Multi-path symmetrical CLLC topological structure and power balance control method thereof

Abstract

The invention discloses a multi-channel symmetrical CLLC topological structure and a power balance control method thereof, and the structure comprises a multi-channel symmetrical CLLC converter main circuit loop, a high-precision sampling module, a phase shift angle controller module, an input capacitor, an output capacitor and an equivalent load. And more efficient electric energy conversion and power management control are realized. According to the power balance control method, phase shift control is carried out on a secondary side switching tube control signal of a power loop through a fundamental wave analysis method, a forward gain formula under the control method is derived, and output gain regulation and control are carried out on converters with power errors in the multi-path symmetrical CLLC converters. And thus, the power balance control among the multi-path symmetrical CLLC converters is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy routers, and in particular relates to a multi-path symmetrical CLLC topology structure and a power balancing control method thereof. Background Art

[0002] Energy router is a new type of power system equipment. It plays an important role in smart grid, microgrid, distributed energy and other fields. Its core functions include energy collection, management and optimal distribution. It can realize efficient conversion and interconnection between different energy forms, and cooperate with the upper energy management system to achieve coordinated control. In the energy router system, it is usually connected to the energy storage system through the DC bus (DC-Bus), and the bidirectional full-process charging and discharging is realized by introducing the DC-DC converter. In the DC-DC converter, multi-channel symmetrical CLLC converter is usually used to realize high-power energy flow. However, because the inductor and capacitor have a parameter error of ±5% at the factory, the multi-channel symmetrical CLLC converter has power imbalance during operation. The symmetrical CLLC converter uses pulse frequency modulation (PFM). This method has limitations in voltage gain control and is difficult to achieve power balance control of multi-channel symmetrical CLLC converters during high-power charging and discharging of the energy storage system, which limits its feasibility in applications such as energy routers. Summary of the invention

[0003] In order to make up for the deficiencies of the prior art, the present invention provides a multi-channel symmetrical CLLC topology structure and a power balancing control method thereof to solve the problem of power imbalance of multi-channel symmetrical CLLC converters in the existing energy router system.

[0004] The technical problem solved by the present invention can be achieved through the following technical solutions:

[0005] On one hand, the present invention provides a multi-channel symmetrical CLLC topology structure, including a multi-channel symmetrical CLLC converter main circuit loop, a high-precision sampling module, a phase angle controller module, an input capacitor, an output capacitor and an equivalent load.

[0006] The main circuit loop of the multi-channel symmetrical CLLC converter is connected in parallel with the front-stage circuit loop through an input capacitor, the front-stage circuit loop includes a circuit part of the DC bus of the energy router, and the main circuit loop is connected in parallel with the equivalent load through an output capacitor. After the main circuit loop of the multi-channel symmetrical CLLC converter under the fundamental wave analysis method adopts a multi-channel resonant balance control strategy to realize the power balance control of the multi-channel symmetrical CLLC converter, the secondary side resonant cavity of the symmetrical CLLC converter can be equivalent to a new impedance to derive the forward voltage gain after adopting the multi-channel resonant balance control strategy;

[0007] The high-precision sampling module uses a high-precision voltage-dividing resistor network and a current sampling resistor, combined with a differential operational amplifier circuit, to collect the voltage and current on both sides of the load;

[0008] The phase-shift angle controller module includes an analog / digital converter sampling unit, a comparator and a pulse width modulation generator. The analog / digital converter sampling unit converts the analog voltage and current signals provided by the voltage and current sampling module into digital signals, and sends the two-way circuit data to the comparator; the comparator receives the current difference of the multi-way symmetrical CLLC converter and makes necessary judgments with the preset threshold value, thereby generating corresponding multi-way symmetrical CLLC converter control parameters and sending them to the pulse width modulation generator to generate corresponding phase-shift control signals to drive the interleaved parallel CLLC circuit loop to perform output gain compensation.

[0009] Furthermore, the main circuit loop of the multi-channel symmetrical CLLC converter is composed of multiple completely identical full-bridge symmetrical CLLC resonant converters connected in parallel, and each full-bridge symmetrical CLLC resonant converter is composed of two groups of full-bridge structures on the primary side and the secondary side and a resonant cavity in the middle. During operation, the switching tubes of each CLLC resonant converter are turned on at a certain phase angle to achieve multi-channel parallel operation under high-power charging and discharging conditions.

[0010] Furthermore, the main circuit loop of the multi-way symmetrical CLLC converter is composed of two completely identical full-bridge symmetrical CLLC resonant converters connected in parallel, and the four groups of full bridges are all composed of N-type switch tubes and are divided into four groups of switch tubes Q1~Q4, switch tubes Q5~Q8, switch tubes Q9~Q12, and switch tubes Q13~Q16; wherein Q1 and Q3 are connected in series to form a group of bridge arms, and Q2 and Q4 are connected in series to form another group of bridge arms, so that the source of Q1 is connected to the drain of Q2, and the source of Q3 is connected to the drain of Q4, and finally a full-bridge structure with two bridge arms connected in parallel is formed, and the connection relationship of the remaining three groups of switch tubes is the same as that of the above switch tubes Q1~Q4; the resonant cavity is composed of a primary side resonant capacitor, a resonant inductor and a transformer with an equivalent excitation inductance in series, and at the same time, the secondary side of the transformer is connected in series with another group of symmetrically designed resonant capacitors and resonant inductors to realize a symmetrical CLLC topology.

[0011] Furthermore, the multi-channel resonant balance control strategy realizes a collaborative working mechanism through a Type-III controller and a comparator, monitors the voltage and current signals collected by the analog / digital converter sampling unit in real time, and adjusts the phase output signal of the pulse width modulation generator in real time based on dynamic feedback to achieve precise balance and stability control of power output.

[0012] Furthermore, the resonant frequency f of the resonant cavity can be determined according to the constant voltage and constant current control strategy. sAnd work, through the current difference S between the CLLC converter and the staggered parallel CLLC converter p The phase angle δ of the phase shift is determined by comparing the preset value of the interleaved parallel power balancing strategy and performing gain compensation on the secondary switching signal of the interleaved parallel CLLC converter.

[0013] Another aspect of the present invention provides a power balancing control method for a multi-channel symmetrical CLLC topology structure, comprising the following steps:

[0014] Step 1: The output voltage sampling module and the output current sampling module respectively collect analog signals of voltage and current, and transmit them to the phase shift angle controller module;

[0015] Step 2: The analog / digital converter sampling unit in the phase angle controller module converts the received voltage and current analog signals into digital signals, and then transmits them to the comparator;

[0016] Step 3: The comparator determines whether the current difference of the multiple symmetrical CLLC converters meets the preset value requirement, and determines whether to perform phase compensation on the rectifier-side switch control signal of each CLLC converter;

[0017] Step 4: If the phase compensation of the rectifier side switch control signal is to be performed, the phase shift angle controller module outputs the required control loop parameters to the pulse width modulation generator. The pulse width modulation generator generates a PWM signal as an output by receiving the control loop parameters, and supplies it to each switch tube in the multi-channel full-bridge symmetrical CLLC resonant converter to control the phase state of its control signal so that the secondary switch tube of each converter is turned on with a compensated phase angle;

[0018] Step 5: The Type-III controller and the comparator perform real-time feedback comparison on the voltage and current signals of the analog / digital converter sampling unit and adjust the amplitude of the phase shift signal to ultimately achieve power balancing control.

[0019] Furthermore, the control mechanism of the power balancing control is that after the power balancing control of the main circuit loop under the fundamental wave analysis method is performed by the rectifier side switch tube control signal, the forward operation gain formula of the FHA (first harmonic approximation principle) equivalent circuit model is as follows:

[0020]

[0021] Where M is the voltage gain, which is the ratio of input voltage to output voltage; L m is the coupled inductor; L r1 is the resonant inductance; C r1 is the resonant capacitance; Z ac is the equivalent impedance of the secondary side of the resonant cavity after adopting the multi-channel resonant balance control strategy; R eqis the equivalent load; s is the complex frequency, which is usually used in Laplace transform.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention adopts a multi-channel symmetrical CLLC resonant topology: the symmetrical CLLC design can usually provide soft switching conditions within the full load range, reduce switching losses, and thus improve the overall conversion efficiency; the CLLC converter can not only achieve a wider input and output voltage range without changing the switching frequency, which is suitable for a variety of battery charging and discharging applications; it can also operate at a frequency close to the resonant frequency, and the voltage and current changes caused by the switching action are smoother, which helps to reduce electromagnetic interference. The simultaneous application of the multi-channel symmetrical CLLC converter of the present application to high-power charging and discharging helps to reduce the ripple of the output voltage and current and provide a smoother output, which is very important for sensitive loads.

[0024] (2) The phase-shifted power balancing control strategy adopted by the present invention: the simultaneous use of multiple parallel symmetrical CLLC converters can reduce the ripple of the output voltage and current, reduce the thermal stress and current stress of the components in a single converter, reduce the overall failure rate of the system, and improve the reliability of the entire system; power balancing control helps to achieve a more uniform heat distribution between the various parallel units, reduce the generation of hot spots, reduce the cost of converter device selection, and extend the life of the equipment; by adjusting the phase difference of the control signal, the power output of each parallel unit can be flexibly controlled, making the system easier to expand to different power levels, improving the performance and application range of the power electronic converter, and is particularly suitable for occasions requiring high reliability and high power density. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a topological structure diagram of a two-way full-bridge symmetrical CLLC resonant converter of the present invention;

[0026] Figure 2 It is a schematic diagram of the multi-channel resonance balance control strategy of the present invention;

[0027] Figure 3 This is a flow chart of the power balancing control method of the present invention;

[0028] Figure 4 It is the FHA equivalent circuit model of the main circuit loop of the full-bridge symmetrical CLLC converter after the secondary side phase shift control under the fundamental wave analysis method of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] This embodiment is a multi-path symmetrical CLLC topology and a power balancing control method thereof applied in an energy router.

[0031] A multi-channel symmetrical CLLC topology structure comprises a multi-channel symmetrical CLLC converter main circuit loop, a high-precision sampling module, a phase-shift angle controller module, an input capacitor, an output capacitor and an equivalent load.

[0032] The main circuit loop of the multi-channel symmetrical CLLC converter is composed of multiple identical full-bridge symmetrical CLLC resonant converters in parallel. Each full-bridge symmetrical CLLC resonant converter consists of two sets of full-bridge structures on the primary side and the secondary side and a resonant cavity in the middle. During operation, the switch tubes of each CLLC resonant converter are turned on with a certain phase angle to achieve multi-channel parallel operation under high-power charging and discharging conditions. The resonant cavity is composed of a primary resonant capacitor, a resonant inductor and a transformer with an equivalent excitation inductance in series. At the same time, the secondary side of the transformer is connected in series with another set of symmetrically designed resonant capacitors and resonant inductors to achieve a symmetrical CLLC topology. The main circuit loop of the multi-channel symmetrical CLLC converter is connected in parallel with the front-stage circuit loop through the input capacitor. The front-stage circuit loop includes the circuit part of the DC bus of the energy router. The main circuit loop is connected in parallel with the equivalent load through the output capacitor. The main circuit loop of the multi-channel symmetrical CLLC converter under the fundamental wave analysis method adopts a multi-channel resonant balance control strategy to realize the power balancing control of the multi-channel symmetrical CLLC converter. The secondary side resonant cavity of the symmetrical CLLC converter can be equivalent to a new impedance to derive the forward voltage gain after adopting the multi-channel resonant balance control strategy.

[0033] The high-precision sampling module of the present invention adopts a high-precision voltage-dividing resistor network and a current sampling resistor, combined with a differential operational amplifier circuit, to collect the voltage and current on both sides of the load. The phase-shift angle controller module includes an analog / digital converter (ADC) sampling unit, a comparator and a pulse width modulation (PWM) generator. The analog / digital converter sampling unit converts the analog voltage and current signals provided by the voltage and current sampling module into digital signals, and sends the two-way circuit data to the comparator; the comparator receives the current difference of the multi-way symmetrical CLLC converter and makes necessary judgments with the preset threshold, thereby generating corresponding multi-way symmetrical CLLC converter control parameters and sending them to the pulse width modulation generator to generate corresponding phase-shift control signals to drive the staggered parallel CLLC circuit loop for output gain compensation.

[0034] like Figure 1As shown, taking a two-way symmetrical CLLC topology as an example, two completely identical full-bridge symmetrical CLLC resonant converters are connected in parallel, and the four groups of full bridges are all composed of N-type switch tubes and are divided into four groups of switch tubes Q1~Q4, switch tubes Q5~Q8, switch tubes Q9~Q12, and switch tubes Q13~Q16; wherein Q1 and Q3 are connected in series to form a group of bridge arms, and Q2 and Q4 are connected in series to form another group of bridge arms, so that the source of Q1 is connected to the drain of Q2, and the source of Q3 is connected to the drain of Q4, and finally a full-bridge structure with two bridge arms connected in parallel is formed, and the connection relationship of the remaining three groups of switch tubes is the same as that of the above switch tubes Q1~Q4; the resonant cavity is composed of a primary side resonant capacitor, a resonant inductor and a transformer with an equivalent excitation inductance in series, and at the same time, the secondary side of the transformer is connected in series with another group of symmetrically designed resonant capacitors and resonant inductors, so as to realize a symmetrical CLLC topology.

[0035] The multi-channel resonant balance control strategy realizes the collaborative working mechanism through the Type-III controller and the comparator, monitors the voltage and current signals collected by the analog / digital converter sampling unit in real time, and adjusts the phase output signal of the pulse width modulation generator in real time based on dynamic feedback to achieve accurate balance and stability control of power output. Figure 2 As shown, the resonant frequency f of the resonant cavity can be determined according to the constant voltage and constant current control strategy. s And work, through the current difference S between the CLLC converter and the staggered parallel CLLC converter p The phase angle δ of the phase shift is determined by comparing the preset value of the interleaved parallel power balancing strategy and performing gain compensation on the secondary switching signal of the interleaved parallel CLLC converter.

[0036] like Figure 3 As shown, the power balancing control method based on the above-mentioned multi-channel symmetrical CLLC topology structure includes the following steps:

[0037] Step 1: The output voltage sampling module and the output current sampling module respectively collect analog signals of voltage and current, and transmit them to the phase shift angle controller module.

[0038] Step 2: The analog / digital converter sampling unit in the phase-shift angle controller module converts the received voltage and current analog signals into digital signals, and then transmits them to the comparator.

[0039] Step 3: The comparator determines whether the current difference of the multiple symmetrical CLLC converters meets the preset value requirement, and determines whether to perform phase compensation on the rectifier-side switch control signal of each CLLC converter.

[0040] Step 4: If the phase compensation of the rectifier side switch control signal is to be performed, the phase shift angle controller module outputs the required control loop parameters to the pulse width modulation generator. The pulse width modulation generator generates a PWM signal as an output by receiving the control loop parameters, and supplies it to each switch tube in the multi-channel full-bridge symmetrical CLLC resonant converter to control the phase state of its control signal so that the secondary switch tube of each converter is turned on with a compensated phase angle; Figure 1 In the two-way symmetrical CLLC topology, the pulse width modulation generator (PWM) generator generates 16 PWM signals as outputs by receiving the control loop parameters, which are supplied to the 16 switch tubes in the two full-bridge symmetrical CLLC resonant converters to control the phase state of their control signals so that the opening time of Q9~Q12 and Q13~Q16 has a certain phase angle.

[0041] Step 5: The Type-III controller and the comparator perform real-time feedback comparison on the voltage and current signals of the analog / digital converter sampling unit and adjust the amplitude of the phase shift signal to ultimately achieve power balancing control.

[0042] The FHA equivalent circuit model of the main circuit loop of the full-bridge symmetrical CLLC converter under the fundamental wave analysis method after phase shift control is as follows: Figure 4 As shown, all switches, inductors, capacitors and high-frequency transformers are ideal lossless devices, and there is no influence of snubber circuits and dead time.

[0043] An approximate analysis of the first harmonic at the operating frequency of the CLLC converter is performed by combining the rectifier bridge and the load R L Equivalent to the primary side of a high-frequency transformer, the resonant tank output impedance R eq , the resonant tank adopts a symmetrical design, and the equivalent resonant capacitance C' can be obtained r2 , resonant inductance L' r2 ,in C' r2 =N1 2 ·C r2 , L' r2 =N1 2 ·L r2 ;

[0044] Due to the phase difference, the secondary side of the resonant tank cannot be simply equated to a resistive load. In order to simplify the analysis process, the secondary side of the resonant tank after gain compensation is equivalent to a new impedance Z ac ;

[0045] According to the evolved first harmonic approximation (FHA) equivalent model, the final forward gain is:

[0046]

[0047] Where M is the voltage gain, which is the ratio of input voltage to output voltage; L m is the coupled inductor; L r1 is the resonant inductance; C r1 is the resonant capacitance; Z ac is the secondary impedance of the resonant cavity; R eq is the output impedance of the resonant circuit; s is the complex frequency, which is usually used in Laplace transform.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-channel symmetrical CLLC topology structure, characterized in that: It includes a multi-channel symmetrical CLLC converter main circuit loop, a high-precision sampling module, a phase-shift angle controller module, input capacitors, output capacitors and equivalent loads. The main circuit loop of the multi-channel symmetrical CLLC converter is connected in parallel with the front-stage circuit loop through an input capacitor, the front-stage circuit loop includes a circuit part of the DC bus of the energy router, and the main circuit loop is connected in parallel with the equivalent load through an output capacitor. The main circuit loop of the multi-channel symmetrical CLLC converter under the fundamental wave analysis method adopts a multi-channel resonant balance control strategy to realize the power balance control of the multi-channel symmetrical CLLC converter, and the secondary side resonant cavity of the symmetrical CLLC converter is equivalent to a new impedance, and the forward voltage gain after adopting the multi-channel resonant balance control strategy is derived; The high-precision sampling module uses a high-precision voltage-dividing resistor network and a current sampling resistor, combined with a differential operational amplifier circuit, to collect the voltage and current on both sides of the load; The phase-shift angle controller module includes an analog / digital converter sampling unit, a comparator and a pulse width modulation generator. The analog / digital converter sampling unit converts the analog voltage and current signals provided by the voltage and current sampling module into digital signals and sends the two-way circuit data to the comparator; The comparator receives the current difference of the multi-way symmetrical CLLC converter and makes necessary judgments with the preset threshold value, thereby generating corresponding multi-way symmetrical CLLC converter control parameters and sending them to the pulse width modulation generator to generate corresponding phase shift control signals to drive the interleaved parallel CLLC circuit loop for output gain compensation.

2. A multi-channel symmetrical CLLC topology structure according to claim 1, characterized in that: The main circuit loop of the multi-channel symmetrical CLLC converter is composed of multiple completely identical full-bridge symmetrical CLLC resonant converters connected in parallel. Each full-bridge symmetrical CLLC resonant converter is composed of two groups of full-bridge structures on the primary side and the secondary side and a resonant cavity in the middle. During operation, the switch tubes of each CLLC resonant converter are turned on at a certain phase angle to achieve multi-channel parallel operation under high-power charging and discharging conditions.

3. A multi-channel symmetrical CLLC topology structure according to claim 2, characterized in that: The main circuit loop of the multi-channel symmetrical CLLC converter is composed of two completely identical full-bridge symmetrical CLLC resonant converters connected in parallel, and the four groups of full bridges are all composed of N-type switch tubes and are divided into four groups of switch tubes Q1~Q4, switch tubes Q5~Q8, switch tubes Q9~Q12, and switch tubes Q13~Q16; among them, Q1 and Q3 are connected in series to form a group of bridge arms, and Q2 and Q4 are connected in series to form another group of bridge arms, so that the source of Q1 is connected to the drain of Q2, and the source of Q3 is connected to the drain of Q4, and finally a full-bridge structure with two bridge arms connected in parallel is formed, and the connection relationship of the remaining three groups of switch tubes is the same as that of the above switch tubes Q1~Q4; the resonant cavity is composed of a primary side resonant capacitor, a resonant inductor and a transformer with an equivalent excitation inductance in series, and at the same time, the secondary side of the transformer is connected in series with another group of symmetrically designed resonant capacitors and resonant inductors to realize a symmetrical CLLC topology.

4. A multi-channel symmetrical CLLC topology structure according to claim 1, characterized in that: The multi-channel resonant balance control strategy realizes a collaborative working mechanism through a Type-III controller and a comparator, monitors the voltage and current signals collected by the analog / digital converter sampling unit in real time, and adjusts the phase output signal of the pulse width modulation generator in real time based on dynamic feedback to achieve precise balance and stability control of power output.

5. A multi-channel symmetrical CLLC topology structure according to claim 4, characterized in that: According to the constant voltage and constant current control strategy, the resonant frequency f of the resonant cavity can be determined s And work, through the current difference S between the CLLC converter and the staggered parallel CLLC converter p The phase angle δ of the phase shift is determined by comparing the preset value of the interleaved parallel power balancing strategy and performing gain compensation on the secondary switching signal of the interleaved parallel CLLC converter.

6. The power balancing control method of a multi-channel symmetrical CLLC topology structure according to claim 1, characterized in that: The following steps are involved: Step 1: The output voltage sampling module and the output current sampling module respectively collect analog signals of voltage and current, and transmit them to the phase shift angle controller module; Step 2: The analog / digital converter sampling unit in the phase angle controller module converts the received voltage and current analog signals into digital signals, and then transmits them to the comparator; Step 3: The comparator determines whether the current difference of the multiple symmetrical CLLC converters meets the preset value requirement, and determines whether to perform phase compensation on the rectifier-side switch control signal of each CLLC converter; Step 4: If the phase compensation of the rectifier side switch control signal is to be performed, the phase shift angle controller module outputs the required control loop parameters to the pulse width modulation generator. The pulse width modulation generator generates a PWM signal as an output by receiving the control loop parameters, and supplies it to each switch tube in the multi-channel full-bridge symmetrical CLLC resonant converter to control the phase state of its control signal so that the secondary switch tube of each converter is turned on with a compensated phase angle; Step 5: The Type-III controller and the comparator perform real-time feedback comparison on the voltage and current signals of the analog / digital converter sampling unit and adjust the amplitude of the phase shift signal to ultimately achieve power balancing control.

7. The power balancing control method according to claim 6, characterized in that: The control mechanism of the power balancing control is that after the power balancing control of the main circuit loop under the fundamental wave analysis method is performed by the rectifier side switch tube control signal, the forward operation gain formula according to the FHA equivalent circuit model is as follows: Where M is the voltage gain, which is the ratio of input voltage to output voltage; L m is the coupled inductor; L r1 is the resonant inductance; C r1 is the resonant capacitance; Z ac is the equivalent impedance of the secondary side of the resonant cavity after adopting the multi-channel resonant balance control strategy; R eq is the equivalent load; s is the complex frequency, which is usually used in Laplace transform.

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