SRC series resonance circuit control method and system based on dynamic parameter adjustment
By dynamically adjusting the inductance and capacitance of the SRC series resonant circuit, the problem of resonant point shift caused by load changes is solved, and low-loss power transmission is achieved across the entire load range.
Patent Information
- Application Number
- CN202510972058.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-15
- Publication Date
- 2025-11-21
AI Technical Summary
The existing SRC series resonant circuit is prone to resonant point shift when the load changes, which leads to soft switching failure. Existing improvement schemes are complex to control and cannot maintain low loss across the entire load range.
By acquiring the input voltage, output voltage, and output current of the circuit system in real time, and using PID control and a mapping table, the variable inductor and VCM capacitor module are dynamically adjusted to adjust the resonant inductor and capacitor, so as to maintain the uniform operating frequency and resonant frequency matching of the switching devices.
Maintaining a high sustain rate for soft switching across the entire load range reduces power loss and enables low-loss transmission of the circuit under varying load conditions.
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Figure CN121000066A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of power electronics, in particular to a SRC series resonant circuit control method and system based on dynamic parameter adjustment. BACKGROUND
[0002] The power circuit is a circuit system in electronic engineering specially used for processing, converting or controlling electric energy, and its core task is to efficiently and stably transmit the input electric energy to the load to drive the equipment to work. In order to pursue switching performance and reduce circuit loss, the prior art uses soft switching technology in the power circuit.
[0003] Soft switching (Soft-Switching) is relative to hard switching (Hard-Switching). In the process of hard switching, the switching device responsible for inversion in the power circuit has a part of time of voltage and current waveform existing at the same time at the switching conversion moment, resulting in large switching loss and electromagnetic interference. The soft switching technology introduces resonance before and after the switching process, so that the voltage is reduced to zero (zero voltage switching ZVS) before the switch is turned on, or the current is reduced to zero (zero current switching ZCS) before the switch is turned off, thereby greatly reducing or even eliminating the switching loss.
[0004] The common soft switching technology is SRC series resonant circuit technology. The soft switching (ZVS / ZCS) of the traditional SRC series resonant circuit depends on the matching of the resonant point frequency and the switching frequency of the device. The existing SRC series resonant circuit soft switching technology has an inherent problem, that is, when the load changes, the resonant point will shift, so that the soft switching cannot be maintained and fails. For example, when the device in the circuit changes from a heavy load state to a light load state, the output voltage of the circuit will instantaneously increase. At this time, according to the relationship between the voltage gain and the frequency, the control unit needs to increase the working frequency of the switching device to reduce the output voltage, and the increase of the switching device frequency will make the frequency value not match the original resonant point frequency value, thereby causing the occurrence of the "resonant point shift" problem. After the resonant point shifts, the soft switching in the circuit will be difficult to maintain, so it is necessary to move the resonant point to make it match the frequency of the switching device after the increase, to re-maintain the soft switching. In the prior art, although the improvement scheme (such as LLC resonance, variable frequency control) can alleviate the above-mentioned problems, it has the problems of high control complexity and cannot realize soft switching in the full load range. SUMMARY
[0005] The purpose of the present application is to provide a SRC series resonant circuit control method and system based on dynamic parameter adjustment, which can ensure a high maintenance rate of soft switching in the full load range on the basis of simple circuit control, so that the circuit can maintain a low power loss rate in the full load range.
[0006] In order to achieve the above-mentioned purpose, the specific technical scheme adopted by the present application is as follows:
[0007] In a first aspect, the present application provides a SRC series resonant circuit control method based on dynamic parameter adjustment, the method comprising:
[0008] Step 01, the acquisition unit acquires the input voltage, output voltage and output current of the circuit system in real time, and sends them to the control unit;
[0009] Step 02, the control unit performs PID control according to the preset reference voltage and the received output voltage, and adjusts the unified working frequency of the switch device group;
[0010] Step 03, the control unit generates an inductance adjustment instruction according to the received output current and the preset reference current, and sends it to the variable inductance module. The variable inductance module receives the inductance adjustment instruction, performs equivalent inductance transformation, and generates a new resonant inductance;
[0011] Step 04, the control unit calculates the target resonant capacitance according to the target resonant frequency and the transformed resonant inductance, generates a capacitance adjustment instruction, and sends it to the VCM capacitance module. The VCM capacitance module receives the capacitance adjustment instruction, performs equivalent capacitance transformation, and generates a new equivalent capacitance; the target resonant frequency is equal to the unified working frequency of the switch device group.
[0012] As a preferred embodiment of the present application, in step 02, the specific way of the control unit performing PID control according to the preset reference voltage and the received output voltage is as follows: calculating the difference between the preset reference voltage and the output voltage, and performing PID control algorithm control based on the difference, and using PWM to control the unified working frequency of the switch device group.
[0013] As a preferred embodiment of the present application, in step 03, the specific way of the control unit generating an inductance adjustment instruction according to the received output current and the preset reference current is as follows: comparing the sizes of the output current and the preset reference current, and generating the inductance adjustment instruction according to the mapping table in the register set in the control unit.
[0014] As a preferred embodiment of the present application, in step 04, the specific calculation method of the control unit calculating the target resonant capacitance according to the target resonant frequency and the transformed resonant inductance is as follows:
[0015]
[0016] Wherein, fr is the target resonant frequency, and fr=fs, fs is the unified working frequency of the switch device group; Lr is the resonant inductance; Cr is the target resonant capacitance.
[0017] In another aspect, the present application provides a SRC series resonant circuit control system based on dynamic parameter adjustment, the system comprising:
[0018] The acquisition unit is configured to acquire input voltage, output voltage and output current of the circuit system in real time and send them to the control unit.
[0019] The control unit is configured to perform PID control according to a preset reference voltage and the received output voltage, to adjust the unified working frequency of the switch device group, and to generate an inductance adjustment instruction according to the received output current and a preset reference current; and to calculate a target resonance capacitance according to a target resonance frequency and a transformed resonance inductance, and generate a capacitance adjustment instruction.
[0020] The variable inductance module is configured to receive the inductance adjustment instruction issued by the control unit, to perform equivalent inductance transformation, and to generate a brand-new resonance inductance.
[0021] The VCM capacitance module is configured to receive the capacitance adjustment instruction issued by the control unit, to perform equivalent capacitance transformation, and to generate a brand-new equivalent capacitance.
[0022] As a preferred embodiment of the present application, the VCM capacitance module comprises a plurality of parallel switchable capacitance units, each of which comprises an SIC MOSFET and a thin film capacitor.
[0023] As a preferred embodiment of the present application, the VCM capacitance module comprises four parallel switchable capacitance units, and the capacitance values of the respective thin film capacitors in the four switchable capacitance units form a 4-bit binary weighted relationship.
[0024] As a preferred embodiment of the present application, the variable inductance module comprises a main inductance connected in series with the VCM capacitance module and a shunt inductance connected in parallel with the main inductance, and the shunt inductance is connected in series with a high-frequency relay switch, which is controlled by the control unit.
[0025] On the other hand, the present application also provides an electronic device comprising a processor and a memory.
[0026] The processor is connected to the memory.
[0027] The memory is configured to store executable program codes.
[0028] The processor runs a program corresponding to the executable program codes by reading the executable program codes stored in the memory, so as to execute the above-mentioned SRC series resonant circuit control method based on dynamic parameter adjustment.
[0029] On the other hand, the present application also provides a computer readable storage medium having a computer program stored thereon, and the computer program is executed by the processor to implement the above-mentioned SRC series resonant circuit control method based on dynamic parameter adjustment.
[0030] In summary, the present application has the following beneficial effects:
[0031] The present application sets variable inductance module and VCM capacitor module, improves the traditional single capacitor and inductance series SRC resonant circuit, and obtains the targeted control command through real-time acquisition of input voltage, output voltage and output current of the circuit system, so that the control unit can perform real-time multi-gear adjustment on the variable inductance module and the VCM capacitor module at the algorithm level; through the arrangement of specific algorithm and mapping table in the control unit, the control logic is clear, so that no matter how the device load changes, the soft switch in the power circuit can be in normal maintenance state, thereby ensuring the low loss of power transmission, and having outstanding practicability. BRIEF DESCRIPTION OF DRAWINGS
[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.
[0033] Figure 1 The flow chart of the present SRC series resonant circuit control method;
[0034] Figure 2 The circuit diagram of one kind of SRC series resonant circuit control in the embodiment;
[0035] Figure 3 The circuit diagram of one kind of four parallel VCM capacitor module in the embodiment. DETAILED DESCRIPTION
[0036] The subject matter described herein will now be discussed with reference to example implementations. It should be understood that these implementations are discussed solely for the purpose of enabling those skilled in the art to better understand and thus implement the subject matter described herein, and are not to be considered limitations on the scope, applicability, or examples set forth in the claims. Changes in the functions and arrangements of elements discussed can be made without departing from the scope of the subject matter described herein. Various examples can omit, substitute, or add various procedures or components as appropriate. For instance, the methods described can be performed in an order different from that described, and / or various steps can be added, omitted, or combined. Also, features described with respect to some examples can be combined in other examples.
[0037] The following embodiment takes a SRC series resonant circuit control circuit as an example, the circuit system thereof is a power circuit for power transmission from left to right, and the power supply side is a direct current source, and the load side drives an alternating current variable load; the power supply side is connected with a low-voltage side switch tube group to convert direct current into square wave form alternating current, then passes through a SRC resonant circuit composed of a VCM capacitor module and a variable inductance module in series, and is connected to a transformer (1:9), and after alternating current transformation, is converted into direct current by a high-voltage side switch tube group to supply the load end. The SRC resonant circuit can ensure that the low-voltage side switch tube group maintains a soft switching state in the full load interval, thereby reducing power loss in the working process. The control method is as shown in Figure 1
[0038] The embodiment provides a SRC series resonant circuit control method based on dynamic parameter adjustment, and the method comprises the following steps:
[0039] Step 01, the acquisition unit acquires the input voltage, output voltage and output current of the circuit system in real time, and sends them to the control unit;
[0040] Specifically, the acquisition unit can be realized by an ADC module. When the load state changes, for example, from a steady state (90% load rate) to a light load state (15% load rate), the ADC module simultaneously acquires the input voltage Uin of the power supply side, the output voltage Uo of the load side and the output current Io of the load side, and sends the above data to the control unit in real time.
[0041] Step 02, the control unit performs PID control according to the preset reference voltage and the received output voltage, and adjusts the unified working frequency of the switch device group;
[0042] The control unit can be realized based on a DSP controller. The DSP controller calculates the difference between the preset reference voltage Uo_ref and the actual output voltage Uo (because the above load reduction causes the output voltage Uo to increase, thereby generating a difference), after obtaining the voltage difference, the DSP controller sends it to the PID controller (the PID controller is arranged in the DSP controller), runs the PID control algorithm for feedback control, and the DSP controller uses PWM to control the unified working frequency fs of the switch device group. In the embodiment, the output voltage Uo increases, according to the relationship between voltage gain and frequency, the switch frequency fs needs to be increased to reduce the output voltage Uo, and it can be known that the unified working frequency fs of the switch device group is increased at this time.
[0043] Step 03, the control unit generates an inductance adjustment instruction according to the received output current and the preset reference current, and sends it to the variable inductance module, and the variable inductance module receives the inductance adjustment instruction, performs equivalent inductance transformation, and generates a brand new resonant inductance;
[0044] When the output voltage Uo increases, the output current Io decreases due to the same power on both sides of the transformer, and the preset reference current is a proportional fraction of the steady-state output current, for example, 20% of the steady-state output current. At this time, the DSP controller will compare the size relationship between the output current Io and the preset reference current. We believe that when the output current Io is less than the preset reference current (for example, 20% of the steady-state output current), it is difficult to maintain soft switching, and therefore the command of the DSP controller is needed. The DSP controller generates an inductance adjustment instruction based on the above output current size comparison result, which will be sent to the variable inductance module to control the equivalent inductance transformation. The variable inductance module is composed of a main inductance and a shunt inductance connected in parallel with the main inductance, and the shunt inductance is connected in series with a high-frequency relay switch. The DSP controller controls the action of the high-frequency relay switch through the inductance adjustment instruction (digital level signal). Based on the principle of inductance parallel connection, the equivalent inductance decreases as a whole after the shunt inductance is connected in parallel with the main inductance. At this time, the reduction of the inductive device is completed.
[0045] Step 04, the control unit calculates the target equivalent capacitance according to the target resonance frequency and the transformed resonance inductance, generates a capacitance adjustment instruction, and sends it to the VCM capacitance module. The VCM capacitance module receives the capacitance adjustment instruction and performs equivalent capacitance transformation to generate a new equivalent capacitance; the target resonance frequency is equal to the unified working frequency of the switch device group.
[0046] In this embodiment, in step 04, the specific calculation method of the control unit for calculating the target resonance capacitance according to the target resonance frequency and the transformed resonance inductance is:
[0047]
[0048] Wherein, fr is the target resonance frequency, and fr = fs, fs is the unified working frequency of the switch device group; Lr is the resonance inductance; Cr is the target resonance capacitance.
[0049] It can be known that when the load decreases, after the DSP controller controls the increase of the unified working frequency fs of the switch device group, the fs and the resonance frequency of the resonance point do not correspond, that is, there is a phenomenon of resonance point shift. As known to those skilled in the art, at this time, it is difficult to continue to maintain soft switching. Therefore, in order to continue to maintain soft switching, it is necessary to increase the resonance frequency synchronously, that is, to set a target resonance frequency fr (which can be regarded as known in the subsequent calculation process).
[0050] As can be seen from equation (1), the target resonance frequency fr and the resonance inductance Lr and the target resonance capacitance Cr are inversely proportional to the square, so when the target resonance frequency fr needs to be adjusted and increased, the resonance inductance Lr and the target resonance capacitance Cr need to be reduced.
[0051] The VCM capacitor module comprises a plurality of parallel switchable capacitor units, each of which comprises an SIC MOSFET and a thin film capacitor.
[0052] Based on the principle of parallel connection of capacitors, the equivalent capacitance of parallel capacitors is equal to the sum of the capacitances of each branch, and it is known that the equivalent capacitance can be increased by increasing the number of parallel branches, and the equivalent capacitance can be reduced by reducing the number of parallel branches.
[0053] In the present application, the register in the DSP controller stores a mapping table, and for different output currents, the corresponding resonant inductance Lr and target resonant capacitance Cr can be obtained by looking up the table.
[0054] Based on the premise of load reduction in the present embodiment, the variable inductance module in step 3 has received the inductance adjustment instruction and has performed equivalent inductance transformation to generate a new equivalent inductance (i.e. resonant inductance) which is reduced; at this time, the DSP controller can determine the target resonant frequency fr and the resonant inductance Lr after transformation based on the mapping table query, and the resonant capacitance required is Cr, i.e. the target resonant capacitance Cr is set.
[0055] Then the DSP controller generates a capacitance adjustment instruction (a plurality of digital level signals) according to the target resonant capacitance Cr, and controls the SIC MOSFET switch in different switchable capacitor units by the plurality of digital level signals to select the required thin film capacitors for parallel connection, since the capacitances of the thin film capacitors in different switchable capacitor units are different, the target resonant capacitance Cr can be combined.
[0056] Finally, based on the balance of equation (1), the target resonant frequency fr is successfully obtained, at this time the balance of fr=fs is restored, the resonant point shift disappears, and the soft switching is maintained.
[0057] The mapping table stored in the register of the above-mentioned DSP controller can be obtained based on previous experiments or artificial setting.
[0058] In another possible implementation, the VCM capacitor module includes four switchable capacitor units in parallel, and the capacitance values of the thin film capacitors in the four switchable capacitor units form a 4-bit binary weighted relationship. For example, the thin film capacitor in the first switchable capacitor unit is 1 μF, the thin film capacitor in the second switchable capacitor unit is 2 μF, the thin film capacitor in the third switchable capacitor unit is 3 μF, and the thin film capacitor in the fourth switchable capacitor unit is 4 μF. Thus, based on the digital level control of the DSP controller, the capacitance adjustment with a step precision of the minimum unit (1 μF) can be realized, that is, by controlling the on-off of each thin film capacitor through the SIC MOSFET, 16 (2 4 )total capacitance values can be combined.
[0059] In another possible implementation, the present embodiment provides a SRC series resonant circuit control system based on dynamic parameter adjustment, which includes:
[0060] The acquisition unit is configured to acquire the input voltage, output voltage and output current of the circuit system in real time and send them to the control unit.
[0061] The control unit is configured to perform PID control according to the preset reference voltage and the received output voltage, to adjust the unified working frequency of the switch device group, and to generate an inductance adjustment instruction according to the received output current and the preset reference current; and to calculate a target resonant capacitance according to the target resonant frequency and the transformed resonant inductance, and generate a capacitance adjustment instruction.
[0062] The variable inductance module is configured to receive the inductance adjustment instruction issued by the control unit, to perform equivalent inductance transformation, and to generate a brand new resonant inductance.
[0063] The VCM capacitor module is configured to receive the capacitance adjustment instruction issued by the control unit, to perform equivalent capacitance transformation, and to generate a brand new equivalent capacitance.
[0064] Further, the technical solutions of the present application will be explained below based on the SRC series resonant circuit control circuit diagram shown in Figure 2 and 3 .
[0065] As shown in Figure 2 and Figure 3 , in the power circuit, the DC power supply at the leftmost side supplies power to the variable load RL at the rightmost side through the transformer T1, Q1-Q4 are the low-voltage side switch tube group, each switch tube is connected in parallel with a freewheeling diode, and the PWM_Drive output port of the DSP controller is used to drive the control electrodes of the four switch tubes in parallel, the high-level signal turns on the switch tube, and the low-level signal turns off. Q5-Q8 are the high-voltage side switch tube group, and the control mode thereof is the same as that of Q1-Q4.
[0066] Q1~Q8 are high-speed switching tubes such as (SiC / GaN), wherein Q1~Q4 are used to invert the direct current power into an alternating square wave, so that it can pass through the transformer T1, and then Q5~Q8 are used to rectify the alternating square wave into direct current power for the load, and the DSP controller controls the switching of Q1~Q8 through a variable frequency square wave. In this process, in order to realize the soft switching of Q1~Q4 and reduce the circuit loss, a SRC series resonance circuit is added in series before the transformer T1, which can be functionally regarded as the above-mentioned variable inductance module and VCM capacitor module connected in series with each other. The variable inductance module is composed of a main inductance Lr and a shunt inductance La connected in parallel with the main inductance Lr, and the shunt inductance La is connected in series with a high-frequency relay switch S1, which is driven and controlled by the S1_Drive end of the DSP controller, and S1 is a normally open switch. When the shunt inductance La needs to be connected in parallel with the main inductance Lr, the S1_Drive outputs a high level to control the high-frequency relay switch S1 to close. The VCM capacitor module is equivalent to the Cr_eq capacitor in Figure 2 , as shown in Figure 3 , the VCM capacitor module includes four parallel switchable capacitor units, each of which is composed of an SIC MOSFET (Q9~Q12) and a film capacitor (D9~D12), and the capacitance values of the respective film capacitors form a 4-bit binary weighted relationship, that is, C1 is 1 μF, C2 is 2 μF, C3 is 3 μF, and C4 is 4 μF, and the four SIC MOSFETs are controlled by the Cap_Sel end. The DSP controller controls the four SIC MOSFETs (Q9~Q12) in real time through the Cap_Sel end, so that the Cr_eq in Figure 2 changes in real time, and cooperates with the resonant inductance to always meet the target resonant frequency fr, so as to ensure that the resonant point deviation is corrected in time, thereby maintaining the soft switching state of Q1~Q4 and reducing the circuit loss.
[0067] The above has described a plurality of embodiments of the present disclosure, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical applications, or technical improvements in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.
Claims
1. A control method for an SRC series resonant circuit based on dynamic parameter adjustment, characterized in that, The method includes: Step 01: The acquisition unit acquires the input voltage, output voltage, and output current of the circuit system in real time and sends them to the control unit; Step 02: The control unit performs PID control based on the preset reference voltage and the received output voltage to adjust the uniform operating frequency of the switching device group; Step 03: The control unit generates an inductance adjustment command based on the received output current and the preset reference current, and sends it to the variable inductance module. The variable inductance module receives the inductance adjustment command, performs equivalent inductance transformation, and generates a new equivalent inductance. Step 04: The control unit calculates the target equivalent capacitance based on the target resonant frequency and equivalent inductance, generates a capacitance adjustment command, and sends it to the VCM capacitor module. The VCM capacitor module receives the capacitance adjustment command, performs equivalent capacitance transformation, and generates a new equivalent capacitance. The target resonant frequency is equal to the unified operating frequency of the switching device group.
2. The SRC series resonant circuit control method based on dynamic parameter adjustment according to claim 1, characterized in that, In step 02, the control unit performs PID control based on the preset reference voltage and the received output voltage in the following way: calculate the difference between the preset reference voltage and the output voltage, and perform PID control algorithm control based on the difference, and use PWM to control the uniform operating frequency of the switching device group.
3. The SRC series resonant circuit control method based on dynamic parameter adjustment according to claim 2, characterized in that, In step 03, the control unit generates the inductor adjustment command based on the received output current and the preset reference current in the following way: compare the magnitude of the output current and the preset reference current, and generate the inductor adjustment command according to the mapping table in the register set in the control unit.
4. The SRC series resonant circuit control method based on dynamic parameter adjustment according to claim 3, characterized in that, In step 04, the control unit calculates the target equivalent capacitance based on the target resonant frequency and equivalent inductance using the following specific method: ， Where fr is the target resonant frequency, and fr = fs, where fs is the unified operating frequency of the switching device group; Lr is the equivalent inductance value; and Cr is the target equivalent capacitance value.
5. A control system based on a dynamically adjustable SRC series resonant circuit, characterized in that, The system includes: The acquisition unit is used to acquire the input voltage, output voltage, and output current of the circuit system in real time and send them to the control unit; The control unit is used to perform PID control based on the preset reference voltage and the received output voltage to adjust the uniform operating frequency of the switching device group; and to generate inductor adjustment commands based on the received output current and the preset reference current; and to calculate the target equivalent capacitance based on the target resonant frequency and the equivalent inductance to generate capacitance adjustment commands. The variable inductor module is used to receive the inductance adjustment command issued by the control unit, perform equivalent inductance transformation, and generate a new equivalent inductance. The VCM capacitor module is used to receive capacitor adjustment commands from the control unit, perform equivalent capacitance transformation, and generate a new equivalent capacitance.
6. A control system for an SRC series resonant circuit based on dynamic parameter adjustment according to claim 5, characterized in that, The VCM capacitor module comprises multiple switchable capacitor units connected in parallel, each of which includes a SiC MOSFET and a thin-film capacitor.
7. A SRC series resonant circuit control system based on dynamic parameter adjustment according to claim 6, characterized in that, The VCM capacitor module includes four switchable capacitor units connected in parallel. The capacitance values of the film capacitors in the four switchable capacitor units form a 4-bit binary weighted relationship.
8. A SRC series resonant circuit control system based on dynamic parameter adjustment according to claim 5, characterized in that, The variable inductor module includes a main inductor connected in series with the VCM capacitor module and a branch inductor connected in parallel with the main inductor. A high-frequency relay switch is connected in series with the branch inductor, and the high-frequency relay switch is controlled by the control unit.
9. An electronic device, characterized in that, Including the processor and memory; The processor is connected to the memory; The memory is used to store executable program code; The processor runs a program corresponding to the executable program code stored in the memory to execute the SRC series resonant circuit control method based on dynamic parameter adjustment as described in any one of claims 1-4.
10. A computer-readable storage medium, characterized in that, It stores a computer program, which, when executed by a processor, implements the SRC series resonant circuit control method based on dynamic parameter adjustment as described in any one of claims 1-4.