Patent Publication Number: US-2020287373-A1

Title: Reverse polarity protection device

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of power input protection, and more particularly to a power supply device and a reverse polarity protection device installed between the power supply device and its load device. 
     BACKGROUND OF THE INVENTION 
     As Internet of Things, AI big data analysis and cloud storage are used extensively, server systems and data centers tend to be built with a modular design to facilitate engineers to adjust electronic devices such as network units and/or storage units contained in the server systems and data centers. In addition, power supply systems also come with the modular design, so that the server systems and/or data centers located at different cabinets can obtain electric power. In general, power supply terminals inside a power supply module in the server systems and data center have a foolproof design to prevent assemblers to connect the positive and negative terminals reversely during an assembling process of the power supply modules and mainboards. However, the power supply module used together with an external power supply device to achieve the effect of electrically connecting an external power supply terminal generally adopts a conventional power supply terminal. Obviously, it is difficult to add the foolproof design to the conventional power supply terminal. 
     At present, diodes used as the reverse polarity protection components are generally installed between a power input terminal and a power supply module of an integrated circuit (IC) and the characteristics of forward conduction and reverse cutoff are used to achieve the reverse polarity protection of the integrated circuit. However, the power consumption and heat generation of the forwardly conducted diode become the issues of a circuit module in the applications of a large-power power supply module and lead to the result of the diode that can be used in the small-power large-voltage power supply module only. For example, some data centers having a 12V/200 W power supply module and the diode cannot be used in these data centers to provide the reverse polarity protection function. 
     In view of the aforementioned problem, R.O.C. Pat. No. M325665 discloses a foolproof circuit structure. With reference to  FIG. 1  for a schematic circuit block diagram of the foolproof circuit structure as disclosed in R.O.C. Pat. No. M325665, the foolproof circuit structure  1 ′ is coupled between a DC power supply  2 ′ and a load device  3 ′. According to the content disclosed in R.O.C. Pat. No. M325665, the foolproof circuit structure  1 ′ is an N-type Metal-Oxide-Semiconductor Field-Effect Transistor (N-type MOSFET) or a P-type MOSFET, and the P-type MOSFET has a drain, a source and a gate coupled to the DC power supply  2 ′, the load device  3 ′ and a common ground GND′ respectively. 
     The foolproof circuit structure  1 ′ can indeed provide the reverse polarity protection to the load device  3 ′. However, it is noteworthy that if only the MOSFET is used for protection and one of the power supplies in a DC power supply  2 ′ is abnormal, then the other power supplies will be affected, and the whole system will become unstable. 
     Therefore, it is necessary to develop a reverse polarity protection component or device that can be applied in a small-power large-voltage circuit. Based on the aforementioned reasons, the inventor of the present invention based on years of experience in the related industry to conduct extensive research and experiment, and finally developed a reverse polarity protection device of the present invention to overcome the aforementioned drawbacks of the prior art. 
     SUMMARY OF THE INVENTION 
     Therefore, it is a primary objective of the present invention to provide a reverse polarity protection device, comprising: a protection unit, a detection unit, and a control unit electrically coupled between a power supply device and a load device, wherein the detection unit is electrically coupled to the power supply device for detecting the polarity of an output signal of the power supply device, and the control unit is electrically coupled to the detection unit and the protection unit. According to the design of the present invention, the detection unit is provided for outputting a detection signal to the control unit according to the detection result of the polarity of the output signal. For example, the control unit will control the protection unit to form an open circuit between the power supply device and the load device if the detection signal shows that the polarity of the output signal is reverse, and this method blocks and prevents the output signal of the power supply device from being transmitted to the load device to achieve a reverse polarity protection of the load device. 
     To achieve the aforementioned objective, the present invention provides a reverse polarity protection device, comprising: 
     a protection unit, electrically coupled between a power supply device and a load device; 
     a detection unit, electrically coupled to the power supply device, for detecting the polarity of an output signal of the power supply device; and 
     a control unit, electrically coupled to the detection unit and the protection unit; 
     wherein, if the detection unit detects that the polarity of the output signal is reverse, then the control unit will control the protection unit to form an open circuit between the power supply device and the load device. 
     In an embodiment of the reverse polarity protection device, the protection unit is an N-type MOSFET or a P-type MOSFET. 
     In an embodiment of the reverse polarity protection device, the output signal is a voltage signal or a current signal. 
     In an embodiment of the reverse polarity protection device, the load device is one selected from the group consisting of an industrial computer host, a server, a data center host, a desktop computer, a notebook computer, a tablet PC, a smartphone, and a smartwatch. 
     The present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic circuit block diagram of a foolproof circuit structure as disclosed in R.O.C. Pat. No. M325665; 
         FIG. 2  is a schematic circuit block diagram of a reverse polarity protection device of the present invention; 
         FIG. 3  is a schematic circuit diagram of a reverse polarity protection device of the present invention; 
         FIG. 4  is a flow chart of a method of operating a detection unit and a control unit in accordance with the present invention; and 
         FIG. 5  is a schematic circuit diagram of a reverse polarity protection device of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIGS. 2 and 3  for a schematic circuit block diagram and a schematic circuit diagram of a reverse polarity protection device of the present invention respectively, the reverse polarity protection device  1  installed on a circuit comprises a protection unit  11 , a detection unit  12  and a control unit  13 . Wherein, the protection unit  11  is electrically coupled between a power supply device  2  and a load device  3 , and the detection unit  12  is electrically coupled to the power supply device  2  for detecting the polarity of an output signal of the power supply device  2 . On the other hand, the control unit  13  is electrically coupled to the detection unit  12  and the protection unit  11 . In the present invention, the protection unit  11  comprises an N-type Metal-Oxide-Semiconductor Field-Effect Transistor (N-type MOSFET) QN. In  FIG. 3 , the N-type MOSFET QN has a source terminal (S) provided for receiving the output signal of the power supply device  2 , and the N-type MOSFET QN has a drain terminal (D) and a gate terminal (G) respectively and electrically coupled to the load device  3  and the control unit  13 . In addition, the N-type MOSFET QN has a source terminal (S) and a drain terminal (D) respectively and electrically coupled to the control unit  13 . The control unit  13  also can self-detect the polarity of the output signal. For example, the control unit  13  compares an electric potential output signal of the source terminal (S) of the N-type MOSFET QN with the electric potential of a common ground to determine the polarity of the output signal. If the polarity of the output signal is correct, then the control unit  13  will drive the N-type MOSFET QN to form a short circuit between the power supply device  2  and the load device  3 . 
     However, the power supply device  2  in a data center generally includes a multiple power output and OR-ing power structure (or a redundant power supply). To prevent the situation that if one of the power supply devices  2  is abnormal, then other power supplies will be affected, the present invention uses the detection unit  12  to notice the control unit  13  to turn on/off the N-type MOSFET QN. 
     According to the detection result of the polarity of the output signal, the detection unit  12  outputs a detection signal to the control unit  13  to drive the control unit  13  to turn on/off the N-type MOSFET QN. With reference to  FIG. 4  for a flow chart of an operating method of a detection unit and a control unit in accordance with the present invention, after the power supply device  2  provides the output signal (step S 1 ), if the detection unit  12  detects that the polarity of the output signal is normal (step S 2 ), then the detection unit  12  will output the detection signal as a low level signal. The so-called normal polarity of the output signal refers to a potential of the output signal greater than zero. For example, if the output signal is a positive voltage signal or a positive current signal, then the detection unit  12  will compare the output signal with the electric potential of a common ground to determine that the potential level is greater than zero. In the step S 3 , the control unit  13  will turn on the N-type MOSFET QN if the detection signal is a low level signal, so that the protection unit  11  will form a short circuit between the power supply device  2  and the load device  3 , and the output signal of the power supply device  2  will be transmitted to the load device  3 . 
     On the contrary, if the detection result shows that the polarity of the output signal is reverse (step S 2 ), the detection unit  12  will output the detection signal as a high level signal. In the step S 4 , the control unit  13  will turn off the N-type MOSFET QN if the detection signal is a high level signal, so that the protection unit  11  will form an open circuit between the power supply device  2  and the load device  3  to block and prevent the output signal of the power supply device  2  from being transmitted to the load device  3  continuously, so as to achieve a reverse polarity protection of the load device  3 . It must be emphasized that the detection unit  12  will output a low level signal or a high level signal if the polarity of the output signal is normal or reverse respectively. It is noteworthy that it is not difficult for related engineers to design the detection unit  12  to output a high level signal or a low level signal when the polarity of the output signal is normal or reverse respectively. 
     Briefly, if one of the power supplies is abnormal or the polarity of the output signal is reverse, then the detection unit  12  will notice the control unit  13  directly to turn off the N-type MOSFET QN. Therefore, the design of the detection unit  12  provides an additional security mechanism. Even if one of the power outputs of the power supply device  2  is abnormal, the other power output will not be affected. It is noteworthy that the present invention is not limited to the load device  3  of this embodiment only, but any electronic device or electrical apparatus that requires an external power supply device such as an industrial computer host, a server, a data center host, a desktop computer, a notebook computer, a tablet PC, a smartphone, or a smartwatch may be used instead. On the other hand, the protection unit  11 , the detection unit  12  and the control unit  13  may be integrated into an integrated circuit (IC) in an application. 
     Although  FIG. 3  shows that the protection unit  11  includes an n-type MOSFET QN, yet the invention is not limited to the circuit of the protection unit  11  only. With reference to  FIG. 5  for a schematic circuit diagram of a reverse polarity protection device of the present invention, the protection unit  11  may comprise a P-type MOSFET QP having a source terminal (S) for receiving the output signal of the power supply device  2 , and a drain terminal (D) and a gate terminal (G) respectively and electrically coupled to the load device  3  and the control unit  13 . In addition, the P-type MOSFET QN has a source terminal (S) and a drain terminal (D) electrically coupled to the control unit  13 . 
     While the invention has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.