Abstract:
A fan controlling device for a frequency converter, which is applied to a high-power frequency transforming system that installs fans according to the heat dissipating requirements and their switching operation, failure detection and control, and the fan controlling device includes a frequency transformer and a plurality of direct current fans connected to the frequency transforming system, and each fan is installed at a desired position for dissipating heat in a casing of the frequency transformer by locking, sliding tracks, drawing or latching and each fan is connected to a fan controlling device, and a sensor of the fan controlling device detects the temperature of each set temperature point for switching the fans, controlling the operating number and speed of the fans, so as to improve the quantity, position, operability of installed fans as well as reducing the power consumption when the fans are at an idle state.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a frequency converter, and more particularly to a fan control device for a frequency converter that installs heat dissipating fans according to the internal mechanical design and the heat dissipating requirements of the frequency converter and uses the internal temperature change to control the speed of the fans of the frequency converter. 
   2. Description of Prior Art 
   In general, present heat dissipating designs used in a frequency converter system adopt heat dissipating fans to achieve a heat dissipating function, and the positions for installing the heat dissipating fans and the operation control of the fans determine the heat dissipating effect. Thus, good layout design and operation control will enhance the operating performance of the frequency converter. 
   The prior art heat dissipating devices applied to a high-power frequency converter system (over 200 HP) install AC fans. Although it is easier to use AC fans, yet the AC fans can be installed and fixed in a specific direction only and thus constituting a limitation to the mechanical design of the frequency converter system. In other words, the direction and position for installing the AC fans cannot be changed flexibly according to the mechanical design and the heat dissipating requirements. Further, the operation of AC fans requires a fixed voltage supply, but a constant operating speed is usually required. The AC fans cannot be operated at different speeds according to the actual temperature change, and thus these AC fans have a poor speed control capability. If it is necessary to control the speed of an AC fan, a complicated drive circuit will be needed. As a result, the production cost will be increased. In addition, the AC fan is driven by a fixed voltage to maintain a constant speed for its operation even when the frequency converter is at an idle state, and thus wasting unnecessary power consumption at an idle state as well as creating a noise problem. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing shortcomings of the prior art, the inventor of the present invention based on years of experience in the related industry to conduct experiments and modifications, and finally designed a fan control device for a frequency converter to overcome the shortcomings of the prior art structure. 
   The present invention is to overcome the shortcomings of the prior art and avoid the existing deficiencies by installing DC fan modules according to the mechanical design and the required quantity and installing position for dissipating heat and detecting the internal temperature to control or switch each DC fan and monitoring any failure of a DC fan and replacing the failed DC fan in a simple and easy manner. The invention installs and controls the AC fans of a frequency converter system to enhance the installation of the fans and overcome the limitation to the mechanical design. The fan control device for a frequency converter of the invention has the capability of controlling the speed of the fans, saving power at an idle state and providing users a simple, easy, low-priced, small-sized and easy-to-install fan control device for a frequency converter. 
   To achieve the foregoing objective, the fan control device for a frequency converter in accordance with the present invention comprises: 
   a rectification circuit, electrically coupled to an external AC power supply, for converting an AC into a DC output; 
   a DC/DC conversion circuit, electrically coupled to the rectification circuit, for converting a DC operating voltage output; 
   a fan module, electrically coupled to the DC/DC conversion circuit and disposed at each mechanical structure of the frequency converter and an installing area that requires heat dissipation; 
   a fan control circuit, electrically coupled to the DC/DC conversion circuit, for receiving and controlling an operation or a halt of the fan module; and 
   a sensor, electrically coupled to the fan control circuit and disposed at each mechanical structure of the frequency converter and a position that requires heat dissipation; 
   wherein the fan control circuit has a temperature parameter for each mechanical structure of the frequency converter and each position that requires heat dissipation and outputs a control signal to control the speed, quantity, start or stop of a fan according to a temperature change of each mechanical structure of the frequency converter and each position that requires heat dissipation detected by the sensor. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself however may be best understood by reference to the following detailed description of the invention, which describes certain exemplary embodiments of the invention, taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a perspective view of a fan control device according to a preferred embodiment of the invention; 
       FIG. 2  is a partial exploded view of a preferred embodiment of the invention; 
       FIG. 3  is an exploded view of the installing each fan module of a fan control device according to a preferred embodiment of the invention; 
       FIG. 4  is a schematic view of mounting a fan module of a fan control device according to a preferred embodiment of the invention; 
       FIG. 5  is a schematic view of installing a fan module onto a sliding track of a fan control device according to a preferred embodiment of the invention; 
       FIG. 6  is a schematic view of detaching a fan module of a frequency converter according to a preferred embodiment of the invention; 
       FIG. 7  is schematic circuit block diagram of a fan control device according to a preferred embodiment of the invention; 
       FIG. 8  shows a list of the temperature when each fan module is turned on or off according to a preferred embodiment of the invention; 
       FIG. 9  is a schematic view of the heat dissipation according to a preferred embodiment of the invention; and 
       FIG. 10  is another schematic view of the heat dissipation according to a preferred embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The technical characteristics, features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings. 
   Referring to  FIGS. 1 to 6  for the perspective view, the partial exploded view, the exploded view, and different schematic views of a fan control device for a frequency converter in accordance with the present invention respectively, the fan control device for a frequency converter according to a preferred embodiment of the invention comprises: a frequency converter  1  and a first, a second and a third fan modules  2 ,  3 ,  4 , and the temperature of each mechanical structure in the frequency converter  1  determines the operating speeds of the first, second and third fan modules  2 ,  3 ,  4 , so as to achieve the optimal speed control effect as well as the power-saving effect when the frequency converter  1  is at an idle state. The speed control device of the invention is applicable to a high-power frequency converter system (over 200 HP). 
   The frequency converter  1  comprises a casing  11  and a frequency conversion circuit  12  disposed in the casing  11 . The casing  11  further includes a first casing  13  disposed at the top of the casing  11  and a second casing  14  disposed at the bottom of the casing  11 , and both sides of the first casing  13  include a first installing area  15 , and a front end of the second casing  14  includes a second installing area  16  and both sides of the second casing  14  include a third installing area  17  for coupling the first, second and third fan modules  2 ,  3 ,  4 . 
   The first, second and third fan modules  2 ,  3 ,  4  include a first fan module  2  coupled to the first installing area  15 , a second fan module  3  coupled to the second installing area  16 , and a third fan module  4  coupled to the third installing area  17 . The first, second and third fan modules  2 ,  3 ,  4  separately comprise at least one DC fan  21 ,  31 ,  41  with a same specification or a different specification, and the first, second and third fan modules  2 ,  3 ,  4  are coupled into the installing areas  15 ,  16 ,  17  at predetermined positions of the first and second casings  13 ,  14  by a coupling method selected from a locking method, a sliding track method, a detaching method, or a latching method. 
   Referring to  FIGS. 3 and 4  for the locking method, the first installing area  15  of the first casing  13  is used for illustration. A support stand  18  is disposed on an internal side of the first installing area  15 , and the support stand  18  includes a plurality of screw holes  181  to collocate with a locking element  182  such as a screw for directly mounting the fan  21  onto the support stand  18 . The support stand  18  further includes a blocking portion  183  to form a blocking position at an internal end when the fan  21  is installed and prevent the casing  14  from being displaced or fallen out. 
   Referring to  FIGS. 3 and 5  for the sliding track method, the third installing area  17  of the second casing  14  is used for illustration. The sliding track method includes a track  19  and a frame  191  capable of sliding into the track  19 , wherein the track  19  is fixed into the third installing area  17 , and the frame  191  includes a frame body  192  and a frame panel  193 , and the frame body  192  is hollow and collocates with a locking element to fix a DC fan  41  of the third fan module  4  into the frame body  192  and couple the frame body  182  into the track  19  by the frame  191 , and the frame panel  193  seals the entry of the corresponding third installing area  17  or collocates with a locking element for positioning and fixing the locking hole  171  onto a sidewall of the corresponding third installing area  17 . 
   Referring to  FIGS. 3 and 6  for the detaching method, the second installing area  16  of the casing  14  is used for illustration. The detaching method comprises a protective cover  10  and a bracket  101  capable of latching a DC fan  31  to the protective cover  10 , wherein the bracket  101  is fixed onto both sides of a plurality of DC fans  31  of the second fan module  3  and the DC fans  31  are detachably latched into the protective cover  10 , and the protective cover  10  corresponds to the second installing area  16  and is locked and positioned by the locking element. 
   Since the first, second and third fan modules  2 ,  3 ,  4  install DC fans to be applied in a high-power frequency converter  1  (over 200 HP), the installing direction and position of the AC fans can be improved and the problems of a limited structural design, a large volume, a large occupying space can be solved. 
   Further, the volume of DC fans is small, and thus the DC fans can meet the requirements of the mechanical design and heat dissipation for the design of the first, second and third fan modules  2 ,  3 ,  4 . The installing position and quantity of the DC fans can simply the design. 
   As to the control of the operations of the first, second and third fan modules  2 ,  3 ,  4  installed in the frequency converter  1 , a control device  5  is used for the control. Referring to  FIG. 7 , the control device  5  is electrically coupled to each of the first, second and third fan modules  2 ,  3 ,  4 , and the internal temperature change of the first and second casing  13 ,  14  determines the control of the operating mode of the first, second and third fan modules  2 ,  3 ,  4 . In  FIG. 7 , the control device  5  comprises a rectification circuit  51  electrically coupled to a DC/DC conversion circuit  52  of the first, second and third fan modules  2 ,  3 ,  4 , a fan control circuit  53  electrically coupled to the DC/DC conversion circuit, and a plurality of temperature sensors  54  electrically coupled to the fan control circuit  53  for detecting the temperature change at each set temperature point anytime as a control parameter of the control circuit. The rectification circuit  51  is electrically coupled to an external power supply (not shown in the figure) through a connecting line  511  for converting the electric power into a DC power output. 
   The DC/DC conversion circuit  52  is coupled to the rectification circuit  51  for obtaining a high-voltage DC power and converting the power into an operating voltage output required for the first, second and third fan modules  2 ,  3 ,  4 , and the DC/DC conversion circuit  52  is coupled separately to a power line  521 , a fan stall line  522 , and the first, second and third fan modules  2 ,  3 ,  4 , wherein each power line  521  is connected for supplying the operating power for the first, second and third fan modules  2 ,  3 ,  4 , and the fan stall line  522  feeds back a failure signal of the first, second and third fan modules  2 ,  3 ,  4 . 
   The sensor  54  is installed on each component such as a capacitor (OH 1 ), a SCR controller (OH 2 ), a casing (OH 3 ), a right gate bipolar transistor (IGBT) (OH 4 ) and a left gate bipolar transistor (IGBT) (OH 5 ) in the frequency converter  1  for detecting the temperature change of each component and sending the detected temperature signal to the fan control circuit  53 . 
   The fan control circuit  53  is electrically coupled to the first, second and third fan modules  2 ,  3 ,  4  through the DC/DC conversion circuit  52  for transmitting control signals through the fan control line  531  and the fan stall line  532  of different components. The fan control circuit  53  sets a plurality of parameters for the quantity, start and stop of the first, second and third fan modules  2 ,  3 ,  4  corresponding to the temperature change of each temperature point as shown in  FIG. 8 . 
   The temperature points of the temperature change is set by a user according to the mechanical design and the heat dissipating requirements for setting the quantity and position of the detections. In this preferred embodiment, the temperature points for detection include the temperature of a capacitor (OH 1 ), the temperature of a SCR controller (OH 2 ), the temperature of an interior of the casing (OH 3 ), the temperature of a right gate bipolar transistor (IGBT) (OH 4 ) and the temperature of a left gate bipolar transistor (IGBT) (OH 5 ). In other words, each sensor  54  detects a different temperature change of each set temperature point, and then transmits the detected signal to the fan control circuit  53 , so that the fan control circuit  53  can control the start or stop of the first, second and third fan modules  2 ,  3 ,  4  at each temperature point or the fan control circuit  53  can control the different operating speeds, so as to optimize the speed control effect of the fans. When the frequency converter is in an idle state, the first, second and third fan modules  2 ,  3 ,  4  are partially operated to save power consumption. 
   Referring to  FIGS. 9 and 10  for the schematic view of controlling the operation and heat dissipation of a frequency converter by a control circuit of the fan control device for a frequency converter in accordance with the present invention, if the sensor detects the temperature of a capacitor (OH 1 ), the temperature of a SCR controller (OH 2 ) and the temperature of an interior of the casing (OH 3 ) in the first casing  13  that meet the control setup parameter for a start, then the fan control circuit  53  will output a control signal to the first fan module  2  for starting the operation of the fans, and controlling the quantity and speed of the operating fans, so as to start the operation of the first fan module  2 , and the heat dissipating airflow will be introduced and discharged as shown in  FIG. 9 . 
   If the sensor  54  detects the temperature of a capacitor (OH), the temperature of a SCR controller (OH 2 ), the temperature of an interior of the casing (OH 3 ), the temperature of a right gate bipolar transistor (IGBT) (OH 4 ) and the temperature of a left gate bipolar transistor (IGBT) (OH 5 ) in the second casing  14  and the temperature change meets the control setup parameter for a start, then the fan control circuit  53  will output a control signal to the second and third fan modules  3 ,  4  to start the operation of fans and control the quantity and speed of the operating fans, so as to start the operations of the second and third fan modules  3 ,  4  and the heat dissipating airflow will be introduced and discharged as shown in  FIG. 10 . 
   If one of the fans in the first, second and third fan modules  2 ,  3 ,  4  fails, then a failure signal will be fed back to the fan control circuit  53  through the fan stall line  532  and the fan control circuit  53  will send out a fan stall signal to stop the operation of the failed fan. The rest of the fans remain operating, and we just need to replace the damaged fan only. Obviously, it is not necessary to stop the operation of all fans, and thus maintaining a continuous operation of the frequency converter  1 . 
   The present invention are illustrated with reference to the preferred embodiment and not intended to limit the patent scope of the present invention. Various substitutions and modifications have suggested in the foregoing description, and other will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.