CN102263496B - Power equalizing control method for multi-module DC-DC (Direct Current-Direct Current) convertor - Google Patents

Abstract

The invention relates to a power sharing control method for multi-module DC-DC converters, in particular to a power sharing control method for isolated DC-DC converters with input series and output series, which belongs to power electronics technology field. The output voltage and output current double closed-loop control is adopted, and the PWM signal of each module is generated by redistribution of the duty cycle, so as to achieve the equal sharing of the output voltage of each module, so as to realize the equal sharing of the power of each module. The control method of the invention is simple, the number of sensors used is small, the requirements for sensors are reduced, the production cost is reduced, the function of redundant switching is provided, and the reliability and stability of the whole system can be improved.

Description

A Power Sharing Control Method for Multi-module DC-DC Converters

technical field

The invention relates to a power sharing control method for multi-module DC-DC converters, in particular to a power sharing control method for isolated DC-DC converters with input series and output series, which belongs to power electronics technology field.

Background technique

For DC power supplies used in high-voltage input applications, the high voltage that power devices withstand is still a challenge, because power devices that can withstand such high voltages are very limited and the cost is very high. Therefore, it is very necessary to reduce the voltage borne by power devices by choosing the correct topology. The isolated DC-DC converter modules are combined through input series connection and output parallel connection or input series connection and output series connection, and this combination can be applied to high voltage input occasions. Among them, the input series output series DC-DC converter is especially suitable for power supply occasions where the input and output voltages are high and the input and output require electromagnetic isolation. The converter has the following advantages:

(1) Each converter module bears the original input and output voltage equally, so that the switching tube with lower voltage stress can be selected, and the on-resistance of the low-voltage switching tube is small, so as to obtain higher working efficiency;

(2) MOSFETs with lower withstand voltage can be used to replace IGBTs with high withstand voltage and lower switching frequency, so the switching frequency of the converter can be increased and the power density of the converter can be improved;

(3) The whole system is composed of standard modules, which increases the redundancy and reliability of the system, and at the same time adopts modular combination to reduce the production cycle and cost;

In order to ensure the normal operation of the converter, it is necessary to ensure that each module shares the total input voltage and output voltage equally, otherwise there will be uneven power among the modules, and the modules with high output power will reduce the reliability of the system due to problems such as overheating. Therefore, it is a key problem to be solved to realize equal power sharing of each module.

For the control of input series and output series isolated DC-DC converters, IEEE Applied PowerElectronics Conference and Exposition published "Input-series and output-series connected modular DC-DC converters with active input voltage and output voltagesharing" in 2004 (input series output Dynamic input and output voltage sharing of series DC-DC converter) This paper presents a method to realize power sharing. For each module, the method consists of an output voltage loop, an output current inner loop, and an input voltage equalization loop for each module, which is a three-closed-loop control strategy. The introduction of the input voltage equalizing ring samples the instantaneous input voltage of each module, and takes the average value of the input voltage of all modules as the given value of the input voltage equalizing ring of each module. Compared with other given value selection methods, it can maximize This triple closed-loop control method realizes output voltage equalization by controlling input voltage equalization, thereby ensuring equal power sharing of each module. However, this method has the following disadvantages:

(1) The system control method adopts a three-closed-loop control method, and the control method is complicated;

(2) Since both the input voltage and the output voltage need to be sampled, a large number of voltage sensors are required, and the cost is greatly increased.

Contents of the invention

In order to overcome the shortcomings of the existing control methods, the present invention proposes a power sharing control method for multi-module DC-DC converters.

The present invention is achieved through the following technical solutions.

A power sharing control method for multi-module DC-DC converters of the present invention adopts double closed-loop control of output voltage and output current, generates PWM signals of each module by redistribution of duty cycle, and achieves The output voltage is shared equally, so as to realize the power sharing of each module. Since the duty cycle is the ratio of the on-state time of the switch tube in one switching cycle, it is numerically equal to the ratio of the amplitude of the modulation wave to the amplitude of the carrier wave, so the redistribution of the duty cycle is also the redistribution of the modulation wave.

The main circuit of the multi-module DC-DC converter is composed of n identical isolated DC-DC converter modules connected in series at the input end and in series at the output end, where n is a number of 2 or more, and each module An inductor is connected in series on the output loop of the inverter, and the converter can be a high-frequency isolated DC-DC converter with a forward, flyback, full-bridge, half-bridge, push-pull or push-pull forward structure.

The power sharing control method of the present invention, its steps are:

也即

1) Determine the output voltage reference of each module, specifically to set the output voltage reference of each module to the main circuit output voltage reference v _ref

that is

2) Sampling the output voltage and output inductor current of each module, the sampling result is recorded as: the output voltage of each module is v _o1 ,..., v _oj ,..., v _on , the output voltage of each module is sampled The obtained values are respectively v _of1 ,...,v _ofj ,...,v _ofn , the output inductor current of each module is i _Lf1 ,...,i _Lfj ,...,i _Lfn , and the output inductor current of each module is obtained after sampling The values are respectively i _f1 ,..., _ifj ,...,ifn , that is, the output voltage of module j is v _oj , the value obtained after sampling _{is v ofj ,} and the output inductor current is i _Lfj , which is obtained after sampling The value of is i _fj , where 1≤j≤n;

进行比较，并经过电压环调节器G_vo补偿以后输出的i_refj作为模块j电流环的给定；3) Determine the setting of the current loop of each module, wherein the specific method of determining the setting of the current loop of module j is: the output voltage sampling result v _ofj of module j and the output voltage setting of module j

Compare and output i _refj after compensation by the voltage loop regulator G _vo as the given of the current loop of module j;

4) Determine the output value of each module current loop, wherein the specific method of determining the output value of the module j current loop is: compare the output inductor current sampling result i _fj of module j with the given i _refj of the module j current loop, and After being compensated by the current loop regulator G _io and limited, the output value is i _outj ;

其中1≤j≤n；5) Redistribute the output values i _out1 , ..., i _outj , ..., i _outn of each module current loop obtained through step 4), where the output of module j after redistribution is

where 1≤j≤n;

6) The output value of the current loop of each module obtained in step 5) is redistributed as a modulated wave and compared with the carrier, and the PWM control signal generated by the comparison controls the on-off of the switch tube in each module.

变为

采用占空比重新分配的控制方法，即对于正常工作的任一模块j电流环的输出值重新分配后的输出为

将其作为调制波与载波进行比较，由比较产生的PWM控制信号控制模块j开关管的通断。When any module k in the main circuit containing n DC-DC converters fails, the module is removed from the system, that is, the whole system is operated by n-1 modules, and n-1 modules are working normally The output voltage is given by the original

becomes

The control method of redistribution of duty cycle is adopted, that is, the output value of the current loop of any module j in normal operation after redistribution is

It is compared with the carrier wave as the modulation wave, and the PWM control signal generated by the comparison controls the on-off of the switching tube of the module j.

变为

采用占空比重新分配的控制方法，即对于正常工作的任一模块j电流环的输出值重新分配后的输出为

将其作为调制波与载波进行比较，由比较产生的PWM控制信号控制模块j开关管的通断。When a new module is added to the above-mentioned main circuit containing n DC-DC converters, the whole system is operated by n+1 modules, and the output voltage of any module j is given by

becomes

The control method of redistribution of duty cycle is adopted, that is, the output value of the current loop of any module j in normal operation after redistribution is

It is compared with the carrier wave as the modulation wave, and the PWM control signal generated by the comparison controls the on-off of the switching tube of the module j.

The whole system adopts this duty cycle redistribution control method to achieve the purpose of equal sharing of input and output voltages, so as to realize equal sharing of power for each module. Even when any module is switched, the system can still operate normally, ensuring high The frequency power supply can work safely, stably and effectively.

Beneficial effect

Compared with the prior art, the present invention adopts a double closed-loop control mode of voltage and current, and the control method is simple; only the output voltage and output current of each module need to be sampled, which reduces the number of sensors used and also reduces the requirements for sensors. The production cost is reduced; the function of redundant switching can improve the reliability and stability of the whole system.

Description of drawings

Fig. 1 schematic diagram of connection of the main circuit of the multi-module DC-DC converter of the embodiment of the present invention;

In Fig. 1, n is the number of converter modules included in the main circuit; v _in represents the total input DC voltage; S ₁ , S ₂ ... S _n are switches connected in parallel with each module and the input voltage dividing capacitor; C _d1 , C _d2 …C _dn is the input voltage dividing capacitor; v _cd1 , v _cd2 …v _cdn is the input voltage of each module; i _in1 , i _in2 …i _inn is the input current of each module; v _o is the total output voltage; i _o is the total output current ; v _o1 , v _o2 ... v _on are the output voltages of each module; S′ ₁ , S′ ₂ ... S′ _n are the switches connected in parallel between each module and the output filter capacitor; i _Lf1 , i _Lf2 ...i _Lfn are the filter capacitors of each module Inductor current; L _f1 , L _f2 ... L _fn is the output filter inductance of each module; C _f1 , C _f2 ... C _fn is the output filter capacitor of each module;

FIG. 2 is a schematic diagram of a power sharing control method adopted in an embodiment of the present invention;

Fig. 3 is the duty cycle redistribution control method in the case of failure of any module k in the main circuit of the multi-module DC-DC converter according to the embodiment of the present invention;

为载波信号；为输出限幅；i_ref1、i_ref2…i_refn为各模块电压环调节器输出；i_f1、i_f2…i_fn为各模块滤波电感电流采样；H_i1、H_i2…H_in为各模块滤波电感电流反馈系数；G_io为各模块的电流环调节器；i_out1、i_out2…i_outn为各模块电流控制器经限幅后的输出；i′_out1、i′_out2…i′_outn为经占空比重新分配后产生的新的调制波幅值；PWM₁、PWM₂…PWM_n为各模块开关管控制信号。In Fig. 2 and Fig. 3, v _ref is given as the main circuit output voltage; v _of1 , v _of2 ... v _ofn is the output voltage sampling of each module; H _v1 , H _v2 ... H _vn is the output voltage feedback coefficient of each module; G _vo It is the voltage loop regulator of each module;

is the carrier signal; is the output limiter; i _ref1 , i _ref2 ... i _refn is the output of the voltage loop regulator of each module; i _f1 , i _f2 ... i _fn is the sampling of the filter inductor current of each module; H _i1 , H _i2 ... H _in is the filter of each module Inductor current feedback coefficient; G _io is the current loop regulator of each module; i _out1 , i _out2 ...i _outn is the output of the current controller of each module after limiting; i′ _out1 , i′ _out2 ...i′ _outn is the The new modulation wave amplitude value generated after the duty cycle is redistributed; PWM ₁ , PWM ₂ ... PWM _n are the control signals of the switching tubes of each module.

Detailed ways

A power sharing control method for a multi-module DC-DC converter, wherein the main circuit of the multi-module DC-DC converter is composed of n isolated DC-DC converter modules in the form of input series connection and output series connection, As shown in Figure 1, the high-frequency isolated converter DC-DC part, filter inductor, capacitor and load, where the input DC voltage is v _in , the converter can be forward, flyback, full bridge, half bridge, push-pull or High frequency isolated DC-DC converter with push-pull forward structure.

各个模块的输出电压为v_o1、v_o2、…、v_on，滤波电感电流为i_Lf1、i_Lf2…i_Lfn。对于模块1，输出电压v_o1通过电压传感器采样得到v_of1为电压反馈，与电压环给定

比较，经过电压环调节器G_vo输出i_ref1作为模块1电流环的给定，模块1的电流环的反馈i_f1与电流环给定i_ref1进行比较，电流环调节器G_io输出的值经过限幅得到i_out1。对于任一模块j，输出电压v_oj通过电压传感器采样得到v_ofj为电压反馈，与电压环给定

比较，经过电压环调节器G_vo，输出i_refj作为模块j电流环的给定，模块j的电流环的反馈i_fj与电流环给定i_refj进行比较，电流环调节器G_io输出的值经过限幅得到i_outj。将各个模块的电流调节器输出经过限幅后的值进行重新分配，对于模块1，将除了模块1以外的其他所有电流调节器输出经过限幅后的值相加，再除以(n-1)，产生新的调制波i′_out1，即

将调制波与载波进行比较后产生PWM₁控制模块1的开关管通断；对于任意模块j，将除了模块j以外的其他所有电流调节器输出限幅后的值相加，再除以(n-1)，产生新的调制波幅值i′_outj，即

将调制波与载波进行比较后产生PWM_j控制模块j的开关管通断。For the isolated DC-DC converter with the input connected in series and the output connected in series, in order to realize the power sharing of each module, the duty cycle redistribution control method is adopted. In Figure 2, the output voltage of the entire converter system is given as v _ref , and the given voltage of the voltage loop of each module is

The output voltages of each module are v _o1 , v _o2 , ..., v _on , and the filter inductor currents are i _Lf1 , i _Lf2 ... i _Lfn . For module 1, the output voltage v _o1 is sampled by the voltage sensor to obtain v _of1 as voltage feedback, which is consistent with the given voltage loop

For comparison, after the voltage loop regulator G _vo outputs i _ref1 as the given of the current loop of module 1, the feedback i _f1 of the current loop of module 1 is compared with the given current loop i _ref1 , and the output value of the current loop regulator G _io is passed through Clipping results in i _out1 . For any module j, the output voltage v _oj is sampled by the voltage sensor to obtain v _ofj as voltage feedback, which is consistent with the given voltage loop

Comparison, through the voltage loop regulator G _vo , output i _refj as the given of the current loop of module j, the feedback i _fj of the current loop of module j is compared with the given i _refj of the current loop, and the output value of the current loop regulator G _io Get i _outj after clipping. Redistribute the clipped values of the current regulator outputs of each module. For module 1, add the clipped values of all other current regulator outputs except module 1, and then divide by (n-1 ), generate a new modulation wave i′ _out1 , namely

Comparing the modulated wave with the carrier wave generates PWM ₁ to control the on-off of the switching tube of module 1; for any module j, add the output limiting values of all other current regulators except module j, and then divide by (n -1), to generate a new modulation amplitude value i′ _outj , namely

After comparing the modulated wave with the carrier wave, PWM _j is generated to control the on-off of the switching tube of module j.

变为

任一模块j的输出电压v_oj通过电压传感器采样得到v_ofj为电压反馈，与该模块电压给定

进行比较，电压调节器G_vo输出i_refj作为模块j电流环的给定，电流反馈i_fj与电流环给定i_refj做比较，电流调节器输出的值经过限幅后得到i_outj。其他n-2个有效模块通过同样的方法产生i_out1、i_out2…i_out(k-1)、i_out(k+1)…i_outn，将这n-1个电流调节器输出限幅的值进行重新分配。对于模块1，将除了模块1以外的其他所有电流调节器输出经过限幅后的值相加，再除以(n-2)，产生新的调制波i′_out1，即

将调制波i′_out1与载波进行比较后产生PWM₁控制模块1的开关管通断。对于任一模块j，将除了模块j以外的其他所有电流调节器输出经过限幅后的值相加，再除以(n-2)，产生新的调制波i′_outj，即

将调制波i′_outj与载波进行比较后产生PWM_j控制模块j的开关管通断。Considering that the system can still work normally when any module in the n modules fails, the following redundant control method is designed: Assuming that module k fails, the switch S _k and the output filter capacitor C _fk are added at both ends of the input capacitor C _dk The switch _S'k is closed, and the module k is removed from the system, and the remaining n-1 modules perform input and output voltage equalization control. The output voltage of each module for normal operation is given by the

becomes

The output voltage v _oj of any module j is sampled by the voltage sensor to obtain v _ofj as voltage feedback, which is consistent with the given voltage of the module

For comparison, the voltage regulator G _vo outputs i _refj as the setting of the current loop of module j, the current feedback i _fj is compared with the current loop setting i _refj , and the output value of the current regulator is limited to obtain i _outj . The other n-2 effective modules generate i _out1 , i _out2 ...i _out(k-1) , i _out(k+1) ...i _outn by the same method, and limit the output of these n-1 current regulators The value is reassigned. For module 1, add the clipped values of the outputs of all other current regulators except module 1, and then divide by (n-2) to generate a new modulation wave i′ _out1 , namely

Comparing the modulated wave i' _out1 with the carrier generates PWM ₁ to control the switch tube of module 1 to turn on and off. For any module j, add the clipped values of all other current regulator outputs except module j, and then divide by (n-2) to generate a new modulation wave i′ _outj , namely

Comparing the modulated wave i' _outj with the carrier generates PWM _j to control the switching of the switch tube of module j.

变为

仍然采用占空比重新分配的控制方法，各个模块进行占空比重新分配后产生的新的调制波为

将调制波i′_outj与载波进行比较，产生的控制信号PWM_j控制模块j开关管的通断。When a new module is added to the main circuit of the multi-module DC-DC converter to work, the whole system is composed of n+1 modules again. The output voltage of any module j is given by

becomes

The control method of redistribution of duty ratio is still adopted, and the new modulation wave generated by each module after redistribution of duty ratio is

Comparing the modulation wave i' _outj with the carrier, the generated control signal PWM _j controls the on-off of the switching tube of the module j.

The entire system achieves the purpose of equally sharing the input and output voltages through the redistribution of duty ratios, and realizes the equal sharing of the power of each module. Even if any module is switched, the system can still operate normally. Through the introduction of the duty ratio distribution link, the system's ability to suppress voltage disturbances during the dynamic response process is improved, thereby realizing the rapid adjustment of the system. The invention is applied to isolated DC-DC converters, and the converters can be all high-frequency isolated DC-DC converters such as forward, flyback, full bridge, half bridge, push-pull, and push-pull forward.

A power sharing control method for multi-module DC-DC converters provided by the present invention has been introduced in detail above. For those of ordinary skill in the art, according to the idea of the present invention, in terms of specific implementation and application range There will be changes. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims (3)

1. power-sharing control method that is used for multimode DC-DC converter, wherein the main circuit of multimode DC-DC converter is made of the form of n identical isolated DC-DC converter module by input series connection, output series connection, wherein n is the numeral more than 2 or 2, be serially connected with inductance on the output loop of each module, a described n converter module is identical normal shock, instead swash, full-bridge, half-bridge, recommend or the high-frequency isolation formula DC-DC converter of push-pull ortho-exciting structure, it is characterized in that the step of method is:

1) determines that the output voltage of each module is given;

2) output voltage and the outputting inductance electric current of each module are sampled, and the record sampled result, the output voltage of each module is designated as v respectively _O1..., v _Oj..., v _On, the output voltage sampling of each module is designated as v respectively _Of1..., v _Ofj..., v _Ofn, each module outputting inductance electric current is designated as i respectively _Lf1..., i _Lfj..., i _Lfn, each module outputting inductance current sample is designated as i respectively _F1..., i _Fj..., i _Fn, also promptly wherein the output voltage of module j be v _Oj, output voltage is sampled as v _Ofj, the outputting inductance electric current is i _Lfj, the outputting inductance current sample is i _Fj, the scope of j is 1≤j≤n;

3) determine the given of each blocks current ring;

4) determine the output valve of each blocks current ring;

5) the output valve i of each blocks current ring that will obtain by step 4) _Out1..., i _Outj..., i _OutnRedistribute;

Output after the output valve of each the blocks current ring that 6) step 5) is obtained is redistributed compares as modulating wave and carrier wave, is controlled the break-make of switching tube in each module by the pwm control signal that relatively produces;

The given method of output voltage of determining each module in the described step 1) is specially: the output voltage of setting each module is given as the given v of main circuit output voltage _Ref

Also be

The given concrete grammar of determination module j electric current loop is in the described step 3): with the output voltage sampled result v of module j _OfjGiven with the output voltage of module j

Compare, and through Voltage loop adjuster G _VoThe i of output after the compensation _RefjGiven as module j electric current loop;

The scope of above-mentioned j is 1≤j≤n;

The concrete grammar of the output valve of described step 4) determination module j electric current loop is: with the outputting inductance current sample of module j i as a result _FjWith the given i of module j electric current loop _RefjCompare, and through electric current loop adjuster G _IoThe value of exporting behind compensation and the process amplitude limit is i _Outj

The scope of above-mentioned j is 1≤j≤n;

The computational methods that described step 5) is redistributed the output valve of module j electric current loop are:

I' wherein _OutjBe the output of module j after redistributing;

The scope of above-mentioned j is 1≤j≤n.

2. a kind of power-sharing control method that is used for multimode DC-DC converter according to claim 1, it is characterized in that: when arbitrary module k in the main circuit of described multimode DC-DC converter lost efficacy and removed the back from system, whole system is carried out work by n-1 module, and wherein the output voltage of arbitrary module j is given as

And after redistributing, the output valve of module j electric current loop is output as $i_{\mathrm{outj}}^{\′}=\frac{1}{n-2}(\underset{i=1}{\overset{k-1}{\mathrm{\Σ}}}{i}_{\mathrm{outi}}+\underset{i=k+1}{\overset{n}{\mathrm{\Σ}}}{i}_{\mathrm{outi}}-i_{\mathrm{outj}}).$

3. a kind of power-sharing control method that is used for multimode DC-DC converter according to claim 1, it is characterized in that: when new when dropping into a module adding job identical in the main circuit of described multimode DC-DC converter with former DC-DC converter module, whole system is carried out work by n+1 module, and wherein the output voltage of arbitrary module j is given as v _Ref, and the output valve of module j electric current loop is output as after redistributing

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