Abstract:
The present invention offers a three-phase converter which conforms to the higher harmonics regulations. 
     According to the present invention, in a converter comprising three AC reactors, a three-phase diode bridge, a plurality of smoothing capacitors connected in series between the DC output side of the three-phase diode bridge and a DC load, two flywheel diodes connected to positive and negative terminals on the DC side of the three-phase diode bridge, respectively, a reactor inserted between the midpoint of the two flywheel diodes and the midpoint of the smoothing capacitors, three both-way energizing switches arranged between the AC side of the three-phase diode bridge and the midpoint of the two flywheel diodes, and a controller for controlling the three both-way energizing switches, the three both-way energizing switches are controlled to reduce higher harmonic components of power source current and, by means of the reactor interposed between the midpoint of the two flywheel diodes and the midpoint of the smoothing capacitors, reverse recovery currents of the three-phase diode bridge during turn-on of the three both-way energizing switches are suppressed.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a converter for converting three-phase alternating current to direct current, a motor driving module and a refrigerating apparatus. 
       BACKGROUND ART 
       [0002]    A converter for converting three-phase alternating current (AC) to direct current (DC) is used for, for example, a motor driving inverter, a battery charger/discharger or a refrigerating apparatus (such as air conditioner or refrigerator). When the converter uses a three-phase diode rectifier, many power source current higher harmonics are generated, having an influence upon an electric power system to now give rise to a social problem. 
         [0003]    In recent years, higher harmonics regulations, including those by IEC (International Electrical Standards Conference): LEC61000-3-2 (phase current&lt;16 A and IEC61000-3-12 (16 A&lt;phase current&lt;75 A), have been established in Europe, China and Japan. In future, countermeasures against power source higher harmonics in those apparatus are expected to be necessary. 
         [0004]    On the other hand, by using a three-phase PWM converter constituted by 6 semiconductor power devices, reduction of higher harmonics in input current and stabilization of output DC voltage can be controlled but many semiconductor power devices and a complicated control means are needed, thus raising a problem that costs of apparatus increase to a great extent. 
         [0005]    Especially, in civil and industrial apparatus such as air conditioners, general-purpose inverters and electric motorcar chargers which make much account of costs of products, inexpensive countermeasures against higher harmonics have been desired. 
         [0006]    Conventionally, as inexpensive countermeasures against higher harmonics in the three-phase converter, a method has been proposed, as described in “Patent Literature 1” and “Patent Literature 2” for instance, according to which an AC reactor and three both-way energizing type switches are provided on the input side of a three-phase diode rectifier and the both-way energizing type switches are turned on nearby a zero-cross alone of power source voltage of each phase so as to improve the input current. 
       CITATION LIST 
     Patent Literatures 
       [0000]    
       
         Patent Literature 1: Japanese Patent No. 3422218 
         Patent Literature 2: Japanese Patent No. 2857094 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0009]    The technique described in “Patent Literature 1” requires a large AC reactor for the sake of clearing the higher harmonics regulations and cannot avoid enlarging the size of apparatus and undergoing cost-up. Especially, heat loss in the AC reactor resistance is in square relationship to input current and accordingly, heat generation in the reactor and reduction in the efficiency of apparatus are apprehended during high-load operation. 
         [0010]    Further, “Patent Literature 2” can materialize a size reduction of the AC reactor by increasing the number of on/off operations of the both-way energizing type switch but, needs to use a rectification diode of fast recovery type and encounters problems that the cost increases and the appropriation of a conventional diode rectifying circuit can not be allowed. 
         [0011]    Accordingly, the present invention offers a converter, a motor driving module and a refrigerating apparatus which can conform to the higher harmonics regulations without resort to employment of a large-size AC reactor and a fast diode. 
       Solution to Problem 
       [0012]    To solve the above problem, a converter for converting three-phase AC to DC according to the present invention comprises: 
         [0013]    a three-phase diode bridge, a plurality of smoothing capacitors connected in series between the DC output side of the three-phase diode bridge and a DC load, two flywheel diodes connected to positive and negative terminals on the DC side of the three-phase diode bridge, respectively, a reactor arranged between the midpoint of the two flywheel diodes and the midpoint of the smoothing capacitors, three both-way energizing switches interposed between the AC side of three-phase diode bridge and the midpoint of the two flywheel diodes, and a controller for controlling the three both-way energizing switches, whereby the three both-way energizing switches are controlled. 
         [0014]    Further, in the converter according to the present invention, in on/off control of the three both-way energizing switches, at least one of pieces of information indicative of power source phase, power source phase sequence, power source frequency and power source voltage is presumed on the basis of a voltage signal detected by a voltage detection means for detecting voltage between the AC side of the three-phase diode bridge and the negative terminal of the smoothing capacitor, and an on/off control signal for the both-way energizing switch is adjusted with the help of the presumed information. 
         [0015]    Further, in the converter according to the present invention, at least one of pieces of information indicative of power source phase, power source phase sequence, power source frequency and power source voltage is presumed by comparing the voltage signal detected by the voltage detection means to a predetermined voltage value. 
         [0016]    Further, in the converter according to the present invention, the predetermined voltage value is adjusted to about ¼ to ⅓ of an amplitude value of the voltage signal by using the amplitude value or an average value of the voltage signals detected by the voltage detection means. 
         [0017]    Further, in the converter according to the present invention, in the on/off control of the three both-way energizing switches, a power source phase is presumed by using the voltage signal detected by the voltage detection means, a modulation wave is prepared from the presumed phase by using a preset modulation wave table, and on/off control signals for the three both-way energizing switches are generated by comparing the modulation wave to a carrier wave. 
         [0018]    Further, in the converter according to the present invention, in the on/off control of the three both-way energizing switches, the magnitude and forward and backward positions of the modulation wave are adjusted by using load information of a DC load and the on/off control signals for the three both-way energizing switches are adjusted in accordance with variations in the DC load. 
         [0019]    Further, in the converter according to the present invention, a general-purpose rectification diode is used as the diode constituting the three-phase diode bridge. 
         [0020]    Further, in the converter according to the present invention, a general-purpose diode is used as the flywheel diode. 
         [0021]    Further, in the converter according to the present invention, the size of the reactor inserted between the midpoint of the two flywheel diodes and the midpoint of the smoothing capacitors has a capacity capable of suppressing an excessive turn-on current passing through the three both-way energizing switches. 
         [0022]    Further, in the converter according to the present invention, an inductance value (L) of the reactor inserted between the midpoint of the two flywheel diodes and the midpoint of the smoothing capacitors is calculated from an equation 
         [0000]    
       
      
       L=Ed×Trr/Isw  
      
     
         [0000]    by using a DC side voltage (Ed) of the three-phase diode bridge, a recovery time (Trr) of the diode constituting the three-phase diode bridge and a rated current (Isw) of the both-way energizing switch. 
         [0023]    Further, in the converter according to the present invention, a current capacity of the reactor inserted between the midpoint between the two flywheel diodes and the midpoint between the smoothing capacitors is set to about less than ¼ of that of the AC reactor. 
         [0024]    Also, to solve the above problems, a motor driving module for converting three-phase AC and supplying it to a motor according to the present invention comprises a three-phase diode bridge, a plurality of smoothing capacitors connected in series between the DC output side of three-phase diode bridge and a DC load, two flywheel diodes connected to positive and negative terminals on the DC side of three-phase diode bridge, respectively, a reactor inserted between the midpoint of the two flywheel diodes and the midpoint of the smoothing capacitors, three both-way energizing switches interposed between the AC side of three-phase diode bridge and the midpoint of the two flywheel diodes, and a controller for controlling the three both-way energizing switches, whereby the three both-way energizing switches are controlled. 
         [0025]    Also, to solve the above problems, a refrigerating apparatus for converting three-phase AC and supplying it to a motor according to the invention comprises a three-phase diode bridge, a plurality of smoothing capacitors connected in series between the DC output side of three-phase diode bridge and a DC load, two flywheel diodes connected to positive and negative terminals on the DC side of three-phase diode bridge, respectively, a reactor inserted between the midpoint of the two flywheel diodes and the midpoint of the smoothing capacitors, three both-way energizing switches arranged between the AC side of three-phase diode bridge and the midpoint of two flywheel diodes, and a controller for controlling the three both-way energizing switches, whereby the three both-way energizing switches are controlled. 
         [0026]    According to the present invention, higher harmonics components in power source current are reduced by controlling the both-way energizing switches, the reactor inserted between the midpoint of the two flywheel diodes and the midpoint of smoothing capacitors materializes suppression of an inverse recovery current of the three-phase diode bridge during turn-on of the three both-way energizing switches, and the two flywheel diodes materializes suppression of overvoltage during turn-off of the three both-way energizing switches. 
       Advantageous Effects of Invention 
       [0027]    According to the present invention, without adopting any large-size AC reactor and fast diode, the converter, the motor driving module and the refrigerating apparatus can be provided which can conform to the higher harmonics regulations. 
     
    
     
       BRIEF DESCRIPTION OF DRAWING 
         [0028]      FIG. 1  is a diagram illustrating the configuration of a converter according to an embodiment of the present invention. 
           [0029]      FIG. 2  is a diagram illustrating the construction of both-way energizing switch and driving circuit according to an embodiment of the invention. 
           [0030]      FIG. 3  is a diagram illustrating the functional block construction of a controller in the converter according to an embodiment of the invention. 
           [0031]      FIG. 4  is a diagram showing waveforms of power source voltage and modulation waves in respective phases. 
           [0032]      FIG. 5  is an equivalent circuit diagram when a both-way energizing switch in the converter is turned on according to an embodiment of the invention. 
           [0033]      FIG. 6  is an equivalent circuit diagram when a both-way energizing switch in the converter is turned on in the presence of a reactor according to an embodiment of the invention. 
           [0034]      FIG. 7  is a current waveform diagram of the both-way energizing switch in the converter according to an embodiment of the invention. 
           [0035]      FIG. 8  is a current waveform diagram of the both-way energizing switch in the converter in the presence of the reactor according to an embodiment of the invention. 
           [0036]      FIG. 9  is a diagram illustrating the configuration of a motor driving apparatus according to an embodiment of the invention. 
           [0037]      FIG. 10  is a waveform diagram showing the power source phase and detected voltage signals. 
           [0038]      FIG. 11  is a diagram illustrating the functional block construction of a power source phase operation unit in the converter according to an embodiment of the invention. 
           [0039]      FIG. 12  is a diagram illustrating the configuration of a motor driving apparatus according to an embodiment of the invention. 
           [0040]      FIG. 13  is a diagram illustrating an external view of a motor driving module according to an embodiment of the invention. 
           [0041]      FIG. 14  is a diagram illustrating the structure of a refrigerating apparatus according to an embodiment of the invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0042]    The present invention will now be described with reference to the drawings. 
       Embodiment 1 
       [0043]    An embodiment of the configuration and control of a three-phase converter according to the present invention will be described hereinafter. 
         [0044]      FIG. 1  is a diagram illustrating the configuration of a converter according to a first embodiment of the present invention. 
         [0045]    The converter includes three AC reactors  2  connected to a three-phase AC power source  1 , a three-phase diode bridge  3  constituted by six diodes, a plurality of smoothing capacitors  4  connected in series on the DC side of three-phase diode bridge  3 , two flywheel diodes  6  and  7  connected to positive and negative terminals on the DC side of three-phase diode bridge  3 , a reactor  5  inserted between the midpoint of flywheel diodes  6  and  7  and the midpoint of smoothing capacitors, three both-way energizing switches  10  connected between the AC input side of three-phase diode bridge  3  and the midpoint of flywheel diodes  6  and  7 , a controller  11  for controlling the three both-way energizing switches  10 , and a power source phase detection means  9 . 
         [0046]    In the plural smoothing capacitors  4  on the DC side, capacitors of the same capacitance are connected in series with each other, forming the midpoint for DC voltage. As will be shown later with reference to  FIG. 2 , the three both-way energizing switches  10  can each be constituted by a one-phase diode bridge  12  and a single semiconductor power device  13  (MOSFET or IGBT device). 
         [0047]      FIG. 2  illustrates an example of arrangement of the semiconductor power device  13  constituting the both-way energizing switch  10 . A driving terminal for the semiconductor power device is connected to a driving circuit  15  via an insulating means  14  such as a photo-coupler or a transformer as shown in  FIG. 2  in order to set up electrical insulation from the controller  11 . 
         [0048]    By using a semiconductor arithmetic operation device such as a microcomputer or DSP (digital signal processor), the controller  11  processes a power source phase supplied from the power source phase detection means  9  and load information supplied from the load  8  to thereby generate an on/off control signal for each of the semiconductor power devices. 
         [0049]    The controller  11  has the functional flock construction as illustrated in  FIG. 3  and each function is materialized with a program the microcomputer has. More specifically, a three-phase modulation wave is prepared from a detected power source phase θs by using a preset modulation wave table  16 . Further, the forward and backward positions and the magnitude of the modulation wave are adjusted from the load information by using a preset adjustment amount table  19 . 
         [0050]    Illustrated in  FIG. 4  is an example of power source voltage waveforms  21 ,  22  and  23  of individual phases and three-phase modulation wave table waveforms  24 ,  25  and  26  of the individual phases set in advance in a memory inside the microcomputer. The modulation wave table is prepared in advance through simulation under a predetermined condition or experiments with an actual product apparatus. 
         [0051]    Further, when the power source input current changes, a corresponding modulation wave must be adjusted for maintaining the effect of suppression of higher harmonics. In a simple realization method, by using the adjustment amount table  19  set in advance as shown in  FIG. 3 , a phase tuning amount θs_adj and a gain Km are determined so as to adjust the forward and backward positions and the magnitude of the modulation wave. 
         [0052]    Finally, a PWM controller  18  compares the adjusted modulation waves Mu, My and Mw with a carrier wave (triangular or saw-tooth wave) and outputs a PWM (Pulse Width Modulation) control signal so as to control on/off of the both-way energizing power device  13 . 
         [0053]    Through the aforementioned PWM control, the current higher harmonics can be reduced by adopting even the small AC reactor and consequently, the volume and cost of the apparatus can be reduced. 
         [0054]    Illustrated in  FIGS. 5 and 6  are equivalent circuits in which under the condition of forward conduction of an upper arm diode corresponding to the U-phase of three-phase diode bridge, the both-way energizing switch corresponding to the U-phase is turned on. 
         [0055]    In the absence of the reactor to be inserted between the midpoint of flywheel diodes  6  and  7  and the midpoint of smoothing capacitors as shown in  FIG. 5 , the recovery time of the rectification diode is long at an instant that the both-way energizing switch corresponding to the U-phase is turned on and consequently, an over-current flows through the both-way energizing switch for a short period of time. The generation of excessive turn-on current adversely affects the semiconductor device to lower its reliability and to increase its loss and affects the apparatus to cause it to generate radiation noises. 
         [0056]    In the presence of the reactor as shown in  FIG. 6 , on the other hand, the change rate of current can be limited and the over current can be suppressed. 
         [0057]    Illustrated in  FIGS. 7 and 8  are actually measured conduction current waveforms  27  passed through the both-way energizing switch in the circuits shown in  FIGS. 5 and 6 . As shown in  FIG. 8 , it was confirmed that the turn-on current of both-way energizing switch can be suppressed by adding the reactor. 
         [0058]    Also, when turning off, the both-way energizing switch causes the current flowing through the reactor to return to the smoothing capacitor via the flywheel diode and as a result, voltage applied to the both-way energizing switch can be suppressed to lower than the DC voltage and the energy loss can be reduced. 
         [0059]    Since the insertion reactor suppresses only the turn-on current of both-way energizing switch, its inductance value may be determined pursuant to the following equation: 
         [0000]        L =( Ed/ 2)× Trr /( Isw/ 2)= Ed×Trr/Isw   (1)
 
         [0000]    where L represents an inductance value of the reactor, Ed a DC voltage value, Trr a diode recovery time of the three-phase diode bridge and Is w a rated current of the both-way energizing switch. 
         [0060]    For example, when the DC voltage value (Ed) is 500 [V], the diode recovery time (Trr) of three-phase diode bridge is 5 [μs] and the rated current (Isw) of both-way energizing switch is 10 [A], the inductance value of reactor may approximately suffice for 
         [0000]        L= 500×5/10=250 [μH].
 
         [0000]    Namely, the inductance value of inserted reactor may be set as being sufficiently smaller than that of AC reactor ( 1/20 or less). 
         [0061]    Also, since the current to be passed through the reactor corresponds to only the current under on-condition of each device, its current capacity may be about ¼ or less of that of the input current to the apparatus. 
         [0062]    In addition, since the current of flywheel diode is also very small, an inexpensive general-purpose product may be adopted. 
         [0063]    As will be seen from the foregoing description, the turn-on current suppression circuit according to the present invention can be materialized at low costs and with the present invention used, a converter for reducing higher harmonics can be materialized by employing even a small size reactor and a general-purpose rectification diode of long inverse recovery time. Accordingly, reduction in cost and volume of a product and improvements in reliability and efficiency can be contrived. 
         [0064]    Embodiments of the construction and control of the three-phase converter according to the present invention have been set forth so far. 
       Embodiment 2 
       [0065]    An embodiment of a motor driving apparatus of the present invention will now be described. 
         [0066]    Referring to  FIG. 9 , a motor driving apparatus according to a second embodiment of the invention is configured as illustrated therein. 
         [0067]    A converter portion for converting three-phase AC to DC is the same as that shown in  FIG. 1 . By using an inverter  100  and an inverter controller  101  on the DC output side of a converter circuit, a motor  102  is driven. Motor load information the inverter controller  101  has is transmitted to a controller  111  through a means such as communication. By using the load information, the controller  111  adjusts the magnitude and position of a modulation wave so as to control the both-way energizing switch  10 . 
         [0068]    With this configuration, fabrication and installation of the converter circuit may alternatively be separated from those of the inverter circuit and therefore, the degree of freedom of design and fabrication of products can be improved. Especially, since the power source higher harmonics can be reduced by adding only the converter portion to the existing inverter module and motor drive substrate, costs of development and manufacture of products can be reduced. 
         [0069]    In this embodiment, a scheme of detecting the power source phase is adopted according to which voltage signals Vun, Vvn and Vwn obtained from a voltage dividing resistor  109  are used with the aim of reducing costs of parts and simplifying the wiring. 
         [0070]    Illustrated in  FIG. 10  are detected voltage waveforms of individual phases  31 ,  32  and  33  obtained from the voltage dividing resistor  109  and a power source phase waveform  30 . It has been proven from these waveforms that when the voltage signals obtained from the voltage dividing resistor  109  are compared to voltage level values of about ¼ to ⅓ of voltage amplitude value, rising edges of the obtained signals substantially coincide with 0°, 120° and 240° of the power source phase. Accordingly, from these voltage signals, the power source phase can be presumed. Also, from a time difference between adjacent rising edges, the power source frequency can be calculated. Further, from the rising edge sequence, the phase sequence of three-phase power source can be judged. 
         [0071]    In addition, by calculating the amplitude value or an average value of the voltage signals, the magnitude of the power source voltage can be presumed. 
         [0072]    Actually, in order to further improve the phase detection accuracy, an error Ms in power source frequency is calculated by using PLL (Phase-Locked Loop) process and an error in power source frequency fs  0  inside the microcomputer is corrected automatically. 
         [0073]    A process for calculating the power source phase will be described hereunder by making reference to  FIG. 11 . 
         [0074]    As shown in  FIG. 11 , through the use of A/D converters  40 , respective voltage detection signals Vun, Vvn and Vwn are detected which in turn are compared to voltage level values to prepare rising edges so that a difference between a corresponding power source phase value (U-phase: 0°, V-phase: 120°, W-phase: 240°) at the time a rising edge is detected and a power source phase calculated inside the microcomputer may be determined and a frequency error Δfs may be calculated by using a PI controller  44 . The frequency error is added to a power source frequency initial setting value f s 0 , so that the inside power source phase can be calculated through an integration process. In case information indicative of the phase sequence and frequency of the power source is not set in advance, however, a judgment must be made from time differences in rising edges and sequences corresponding to the individual phases before proceeding with the phase detection process. 
         [0075]    The voltage level value herein may be set to a fixed value (about ¼ to ⅓ of inter-phase voltage amplitude value) in advance in accordance with the power source voltage but when, with a view to reducing the influence of power source voltage variation, adjustment is carried out on line in accordance with a magnitude of power source voltage presumed from the voltage signal obtained from the voltage dividing resistor  109 , the phase detection accuracy can further be improved. 
         [0076]    Since the error in power source frequency can be adjusted automatically through the PLL process as described above, the power source phase detection error can be small even when the power source frequency varies or the microcomputer oscillator operates with errors. 
         [0077]    Further, when the number of A/D converters in the microcomputer is lacking, the power source phase can be calculated through a similar process by using even voltage signals of two phases or that of one phase. With one-phase voltage signal used, however, the phase sequence of the three-phase power source cannot be detected. 
         [0078]    With the means and construction as above, power source information necessary for controlling can be detected through the use of the voltage dividing resistor alone and so, reduction in the circuit cost and improvements in the control performance can be contrived. Further, in applying the present invention to global products, power source information (power source frequency, phase sequence, power source voltage and the like) for each region need not be set in advance and accordingly, general-purpose utility and reliability of the apparatus can be improved. 
         [0079]    Further, by using an external analog comparator in place of the microcomputer with internal A/D, the phase can also be detected through comparison of the voltage signal detected from the voltage dividing resistor  109  with a voltage level value. In such a construction, the A/D converter is not used and data processing inside the microcomputer can be simplified, the use of an inexpensive low-functional microcomputer can be permitted. 
       Embodiment 3 
       [0080]    Referring to  FIG. 12 , a motor driving apparatus according to a third embodiment of the present invention is configured as illustrated therein. 
         [0081]    A converter portion adapted to convert three-phase AC to DC is the same as that shown in  FIG. 1 . An inverter  100  and an inverter controller  101  are used on the DC output side of a converter circuit to drive a motor  102 . 
         [0082]    A converter/inverter controller  105  uses a single microcomputer. By using voltage dividing resistors  109  and  120 , a shunt resistor  121  and an amplifier  122 , a power source phase, a DC voltage and an output current of the inverter are detected which in turn are processed by the converter/inverter controller  105  so as to control the converter and inverter. 
         [0083]    With this configuration, the microcomputer for control and the substrate can be shared and so, the cost and volume of the whole of a product can be reduced. Also, since information for control of inverter and that for converter can be shared, the overall control performance can be improved. 
       Embodiment 4 
       [0084]      FIG. 13  shows a form of a final product by diagrammatically illustrating an external view of a motor driving module  200  according to a fourth embodiment of the present invention. 
         [0085]    The module  200  is a motor driving module in which a semiconductor device representing a power module is carried on a controller substrate  201 , and the controller substrate  201  is packaged with the voltage/current detection circuit and the controller described in connection with the previously described embodiment. Corpuscular formation is achieved by module and the cost of apparatus can be reduced. It is to be understood that the module is meant by “a normalized constituent unit” and is constituted by separable parts of hardware/software. From the standpoint of fabrication, parts are preferably structured on the same substrate but this is not limitative. Thus, parts may be structured on a plurality of circuit substrates built in the same chassis. 
         [0086]    According to the present embodiment, the cost and volume of the overall product can be reduced and therefore, the general purpose and utility convenience of the motor driving apparatus using the module of the present embodiment can be improved. 
       Embodiment 5 
       [0087]    Referring to  FIG. 14 , a refrigerating apparatus such as an air conditioner, a refrigerator or the like according to a fifth embodiment of the present invention, having its compressor motor driven by using the aforementioned motor driving module, is constructed as illustrated therein. 
         [0088]    The refrigerating apparatus  300  is an apparatus for harmonizing temperatures and comprises heat exchangers  301  and  302 , fans  303  and  304 , a compressor  305 , a piping  306  and a motor driving unit  307 . As an compressor motor  308 , a permanent magnet synchronous motor or a three-phase induction motor is used which is arranged inside the compressor  305 . The motor driving unit  307  converts AC power source to DC which in turn is supplied to a motor driving inverter so as to drive the motor. 
         [0089]    By using the converter/inverter module according to the fourth embodiment, higher harmonics in the power source current can be reduced and the power factor can be improved at low costs by adopting even a small size AC reactor and a general-purpose diode and therefore, clearing the higher harmonics regulations can be realized. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               1  Three-phase AC power source 
               2  Three-phase AC reactor 
               3  Three-phase diode bridge 
               4  Smoothing capacitors 
               5  Reactor 
               6 ,  7  Flywheel diodes 
               8  DC load 
               9  Power source phase detection means 
               10  Both-way energizing switch 
               11 ,  111  Controllers 
               12  Single-phase diode bridge 
               13  Semiconductor power device 
               14  Insulation means 
               15  Driving circuit 
               16  Modulation wave table 
               17  Modulation wave adjuster 
               18  PWM controller 
               19  Adjusting amount table 
               20  Carrier generator 
               21  U-phase power source voltage waveform 
               22  V-phase power source voltage waveform 
               23  W-phase power source voltage waveform 
               24  Modulation waveform corresponding to U-phase 
               25  Modulation waveform corresponding to V-phase 
               26  Modulation waveform corresponding to W-phase 
               27  Energizing current waveform 
               30  Power source phase waveform 
               31  Detection voltage waveform corresponding to U-phase 
               32  Detection voltage waveform corresponding to V-phase 
               33  Detection voltage waveform corresponding to W-phase 
               40  A/D converter 
               41  Comparator 
               42  Rising edge detector 
               43  Phase error operation unit 
               44  PI controller 
               45  Phase operation unit 
               100  Inverter 
               101  Inverter controller 
               102  Motor 
               105  Converter/inverter controller 
               109  Voltage dividing resistor 
               120  Voltage dividing resistor for DC voltage detection 
               121  Shunt resistor 
               122  Amplifier 
               200  Module 
               201  Controller substrate 
               202  Semiconductor device 
               203  Microcomputer 
               300  Refrigerating apparatus 
               301 ,  302  Heat exchangers 
               303 ,  304  Fans 
               305  Compressor 
               306  Piping 
               307  Motor driving unit 
               308  Compressor motor