Abstract:
It provides the effective power conversion control technique which it can control which it made use of a characteristic (nature) of each A/D converter in. It comprises the third control part including the third operating circuit it inputs signal from third A/D converter inputting the detecting signal which is different from the detecting signal which is the same as the detecting signal or the detecting signal and above third A/D converter, and to generate the third operating signal, and the above actuating management circuit manages the actuating of an above first control part and the second above control part and the third above control part.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a control device of a power converter circuit generating ON/OFF control signal for power conversion switch. The ON/OFF control signal is generated based on detecting signals such as output voltage, output current, electric switch current, and so on. By using characteristic of a analog-to-digital (hereinafter, “A/D”) converter, efficient control can be performed. 
     TECHNICAL BACKGROUND 
     In a control device of a power converter circuit, detecting signals such as output voltage, output current, switch current, etc. are used for calculating a plurality of control elements. 
       FIG. 8  shows a power conversion system. In this power conversion system, an output voltage e o  of a power converter circuit  9  is detected. A control device  8  drives a power conversion switch of the power converter circuit  9 . 
     The control device  8  converts analog output voltage e o  into digital voltage value by an A/D converter  81 . The A/D converter  81  sends out the digital voltage value E_OUT to a first arithmetic logical unit  8211  and sends out to a second arithmetic logical unit  8212 . 
     A result of an operation (output signal D 1 ) of the first arithmetic logical unit  8211  is sent to an adder  822  of the subsequent stage. 
     Also, a result of an operation (output signal D 2 ) of the second arithmetic logical unit  8212  is sent to the adder  822  of the subsequent stage, too. 
     The adder  822  outputs an addition result (output signal D) to a driving signal generation part  83  of the subsequent stage by an operation cycle of the first arithmetic logical unit  8211 . 
     As a preceding patent document, PCT/JP2009/053773 (or U.S. Application Publication No. 2011/0181260) exists. 
     Problem to be Solved 
     Generally sampling rate goes low as resolution becomes higher in the A/D converter. If sampling rate of A/D converter  81  is higher in the control device  8  of  FIG. 8 , a response of the control device is high but accuracy is low. 
     On the contrary, if resolution of A/D converter  81  is high, accuracy of the control device is high but response is low. 
     The object of the present invention is to provide a control device of power converter circuit that performs A/D conversion of a detecting signal by A/D converter of “high resolution/low sampling rate” and by A/D converter of “low resolution/high sampling rate”. 
     Means to Solve the Problem 
     In a stationary state, sampling rate of an A/D converter circuit may be low, however resolution of the A/D converter circuit has to be high. 
     In a transient state, sampling rate of an A/D converter circuit has to be high, however resolution of the A/D converter circuit may be low. 
     When a certain arithmetic is performed about a certain data, a part of data is calculated with a low bit (e.g., resolution 8 bit) and other parts are calculated with a high bit (e.g., resolution 16-bit). 
     That is, an A/D converter of high-speed low bit (e.g., 8 bit) and an A/D converter of a low-speed high bit (e.g., 16-bit) are used. 
     High-speed high bit A/D converter has not to be used by carrying out this invention. 
     A control device of power converter circuit which generates switch operating time data based on at least one detecting signal among output voltage, output current, electric switch current and electric reactor current, and generates ON/OFF control signal for power conversion switch based on the switch operating time data, comprising: 
     a first control part which includes a first A/D converter that inputs the at least one detecting signal and performs A/D conversion, and a first operating circuit that generates first operation signal by inputting digital signal from the first A/D converter, 
     a second control part which includes a second A/D converter that inputs the at least one detecting signal and performs A/D conversion, and a second operating circuit that generates second operation signal by inputting digital signal from the second A/D converter, 
     a third control part which includes a third A/D converter that inputs the at least one detecting signal and performs A/D conversion, and a third operating circuit that generates third operation signal by inputting digital signal from the third A/D converter, 
     a switch operating time data generation part which synthesizes the first operation signal, the second operation signal and the third operation signal, and generates the switch operating time data, 
     a driving signal generation part which generates ON/OFF control signal for the power conversion switch, and 
     a operation management circuit which manages the first control part, the second control part, the third control part, the switch operating time data generation part and the driving signal generation part, 
     wherein 
     (a) the first A/D converter, the second A/D converter and the third A/D converter have next relations,
         sampling rate of the first A/D converter≧sampling rate of the second A/D converter≧sampling rate of the third A/D converter,   sampling rate of the first A/D converter≧sampling rate of the third A/D converter≧sampling rate of the second A/D converter,   and,   resolution of the first A/D converter≦resolution of the second A/D converter≦resolution of the third A/D converter,   or,   resolution of the first A/D converter≦resolution of the third A/D converter≦resolution of the second A/D converter,   (b) the first operating circuit, the second operating circuit and the third operating circuit have next relations,   unit operating time of the first operating circuit≦unit operating time of the second operating circuit≦unit operating time of the third operating circuit,   or,    unit operating time of the first operating circuit≦unit operating time of the third operating circuit≦unit operating time of the second operating circuit,   where unit operating time is a time required for each operating circuit generating one result of an operation.       

     The control device of power converter circuit may further include a filter before the first A/D converter, the second A/D converter and the third A/D converter, respectively. 
     The control device of the power converter circuit may further include an amplifier before the first A/D converter. The amplifier clips the detecting signal in predetermined range width and amplifies it. 
     In the control device of the power converter circuit, the calculation number of times of the first operating circuit by one ON/OFF period of power conversion switch may be more than the calculation number of times of the second operating circuit and the third operating circuit. 
     In the control device of the power converter circuit, the calculation result of the first operating circuit is updated at least one time in one ON/OFF period of the power conversion switch. 
     Effect of the Invention 
     In the present invention, A/D converters of “high resolution/low sampling rate” and “low resolution/high sampling rate” are used. 
     When the output of the power converter circuit changes dynamically, the arithmetic by the control part of “low resolution/high sampling rate” occupies larger ratio. 
     When the output of the power converter circuit changes little, the arithmetic by the control part of “high resolution/low sampling rate” occupies larger ratio. 
     According to the present invention, an A/D converter used for control part of “high resolution/low sampling rate” and an A/D converter used for control part of “low resolution/high sampling rate” are not expensive. 
     Therefore, production cost of the control device can become lower. 
     Specifically, a price of A/D converter of 8 bit or less is low. 
     A price of A/D converter of greater than 8 bit suddenly becomes higher. 
     Low-speed A/D converter of greater than 8 bit can be manufactured, for example, by combination of a plurality of A/D converter of 8 bit or less. 
     When output voltage changes dynamically, the stability of the output voltage of the control device of the present invention is high. 
     Therefore, a capacitor of small capacity can be adopted as an output capacitor of the power converter circuits. 
     As a result, small power consumption can be achieved. 
     For example, the total power consumption of a high-speed 8 bit A/D converter and a low-speed 16 bit A/D converter is smaller than the power consumption of a high-speed 16 bit A/D converter. 
     The recent electronic devices may repeat a sleep mode and an active mode every several minutes or every dozens of seconds. 
     Thus, the control device of the present invention is suitable for the power supply of such electronic devices. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a figure showing examples of the calculation number of times of the first operating circuit and the second operating circuit per one ON/OFF period of the power conversion switch. 
         FIG. 2  is explanatory drawing of a power conversion system in which a detecting signal is output current of a power converter circuit. 
         FIG. 3  is an illustration which shows clipping a detecting signal by an amplifier. 
         FIG. 4  is explanatory drawing showing an embodiment of the present invention. 
         FIG. 5  is explanatory drawing of a power conversion system in which one detecting signal is output voltage and another one is switch current of a power converter circuit. 
         FIG. 6  is explanatory drawing showing another embodiment of the present invention. 
         FIG. 7  is explanatory drawing of a power conversion system in which a detecting signal is reactor current of a power converter circuit. 
         FIG. 8  is explanatory drawing of a conventional control device of a power converter circuit. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 4  is explanatory drawing showing another embodiment of the present invention. In  FIG. 4 , a control device  1 D is comprised of a first control part  11 D, a second control part  12 D, a third control part  13 D, a switch-off time data generation part  14 , a driving signal generation part  15  and an operation management circuit  16 D. 
     In this embodiment, as shown in a circuit diagram of  FIG. 5 , the power converter circuit  2  is comprised of a power conversion switch SW, a flywheel diode FD, a reactor L and a capacitor C. A DC power supply  201  is connected to an input side of the power converter circuit  2 , and a load  202  is connected to an output side of the power converter circuit  2 , and the output voltage e o  and switch current i SW  are sent out to the control device  1 D. 
     The first control part  11 D is comprised of a first A/D converter  111 , a first operating circuit  112  and a filter  113 . The first control part  11 D inputs the output voltage e o  and generates a first operating signal (output signal D 1 ). The first operating circuit  112  inputs a digital signal from the first A/D converter  111  and generates a proportional control signal. The first A/D converter  111  is a high-speed/8 bit one. 
     The second control part  12 D is comprised of a second A/D converter  121 , a second operating circuit  122  and a filter  123 . The second control part  12 D inputs the output voltage e o  and generates a second operating signal (output signal D 2 ). The second operating circuit  122  inputs a digital signal from the second A/D converter  121  and generates an integral control or a derivative/integral control signal. The second A/D converter  121  is a low-speed/16 bit one. 
     The third control part  13 D is comprised of a third A/D converter  131 , a third operating circuit  132  and a filter  133 . The third control part  13 D inputs the switch current i SW  and generates a third operating signal (output signal D 3 ). Third operating circuit  132  inputs a digital signal from the third A/D converter  131  and generates an integral control or a derivative/integral control signal. The third A/D converter  131  is a low-speed/16 bit one. 
     The operation management circuit  16 D manages operation of the first control part  11 D, the second control part  12 D and the third control part  13 D. 
     In this embodiment, the first A/D converter  111 , the second A/D converter  121  and the third A/D converter  131  have next relations,
          sampling rate of the first A/D converter&gt;sampling rate of the second A/D converter=sampling rate of the third A/D converter    and   resolution of the first A/D converter&lt;resolution of the second A/D converter=resolution of the third A/D converter        

     Even more, the first operating circuit  112 , the second operating circuit  122  and the third operating circuit  132  have next relations,
         unit operating time of first operating circuit&lt;unit operating time of the second operating circuit≦unit operating time of the third operating circuit   or,   unit operating time of the first operating circuit&lt;unit operating time of the third operating circuit≦unit operating time of the second operating circuit,   where the unit operating time is a time required for each operating circuit generating one result of an operation.       

     The switch-off time data generation part  14  synthesizes input signal D 1 , input signal D 2 , and input signal D 3  and generates output signal D as a switch operating time data of the power conversion switch SW, which is a switch-off time data in this embodiment. 
     As shown in  FIG. 1 , a calculation number of times of the first operating circuit  112  per one ON/OFF period of the power conversion switch may exceed a calculation number of times of the second operating circuit  122 . 
     In one ON/OFF period of the power conversion switch, the switch-off time data generation part  14  can update the computed result of the first operating circuit  112  several times. 
     The switch-off time data generation part  14  can thereby generate the switch operating time data in a cycle which is shorter than the unit operating time of the second operating circuit  122 . 
     The driving signal generation part  15  generates ON/OFF control signal for the power conversion switch according to the switch operating time data. 
       FIG. 6  is explanatory drawing showing another embodiment of the present invention. In  FIG. 6 , a control device  1 F is comprised of a first control part  11 F, a second control part  12 F, a third control part  13 F, a switch-off time data generation part  14 , a driving signal generation part  15  and an operation management circuit  16 F. The first control part  11 F is comprised of a first A/D converter  111 , a first operating circuit  112 , a filter  113  and an amplifier  115  provided just before the first A/D converter  111 . 
     The amplifier  115  inputs an output voltage e o  of a power converter circuit  2 , and clips it in the predetermined value width (see  FIG. 3(A) ) and amplifies it (see  FIG. 3(B) ). 
     The first operating circuit  112  inputs a digital signal from the first A/D converter  111  and generates a proportional control signal (output signal D 1 ). The first A/D converter  111  is a high-speed/8 bit one. 
     The second control part  12 F is comprised of a second A/D converter  121 , a second operating circuit  122  and a filter  123 . The second control part  12 F inputs the output voltage e o  and generates a second operating signal (output signal D 2 ). The second operating circuit  122  inputs a digital signal from the second A/D converter  121  and generates an integral control or a derivative/integral control signal. The second A/D converter  121  is a low-speed/16 bit one. 
     The third control part  13 F is comprised of a third A/D converter  131 , a third operating circuit  132  and a filter  133 . The third control part  13 F inputs the switch current i SW  and generates a third operating signal (output signal D 3 ). The third operating circuit  132  inputs a digital signal from the third A/D converter  131  and generates a proportional control signal. The third A/D converter  131  is a high-speed/8 bit one. 
     The operation management circuit  16 F manages operation of the first control part  11 F, the second control part  12 F and the third control part  13 F. 
     In this embodiment, sampling rate of the first A/D converter  111 , sampling rate of the third A/D converter  113  and sampling rate of the second A/D converter  121  have next relations,
         sampling rate of first A/D converter 111=sampling rate of third A/D converter 131&gt;sampling rate of second A/D converter 121        

     Even more, unit operating time of the first operating circuit  112 , unit operating time of the third operating circuit  132 , unit operating time of the second operating circuit  122  have next relations,
          unit operating time of the first operating circuit 112=unit operating time of the third operating circuit 132&lt;unit operating time of the second operating circuit 122       

     A switch-off time data generation part  14  synthesizes input signal D 1 , input signal D 2 , and input signal D 3 , and generates output signal D as a switch operating time data of the power conversion switch SW. And the driving signal generation part  15  generates ON/OFF control signal for the power conversion switch according to the switch operating time data. According to the present invention, an output current i o  (see  FIG. 2 ) and/or electric reactor current i L  (see  FIG. 7 ) of a power converter circuit  2  may be used as a detecting signal. 
     Also, in the embodiment, the ON/OFF control signal is a switch-off time signal. 
     However, the present invention is not limited to above. 
     When the ON/OFF control signal is a switch-on time signal, the present invention is applied. 
     When the ON/OFF control signals are switch-on time signal and switch-off time signal, the present invention is applied too. 
     Power converter circuit is often operated by an analog control device. 
     With an analog control device, operating characteristic depends on characteristic of configuration elements. 
     Thus, there are various kinds of disadvantages such as accuracy of component properties, heterogeneity of the quality, limitation of the operating range due to device characteristic, and others. The development of the digital controller is desired to overcome such disadvantages. 
     However, an A/D converter of the high-speed/16-bit, which is necessary in a conventional digital control device having the same performance as an analog control device, is expensive. 
     Market demands a digital control device of which price is same as an analog control device. 
     In case of an analog control device, it must adopt a capacitor of large-capacity as an output capacitor of a power converter circuit. 
     Control device of the present invention is implemented in digital circuit. 
     Thus, the control device is downsized in comparison with the analog control device, and production cost can be reduced.