A high-ratio DC / DC conversion circuit and control method

Abstract

The present invention is a high transformation ratio DC / DC conversion circuit and control method, the circuit includes an input interface, a first fully controlled switch device Q1, a second fully controlled switch device Q2, a third fully controlled switch device S1, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1, a second inductor L2, a third inductor L3, a first diode D1, a second diode D2, a third diode D3 and an output interface, by controlling the working state of the first fully controlled switch device Q1, the second fully controlled switch device Q2 and the third fully controlled switch device S1, different conversion circuit working modes and corresponding functions are realized. The conversion circuit of the present invention can select different working modes according to the difference between input and output, determine different working states, and can realize high transformation ratio operation, and is particularly suitable for application in DC wide voltage conversion occasions such as photovoltaic new energy.

Description

Technical Field

[0001] The present invention relates to the field of voltage transformation technology, and in particular to a high transformation ratio DC / DC conversion circuit and a control method. Background Art

[0002] Direct current-to-direct current (DC / DC) conversion circuits are widely used in various power conversion systems. They are one of the important conversions for realizing power conversion management, and their main function is to realize voltage conversion. Since direct current has different characteristics from alternating current, alternating current can be easily converted and adjusted between various voltage levels through transformers. Since direct current cannot use the transformer-like transformation principle to realize voltage regulation, various DC / DC conversion circuits must be used to realize it. The voltage conversion of direct current can be mainly divided into boost, buck, and boost-boost according to different application scenarios. Conventional conversion circuits have the disadvantages and shortcomings of limited transformation ratio in engineering applications and single functional mode. In particular, for occasions with large fluctuation range of direct current voltage such as solar photovoltaic power generation, it is necessary to adopt multiple circuit combinations and other methods to realize high transformation ratio applications. The present invention solves the engineering application requirements of similar high transformation ratio occasions by designing high transformation ratio and high performance circuits. Summary of the invention

[0003] The purpose of the present invention is to overcome the problems existing in the prior art and provide a high transformation ratio DC / DC conversion circuit and control method. The circuit can be adjusted as needed according to different application modes to achieve high transformation ratio and multi-mode operation, meeting the needs of engineering applications such as solar photovoltaic power generation.

[0004] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0005] A high transformation ratio DC / DC conversion circuit, the circuit comprises an input interface, a first fully controlled switch device Q1, a second fully controlled switch device Q2, a third fully controlled switch device S1, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1, a second inductor L2, a third inductor L3, a first diode D1, a second diode D2, a third diode D3 and an output interface, and realizes different conversion circuit working modes and corresponding functions by controlling the working states of the first fully controlled switch device Q1, the second fully controlled switch device Q2 and the third fully controlled switch device S1; wherein,

[0006] The first end of the third fully-controlled switch device S1 is connected to the positive terminal of the input interface, a common connection point of the first fully-controlled switch device Q1 and the first capacitor C1, and the second end of the third fully-controlled switch device S1 is connected to the first inductor L1, the third inductor L3, the third capacitor C3 and a common connection point of the second fully-controlled switch device Q2;

[0007] The second end of the first fully-controlled switch device Q1 is connected to the cathode end of the first diode D1 and the anode end of the second diode D2;

[0008] The second end of the second fully-controlled switch device Q2 is connected to a common connection point of the second inductor L2, the second capacitor C2, the negative terminal of the output interface and the fourth capacitor C4;

[0009] The positive terminal of the first diode D1 is connected to the negative terminal of the input interface, the first capacitor C1, the third capacitor C3 and another common connection point of the second inductor L2;

[0010] The cathode terminal of the second diode D2 is connected to another common connection point of the first inductor L1 and the second capacitor C2;

[0011] The first capacitor C1 is connected in parallel with the input interface, the fourth capacitor C4 is connected in parallel with the output interface, the third inductor L3 is connected to the positive terminal of the output interface through the third diode D3, and the second inductor L2 is connected between the input interface and the negative terminal of the output interface.

[0012] Furthermore, the positive terminal of the input interface is electrically connected in sequence to the third fully-controlled switch device S1, the third inductor L3, the third diode D3 and the positive terminal of the output interface to form a DC conversion high-efficiency direct-through circuit to achieve direct connection of the input interface electrical energy equivalent to the output interface.

[0013] Furthermore, the first fully-controlled switch device Q1, the first diode D1, the second diode D2, the third diode D3, the first inductor L1, the second inductor L2 and the third inductor L3 form a buck conversion circuit to achieve buck conversion from input interface power to output interface power.

[0014] Furthermore, the second diode D2, the first inductor L1, the second inductor L2, the second capacitor C2 and the third capacitor C3 form a Z-source conversion circuit.

[0015] Furthermore, the second diode D2, the first capacitor C1, the second capacitor C2, the second fully-controlled switch device Q2, the first inductor L1, the second inductor L2, the third inductor L3 and the third diode D3 form a high-transformation ratio boost Z-Boost conversion circuit to achieve a high-transformation ratio boost conversion from input interface power to output interface power.

[0016] Furthermore, the disconnected states of the first fully-controlled switch device Q1 , the second fully-controlled switch device Q2 , and the third fully-controlled switch device S1 form a protection circuit to achieve circuit isolation between input and output.

[0017] A control method for a high-ratio DC / DC converter circuit, the method comprising the following steps:

[0018] Step 1) Detect the input voltage value Uin and the output voltage setting value Uout_set;

[0019] Step 2) Compare the input voltage value Uin and the output set voltage value Uout_set, and calculate the absolute difference Ue;

[0020] Step 3) Determine the circuit operation mode according to the comparison result of step 2), and compare the value of Ue with the set voltage difference Ue_set1 or Ue_set2 to determine the circuit operation mode, specifically: if the input voltage Uin is greater than the output voltage Uout_set, and Ue is less than the set voltage difference Ue_set1, the circuit operates in the pass-through mode; otherwise, the circuit operates in the step-down Buck circuit mode; if the input voltage Uin is less than the output voltage Uout_set, the circuit operates in the high-ratio step-up Z-Boost mode;

[0021] Step 4) According to the different circuit working states of step 3), different controls are implemented on the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1, specifically: in the through working state, the first fully-controlled switch device Q1 and the second fully-controlled switch device Q2 are in the off state, and the third fully-controlled switch device S1 is in the on state; in the Buck circuit working state, the first fully-controlled switch device Q1 works in the PWM signal control state, and the second fully-controlled switch device Q2 and the third fully-controlled switch device S1 are in the off state; if working in the Z-Boost working state, the first fully-controlled switch device Q1 is in the on state, the second fully-controlled switch device Q2 works in the PWM signal control state, and the third fully-controlled switch device S1 is in the off state;

[0022] Step 5) According to the working control mode of the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1 determined in step 4), control is implemented to complete the conversion function of the circuit, wherein in the Buck circuit working state and the Z-Boost working state, the duty cycle of the PWM control signal is adjusted in real time according to the size of the difference Ue;

[0023] Step 6) If a fault is detected, the conversion circuit enters an isolation protection state by disconnecting the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1.

[0024] The beneficial effects of the present invention are:

[0025] The conversion circuit of the present invention can select different working modes according to the difference of input and output, determine different working states, and can realize high transformation ratio operation, and is particularly suitable for application in DC wide voltage conversion occasions such as photovoltaic new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of a conversion circuit of the present invention;

[0027] Figure 2a A through-mode circuit connection diagram of the conversion circuit of the present invention;

[0028] Figure 2b It is a connection diagram of the buck mode circuit of the conversion circuit of the present invention;

[0029] Figure 2c It is a connection diagram of the boost mode circuit of the conversion circuit of the present invention;

[0030] Figure 2d A protection mode circuit connection diagram of the conversion circuit of the present invention;

[0031] Figure 3 It is a control flow chart of the conversion circuit of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0033] like Figure 1 As shown, a high transformation ratio DC / DC conversion circuit includes an input interface, a first fully-controlled switch device Q1, a second fully-controlled switch device Q2, a third fully-controlled switch device S1, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1, a second inductor L2, a third inductor L3, a first diode D1, a second diode D2, a third diode D3 and an output interface. By controlling the working states of the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1, different conversion circuit working modes and corresponding functions are realized; wherein,

[0034] The first end of the third fully-controlled switch device S1 is connected to the positive terminal of the input interface, a common connection point of the first fully-controlled switch device Q1 and the first capacitor C1, and the second end of the third fully-controlled switch device S1 is connected to the first inductor L1, the third inductor L3, the third capacitor C3 and a common connection point of the second fully-controlled switch device Q2;

[0035] The second end of the first fully-controlled switch device Q1 is connected to the cathode end of the first diode D1 and the anode end of the second diode D2;

[0036] The second end of the second fully-controlled switch device Q2 is connected to a common connection point of the second inductor L2, the second capacitor C2, the negative terminal of the output interface and the fourth capacitor C4;

[0037] The positive terminal of the first diode D1 is connected to the negative terminal of the input interface, the first capacitor C1, the third capacitor C3 and another common connection point of the second inductor L2;

[0038] The cathode terminal of the second diode D2 is connected to another common connection point of the first inductor L1 and the second capacitor C2;

[0039] The first capacitor C1 is connected in parallel with the input interface, the fourth capacitor C4 is connected in parallel with the output interface, the third inductor L3 is connected to the positive terminal of the output interface through the third diode D3, and the second inductor L2 is connected between the input interface and the negative terminal of the output interface.

[0040] like Figure 2a As shown, it is a direct-pass mode: the positive terminal of the input interface is electrically connected to the third fully-controlled switch device S1, the third inductor L3, the third diode D3 and the positive terminal of the output interface in sequence to form a DC conversion high-efficiency direct-pass circuit, so as to realize the input interface electrical energy equivalently and directly connected to the output interface.

[0041] like Figure 2b As shown, it is a buck mode: the first fully-controlled switch device Q1, the first diode D1, the second diode D2, the third diode D3, the first inductor L1, the second inductor L2 and the third inductor L3 form a buck conversion circuit to achieve buck conversion from input interface power to output interface power.

[0042] The second diode D2, the first inductor L1, the second inductor L2, the second capacitor C2 and the third capacitor C3 form a Z-source conversion circuit.

[0043] like Figure 2c As shown, it is a boost mode: the second diode D2, the first capacitor C1, the second capacitor C2, the second fully-controlled switch device Q2, the first inductor L1, the second inductor L2, the third inductor L3 and the third diode D3 form a high-transformation ratio boost Z-Boost conversion circuit to achieve a high-transformation ratio boost conversion from input interface power to output interface power.

[0044] like Figure 2d As shown, it is a protection mode: the disconnected state of the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1 forms a protection circuit to achieve circuit isolation between input and output.

[0045] like Figure 3 As shown, a control method for a high transformation ratio DC / DC converter circuit comprises the following steps:

[0046] Step 1) Detect the input voltage value Uin and the output voltage setting value Uout_set;

[0047] Step 2) Compare the input voltage value Uin and the output set voltage value Uout_set, and calculate the absolute difference Ue;

[0048] Step 3) Determine the circuit operation mode according to the comparison result of step 2), and compare the value of Ue with the set voltage difference Ue_set1 or Ue_set2 to determine the circuit operation mode. Specifically, if the input voltage Uin is greater than the output voltage Uout_set, and Ue is less than the set voltage difference Ue_set1, the circuit operates in the pass-through mode; otherwise, the circuit operates in the step-down Buck circuit mode; if the input voltage Uin is less than the output voltage Uout_set, the circuit operates in the high-ratio step-up Z-Boost mode; the specific formula can be intuitively expressed as follows: ;

[0049] Step 4) According to the different circuit working states of step 3), different controls are implemented on the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1, specifically: in the through working state, the first fully-controlled switch device Q1 and the second fully-controlled switch device Q2 are in the off state, and the third fully-controlled switch device S1 is in the on state; in the Buck circuit working state, the first fully-controlled switch device Q1 works in the PWM signal control state, and the second fully-controlled switch device Q2 and the third fully-controlled switch device S1 are in the off state; if working in the Z-Boost working state, the first fully-controlled switch device Q1 is in the on state, the second fully-controlled switch device Q2 works in the PWM signal control state, and the third fully-controlled switch device S1 is in the off state;

[0050] Step 5) According to the working control mode of the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1 determined in step 4), control is implemented to complete the conversion function of the circuit, wherein in the Buck circuit working state and the Z-Boost working state, the duty cycle of the PWM control signal is adjusted in real time according to the size of the difference Ue;

[0051] Step 6) If a fault is detected, the conversion circuit enters an isolation protection state by disconnecting the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1.

[0052] In addition, it should be noted that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high transformation ratio DC / DC conversion circuit, characterized in that: The circuit includes an input interface, a first fully-controlled switch device Q1, a second fully-controlled switch device Q2, a third fully-controlled switch device S1, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1, a second inductor L2, a third inductor L3, a first diode D1, a second diode D2, a third diode D3 and an output interface. By controlling the working states of the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1, different conversion circuit working modes and corresponding functions are realized; wherein, The first end of the third fully-controlled switch device S1 is connected to the positive terminal of the input interface, a common connection point of the first fully-controlled switch device Q1 and the first capacitor C1, and the second end of the third fully-controlled switch device S1 is connected to the first inductor L1, the third inductor L3, the third capacitor C3 and a common connection point of the second fully-controlled switch device Q2; The second end of the first fully-controlled switch device Q1 is connected to the cathode end of the first diode D1 and the anode end of the second diode D2; The second end of the second fully-controlled switch device Q2 is connected to a common connection point of the second inductor L2, the second capacitor C2, the negative terminal of the output interface and the fourth capacitor C4; The positive terminal of the first diode D1 is connected to the negative terminal of the input interface, the first capacitor C1, the third capacitor C3 and another common connection point of the second inductor L2; The cathode terminal of the second diode D2 is connected to another common connection point of the first inductor L1 and the second capacitor C2; The first capacitor C1 is connected in parallel with the input interface, the fourth capacitor C4 is connected in parallel with the output interface, the third inductor L3 is connected to the positive terminal of the output interface through the third diode D3, and the second inductor L2 is connected between the input interface and the negative terminal of the output interface.

2. The high transformation ratio DC / DC conversion circuit according to claim 1, characterized in that: The positive terminal of the input interface is electrically connected to the third fully-controlled switch device S1, the third inductor L3, the third diode D3 and the positive terminal of the output interface in sequence to form a DC conversion high-efficiency direct-through circuit to achieve direct connection of the input interface electrical energy equivalent to the output interface.

3. The high transformation ratio DC / DC conversion circuit according to claim 1, characterized in that: The first fully-controlled switch device Q1, the first diode D1, the second diode D2, the third diode D3, the first inductor L1, the second inductor L2 and the third inductor L3 form a buck conversion circuit to achieve buck conversion from input interface power to output interface power.

4. The high transformation ratio DC / DC conversion circuit according to claim 1, characterized in that: The second diode D2, the first inductor L1, the second inductor L2, the second capacitor C2 and the third capacitor C3 form a Z-source conversion circuit.

5. The high transformation ratio DC / DC conversion circuit according to claim 1, characterized in that: The second diode D2, the first capacitor C1, the second capacitor C2, the second fully-controlled switch device Q2, the first inductor L1, the second inductor L2, the third inductor L3 and the third diode D3 form a high-transformation ratio boost Z-Boost conversion circuit to achieve high-transformation ratio boost conversion from input interface power to output interface power.

6. The high transformation ratio DC / DC conversion circuit according to claim 1, characterized in that: The disconnected states of the first fully-controlled switch device Q1 , the second fully-controlled switch device Q2 and the third fully-controlled switch device S1 form a protection circuit to achieve circuit isolation between input and output.

7. The control method of a high transformation ratio DC / DC converter circuit according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: Step 1) Detect the input voltage value Uin and the output voltage setting value Uout_set; Step 2) Compare the input voltage value Uin and the output set voltage value Uout_set, and calculate the absolute difference Ue; Step 3) Determine the circuit operation mode according to the comparison result of step 2), and compare the value of Ue with the set voltage difference Ue_set1 or Ue_set2 to determine the circuit operation mode, specifically: if the input voltage Uin is greater than the output voltage Uout_set, and Ue is less than the set voltage difference Ue_set1, the circuit operates in the pass-through mode; otherwise, the circuit operates in the step-down Buck circuit mode; if the input voltage Uin is less than the output voltage Uout_set, the circuit operates in the high-ratio step-up Z-Boost mode; Step 4) According to the different circuit working states of step 3), different controls are implemented on the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1, specifically: in the through working state, the first fully-controlled switch device Q1 and the second fully-controlled switch device Q2 are in the off state, and the third fully-controlled switch device S1 is in the on state; in the Buck circuit working state, the first fully-controlled switch device Q1 works in the PWM signal control state, and the second fully-controlled switch device Q2 and the third fully-controlled switch device S1 are in the off state; if working in the Z-Boost working state, the first fully-controlled switch device Q1 is in the on state, the second fully-controlled switch device Q2 works in the PWM signal control state, and the third fully-controlled switch device S1 is in the off state; Step 5) According to the working control mode of the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1 determined in step 4), control is implemented to complete the conversion function of the circuit, wherein in the Buck circuit working state and the Z-Boost working state, the duty cycle of the PWM control signal is adjusted in real time according to the size of the difference Ue; Step 6) If a fault is detected, the conversion circuit enters an isolation protection state by disconnecting the first fully-controlled switch device Q1, the second fully-controlled switch device Q2 and the third fully-controlled switch device S1.

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