Double-switch capacitor DC-DC converter for permanent magnet motor control

Abstract

The invention belongs to the technical field of DC-DC converters, and particularly relates to a dual-switch capacitor DC-DC converter for permanent magnet motor control, which comprises coupling windings N1 and N2, switch tubes S1 and S2, diodes D1, D2, D3, D4 and Do, capacitors C1, C2, C3 and C0 and a load R, according to the novel double-switch capacitor structure, a double-switch clamping structure is adopted, and adjustment of a conduction duty ratio D is realized by two switches through synchronous control, so that the level of voltage output by the converter is adjusted. The application of the clamping capacitor effectively reduces the voltage spike generated when the switch tube is turned off, and prolongs the service life of the switch tube. The design of the coupling inductor and the boosting module enables the boosting capacity of the converter to be more flexible and adjustable, the boosting capacity is achieved by changing the turn ratio of the primary winding and the secondary winding of the coupling inductor, the design of the coupling inductor can be optimized according to the output voltage and the output power of the new energy module, and the converter is made to be suitable for various boosting occasions.

Description

Technical Field

[0001] The present application belongs to the technical field of DC-DC converters, and specifically relates to a dual-switched capacitor DC-DC converter for permanent magnet motor control. Background Art

[0002] The stability and reliability of permanent magnet motor servo control systems are critical issues that urgently need to be addressed. This invention addresses this issue by proposing a new method for stable DC voltage conversion. As a cutting-edge technology in my country's high-end equipment sector, permanent magnet motor servo control has made significant contributions to the development of the electric traction industry. However, the unstable nature of the power supply poses challenges to system integration and operation. To improve system stability and reliability, innovative measures are imperative.

[0003] In light of this, the present invention proposes a novel solution that leverages advanced electronic components and control technology to achieve stable conversion of the power supply output voltage, thereby improving the overall performance and reliability of the system. This new approach not only effectively copes with changing environments but also reduces system failure rates, improving system security and resource utilization.

[0004] While traditional DC-DC converters offer excellent voltage-boosting capabilities, they also suffer from significant drawbacks: Achieving high voltage gain requires a high duty cycle, which increases voltage stress on the power switches. This increases power switch losses and reduces converter efficiency. To improve the efficiency of traditional boost converters and reduce the high duty cycles required by power switches under high voltage stress, researchers have developed several boost technologies that are now widely used in DC-DC converter design.

[0005] The isolation transformer's high boost capability stems from its large number of turns. However, due to the transformer's presence, its leakage inductance is much higher than that of a traditional boost converter. This causes high voltage stress on the power switches, which in turn reduces the isolation transformer's efficiency and limits its application range.

[0006] Cascading technology increases converter gain by repeatedly nesting different boost units, significantly improving the converter's voltage gain. However, this technology also has significant drawbacks. When boost units are nested, the number of converter components increases exponentially, leading to increased costs and complex structures, making its application prospects less than ideal.

[0007] In a coupled-inductor structure, the turns ratio n of the converter's coupled inductor is crucial for amplifying converter gain and controlling output voltage. However, as the turns ratio n increases, power losses due to leakage inductance increase, reducing efficiency. Furthermore, integrating the coupled inductor increases the size and weight of the converter and the complexity of the circuit structure.

[0008] The use of switched-inductor structures in DC-DC converters effectively improves voltage gain compared to traditional boost converters. However, similar to cascade technology, this structure requires a large number of components, resulting in increased cost and a complex converter structure. Furthermore, increased diode voltage stress limits its industrial application.

[0009] The application of switched capacitor technology can enhance the boost capability of DC-DC converters while reducing the size of the converter. However, using switched capacitors alone in the converter will cause significant stress on the diodes and lead to higher conduction losses. Summary of the Invention

[0010] To address the need for a stable, high-DC voltage output converter in a permanent magnet motor servo control system, this invention achieves high converter gain through coupled inductors and a boost module. A novel dual-switched-capacitor structure reduces voltage spikes caused by the coupled inductors, resulting in a novel dual-switched-capacitor DC-DC converter.

[0011] To achieve the above object, the present invention applies the following scheme:

[0012] A dual-switched capacitor DC-DC converter for permanent magnet motor control, comprising coupled windings N1 and N2, switch tubes S1 and S2, diodes D1, D2, D3, D4, and D o , capacitors C1, C2, C3, C o and load R; the same-name end of the coupling winding N1 is connected to the input DC power supply V g The opposite-name end of the coupling winding N1 is connected to the anode of the diode D1, the drain of the switch tube S2 and the same-name end of the coupling winding N2;

[0013] The anode of the diode D1 is connected to the drain of the switch tube S1, the opposite-name end of the coupling winding N1 and the same-name end of the coupling winding N2; the cathode of the diode D1 is connected to the positive electrode of the clamping capacitor C1 and the drain of the switch tube S2; the positive electrode of the clamping capacitor C1 is connected to the drain of the switch tube S2 and the anode of the diode D1; the cathode of the diode D2 is connected to the source of the switch tube S2 and is grounded;

[0014] The opposite end of the coupling winding N2 is connected to the negative electrode of the capacitor C2, and the positive electrode of the capacitor C2 is connected to the cathode of the diode D4 and the diode D o The anode of the diode D o The cathode of capacitor C2 is connected to the negative electrode of the output capacitor C o The positive electrode of and the load, the cathode of diode D3 and the positive electrode of capacitor C3 and the anode of diode D4 are connected;

[0015] Load R and capacitor C o in parallel.

[0016] Preferably, diodes D3, D o Together with capacitors C2, C3 and diode D4, a boost module is formed; the turns ratio between the coupled windings is N1:N2=1:n.

[0017] Preferably, the switching signal adopts PWM control, and the working states of the switching tubes S1 and S2 are synchronized, and they are turned on and off at the same time.

[0018] Preferably, assuming that the coupled winding is an ideal transformer and ignoring the switching loss of the power devices, the gain of the converter in CCM is calculated as follows:

[0019]

[0020] Among them, V N1_ON 、V N2_ON Represents the voltage difference between N1 and N2 when the power switch is turned on; V N1_OFF 、V N2_OFF Represents the voltage difference between N1 and N2 when the power switch is turned on; V C1 、V C2 、V C3 、V C0 Represents C1, C2, C3, C o The voltage difference between the two ends.

[0021] Preferably, the output voltage V o The expression is:

[0022]

[0023] n is the turns ratio of the converter coupled inductor, and D is the duty cycle.

[0024] Preferably, if the converter coupling winding turns ratio is N1:N2=1:1 and the switch duty cycle is 0.25, the converter can achieve a 9-fold boost gain, and the voltage stresses that the switch withstands when it is turned off are V S1 、V S2 , whose expression is:

[0025]

[0026] The voltage stress on the switch is only 1 / 4 of the output voltage.

[0027] Preferably, when the topology circuit is in continuous operation mode, the two operating modes of the converter are:

[0028] State 1: At t=t0, the switches S1 and S2 remain on, and the diodes D1, D2, D3, and D o Reverse cutoff, the leakage current of the coupled winding N2 keeps D4 turned on;g Under the action of the coupling inductor, the leakage current i Lk with i Lm Continue to increase linearly, the capacitance C3 and C o C2 is positively charged via D4. At time t1, when the current of diode D4 drops to 0, the mode ends.

[0029] State 2: At t=t1, the switches S1, S2 and diode D4 are cut off, and the diodes D1, D2, D3, D o For the leakage current i of the coupled inductor, Lm 、i Lk and i N2 Linear decrease; V g Through the coupling winding N1 and diode D3, the capacitor C3 and C o Forward charging; capacitor C2 absorbs the leakage inductance energy of the coupled winding N2 and passes through diode D o With capacitor C o Together they charge the load R; when the current i D3 When it drops to 0, the mode ends and enters the next working cycle.

[0030] Preferably, there are four designs of the converter:

[0031] (1) When the coupled inductor turns ratio N1:N2=1:0.25, the prototype power is 300W, and the open-loop duty cycle D is 0.25, the converter boost factor is 7;

[0032] (2) When the coupled inductor turns ratio N1:N2=1:0.5, the prototype power is 200W, and the open-loop duty cycle D is 0.25, the converter boost factor is 8;

[0033] (3) When the coupled inductor turns ratio N1:N2=1:1, the prototype power is 100W, and the open-loop duty cycle D is 0.25, the converter boost factor is 10;

[0034] (4) When the coupled inductor turns ratio N1:N2=1:2, the prototype power is 50W, and the open-loop duty cycle D is 0.25, the converter boost factor is 35.

[0035] Preferably, the diodes D1, D2, D3, D4, D o For fast recovery diodes.

[0036] Compared with the prior art, this application has the following beneficial effects:

[0037] The proposed dual-switch capacitor-coupled inductor DC-DC converter design exhibits significant advantages. Compared to existing high-gain DC-DC converter circuits, this solution can achieve high voltage gain output at a relatively small switch duty cycle, combining the advantages of a small number of components with high conversion efficiency. By rationally adjusting the turns ratio of the coupled winding, it achieves high gain output while maintaining a high efficiency level. Unlike the traditional single-switch structure, the introduction of the new dual-switch capacitor architecture effectively reduces the voltage stress across the switch tube and suppresses voltage spikes during the switching process. At the same time, the energy storage capacitor's absorption mechanism of the coupled winding leakage inductance energy further improves the converter's energy conversion efficiency.

[0038] This converter design boasts a rational structure, strong boost capability, and convenient control, demonstrating broad engineering application prospects and significant practical value. Its relatively small number of components not only reduces manufacturing costs but also minimizes semiconductor device losses, thereby improving overall system stability and effectively meeting the design requirements for high-gain DC-DC converters. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the overall topological structure and working principle of the present invention.

[0040] Figure 2 In the CCM mode of the present invention, the power switch tubes S1 and S2 are turned on, the diode D4 is turned on, and the diodes D1, D2, D3, and D o Schematic diagram of the working state when reverse cutoff occurs. (State 1)

[0041] Figure 3 In the CCM mode of the present invention, the power switch tubes S1 and S2 are turned off, the diode D4 is reversely turned off, and the diodes D1, D2, D3, and D o Schematic diagram of the working state when conducting. (State 2) DETAILED DESCRIPTION

[0042] In order to make the purpose and technical solution of this application clearer, the present invention is further described below with reference to the accompanying drawings and specific implementations. It should be understood that the specific embodiments described herein are only used to illustrate the present invention and should not be used to limit the scope of protection of the present invention.

[0043] In the description of the present invention, if there is a description of first, second, and third, it is only used to distinguish the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0044] The topological structure diagram of the present invention is as follows: Figure 1Figure 1 shows a dual-switch capacitor DC-DC converter for permanent magnet motor control, which includes a new dual-switch capacitor structure, coupled inductors, and a boost module. It controls the on-duty cycle D of the power semiconductor to achieve voltage level conversion between the converter input and output. Power switches S1 and S2, diodes D1 and D2, and capacitor C1 form a new dual-switch structure; diodes D3 and D o Together with capacitors C2, C3 and diode D4, it forms a boost module; the turns ratio of the coupled inductor is 1:n.

[0045] The same-name end of the coupling winding N1 is connected to the positive electrode of the input power supply, and the opposite-name end of the coupling winding N1 is connected to the anode of the diode D1, the drain of the switch tube S2 and the same-name end of the coupling winding N2.

[0046] The novel dual-switched capacitor structure is embedded in a boost circuit, replacing the switching transistor in the boost circuit. The anode of diode D1 is connected to the drain of switching transistor S1, the opposite-name terminals of coupling winding N1, and the same-name terminals of coupling winding N2. The cathode of diode D1 is connected to the positive electrode of clamping capacitor C1 and the drain of switching transistor S2. The positive electrode of clamping capacitor C1 is connected to the drain of switching transistor S2 and the anode of diode D1. The cathode of diode D2 is connected to the source of switching transistor S2 and to ground. This novel dual-switched capacitor structure effectively clamps the voltage spikes generated when switching transistors S1 and S2 and diodes D1 and D2 are turned off.

[0047] The coupling inductor and boost module are composed of coupling inductors N1 and N2 combined with the boost module. The same-name end of winding N2 is connected to the opposite-name end of coupling winding N1, the anode of diode D1 and the drain of switch tube S1. The opposite-name end of winding N2 is connected to the negative electrode of capacitor C2. The positive electrode of capacitor C2 is connected to the cathode of diode D4 and the drain of diode D o The anode of the diode D o The cathode of capacitor C2 is connected to the negative electrode of the output capacitor C o The cathode of diode D3 is connected to the positive electrode of capacitor C3 and the anode of diode D4.

[0048] The switch tubes S1 and S2 of the novel dual-switched capacitor structure adopt the same control method, which is a PWM synchronous control method.

[0049] In this embodiment, the coupled inductor and the boost module have a turns ratio between coupled windings of N1:N2=1:n. Reasonable changes in the turns ratio of the coupled windings can change the topology gain conversion capability.

[0050] When the topology circuit is in continuous operation mode, the two working states of the proposed dual-switched capacitor-coupled inductor DC-DC converter are:

[0051] State 1( Figure 2): At t=t0, the switches S1 and S2 remain on, and the diodes D1, D2, D3, and D o In reverse cutoff, the leakage current of N2 keeps D4 on. g Under the effect of Lk with i Lm Continue to increase linearly. C3 and C o C2 is positively charged via D4. At time t1, when the current in D4 drops to 0, the mode ends.

[0052] State 2( Figure 3 ): t = t1, S1, S2 and D4 are turned off, D1, D2, D3, D o Conductive. Lm 、i Lk and i N2 Linearly decreasing. V g Through N1 and D3, the capacitor C3 and C o Forward charging. Capacitor C2 absorbs the leakage inductance energy of N2 and passes through D o With capacitor C o They charge the load R together. When the current i D3 When it drops to 0, the mode ends and enters the next working cycle.

[0053] Diodes D1, D2, D3, D4, D o A fast recovery diode is a special type of diode with excellent switching characteristics and a fast recovery time. Compared to ordinary PN junction diodes, the design structure of a fast recovery diode is significantly different. It belongs to the PIN junction type. Its principle is to add a thin base region between the P-type silicon material and the N-type silicon material to form a PIN structure silicon wafer.

[0054] Due to its thin base region, the fast recovery diode has very little reverse recovery charge, resulting in a fast reverse recovery time. In the present invention, the fast recovery diode is used to achieve a short reverse recovery time, a relatively low voltage drop, and a high reverse withstand voltage. These characteristics enable the fast recovery diode to effectively achieve fast and stable switching operation in the circuit, thereby improving system performance and efficiency.

[0055] The switching signal adopts the PWM control method, and the working states of the switching tubes S1 and S2 are synchronized, and they are turned on and off at the same time.

[0056] The working state diagram of the present invention is as follows Figure 2 、 Figure 3As shown. In one working cycle, there are two main working states. To simplify the analysis, the leakage inductance of the coupled inductor is ignored. The coupled winding is an ideal transformer, and the turns ratio between the coupled windings is N1:N2=1:n. At the same time, the switching loss of the power device is also ignored. In the first state, Figure 2 The following equation can be obtained:

[0057]

[0058] In the second state, from Figure 3 The following equation can be obtained:

[0059]

[0060] According to the inductor volt-second balance formula, the gain of the proposed dual-switch capacitor-coupled inductor DC-DC converter in CCM is obtained:

[0061]

[0062] Example 2:

[0063] The traditional Boost circuit converter boost expression is:

[0064]

[0065] When the boost gain of the converter exceeds 10 times, the duty cycle (D) of the switch tube will reach more than 0.9, which is close to the limit. In this case, the voltage that the switch tube withstands when it is turned off is equivalent to the output voltage, which not only increases the switching loss of the switching device, but also reduces the working efficiency of the entire circuit and may cause the converter to malfunction during operation. The marginality of the working state of the switch tube under such high boost gain conditions makes its stability and reliability challenged. The operation of the switch tube at a high duty cycle is prone to overheating and damage to the device, thereby affecting the performance of the entire converter. Therefore, when designing the converter, it is necessary to fully consider the working boundaries of the switch tube and adopt appropriate control strategies and protection measures to ensure the stable operation and long-term reliability of the system. In this embodiment, based on the steady-state operation analysis of the circuit, the output and input voltage expressions of the dual-switch capacitor-coupled inductor DC-DC converter topology involved in the invention are:

[0066]

[0067] If the converter coupling winding turns ratio is set to N1:N2 = 1:1 and the switch duty cycle is 0.25, the converter can achieve a boost gain of 9 times. The voltage stress that the switch withstands when it is turned off is expressed as:

[0068]

[0069] The voltage stress on the switch is only 1 / 4 of the output voltage. Therefore, when a higher voltage is required, the converter can avoid the occurrence of extreme duty cycles of the switch tube, reduce the voltage stress of the switch tube, and reduce the probability of converter failure, thereby improving the stability and safety of the entire boost system.

[0070] According to the output voltage and output power of the new energy module, there are four converter design options:

[0071] (1) When the coupled inductor turns ratio N1:N2=1:0.25, the prototype power is 300W, and the open-loop duty cycle D is 0.25, the converter boost factor is 7.

[0072] (2) When the coupled inductor turns ratio N1:N2=1:0.5, the prototype power is 200W, and the open-loop duty cycle D is 0.25, the converter boost factor is 8.

[0073] (3) When the coupled inductor turns ratio N1:N2=1:1, the prototype power is 100W, and the open-loop duty cycle D is 0.25, the converter boost factor is 10.

[0074] (4) When the coupled inductor turns ratio N1:N2=1:2, the prototype power is 50W, and the open-loop duty cycle D is 0.25, the converter boost factor is 35.

[0075] The above text briefly recapitulates the specific embodiments of the present invention in conjunction with the accompanying drawings, but it does not limit the scope of protection of the present invention. Those skilled in the art will understand that, based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A dual-switched capacitor DC-DC converter for permanent magnet motor control, characterized in that: Including coupling windings N1, N2, switch tubes S1, S2, diodes D1, D2, D3, D4, D o , capacitors C1, C2, C3, C o and load R; The same-name end of the coupling winding N1 is connected to the input DC power supply V g The opposite-name end of the coupling winding N1 is connected to the anode of the diode D1, the drain of the switch tube S2 and the same-name end of the coupling winding N2; The anode of the diode D1 is connected to the drain of the switch tube S1, the opposite-name end of the coupling winding N1 and the same-name end of the coupling winding N2; the cathode of the diode D1 is connected to the positive electrode of the clamping capacitor C1 and the drain of the switch tube S2; the positive electrode of the clamping capacitor C1 is connected to the drain of the switch tube S2 and the anode of the diode D1; the cathode of the diode D2 is connected to the source of the switch tube S2 and is grounded; The opposite end of the coupling winding N2 is connected to the negative electrode of the capacitor C2, and the positive electrode of the capacitor C2 is connected to the cathode of the diode D4 and the diode D o The anode of the diode D o The cathode of capacitor C2 is connected to the negative electrode of the output capacitor C o The positive electrode of and the load, the cathode of diode D3 and the positive electrode of capacitor C3 and the anode of diode D4 are connected; Load R and capacitor C o in parallel.

2. The dual-switched capacitor DC-DC converter for permanent magnet motor control according to claim 1, characterized in that: Diode D3, D o Together with capacitors C2, C3 and diode D4, a boost module is formed; the turns ratio between the coupled windings is N1:N2=1:n.

3. The dual-switched capacitor DC-DC converter for permanent magnet motor control according to claim 1, characterized in that: The switching signal adopts PWM control, and the working states of the switching tubes S1 and S2 are synchronized, and they are turned on and off at the same time.

4. The dual-switched capacitor DC-DC converter for permanent magnet motor control according to claim 2, characterized in that: Assuming the coupled winding is an ideal transformer and ignoring the switching losses of the power devices, the converter gain in CCM is calculated as follows: Among them, V N1_ON 、V N2_ON Represents the voltage difference between N1 and N2 when the power switch is turned on; V N1_OFF 、V N2_OFF Represents the voltage difference between N1 and N2 when the power switch is turned on; V C1 、V C2 、V C3 、V C0 Represents C1, C2, C3, C o The voltage difference between the two ends.

5. The dual-switched capacitor DC-DC converter for permanent magnet motor control according to claim 1, characterized in that: Output voltage V of the converter topology o The expression is: n is the turns ratio of the converter coupled inductor, and D is the duty cycle.

6. The dual-switched capacitor DC-DC converter for permanent magnet motor control according to claim 1, characterized in that: If the converter coupling winding turns ratio is N1:N2=1:1, the switch duty cycle is 0.25, and the voltage stresses that the switch withstands when it is turned off are V S1 、V S2 , whose expression is: The voltage stress on the switch is only 1 / 4 of the output voltage.

7. The dual-switched capacitor DC-DC converter for permanent magnet motor control according to claim 1, characterized in that: When the topology circuit is in continuous working mode, the converter has two working modes: State 1: At t=t0, the switches S1 and S2 remain on, and the diodes D1, D2, D3, and D o Reverse cutoff, the leakage current of the coupled winding N2 keeps D4 turned on; g Under the action of the coupling inductor, the leakage current i Lk with i Lm Continue to increase linearly, the capacitance C3 and C o C2 is positively charged via D4. At time t1, when the current of diode D4 drops to 0, the mode ends. State 2: At t=t1, the switches S1, S2 and diode D4 are cut off, and the diodes D1, D2, D3, D o For the leakage current i of the coupled inductor, Lm 、i Lk and i N2 Linear decrease; V g Through the coupling winding N1 and diode D3, the capacitor C3 and C o Forward charging; capacitor C2 absorbs the leakage inductance energy of the coupled winding N2 and passes through diode D o With capacitor C o Together they charge the load R; when the current i D3 When it drops to 0, the mode ends and enters the next working cycle.

8. The dual-switched capacitor DC-DC converter for permanent magnet motor control according to claim 1, characterized in that: There are four converter designs: (1) When the coupled inductor turns ratio N1:N2=1:0.25, the prototype power is 300W, and the open-loop duty cycle D is 0.25, the converter boost factor is 7; (2) When the coupled inductor turns ratio N1:N2=1:0.5, the prototype power is 200W, and the open-loop duty cycle D is 0.25, the converter boost factor is 8; (3) When the coupled inductor turns ratio N1:N2=1:1, the prototype power is 100W, and the open-loop duty cycle D is 0.25, the converter boost factor is 10; (4) When the coupled inductor turns ratio N1:N2=1:2, the prototype power is 50W, and the open-loop duty cycle D is 0.25, the converter boost factor is 35.

9. The dual-switched capacitor DC-DC converter for permanent magnet motor control according to claim 1, characterized in that: The diodes D1, D2, D3, D4, D o For fast recovery diodes.

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