the resonant current peak value of the primary side Y connection, and n is the transformer turns ratio.

[0026] Optionally, the method for obtaining the resonant current effective value of the secondary side is:

[0027]

[0028] wherein I s_rms is the resonant current effective value of the secondary side Y connection.

[0029] The method for obtaining the resonant current effective value of the primary side is:

[0030] I p_rms = I s_rms / n

[0031] wherein I p_rms is the resonant current effective value of the primary side Y connection.

[0032] Optionally, the method for calculating the inductance value under different turns ratios is as follows:

[0033]

[0034] Wherein, L is the Boost chopper inductance value, t d is the dead zone value for realizing soft switching, V i is the input voltage, f r is the resonance frequency, D is the duty cycle, P is the input power, f s is the resonance frequency, C p is the junction capacitance of the primary side switch tube, C s is the junction capacitance of the secondary side switch tube, and n is the turns ratio of the transformer.

[0035] Optionally, the turns ratio with minimum loss comprises:

[0036] According to the effective value of the chopper inductance current, the effective value of the resonance current and the inductance value under different turns ratios, the turns ratio with minimum loss is obtained.

[0037] According to the minimum loss, the turns ratio with minimum loss is obtained.

[0038] Optionally, the method for obtaining the minimum loss comprises:

[0039] P sw_con_p = 3 (I L_rms 2 + I p_rms 2 ) R dson_p

[0040] P sw_con_s = 3I s_rms 2 R dson_s

[0041] Wherein, P sw_con_p is the conduction loss of the primary side switch tube, P sw_con_s is the conduction loss of the secondary side switch tube, I L_rms is the effective value of the Boost chopper inductance current, I p_rms is the effective value of the primary side Y-type connection resonance current, I s_rms is the effective value of the secondary side Y-type connection resonance current, and R dson_s is the conduction resistance of the secondary side switch tube.

[0042] Compared with the prior art, the present application has the following advantages and technical effects:

[0043] 1. The present application can realize the minimum device loss and improve the efficiency by optimizing the transformer turns ratio design.

[0044] 2. The method has simple principles, is easy to implement, and has high implementability;

[0045] 3. The application solves the problem of difficult scientific and efficient design of the turn ratio in the integrated three-phase Boost-LLC topology. BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of this application, and their

[0047] Figure 1 is a turn ratio optimization method flow chart of an integrated three-phase Boost-LLC topology according to an embodiment of the application;

[0048] Figure 2 is a circuit structure diagram of a three-phase integrated Boost-LLC converter according to an embodiment of the application;

[0049] Figure 3 is a loss calculation result diagram under each turn ratio according to an embodiment of the application. DETAILED DESCRIPTION

[0050] It should be noted that the embodiments and features in the application can be combined with each other without conflict. The application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0051] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a group of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0052] The application provides a turn ratio optimization method for an integrated three-phase Boost-LLC topology, as shown in Figure 1 specifically comprising the following steps:

[0053] obtaining the positive peak value and the negative peak value of the Boost chopper inductance current;

[0054] obtaining the effective value of the chopper inductance current according to the positive peak value and the negative peak value;

[0055] obtaining the resonance current peak value of the Boost primary side and the secondary side;

[0056] obtaining the resonance current effective value of the primary side and the secondary side according to the resonance current peak value;

[0057] calculating the inductance value under different turn ratios when the output voltage is fixed;

[0058] According to the effective value of the chopping inductance current, the effective value of the resonant current and the inductance value under different turns ratios, the turns ratio with minimum loss is obtained.

[0059] Specifically, the circuit structure diagram of the three-phase integrated Boost-LLC converter is as shown in the figure Figure 2 The turns ratio optimization method specifically includes the following steps:

[0060] Step one, according to the power, duty cycle, input voltage, the positive peak value and negative peak value of the Boost chopping inductance current are calculated;

[0061] Step two, according to the Boost chopping inductance current waveform and its positive and negative peak values, the effective value of the current is calculated;

[0062] Step three, according to the charge balance, the resonant current peak value and effective value of the primary and secondary Y-type connection can be calculated;

[0063] Step four, when the output voltage is fixed, the different bus voltages, different duty cycles, different switching frequencies and the maximum realizable soft switching Boost chopping inductance under different turns ratios are calculated;

[0064] Step five, under the given working condition and device parameters, the device loss under different turns ratios is calculated, and the turns ratio with minimum loss is selected.

[0065] Further, the method for obtaining the positive peak value of the Boost chopping inductance current is:

[0066]

[0067] Wherein, I L_p is the positive peak value of the Boost chopping inductance current, V in is the input voltage, f r is the resonant frequency, D is the duty cycle, and P is the input power.

[0068] The method for obtaining the negative peak value of the Boost chopping inductance current is:

[0069]

[0070] Wherein, I L_n is the negative peak value of the Boost chopping inductance current.

[0071] Further, the method for obtaining the effective value of the chopping inductance current is:

[0072]

[0073] Wherein, I L_rms is the effective value of the Boost chopping inductance current.

[0074] Further, the method for obtaining the peak value of the resonant current of the secondary side of the Boost is:

[0075]

[0076] wherein I s_pk is the peak value of the Y-connected resonant current of the secondary side, I o is the output current, D is the duty cycle, and x is an integral variable;

[0077] The method for obtaining the peak value of the resonant current of the primary side of the Boost is:

[0078] I p_pk = I s_pk / n

[0079] wherein I p_pk is the peak value of the Y-connected resonant current of the primary side, and n is the turns ratio of the transformer.

[0080] Further, the method for obtaining the effective value of the resonant current of the secondary side is:

[0081]

[0082] wherein I s_rms is the effective value of the Y-connected resonant current of the secondary side;

[0083] The method for obtaining the effective value of the resonant current of the primary side is:

[0084] I p_rms = I s_rms / n (6)

[0085] wherein I p_rms is the effective value of the Y-connected resonant current of the primary side.

[0086] Further, the method for calculating the inductance value under different turns ratios is:

[0087]

[0088] wherein L is the inductance value of the Boost chopper, t d is the dead time value for realizing soft switching, V i is the input voltage, f r is the resonant frequency, P is the input power, f s is the resonant frequency, C p is the junction capacitance of the primary side switch tube, C s is the junction capacitance of the secondary side switch tube, n is the turns ratio of the transformer, G tot is the total circuit gain, and D is the duty cycle, which is calculated according to formula (8) under the input and output voltages.

[0089] Further, the turn ratio of minimum loss comprises:

[0090] According to the effective value of the chopping inductance current, the effective value of the resonance current and the inductance value under different turn ratios, the turn ratio of minimum loss is obtained.

[0091] According to the minimum loss, the turn ratio of minimum loss is obtained.

[0092] Further, the minimum loss is calculated according to Table 1:

[0093] P sw_con_p = 3 (I L_rms 2 + I p_rms 2 ) R dson_p (10)

[0094] P sw_con_s = 3 I s_rms 2 R dson_s (11)

[0095] Wherein, P sw_con_p is the conduction loss of the primary side switch tube, P sw_con_s is the conduction loss of the secondary side switch tube, I L_rms is the effective value of the Boost chopping inductance current, I p_rms is the effective value of the primary side Y-type connection resonance current, I s_rms is the effective value of the secondary side Y-type connection resonance current, and R dson_s is the conduction resistance of the device.

[0096] Table 1

[0097]

[0098]

[0099] According to Figure 3 The turn ratio of minimum loss n = 4 can be selected.

[0100] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be limited by the protection scope of the claims.

Claims

1. A method for turn ratio optimization of an integrated three-phase Boost-LLC topology, characterized in that, The method comprises the following steps: obtaining a positive peak value and a negative peak value of a Boost chopper inductance current; obtaining an effective value of the chopper inductance current according to the positive peak value and the negative peak value; obtaining a resonance current peak value of a primary side and a secondary side of the Boost; obtaining an effective value of the resonance current of the primary side and the secondary side according to the resonance current peak value; calculating inductance values under different turn ratios when a fixed output voltage is outputted; obtaining a turn ratio with minimum loss according to the effective value of the chopper inductance current, the effective value of the resonance current and the inductance values under different turn ratios.

2. The method of claim 1, wherein the integrated three-phase Boost-LLC topology is optimized for turns ratio. The method for obtaining the positive peak value of the Boost chopper inductance current comprises the following steps: where I L_p is the positive peak value of the boost chopper inductor current, V i is the input voltage, f r is the resonant frequency, D is the duty cycle, and P is the input power; The method for obtaining the negative peak value of the Boost chopper inductance current comprises the following steps: where I L_n is the negative peak value of the boost chopper inductor current.

3. The method of claim 2, wherein the integrated three-phase Boost-LLC topology is optimized for turns ratio. The method for obtaining the effective value of the chopper inductance current comprises the following steps: where I L_rms is the Boost chopper inductor current root mean square value.

4. The method of claim 1, wherein the integrated three-phase Boost-LLC topology is optimized for turns ratio. The method for obtaining the resonance current peak value of the secondary side of the Boost comprises the following steps: where I s_pk is the peak value of the secondary Y-connected resonant current, I o is the output current, D is the duty cycle, and x is the integration variable; The method for obtaining the resonance current peak value of the primary side of the Boost comprises the following steps: I p_pk = I s_pk / n where I p_pk is the primary Y-connected resonant current peak, and n is the transformer turns ratio.

5. The method of claim 4, wherein the integrated three-phase Boost-LLC topology is optimized for turns ratio. The method for obtaining the effective value of the resonance current of the secondary side comprises the following steps: wherein I s_rms is the effective value of the secondary Y-connected resonant current; The method for obtaining the effective value of the resonance current of the primary side comprises the following steps: I p_rms = I s_rms / n where I p_rms is the primary Y-connected resonant current effective value.

6. The method of claim 1, wherein the integrated three-phase Boost-LLC topology is optimized for turns ratio. The method for calculating the inductance values under different turn ratios comprises the following steps: Where L is the Boost chopper inductance value, t d To achieve the dead zone value of soft switching, V i is the input voltage, f r is the resonant frequency, D is the duty cycle, P is the input power, f s is the resonant frequency, C p is the primary side switch tube junction capacitance, C s is the secondary side switch tube junction capacitance, n is the transformer turns ratio.

7. The method of claim 1, wherein the integrated three-phase Boost-LLC topology is optimized for turns ratio. The method for obtaining the turn ratio with minimum loss comprises the following steps: obtaining a minimum switch device loss according to the effective value of the chopper inductance current, the effective value of the resonance current and the inductance values under different turn ratios; obtaining the turn ratio with minimum loss according to the minimum switch device loss.

8. The method of claim 7, wherein the integrated three-phase Boost-LLC topology is optimized for turns ratio. The method for obtaining the minimum loss comprises the following steps: P sw_con_p = 3(I L_rms 2 + I p_rms 2 )R dson_p P sw_con_s = 3I s_rms 2 R dson_s Wherein, P sw_con_p is the conduction loss of the primary side switch tube, P sw_con_s is the conduction loss of the secondary side switch tube, I L_rms is the effective value of the Boost chopper inductance current, I p_rms is the effective value of the primary side Y-type connection resonance current, I s_rms is the effective value of the secondary side Y-type connection resonance current, R dson_s is the on-resistance of the device.

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