Abstract:
A half-controlled silicon control rectifying system and method thereof are provided. In this case, the first detection unit detects the zero cross phase of the triphase AC in input port thereof. The second detection unit detects the voltage of the DC bus. Then the control unit controls the silicon-controlled rectifying unit by software. Therefore, the efficiency of soft actuation is achieved.

Description:
BACKGROUND 
   1. Field of the Invention 
   The invention relates to a half-controlled silicon-controlled rectifying system and method thereof, in particular, to a rectifying system and method applied to the electric power actuator. 
   2. Related Art 
   With the increasing popularity of various portable electronic products, the importance of power management is ever increasing. The related manufacturers are engaged and dedicated in the research and development of elements with smaller size, higher degree of integration, and higher power conversion efficiency, utilized in such portable electronic products, to increase the service life of the system and the durability of the battery. 
   With regard to the power management, usually the soft actuation equipment is included to restrict the actuation current, as such to reduce the impact of the system on the instantaneous actuation current caused by the power actuation. Presently, a silicon-controlled rectifier with the soft actuation equipment achieves the utility of the soft actuation by utilizing the fully-controlled silicon-controlled rectifying system having quite a few complicated hardware structures. Such equipment, as shown in  FIG. 1 , comprises: a silicon-controlled rectifying unit  101 , a direct current (DC) bus  102 , a diode unit  103 , an actuation resistor unit  104  and a transformer  105 . When the silicon-controlled rectifying unit  101  is driven to transmit the power, the diode unit  103  and the actuation resistor unit  104  first are actuated, and then the actuation resistor unit  104  isn&#39;t actuated until the voltage on the DC bus  102  reaches a threshold conducting voltage. 
   However, there are some technical problems in the structure as shown in  FIG. 1 . For example, when the silicon-controlled rectifying unit  101  is out of control, whether the silicon-controlled rectifying unit  101  is driven normally is not able to be determined, so that it may be damaged. Further, these structures utilized presently all belong to a hardware driving type, which lacks any proper protection and feedback control to protect the commutation angle of the silicon-controlled rectifying unit  101 . 
   SUMMARY 
   In view of the foregoing, the object of the invention is to provide a half-controlled silicon-controlled rectifying system and method thereof, to solve the technical problems concerning the silicon-controlled rectifier in the prior art. 
   To achieve the above-mentioned objective, the invention discloses a half-controlled silicon-controlled rectifying system, comprising: a first detection unit, a silicon-controlled rectifying unit, a direct current (DC) bus, a second detection unit, and a control unit. The first detection unit has a first input port to detect the zero cross phase of the triphase alternating current (AC) inputted into the first input port. The silicon-controlled rectifying unit has a second input port to receive the triphase alternating current. The DC bus is connected to the silicon-controlled rectifying unit to receive the output of the silicon-controlled rectifying unit. The second detection unit is connected to the DC bus to detect the voltage on the DC bus. The control unit receives the outputs of the first and the second detection units, and determines whether to send a trigger signal to the silicon-controlled rectifying unit based on the detecting results of the first detection unit and the second detection unit, thereby conducting the triphase AC inputted into the second input port of the silicon-controlled rectifying unit. 
   According to an embodiment of the invention, the zero cross phase of the triphase AC passing the input of the system is detected by the first detection unit, the voltage on the DC bus is detected by the second detection unit, and the silicon-controlled rectifying unit is controlled by the control unit through software, thereby achieving the rectifying function. 
   According to the embodiment of the invention, the disclosed half-controlled silicon-controlled rectifying system and method thereof achieve the efficiency of soft actuation through a software control in cooperation with a simple hardware structure, that replaces the complicated hardware structure of the prior art. As such, not only the cost of the circuit design is reduced, but the control of the silicon-controlled rectifier is also more precisely. Further, when the commutation angle of the silicon-controlled rectifier is controlled, the voltage on the DC bus is also controlled and the voltage drop on the circuit is also compensated, thereby achieving the increase of the operation efficiency and reducing the power loss during the switching of the transistors to raise the power utilization efficiency. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given below, which is for illustration only and thus is not limitative of the present invention, wherein: 
       FIG. 1  is a schematic diagram shown the structure of a silicon-controlled rectifying system of the prior art; 
       FIG. 2  is a schematic diagram shown the structure of the half-controlled silicon-controlled rectifying system according to the first embodiment of the invention; 
       FIG. 3  is a software control flowchart of the half-controlled silicon-controlled rectifying system according to the first embodiment of the invention; and 
       FIG. 4  is a circuit diagram of the first detection unit of the half-controlled silicon-controlled rectifying system according to the first embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As shown in  FIG. 2 , the half-controlled silicon-controlled rectifying system according to the first embodiment of the invention comprises: a first detection unit  201 , a silicon-controlled rectifying unit  101 , a DC bus  102  connected to the silicon-controlled rectifying unit  101 , a second detection unit  203  connected to the DC bus  102 , a control unit  202 , a first resistor  112 , and an inductor  130 . 
   Herein, the first detection unit  201  is provided with a first input port  204 , which receives the triphase AC, to detect the zero cross phase at 0 degree and 180 degrees of the triphase AC from the first input port  204  which the preference point for the phase angles 0 degrees and 180 degrees are the phases of the  1   st  zero value of each sine wave of the triphase AC within one period. The silicon-controlled rectifying unit  101  includes a plurality of silicon-controlled rectifiers  111  and a plurality of diodes  121 , and is provided with a second input port  205  receiving the triphase alternating current in synchronization with the first input port to determine whether to conduct the output of the triphase AC from the second input port  205 . The DC bus  102  includes a charging capacitor C and a second resistor  113 . The second detection unit  203  is used to detect the voltage of the charging capacitor C of the DC bus  102 . The control unit  202  is used to receive the detection results from the first detection unit  201  and the second detection unit  203 , and to determine whether to send a trigger signal to the silicon-controlled rectifying unit  101  depending on the detection results of the first detection unit  201  and the second detection unit  203 , thereby conducting the silicon-controlled rectifying unit  101  to enable the triphase AC from the second input port  205  to be circulated. 
   The control unit  202  executes by a software control, and the flowchart of its control process is shown in  FIG. 3 . When the triphase AC flows through the first input port  204 , the first detection unit  201  detects the zero cross phase of the voltage of the triphase AC and sends a signal indicating the zero cross phase of the voltage into the control unit  202  (step  301 ), and the control unit  202  sends a trigger signal to conduct one of the silicon rectifiers  111  in the silicon-controlled rectifying unit  101  (step  302 ). Then the control unit  202  determines whether the detected voltage value concerning the charging capacitor C of the DC bus  102  from the second detection unit  203  is greater than a threshold conducting voltage (step  303 ). If the detected voltage value is greater than the threshold conducting voltage, the control unit  202  sends a trigger signal to conduct all the silicon-controlled rectifiers  111  of the silicon-controlled rectifying unit  101  (step  304 ). If not, the control unit  202  sends out a trigger signal to conduct a silicon rectifier  111  of the silicon-controlled rectifying unit  101  in the next time when the input triphase AC is close to the zero cross phase. 
   In the step  303 , suppose that the detected voltage value, concerning the charging capacitor C of the DC bus  102 , from the second detection unit  203  is not greater than the threshold conducting voltage. The control unit  202  sends a trigger signal to conduct one of silicon-controlled rectifier  111  of the silicon-controlled rectifying unit  101  in the next period, when the triphase AC is close to the zero cross phase. Thus, in the process of repeated determination, each of silicon rectifiers  111  of the silicon-controlled rectifying unit  101  is gradually made conductive in advance in each period, thereby prolonging the overall conduction duration of the silicon-controlled rectifying unit  101 , so that the voltage of the charging capacitor C of the DC bus  102  is increased gradually. Until the voltage of the charging capacitor C of the DC bus  102  is greater than the threshold conducting voltage, the control unit  202  sends a trigger signal to conduct all the silicon-controlled rectifiers of the silicon-controlled rectifying unit  101 , so that the effect of soft actuation is achieved. In addition, the zero cross phase is chosen at 0° or 180°. 
   Furthermore, the first detection unit  201 , as shown in  FIG. 4 , comprises: a comparator  401 , a first voltage source  411  connected to the negative input terminal of the comparator  401 , a second voltage source  412  connected to the calibration terminal of the comparator  401 , a third voltage source  413  connected to the negative terminal of the comparator  401 , a fourth voltage source  414  connected to the output terminal of the comparator  401 , a first resistor  431  connected between the comparator  401  and the first voltage source  411 , a second resistor  432  connected between the comparator  401  and the first resistor  431 , a third resistor  433  connected between the positive terminal of the comparator  401  and the ground, a fourth resistor  434  connected between the comparator  401  and the fourth voltage source  414 , a first capacitor  421  connected between the positive terminal of the comparator  401  and the ground and connected in parallel with the third resistor  433 , and a second capacitor  422  connected between the negative terminal of the comparator  401  and the second voltage source  412 . 
   When the input terminal  402  receives the voltage of the triphase AC from the first input port  204 , the voltage is compared with the predetermined voltage set in the comparator  401 . While the voltage value of the received triphase AC reaches the zero cross phase, the comparator  401  outputs a signal with a high voltage level to inform the control unit  202  that the voltage of the input signal has reached the zero cross phase. 
   Knowing the invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.