Abstract:
An electric motor control apparatus including an inverter which drives a motor of an electric motor car, storage unit for storing energy for the motor, and a converter which is connected to the storage unit, the inverter comprising detection unit for detecting a power value of the motor, and transmission unit for transmitting the power value detected by the detection unit to the converter, and the converter comprising calculation unit for receiving the power value transmitted by the transmission unit, and calculating an absorption current on the basis of the received power value, and control unit for controlling the storage unit on the basis of the absorption current calculated by the calculation unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2005-136670, filed May 9, 2005, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an electric motor car control apparatus.  
         [0004]     2. Description of the Related Art  
         [0005]     According to general techniques of electric double layer capacitor series connection in railway vehicles, as disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2003-18702 and “A Study for Electric Double Layer Capacitor Series Connection for Railway Contraction”, 2003 JIASC Conference 3-32, so-called regeneration limiter control is performed in a technique using a VVVF inverter. Regeneration limiter control is performed as follows. When a VVVF inverter is set, during regeneration braking, in a light-load regeneration state in which a load which absorbs regeneration energy on the overhead wire side becomes insufficient, a rise in overhead wire voltage due to a rise in the capacitor voltage of the VVVF inverter is detected, and the rise in overhead wire voltage is suppressed by reducing the regeneration braking force in accordance with the capacitor voltage. In this case, when the regeneration braking force is reduced, the reduced braking force is compensated for by the force generated by a mechanical brake. A DC/DC converter which performs charging control on a power storage device detects a light-load regeneration state upon a rise in the capacitor voltage of the DC/DC converter during braking, and controls a charging current to the power storage device so as to suppress a rise in capacitor voltage. The amount of power absorbed in the power storage device by the DC/DC converter and the regeneration braking force reduction control amount by VVVF regeneration limiter control are based on the respective filter capacitor voltages. In addition, control is performed to make an input current to the VVVF invert equal to an input current to the DC/DC converter. Alternatively, control is performed to make an input current to the overhead wire zero.  
         [0006]     According to the above technique, the DC/DC converter detects a light-load regeneration state upon a rise in the capacitor voltage of the DC/DC converter during braking, and controls a charging current to the power storage device so as to suppress a rise in capacitor voltage. At this time, the amount of power absorbed in the power storage device by the DC/DC converter and the regeneration braking force reduction control amount by VVVF regeneration limiter control are determined by the respective filter capacitor voltages without direct control of them. For this reason, absorbed energy becomes insufficient or excessive with respect to energy corresponding to a regeneration load shortage due to capacitor voltage detection errors and voltage differences, resulting in failure to effectively absorb energy.  
         [0007]     Although control is performed to make an input current with a VVVF equal to an input current to the DC/DC converter or control is performed to make an input current to the overhead wire zero, it is difficult in this method to discriminate a load state on the overhead wire side, and regeneration energy which can be returned to the overhead wire side may be absorbed by the power storage device through the DC/DC converter.  
         [0008]     If absorbed energy is insufficient relative to energy corresponding to a regeneration load shortage, the overhead wire voltage rises, and VVVF regeneration limiter control operates to reduce the regeneration braking force. As a result, compensation by the mechanical brake is executed. In contrast to this, when absorbed energy becomes excessive, energy that can be returned to the overhead wire side is absorbed by the power storage device. Since the absorption capacity of the power storage device is limited, absorption cannot be continued.  
         [0009]     In either of the above cases, the capacity of the VVVF power storage device cannot be used fully. That is, absorption cannot be effectively performed.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     In consideration of the above point, it is an object of the present invention to provide an electric motor car control apparatus which can effectively absorb power in a power storage device while keeping a balance between energy corresponding to a regeneration load shortage and absorbed energy.  
         [0011]     In order to achieve the above object, according to an aspect of the present invention, there is provided an electric motor control apparatus comprising an inverter which drives a motor of an electric motor car, storage means for storing energy for the motor, and a converter which is connected to the storage means, the inverter comprising detection means for detecting a power value of the motor, and transmission means for transmitting the power value detected by the detection means to the converter, and the converter comprising calculation means for receiving the power value transmitted by the transmission means, and calculating an absorption current on the basis of the received power value, and control means for controlling the storage means on the basis of the absorption current calculated by the calculation means.  
         [0012]     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0013]     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
         [0014]      FIG. 1  is an external view showing an electric motor car comprising an electric motor car control apparatus according to a first embodiment of the present invention;  
         [0015]      FIG. 2  is a block diagram showing the arrangement of the electric motor car control apparatus;  
         [0016]      FIG. 3  is a block diagram showing the arrangements of a VVVF inverter and a DC/DC converter and signal processing;  
         [0017]      FIG. 4  is a graph showing the relationship between the motor torque, velocity, and power of the electric motor car;  
         [0018]      FIG. 5  is a graph showing the relationship between an absorption current and power;  
         [0019]      FIG. 6  is a block diagram showing the arrangements of the VVVF inverter and DC/DC converter of an electric motor car control apparatus according to a second embodiment of the present invention;  
         [0020]      FIG. 7  is a graph showing the relationship between a regeneration brake choke amount α and an operation start voltage set value (regeneration limiter start voltage value) V 1  of a filter capacitor voltage value;  
         [0021]      FIG. 8  is a graph showing the relationship between an absorption current and a VVVF inverter capacitor voltage;  
         [0022]      FIG. 9  is a block diagram showing the arrangements of the VVVF inverter and DC/DC converter of an electric motor car control apparatus according to a third embodiment of the present invention;  
         [0023]      FIG. 10  is a graph showing the relationship between an absorption current and a DC/DC converter capacitor voltage;  
         [0024]      FIG. 11  is a block diagram showing the arrangements of the VVVF inverter and DC/DC converter of an electric motor car control apparatus according to a fourth embodiment of the present invention;  
         [0025]      FIG. 12  is a graph showing the relationship between an absorption current and a DC/DC converter capacitor voltage;  
         [0026]      FIG. 13  is a schematic view showing the arrangement of an electric motor car control apparatus according to a fifth embodiment of the present invention; and  
         [0027]      FIG. 14  is a schematic view showing the arrangement of an electric motor car control apparatus according to a sixth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]     An embodiment of the present invention will be described below with reference to the views of the accompanying drawing.  
       First Embodiment  
       [0029]      FIG. 1  is an external view showing an electric motor car comprising an electric motor car control apparatus according to a first embodiment of the present invention.  
         [0030]     As shown in  FIG. 1 , an electric motor car  10  receives electricity from an overhead wire  21  through a pantograph  1 . The received electricity is input to an electric motor car control apparatus  20 .  
         [0031]      FIG. 2  is a block diagram showing the arrangement of the electric motor car control apparatus  20 .  
         [0032]     The electric motor car control apparatus  20  comprises the pantograph  1 , a contactor  2 , a filter reactor  3 , a VVVF inverter  4 , a DC/DC converter  6 , a motor  7 , a reactor  8 , a wheel  9 , and a power storage device  11 . Let V F , V D , and V E  be the voltages to be respectively applied to the VVVF inverter  4 , DC/DC converter  6 , and power storage device  11 , and I E  be the current flowing from the DC/DC converter  6  to the power storage device  11 .  
         [0033]     The operation of the electric motor car control apparatus  20  having the above arrangement will be described below.  
         [0034]      FIG. 3  is a block diagram showing the arrangements of the VVVF inverter  4  and DC/DC converter  6  and signal processing.  
         [0035]     The VVVF inverter  4  comprises a detection/control device  4   a . The detection/control device  4   a  receives a VVVF inverter filter capacitor voltage value  100 , the velocity information of the electric motor car, the torque information of the motor, a regeneration brake command  105 , and the like. The detection/control device  4   a  calculates regeneration brake choke amount information  103  from the input information, and outputs, to the motor  7 , a value obtained by subtracting the regeneration brake choke amount information  103  from the regeneration brake command  105  as a motor torque command, thereby controlling the motor  7 .  
         [0036]     The detection/control device  4   a  also calculates a power P from the input information by using the following equation, as shown in  FIG. 4 . 
 
(torque of motor)*(velocity of electric motor car)=power  P  
 
         [0037]     The detection/control device  4   a  outputs power P information  102  to a detection/control device  6   a  which the DC/DC converter  6  comprises. A DC/DC converter filter capacitor voltage value  101  is input to the detection/control device  6   a . In addition, a charging voltage value  110  is input from the power storage device  11  to the detection/control device  6   a.    
         [0038]     The detection/control device  6   a  calculates an absorption current I from the input information by using the following equation, as shown in, for example,  FIG. 5 . 
 
(power  P )/(charging voltage from power storage device)=absorption current  I  
 
         [0039]     Upon calculating the absorption current I, the detection/control device  6   a  outputs the absorption current I as an absorption current command  104  to the power storage device  11  to control the power storage device  11 .  
         [0040]     With the above operation, the DC/DC converter is made to operate in accordance with various kinds of information detected by the VVVF inverter, thereby allowing the power storage device to effectively absorb power while keeping a balance between energy corresponding to a regeneration load shortage and absorbed energy.  
       Second Embodiment  
       [0041]     An electric motor car control apparatus according to a second embodiment of the present invention will be described next with reference to FIGS.  6  to  8 . The same reference numbers as in the first embodiment denote the same parts in the second embodiment, and a detailed description thereof will be omitted.  
         [0042]     The second embodiment differs from the first embodiment in that a detection/control device  4   a  of a VVVF inverter  4  outputs no information to a detection/control device  6   a  of a DC/DC converter  6 , and an absorption start voltage value V 3  of a DC/DC converter filter capacitor voltage value  101  with respect to a power storage device  11  is set in advance to be equal to an operation start voltage set value (regeneration limiter start voltage value) V 1  of a filter capacitor voltage value  100 .  
         [0043]      FIG. 7  shows the relationship between a regeneration brake choke amount α and the operation start voltage set value (regeneration limiter start voltage value) V 1  of the filter capacitor voltage value  100 . As in the first embodiment, the DC/DC converter filter capacitor voltage value  101  is input to the detection/control device  6   a.    
         [0044]     As shown in  FIG. 8 , the detection/control device  6   a  of the DC/DC converter  6  sets the absorption start voltage value V 3  of the DC/DC converter filter capacitor voltage value  101  with respect to the power storage device  11  to be equal to the value of V 1 . The detection/control device  6   a  then calculates an absorption current I on the basis of the DC/DC converter filter capacitor voltage value  101 , and outputs it as the absorption current command  104  to the power storage device  11 , thereby controlling the power storage device  11 .  
         [0045]     The above operation makes it possible to ensure proper balance and cooperation between regeneration energy from the VVVF inverter and absorbed power by the DC/DC converter, thereby solving problems in terms of shortage or excess of absorbed energy.  
       Third Embodiment  
       [0046]     An electric motor control apparatus according to a third embodiment of the present invention will be described next with reference to  FIGS. 9 and 10 . The same reference numbers as in the first embodiment denote the same parts in the third embodiment, and a detailed description thereof will be omitted.  
         [0047]     The third embodiment differs from the first embodiment in that information output from a detection/control device  4   a  of a VVVF inverter  4  to a detection/control device  6   a  of a DC/DC converter  6  is different from regeneration brake choke amount information  103 .  
         [0048]     The DC/DC converter  6  further comprises a predetermined value detection unit  6   b . The predetermined value detection unit  6   b  outputs a correction command for correcting an absorption start voltage value V 3  to a value V 3 ′ to the detection/control device  6   a  of the DC/DC converter  6  on the basis of the input regeneration brake choke amount information  103  (see  FIG. 10 ). The predetermined value detection unit  6   b  is set to output a correction command to the detection/control device  6   a  of the DC/DC converter  6  if, for example, α&gt;0 (regeneration brake choke amount α).  
         [0049]     The detection/control device  4   a  of the VVVF inverter  4  outputs the regeneration brake choke amount a as the regeneration brake choke amount information  103  to the detection/control device  6   a  of the DC/DC converter  6 . At the same time, an operation start voltage set value V 1  is output to the detection/control device  6   a  of the DC/DC converter  6 . As in the first embodiment, a DC/DC converter filter capacitor voltage value  101  is input to the detection/control device  6   a.    
         [0050]     As shown in  FIG. 10 , the detection/control device  6   a  of the DC/DC converter  6  sets and controls the absorption start voltage value V 3  of the DC/DC converter filter capacitor voltage value  101  for the power storage device  11  to be equal to the value of V 1  on the basis of the input regeneration brake choke amount information  103 , operation start voltage set value V 1 , and DC/DC converter filter capacitor voltage value  101 . The detection/control device  6   a  calculates an absorption current I on the basis of the DC/DC converter filter capacitor voltage value  101 , and outputs it as an absorption current command  112  to a power storage device  11 , thereby controlling the power storage device  11 .  
         [0051]     In the above state, if the predetermined value detection unit  6   b  discriminates, on the basis of the regeneration brake choke amount information  103  input to the predetermined value detection unit  6   b , that, for example, α&gt;0 (regeneration brake choke amount α), a correction command for correcting the absorption start voltage value V 3  to the value V 3 ′ is output to the detection/control device  6   a  of the DC/DC converter  6 . Upon receiving the correction command, the detection/control device  6   a  of the DC/DC converter  6  corrects the absorption start voltage value V 3  to the value V 3 ′, as shown in  FIG. 10 .  
         [0052]     That is, when regeneration limiter control is started upon a rise in the capacitor voltage of the VVVF inverter  4 , the VVVF inverter  4  outputs the regeneration brake choke amount information  103  to the DC/DC converter  6 . If the value of the regeneration brake choke amount exceeds a predetermined value, the DC/DC converter  6  corrects the absorption start voltage value V 3  so as to decrease it to the value V 3 ′. As a consequence, the capacitor voltage of the VVVF inverter becomes lower than the capacitor voltage of the DC/DC converter  6 , and the operation of the DC/DC converter  6  is started to start absorption in the power storage device  11 .  
         [0053]     With the above operation, if the capacitor voltage of the VVVF inverter is higher than that of the DC/DC converter, power absorption by the DC/DC converter by only VVVF regeneration limiter control can be prevented, thereby eliminating the problem of insufficient power absorption by performing regeneration limiter control operation using the VVVF inverter in synchronism with power absorption control operation by the DC/DC converter.  
       Fourth Embodiment  
       [0054]     An electric motor car control apparatus according to a fourth embodiment of the present invention will be described next with reference to  FIGS. 11 and 12 . The same reference numbers as in the third embodiment denote the same parts in the fourth embodiment, and a detailed description thereof will be omitted.  
         [0055]     The fourth embodiment differs from the third embodiment in that regeneration brake choke amount information  103  output from a detection/control device  4   a  of a VVVF inverter  4  to a detection/control device  6   a  of a DC/DC converter  6  is a digital signal.  
         [0056]     For this reason, the DC/DC converter  6  does not comprise a predetermined value detection unit  6   b . In contrast, the VVVF inverter  4  comprises a predetermined value detection unit  4   b.    
         [0057]     With the above arrangement, an operation command  120  is transmitted as a digital signal from the VVVF inverter  4  to the DC/DC converter  6 .  
         [0058]     When regeneration limiter control is started upon a rise in the capacitor voltage of the VVVF inverter  4 , the VVVF inverter  4  transmits the operation command  120  as a digital signal to the DC/DC converter  6  through the predetermined value detection unit  4   b . As shown in  FIG. 12 , upon receiving the operation command  120 , the DC/DC converter  6  calculates an absorption current I 2 , and outputs it as an absorption current command  114  to a power storage device  11 , thereby controlling the power storage device  11 .  
         [0059]     With the above operation, the start of regeneration limiter control using the VVVF inverter  4  can be synchronized with the start of power absorption by the DC/DC converter  6 , thereby preventing the occurrence of insufficient power absorption. In addition, using a digital signal as the operation command  120  makes it possible to simplify the arrangement of the DC/DC converter  6 .  
       Fifth Embodiment  
       [0060]     An electric motor control apparatus according to a fifth embodiment of the present invention will be described next with reference to  FIG. 13 .  
         [0061]     In the fifth embodiment, as shown in  FIG. 13 , both the absorption current command  104  in the first embodiment and the absorption current command  114  in the fourth embodiment are used.  
         [0062]     The absorption current command  104  and the absorption current command  114  can be switched by using a switch  116 , and each command can be output as an output absorption current command  130 . If, for example, the switch  116  switches the commands to output the absorption current command  104 , the output absorption current command  130  becomes a power running command. If the switch  116  switches the commands to output the absorption current command  114 , the output absorption current command  130  becomes a regeneration command. The output absorption current command  130  is then output to a power storage device  11  to control it.  
         [0063]     With the above operation, in addition to the effects of the first and fifth embodiments, the power storage device can be controlled by switching the embodiments of power running and regeneration.  
       Sixth Embodiment  
       [0064]     An electric motor control apparatus according to a sixth embodiment of the present invention will be described next with reference to  FIG. 14 .  
         [0065]     In the sixth embodiment, as shown in  FIG. 14 , both the absorption current command  104  in the first embodiment and the absorption current command  112  in the second embodiment are used.  
         [0066]     The absorption current command  104  and the absorption current command  112  are subjected to addition processing by using an adder  118 , and the resultant information is output as an output absorption current command  140 . The output absorption current command  140  is then output to a power storage device  11  to control the power storage device  11 .  
         [0067]     With the above operation, in addition to the effects of the first and second embodiments, the power storage device can be controlled on the basis of the absorption current commands in the first and second embodiments.  
         [0068]     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.