Abstract:
An apparatus has a plurality of power supplies coupled to a common output power bus and a single controller. To avoid ground loops, interference, high cost, and line-of-sight operation, sound waves are used to communicate between the controller and the power supplies. The sound waves are preferably of at least 18 KHz in frequency and preferably FSK modulated with control or data information.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
         [0001]    Not Applicable  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0003]    1. Field of the Invention  
           [0004]    The present invention relates to apparatus and method for communicating and control, and, more particularly, between a controller and a plurality of power supplies connected to a common output power bus.  
           [0005]    2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98  
           [0006]    In many applications it is desirable to have a plurality of power supplies coupled to a common output power bus and controlled by a single controller. One way of doing this is to use a plurality of direct electrical control connection wires to couple the controller to each of the respective power supplies for the transmission of data signals from the power supplies to the controller and the transmission of control signals from the controller to the power supplies.  
           [0007]    However, this results in several problems. The main one is that of galvanic interaction (“ground loops”) caused by multiple grounding points, which in turn causes spurious signals, e.g., a 50 or 60 Hz power bus frequency signal, to be present on the control wires. These spurious signals can cause erroneous data and/or control signals. Other problems are erroneous signals due to miswiring; and low reliability and high cost due to the use of electrical contacts and fragile wiring. If RF (radio frequency) control is used instead of the control connection wires, the result can be electrical interference due to radiation to and from the wiring. Some of these problems can be solved by using infrared signals in place of the direct connection wiring. However, such control is highly directional, thereby requiring nearly direct line-of-sight operation.  
           [0008]    It is therefore desirable to have a control method and apparatus that does not cause ground loops, is not subject to miswiring, does not cause or receive electrical interference, has a high reliability and low cost, and does not require line-of-sight operation.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    A method of communicating between a plurality of power supplies coupled to a common output power bus and a controller comprises transmitting and receiving sound waves between said controller and said power supplies.  
           [0010]    An apparatus comprises a plurality of power supplies coupled to a common output power bus; and a controller, each of said power supplies and said controller comprising an interface transmitting and receiving sound waves between said controller and said power supplies for communication therebetween. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0011]    [0011]FIG. 1 is a block diagram of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]    [0012]FIG. 1 shows a controller  10 , which can either be fixed or mobile, e.g., handheld. It comprises, in general, a data source, such as a keyboard  12 , coupled to a microprocessor  14 , a data utilizer, such as a display  16 , coupled to the microprocessor  14 , an interface  18 , such as oscillators, modulators, amplifiers and detectors (none shown) and all as known in the art, coupled to microprocessor  18 , and a sonic or ultrasonic transducer  20  coupled to interface  18 . In a preferred embodiment, interface  18  transmits and receives energy of at least 18 KHz to avoid the audible range, but any desired frequency can be used. Further, frequency shift keying (FSK) modulation is used for noise rejection, but any other analog or digital modulation type, e.g., AM, PSK, PWM, etc., can be used. The typical data rate is a few hundred baud, but any desired data rate can be used.  
         [0013]    As indicated by sound waves  22 , controller  10  is in two-way communication with power supplies  24   a ,  24   b , . . .  24   n , which are typically within a few meters of controller  10 . Alternatively, controller  10  can be located within one of supplies  24  (the master) with the remaining supplies  24  being controlled (the slaves). Further, a plurality of supplies  24  (up to all of them) could have controllers  10  with one of controllers  10  being designated the master controller. This designation can be automatic using methods known in the art. Power supplies  24  are optionally mounted within the same rack (not shown) and can have different output current capabilities.  
         [0014]    Power supply  24   a  comprises a transducer  26   a , an interface  28   a , coupled to transducer  26   a , and a converter  30   a  coupled to interface  28   a . In turn, interface  28   a  can comprise oscillators, modulators, amplifiers, detectors, and a microprocessor (none shown) and all as known in the art. Similarly, power supplies  24   b  and  24   n  comprise the same elements with “b” and “n” respectively used as suffixes.  
         [0015]    An AC input power bus  32  is coupled to a source of AC power  34  such as the AC mains line, or a local alternator. Bus  32  is also coupled to power supplies  30 . If desired, bus  32  can convey DC power from, e.g., a battery or DC generator (neither shown). Further, if desired, converters  30  can be respectively coupled to different AC and/or DC power sources. A DC output power bus  36  is coupled to converters  30  and also to a load, which is represented by a resistor  38 . Although power supplies  24  are shown as having their outputs parallel coupled, the outputs can be coupled together in series. Further, power supplies  24  can provide AC power.  
         [0016]    If the input power is AC and the output power is DC, then converters  30  can each comprise a transformer, full or half-wave SCR or GTO solid state rectifiers or thyristor vacuum tubes, and a filter (none shown), all as known in the art. The DC output voltage can be controlled by, e.g., pulse width modulating the gate or grid voltage although any other method can be used. If the input power is DC and the output power is DC, then converters  30  can each comprise a voltage inverter circuit (not shown) as known in the art. This can have similar output voltage control as described above. If the input power is AC or DC and the output power is AC, then converters  30  can each comprise an oscillator (not shown) powered by the input power bus  32  and having an optional amplitude control.  
         [0017]    In operation, power supplies  24  would transmit identification and data, e.g., output voltage and current, power consumption, power supply failure, etc., to controller  10  for display by display  16 . An operator (not shown) views display  16 , and if the values are not satisfactory, enters commands on keyboard  12  for transmission back to at least one of the power supplies  24  to correct the problem, e.g., reduce the output current and/or voltage from at least one of supplies  24  so that it is within its rating. Alternatively, the control function can be partially or completely automatic, i.e., without requiring an operator, by methods known in the art. Such automatic operation eliminates the need for keyboard  12  and/or display  16 . Also, controller  10  can receive commands from higher level (line or plant level) controllers (not shown) and use these commands to control supplies  24 .  
         [0018]    While the present invention has been particularly described with respect to preferred embodiments, it will be understood that the invention is not limited to these particular preferred embodiments, the process steps, the sequence, or the final structures depicted in the drawings. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention defined by the appended claims. In addition, other methods and/or devices may be employed in the method and apparatus of the instant invention as claimed with similar results.