Abstract:
A detecting means easily detects the abnormality of a generator having a plurality of power supply units. Each of the power supply units includes one of a plurality of output windings L1 to L4, which are wound independently of each other around single iron core, and one of rectifiers 2 to 5 that are provided in correspondence to the output windings and produces an integrated output. Controllers 33 to 35 control the rectifiers such that the output voltage corresponds with a target. A voltage deviation judgment section 37 outputs the abnormal signal when one of the output voltages of the rectifiers 2 to 5 is different from remains. A current deviation judgment section 39 outputs the abnormal signal when one of the output currents of the rectifiers 2 to 5 is different from remains. When the abnormal signal is detected, the outputs of the rectifiers 2 to 5 are stopped.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a generator and, in particular, to a generator capable of outputting a comparatively large direct current and detecting the occurrence of an abnormality with ease.  
         [0003]     2. Description of the Related Art  
         [0004]     A generator driven by an engine or the like has been conventionally widely employed as the power supply of an electric appliance especially used for outdoor works and for leisure-time activities. Further, in recent years, the uses of the generator are spreading also to the back-up power supply, that is, the so-called uniterruptible power supply (UPS) for computers and the like. When the generator of this kind is constructed as a generator for outputting a direct current, there is a tendency that the generator is required to be small in size and to be able to output a comparatively low voltage and a large current. In the generator required to output a large current like this, a larger size of wire for an output winding is needed and a higher level of consideration is required to be given also to a dielectric breakdown voltage between windings and a material for insulator.  
         [0005]     Hence, the present applicant proposed a generator that could be reduced in the wire diameter of an output winding and could be reduced in the capacity of a power device (Japanese Utility Model Registration No. 2511843). In a device in accordance with this registered utility model, a plurality of power supply units independent of each other are formed, respectively, of a plurality of output windings that are wound independently of each other around the same iron core and thyristor bridge rectifier circuits connected to the plurality of output windings, and the outputs of the power supply units are connected in parallel, thereby being integrated into one output.  
         [0006]     In the device disclosed in the above patent document, a plurality of power supply units that have a power generating source in common are connected in parallel. Hence, there is presented a problem that when an abnormality occurs in any one of the plurality of power supply units, it is not easy to find the occurrence of the abnormality by a detecting system on the output side of the generator.  
       SUMAMRY OF THE INVENTION  
       [0007]     The object of the present invention is to provide a generator capable of solving the above problem and detecting an abnormality in a plurality of power supply units with ease and with reliability.  
         [0008]     The first characteristic of the present invention is that a generator so constructed as to have a plurality of power supply units which are independent respectively and each of which has one of a plurality of output windings that are wound independently of each other around a single iron core and each of which has a rectifier circuit including a rectifier device with control terminals connected to respective phases of one of the plurality of output windings, wherein the plurality of power supply units are connected in parallel so as to integrate their outputs into one output, current detecting means that detects an output current of each of the rectifier circuits, current judgment means that examines each of the output currents detected by the current detecting means and out puts a current abnormality detecting signal when a difference between one of the output currents and at least one of the other remaining output currents is larger than a predetermined value; and output stopping means that stops outputs of all of the rectifier circuits in response to the current abnormality detecting signal.  
         [0009]     The second characteristic of the present invention is that a generator so constructed as to have a plurality of power supply units which are independent respectively and each of which has one of a plurality of output windings that are wound independently of each other around a single iron core and each of which has a rectifier circuit including a rectifier device with control terminals connected to respective phases of one of the plurality of output windings, wherein the plurality of power supply units are connected in parallel so as to integrate their outputs into one output, voltage detecting means that detects an output voltage of each of the rectifier circuits, voltage judgment means that examines each of the output voltages detected by the voltage detecting means and outputs a voltage abnormality detecting signal when a difference between one of the output voltages and at least one of the other remaining output voltages is larger than a predetermined value; and output stopping means that stops outputs of all of the rectifier circuits when the voltage judgment means detects an abnormality.  
         [0010]     The third characteristic of the present invention is that said generator further comprising means that stops the engine when at least one of the current detecting means still detects an output current after the output stopping means stops outputs of the rectifier circuits.  
         [0011]     According to the present invention, it is possible to detect an abnormality with ease by determining whether or not the outputs of the rectifier circuits of the plurality of power supply units are different from each other. In particular, according to the first characteristic, when a load is applied, it is possible to detect an abnormality on the basis of the output currents of the rectifier circuits. Moreover, according to the second characteristic, even in a case where a current is not detected when a load is not applied, it is possible to detect an abnormality on the basis of the output voltages of the rectifier circuits.  
         [0012]     According to the third characteristic of the present invention, when an abnormality is detected, it is possible to stop the outputs of the plurality of rectifier circuits at the same time with ease and with reliability. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a connection diagram (No. 1) relating to the main portion of a generator in accordance with an embodiment of the present invention.  
         [0014]      FIG. 2  is a connection diagram (No. 2) relating to the main portion of the generator in accordance with the embodiment of the present invention.  
         [0015]      FIG. 3  is a block diagram showing the main function of control section of the generator in accordance with the embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     An embodiment of the present invention will be described below in detail with reference to the drawings.  FIG. 1  is a construction diagram of the main portion of a portable generator in accordance with an embodiment of the present invention. In  FIG. 1 , the stator  1  of a generator body consists of four output windings L 1 , L 2 , L 3 , and L 4  those are independent of each other and an auxiliary winding L 5  independent of these output windings L 1  to L 4 , wherein the four output windings L 1 , L 2 , L 3 , and L 4  and the auxiliary winding L 5  are wound around the protruding poles of a single stator iron core (not shown). The output windings L 1  to L 4  are equal to each other in the number of windings and in the diameter of the wire, that is, identical in specifications.  
         [0017]     The stator  1  is disposed in the center of the generator body and a rotor having a plurality of magnets disposed annularly, that is, an outer rotor is commonly arranged on the outer periphery of the stator  1 . The rotor is connected to a driving unit (that is here thought to be an engine) and is driven by the engine so as to rotate along the outer periphery of the stator  1 .  
         [0018]     The output windings L 1 , L 2 , L 3 , and L 4  are connected to three-phase rectifier bridge circuits  2 ,  3 ,  4 , and  5 , respectively, each of which is constructed of rectifier devices having control terminals (thyristors) and diodes. Symbols showing the thyristors and the diodes in the drawing are well known and hence are not denoted by reference numerals for the purpose of avoiding the drawings from being complicated. Smoothing capacitors  6 ,  7 ,  8 , and  9  are provided on the outsides of the three-phase rectifier bridge circuits  2 ,  3 ,  4 , and  5 , respectively. The plus-side output lines of the three-phase rectifier bridge circuits  2 ,  3 ,  4 , and  5  are integrated into one line and connected to a plus-side output terminal  10  and the minus-side output lines thereof are integrated into one line and connected to a minus-side output terminal  11 .  
         [0019]     Shunts  12 ,  13 ,  14 , and  15  are connected to the respective plus-side output lines before the plus-side output lines are integrated into one line. A potential difference across both ends of each of the shunts  12 ,  13 ,  14 , and  15  is inputted as a signal showing each of output currents Id 1 , Id 2 , Id 3 , and Id 4  of the three-phase rectifier circuits  2 ,  3 ,  4 , and  5  to a microcomputer, that is, a controller  16  (see  FIG. 2 ). A potential difference across both ends of each of the capacitors  6 ,  7 ,  8 , and  9  is inputted as each of output voltages Vd 1 , Vd 2 , Vd 3 , and Vd 4  of the three-phase rectifier circuits  2 ,  3 ,  4 , and  5  to the controller  16 .  
         [0020]     A fuse  17  is provided in a line into which the respective plus-side output lines are integrated. The fuse  17  is selected so as to allow the maximum value of the added value of the respective output currents of the three-phase rectifier bridge circuits  2 ,  3 ,  4 , and  5 . A diode  18  is interposed between the upstream side of the fuse  17  of the one line, into which the plus-side output lines are integrated, and at least one line (two lines in the example shown in  FIG. 1 ) of the four minus-side output lines. For example, when a battery  19  of a load is connected in reverse polarity by mistake, a current from a load side passes through one line, into which the output lines are integrated, via this diode  18 . Hence, this can prevent a current from passing from a load connected in reverse polarity to the respective three-phase rectifier bridge circuits  2  to  5  having a smaller allowable current than this output lines.  
         [0021]     The battery  19  and a UPS  20  are connected to the output terminal  10  on the plus side and the output terminal  11  on the minus side. The output side of the UPS  20  is connected to an electronic unit (not shown), for example, a computer system. A commercial AC power supply  21 , for example, is connected to the UPS  20  and the battery  19  is always charged with this commercial AC power supply  21 . The portable generator of the present embodiment is connected to the UPS  20  to supply the UPS  20  and the battery  19  with power in the event of a failure of the commercial AC power supply  21  or the like. Batteries of different rated voltages of 48 V and 36 V, for example, can be selectively connected as the battery  19 .  
         [0022]      FIG. 2  is a connection diagram of a controller and its peripheral parts. The auxiliary winding L 5  is connected to a constant-voltage circuit  22 . The constant-voltage circuit  22  includes positive/negative (+5 V and −5 V) regulators  221 ,  222  with three terminals and generates DC power supply voltages stabilized at +5 V and −5 V by the voltage applied by the auxiliary winding L 5 . This DC power supply voltages are used as the power supply of the controller  16 . Moreover, the output waveform of the auxiliary winding L 5  is supplied as a signal for detecting the rotation of the rotor of the generator body to the controller  16 . An EEP-ROM  23  for storing data used by the controller  16  is connected to the controller  16 .  
         [0023]     The controller  16  outputs thyristor control signals (gate pulses)  16   a ,  16   b , and  16   c  for turning on and off the respective thyristors of each of the three-phase rectifier bridge circuits  2 ,  3 ,  4 , and  5 , as shown in  FIG. 1 . These gate pulses  16   a ,  16   b , and  16   c  are supplied to the gate terminals, that is, the control terminals of the respective thyristors. Each of the three-phase rectifier bridge circuits  2 ,  3 ,  4 , and  5  is provided with three thyristors corresponding to the respective phases U, V, and W of each of the output windings L 1  to L 4 , and the thyristors corresponding to the respective phases are controlled by these gate pulses  16   a ,  16   b , and  16   c  common to the three-phase rectifier bridge circuits  2 ,  3 ,  4 , and  5 . Hence, the three-phase rectifier bridge circuits  2 ,  3 ,  4 , and  5  are controlled in synchronization with each other by the gate pluses  16   a ,  16   b , and  16   c.    
         [0024]     To control the opening or closing of the throttle valve of the engine for driving the outer rotor by a stepping motor (not shown), the controller  16  outputs motor driving signals  16   d ,  16   e ,  16   f , and  16   g  to this stepping motor.  
         [0025]     An output stop switch  24  is a switch for stopping the portable generator in this embodiment from outputting generated power. When this output stop switch  24  is held pressed for a predetermined time, the gate pulses  16   a ,  16   b , and  16   c  are stopped by the ON signal  16   h  of this switch  24 , whereby the outputting of power is stopped. However, only the outputting of the generated power is stopped by this operation of the output stop switch  24  and the engine is not stopped only by the operation of this output stop switch  24 .  
         [0026]     A voltage selector switch  25  is a switch for setting an output voltage according to a connected load (battery  19  or the like). For example, when the voltage selector switch  25  is turned ON (selecting signal  16   i  is ON), a voltage of 36 V is set as an output voltage, and when the voltage selector switch  25  is turned OFF (selecting signal  16   i  is OFF), a voltage of 48 V is set as an output voltage.  
         [0027]     There are provided an output indicating light  26 , an overload indicating light  27 , and an oil-alert indicating light  28 . The oil-alert indicating light  28  is connected to the controller  16  through an oil-alert circuit  29 . The output indicating light  26  is turned on while power is generated and outputted. The overload indicating light  27  is turned on in the case of an overload, that is, in the case of an over-current or an over-voltage.  
         [0028]     There is provided a circuit section  30  of a transistor type magnet ignition unit. A well-known unit can be used as the main portion of the transistor type magnet ignition unit. The grounding line of the circuit section  30  of a transistor type magnet ignition unit and the grounding line of the oil-alert circuit  29  are connected to the terminal G of the controller  16 . The other line of the circuit section  30  is connected to the coil part  31  of the ignition unit. An ignition plug  32  is connected to the secondary side of the coil part  31 . The other terminal of the oil-alert circuit  29  is connected to the terminal LS of the controller  16 . The terminals G and LS of the controller  16  are constructed to be short-circuited in the controller  16  so as to stop ignition.  
         [0029]     The operation of the generator body will be described. The generator is started by the use of a recoil starter coupled to the engine of the driving source of the generator. When the recoil starter is pulled, the crankshaft of the engine is rotated and hence the rotor coupled to the crankshaft is rotated to develop a voltage in the auxiliary winding L 5 , and this voltage develops a predetermined voltage in the constant-voltage circuit  22 . When the controller  16  has this voltage applied thereto, the controller  16  can start a controlling operation.  
         [0030]     When the engine is rotated by the recoil starter, the engine is ignited by the ignition unit, whereby the generator is started. The windings L 1  to L 4  and L 5  of the generator start generating power and the generated powers are integrated and outputted as generated power from the output terminals  10 ,  11 . This power is supplied to the battery  19  and the UPS  20 .  
         [0031]     When the generated power is outputted, the output indicating light  26  is energized. Further, in the event of an over-current or an over-voltage, the overload indicating light  27  is energized. Still further, when it is determined by a well-known method that the oil of the engine is decreased to a level lower than a predetermined required value, the oil-alert circuit  29  is operated to energize the oil-alert indicating light  28 . For example, the oil-alert circuit  29  is a switching circuit constructed such that a current passes through the oil-alert indicating light  28  according to a signal from the terminal LS. Further, when the oil decreases or an abnormality occurs in the power generating system, which will be described later, the controller  16  short-circuits the terminals LS and G in the controller  16  to stop igniting.  
         [0032]     In this embodiment, the outputs of four power generating sections (power supply units) each including the windings and the rectifier circuit are integrated, that is, superimposed to the final output. When an abnormality occurs in the individual power supply units, the abnormality can be coped with in the following manner.  
         [0033]      FIG. 3  is a block diagram showing the function of the controller  16  to cope with the abnormality. In a voltage setting section  33 , a target value Vref of the output voltage Vout of the generator (voltage across the terminals  10  and  11 ) is previously set and stored. The target value Vref is switched according to the selection of the voltage selector switch  25 . A deviation computing section  34  computes a deviation ΔV of the output voltage Vout of the generator with respect to the target value Vref inputted by the voltage setting section  33 . The output voltage Vout can be typified by any one of the voltages Vd 1 , Vd 2 , Vd 3 , and Vd 4 . The computed deviation ΔV is inputted to a gate pulse generator  35 . The gate pulse generator  35  has a proportion control function of determining a gain proportional to this deviation ΔV so as to cancel the deviation ΔV. The gate pulse generator  35  determines the conduction angle of the thyristor according to this gain and produces a gate pulse corresponding to this conduction angle. This gate pulse is supplied to the three-phase bridge circuits  2 ,  3 ,  4 , and  5 , whereby the thyristors of the three-phase bridge circuits  2 ,  3 ,  4 , and  5  are controlled at the same time.  
         [0034]     A voltage comparing section  36  compares the output voltages Vd 1 , Vd 2 , Vd 3 , and Vd 4  of the three-phase bridge circuits  2 ,  3 ,  4 , and 5  to compute the differences between them. A voltage deviation judgment section  37  determines whether or not the differences between the output voltages Vd 1 , Vd 2 , Vd 3 , and Vd 4  computed by the voltage comparing section  36  are within a predetermined range and outputs an abnormality detecting signal when at least one of the differences is out of the planed range. That is, when one of the voltages Vd 1 , Vd 2 , Vd 3 , and Vd 4  is largely different from at least one of the remaining differences, the voltage deviation judgment section  37  determines that an abnormality such as a break in the wiring occurs in any one of the power generating systems and outputs an abnormality detecting signal.  
         [0035]     The determination of an abnormality by the difference between the voltages is useful in that the abnormality can be detected even when a current cannot be detected in the case of no-load operation.  
         [0036]     A current comparing section  38  compares the output currents Id 1 , Id 2 , Id 3 , and Id 4  of the three-phase bridge circuits  2 ,  3 ,  4 , and  5  to compute the differences between them. A current deviation judgment section  39  determines whether or not the differences between the output currents Id 1 , Id 2 , Id 3 , and Id 4  computed by the current comparing section  38  are within a predetermined range and outputs an abnormality detecting signal when at least one of the differences is out of the predetermined range. That is, when one of the currents Id 1 , Id 2 , Id 3 , and Id 4  is largely different from at least one of the remaining differences, the current deviation judgment section  39  determines that an abnormality occurs in any one of the power generating systems and outputs an abnormality detecting signal.  
         [0037]     In this regard, the determination of an abnormality is not performed by comparing the output voltages or the output currents of the three-phase bridge circuits  2 ,  3 ,  4 , and  5 , but may be performed by determining whether or not the voltages and the currents are within a predetermined voltage range or a predetermined current range which are base ranges.  
         [0038]     The abnormality detecting signal is inputted to a gate pulse generator  35  from each of the voltage deviation judgment section  37  and the current deviation judgment section  39 . When the abnormality detecting signal is inputted to the gate pulse generator  35 , the gate pulse generator  35  stops outputting the gate pulse, in other words, the outputs of the three-phase bridge circuits  2 ,  3 ,  4 , and  5  are stopped.  
         [0039]     The abnormality detecting signal is inputted also to a current judgment section  40 . When the current judgment section  40  has the abnormality detecting signal inputted thereto, the current judgment section  40  determines whether or not the currents Id 1  to Id 4  exist. When the current is detected, the igniting of the engine is stopped. The igniting of the engine is stopped by short-circuiting the terminals LS and G of the controller  16 .  
         [0040]     In this embodiment, when an abnormality is detected in any one of the output current and the output voltage, the output of the rectifier circuit is stopped, and when it is detected that the output current still passes, an ignition stop command is provided.  
         [0041]     In this manner, according to the present embodiment, it is possible to detect the abnormality of the respective power supply units with ease and with reliability and to stop their outputs.