Abstract:
The present invention relates to a controlling method for multi-leg isolation DC/DC converter with wide input voltage scope, in which a transformer having at least three primary winding coils and one secondary winding coil is provided in a multi-leg DC/DC converter. Moreover, a converter controlling module is provided to treat the DC input voltage and the DC output voltage received from the multi-leg DC/DC converter with an over voltage determination, therefore the converter controlling module is able to output a proper driving signal to a plurality of power switch sets of the multi-leg DC/DC converter for making the power switch sets be operated at different ON/OFF states, so as to make the transformer has a specific coil turn ratio. By such way, the DC input voltage of the multi-leg DC/DC converter would be automatic modulated for facilitating the multi-leg DC/DC converter to provide a stable DC output voltage.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to the technology field of DC/DC converters, and more particularly to a controlling method for a multi-leg isolation DC/DC converter with wide input voltage scope. 
         [0003]    2. Description of the Prior Art 
         [0004]    With the development and advancement of industry and science technology, various electronic and electrical products are widely applied and used in human life, and it is well known that the electronic (electrical) products must be powered by electricity. However, since the power formation of the market electricity is AC power but not all electronic (electrical) products can be driven by AC power; for this reason, a variety of power converters are gradually designed and then proposed. 
         [0005]    With reference to  FIG. 1 , there is shown a block diagram of a conventional regulated power supply. As shown in  FIG. 1 , the regulated power supply  1 ′ is able to output multi output voltages through the work of the voltage conversion module B and the voltage regulation module C. However, the application of the regulated power supply  1 ′ is still limited because having the disadvantage of low DC input voltage scope. 
         [0006]    Referring to  FIG. 2 , which illustrates a circuit framework diagram of a conventional buck DC/DC converter. As shown in  FIG. 2 , the buck DC/DC converter  2 ′ is able to effectively transform the input voltage Vg′ to a target output voltage through the two power switch (S, S′) and the two power diode (CR 1 , CR 2 ). However, it must uses many power switch driving circuits to drive the power switch (S, S′) because the buck DC/DC converter  2 ′ includes many power switch (S, S′), and that causes the increasing of the circuit manufacturing cost of the buck DC/DC converter  2 ′. 
         [0007]    Accordingly, in view of the conventional regulated power supply and the conventional buck DC/DC converter still including drawbacks and shortcomings, the inventor of the present application has made great efforts to make inventive research thereon and eventually provided a controlling method for multi-leg isolation DC/DC converter with wide input voltage scope. 
       SUMMARY OF THE INVENTION 
       [0008]    The primary objective of the present invention is to provide a controlling method for multi-leg isolation DC/DC converter with wide input voltage scope, in which a transformer having at least three primary winding coils and one secondary winding coil is provided in a multi-leg DC/DC converter. Moreover, a converter controlling module is provided to treat the DC input voltage and the DC output voltage received from the multi-leg DC/DC converter with an over voltage determination, therefore the converter controlling module is able to output a proper driving signal to a plurality of power switch sets of the multi-leg DC/DC converter for making the power switch sets be operated at different ON/OFF states, so as to make the transformer has a specific coil turn ratio. By such way, the DC input voltage of the multi-leg DC/DC converter would be automatic modulated for facilitating the multi-leg DC/DC converter to provide a stable DC output voltage. 
         [0009]    Accordingly, to achieve the primary objective of the present invention, the inventor of the present invention provides a controlling method for multi-leg isolation DC/DC converter with wide input voltage scope, comprising following steps:
   (1) a converter controlling module receiving a DC input voltage and a DC output voltage from a multi-leg DC/DC converter;   (2) the converter controlling module determining whether the DC input voltage and the DC output voltage range between a specific input voltage scope and a specific output voltage scope, respectively; if yes, proceeding to step (3);   (3) according to the DC input voltage and the DC output voltage, the converter controlling module driving a plurality of power switch sets of the multi-leg DC/DC converter by a proper driving mode; and   (4) the power switch sets working for making a transformer of the multi-leg DC/DC converter has a specific coil turn ratio, so as to facilitate the transformer to treat the DC input voltage with a voltage transforming process by a specific voltage transformation ratio; wherein the transformer of the multi-leg DC/DC converter is winded with a first primary winding coil, a second primary winding coil, a third primary winding coil, and a secondary winding coil.   
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention as well as a preferred mode of use and advantages thereof will be best understood by referring to the following detailed description of an illustrative embodiment in conjunction with the accompanying drawings, wherein: 
           [0015]      FIG. 1  is a block diagram of a conventional regulated power supply; 
           [0016]      FIG. 2  is a circuit framework diagram of a conventional buck DC/DC converter; 
           [0017]      FIG. 3  is a block diagram of a multi-leg isolation DC/DC converter with wide input voltage scope according to the present invention; 
           [0018]      FIG. 4  is a circuit framework diagram of the multi-leg isolation DC/DC converter with wide input voltage scope according to the present invention; 
           [0019]      FIG. 5  shows a drive mode selecting table; 
           [0020]      FIG. 6  shows an operation state table for a plurality of power switch sets of a multi-leg DC/DC converter; 
           [0021]      FIG. 7  is a flow chart of a controlling method for multi-leg isolation DC/DC converter with wide input voltage scope according to the present invention; 
           [0022]      FIG. 8  shows a measurement plot of the DC input voltage of the multi-leg DC/DC converter; and 
           [0023]      FIG. 9  shows a measurement plot of the DC output voltage of the multi-leg DC/DC converter. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    To more clearly describe a controlling method for multi-leg isolation DC/DC converter with wide input voltage scope according to the present invention, embodiments of the present invention will be described in detail with reference to the attached drawings hereinafter. 
         [0025]    With reference to  FIG. 3  and  FIG. 4 , there are respectively shown a block diagram and a circuit framework diagram of a multi-leg isolation DC/DC converter with wide input voltage scope according to the present invention. As shown in  FIG. 3  and  FIG. 4 , the multi-leg isolation DC/DC converter  1  with wide input voltage scope of the present invention consists of a multi-leg DC/DC converter  11  and a converter controlling module  12  for receiving a DC input voltage V in  and a DC output voltage V O  from the multi-leg DC/DC converter  11 . The converter controlling module  12  is able to drive a plurality of power switch sets ( 111 ,  112 ,  113 ,  114 ) of the multi-leg DC/DC converter  11  by a selectively proper driving mode according to the DC input voltage V in  and the DC output voltage V O , so as to make a transformer of the multi-leg DC/DC converter  11  has a specific coil turn ratio by the working of the power switch sets ( 111 ,  112 ,  113 ,  114 ), and then facilitate the transformer to treat the DC input voltage V in  with a voltage transforming process by a specific voltage transformation ratio. 
         [0026]    As shown in  FIG. 3  and  FIG. 4 , the transformer of the multi-leg DC/DC converter  11  is winded with a first primary winding coil N P1 , a second primary winding coil N P2 , a third primary winding coil N P3 , and a secondary winding coil N S . 
         [0027]    In the transformer of the multi-leg DC/DC converter  11 , the coil turn ratio between the first primary winding coil N P1  and the secondary winding coil N S  is n. The coil turn ratio between the second primary winding coil N P2  and the secondary winding coil N S  is 2n. The coil turn ratio between the third primary winding coil N P3  and the secondary winding coil N S  is 3n. The coil turn ratio between the first primary winding coil N P1  as well as the third primary winding coil N P3  and the secondary winding coil N S  is 4n. The coil turn ratio between the second primary winding coil N P2  as well as the third primary winding coil N P3  and the secondary winding coil N S  is 5n. The coil turn ratio between the first primary winding coil N P1 , the second primary winding coil N P2  as well as the third primary winding coil N P3  and the secondary winding coil N S  is 6n. 
         [0028]    Moreover, the multi-leg DC/DC converter  11  is disposed with a full-wave rectifier unit  110 , an output capacitor C O  and an output resistor R O  at the output end thereof, wherein the full-wave Rectifier unit  110  is coupled to the secondary winding coil N S , and the output capacitor C O  is parallel to the output resistor R O  and coupled to the full-wave Rectifier unit  110 . Besides, the converter controlling module  12  is consisted of a counter  121 , a feedback unit  123 , an over voltage determining unit  122 , a modulation unit  125 , and a power switch driving module  126 , wherein the feedback unit  123  is used for receiving the DC input voltage V in . The over voltage determining unit  122  is coupled to the feedback unit  123  and the input end of the multi-leg DC/DC converter  11  for receiving the DC input voltage V in  and the DC output voltage V O , so as to respectively determine whether the DC input voltage V in  and the DC output voltage V O  range between a user-set specific input voltage scope and a user-set specific output voltage scope. The modulation unit  125  is coupled to the over voltage determining unit  122  and has a drive mode selecting function. In the present invention, the modulation unit  125  is able to select the proper driving mode to drive the power switch sets ( 111 ,  112 ,  113 ,  114 ) according to an over voltage determination signal outputted by the over voltage determining unit  122 . The power switch driving module  126  is coupled to the modulation unit  125  and the power switch sets ( 111 ,  112 ,  113 ,  114 ), used for driving the power switch sets ( 111 ,  112 ,  113 ,  114 ) according to the proper driving mode. 
         [0029]    Continuously referring to  FIG. 3  and  FIG. 4 , and please simultaneously refer to  FIG. 5 , which shows a drive mode selecting table. As shown in FIGs., the modulation unit  125  selects the proper driving mode for the power switch sets ( 111 ,  112 ,  113 ,  114 ) from the drive mode selecting table according to the over voltage condition of the DC input voltage V in  and the DC output voltage V O . When the modulation unit  125  selects driving mode  1 , the ON/OFF states of the power switch sets ( 111 ,  112 ,  113 ,  114 ) driven by the power switch driving module  126  are (ON, ON, OFF, OFF), respectively. Therefore, the transformer of the multi-leg DC/DC converter  11  would has a specific coil turn ratio of n. Besides, When the modulation unit  125  selects driving mode  2 , the ON/OFF states of the power switch sets ( 111 ,  112 ,  113 ,  114 ) driven by the power switch driving module  126  are respectively (OFF, ON, ON, OFF), and the specific coil turn ratio of the transformer of the multi-leg DC/DC converter  11  becomes to 2n. Moreover, When the modulation unit  125  selects driving mode  3 , the ON/OFF states of the power switch sets ( 111 ,  112 ,  113 ,  114 ) driven by the power switch driving module  126  are respectively (OFF, OFF, ON, ON), and the specific coil turn ratio of the transformer of the multi-leg DC/DC converter  11  becomes to 3n. 
         [0030]    Inheriting to above descriptions, when the modulation unit  125  alternatively selects driving mode  4 , the ON/OFF states of the power switch sets ( 111 ,  112 ,  113 ,  114 ) driven by the power switch driving module  126  are (ON, OFF, ON, OFF), respectively; therefore, the transformer of the multi-leg DC/DC converter  11  would has a specific coil turn ratio of 4n. Besides, When the modulation unit  125  selects driving mode  5 , the ON/OFF states of the power switch sets ( 111 ,  112 ,  113 ,  114 ) driven by the power switch driving module  126  are respectively (OFF, ON, OFF, ON), and the specific coil turn ratio of the transformer of the multi-leg DC/DC converter  11  becomes to 5n. Moreover, When the modulation unit  125  selects driving mode  3 , the ON/OFF states of the power switch sets ( 111 ,  112 ,  113 ,  114 ) driven by the power switch driving module  126  are respectively (ON, OFF, OFF, ON), and the specific coil turn ratio of the transformer of the multi-leg DC/DC converter  11  becomes to 6n. 
         [0031]    Furthermore, as the operation state table of the power switch sets ( 111 ,  112 ,  113 ,  114 ) shown in  FIG. 6 , it is able to know that each of the power switch transistors in the power switch sets ( 111 ,  112 ,  113 ,  114 ) are driven by PWM driving signal. Moreover, from  FIG. 4  and  FIG. 6 , it can also know that the power switch transistors are denoted to T 1   + , T 1   − , T 2   + , T 2   − , T 3   + , T 3   − , T 4   + , and T 4   − , respectively. 
         [0032]    Thus, above descriptions have been completely and clearly introduced the multi-leg isolation DC/DC converter  1  with wide input voltage scope of the present invention. Next, a controlling method for the multi-leg isolation DC/DC converter  1  will be introduced in follows. Please refer to  FIG. 7 , there is shown a flow chart of a controlling method for the multi-leg isolation DC/DC converter with wide input voltage scope according to the present invention. As shown in  FIG. 7  and FIG.  FIG. 3 , the controlling method of the present invention firstly executes step (S 01 ) for facilitating the converter controlling module  12  to receive a DC input voltage V in  and a DC output voltage V O  from the multi-leg DC/DC converter  11 . Then, the converter controlling module  12  would determine whether the DC input voltage V in  and the DC output voltage V O  range between a user-set specific input voltage scope and a user-set specific output voltage scope, respectively (step (S 02 )). Therefore, according to the DC input voltage V in  and the DC output voltage V O , the converter controlling module  12  drives a plurality of power switch sets ( 111 ,  112 ,  113 ,  114 ) of the multi-leg DC/DC converter  11  by a selected proper driving mode. Eventually, the power switch sets ( 111 ,  112 ,  113 ,  114 ) would be driven to work for making a transformer of the multi-leg DC/DC converter  11  has a specific coil turn ratio, so as to facilitate the transformer to treat the DC input voltage V in  with a voltage transforming process by a specific voltage transformation ratio (step (S 04 )). 
         [0033]    However, before the step (S 01 ) is executed, it must execute steps (SP 1 ) and (SP 2 ) in advance; such that the user is able to set the specific input voltage scope and the specific output voltage scope by using an external host  2  connected to the converter controlling module  12 , and set a counter  121  of the converter controlling module  12  through the external host, so as to make the counter  121  count a converter-modulating period when the steps (1)˜(4) are executed. Therefore, the steps (1)˜(4) would be completed during the converter-modulating period. Besides, the plurality of power switch sets ( 111 ,  112 ,  113 ,  114 ) of the multi-leg DC/DC converter  11  are turned off when the steps (1)˜(3) are executed. 
         [0034]    Please refer to  FIG. 8  and  FIG. 9 , there are shown two measurement plots of the DC input voltage of the multi-leg DC/DC converter. As shown in  FIG. 8 , the converter controlling module  12  treats the DC input voltage V in  with a voltage modulating process in the converter-modulating period of 0.01 s, so as to gradually adjust the DC input voltage V in  from 60V to 420V. Moreover, from  FIG. 9 , it is able to find that the DC output voltage V out  provided by the multi-leg isolation DC/DC converter  1  is maintained at 24V even if the DC input voltage V in  is adjusted from 60V to 420V. 
         [0035]    The above description is made on embodiments of the present invention. However, the embodiments are not intended to limit scope of the present invention, and all equivalent implementations or alterations within the spirit of the present invention still fall within the scope of the present invention.