Abstract:
Present invention involves current mode and voltage mode which utilizes specific heat flux and heat transfer coefficient which when applied to the tissue, result in extra ordinarily effective.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a continuation-in-part application of U.S. provisional patent application Ser. No. 61/273644, filed Aug. 7, 2009, for VARIABLE DUAL MODE TISSUE HEATING SYSTEM CONTROLLER, by Htwe W. Naing, included by reference herein and for which benefit of the priority date is hereby claimed. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to tissue heating system controller and, more particularly, to a variable voltage and current, as well as methods to accurately control series parallel combination resonance power inverter 
       BACKGROUND OF THE INVENTION 
       [0003]    Various kinds of typical single mode tissue heating systems have been developed and used today, such as Voltage mode (variable voltage and fixed current), current mode (fixed voltage and variable current). However, dual mode tissue heating system requires intelligent power conversion controller which integrates a micro controller or digital signal controller for a fully programmable and flexible solution. A micro controller or digital signal controller is a quite high noise sensitive device and difficult to implement for power conversion system. 
         [0004]    Modern tissue heating systems include a resonance tank. The main purpose of the tissue heating system resonance tank is to provide maximum system performance with the least amount of current consumption and the best power efficiency possible. The resonance tank consists of the electronic passive components which require specific formula to generate clean signal. The passive components controlled by the source voltage and pulse current. In order to provide maximum performance to the system, it requires both source voltage and pulse current must be variable. 
         [0005]    It would be advantageous to provide a variable voltage and variable current to tissue heating system. 
         [0006]    It would also be advantageous to provide a series parallel resonance tank to tissue heating system. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to avoid the aforementioned and other disadvantages of conventional tissue heating system controller. 
         [0008]    Accordingly, one object of the present invention is to provide an improved tissue heating systems accomplishing a variable voltage and variable current in the demanded series parallel resonance tank. 
         [0009]    Another object of the present invention is to provide a tissue heating system for controlling the series parallel resonance tank in response to the alternative energy of system in order to improve system performance and reduce electrical energy consumption. 
         [0010]    Furthermore, it is an object of the present invention is to provide a tissue heating system which can use a microcontroller or digital signal controller, and particularly, non analog controller which requires no higher component count. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent, detailed description, in which: 
           [0012]      FIG. 1  is a circuit diagram showing the operating circuit elements as well as their interconnections according to the present invention; and 
           [0013]      FIG. 2  is a waveform diagrams, w 1  to w 6  are a series of curves view showing the voltage characteristics at various selected places throughout the circuitry of  FIG. 1  and truth table of respective curves relationship. 
       
    
    
       [0014]    For purposes of clarity and brevity, like elements and components will bear the same designations and numbering throughout the Figures. 
       DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    Referring now to the drawings, there is  FIG. 1  shown an electrical schematic of a dual mode tissue heating system controller including a voltage variable boost converter  16  acting as a variable voltage source, current sensor  1  for sensing system current information, relay  15  for mechanical isolation between a voltage variable boost converter  16  and load  14 , series parallel resonance tank  22 , dc blocking capacitor  12  for blocking unwanted low frequency or dc voltage, MOSFET  11  for switching between system on time and off time, ultra fast diode  7  for guiding current flow direction of current limit transformer secondary winding  32  during MOSFET  11  off time, snubber circuitry  23  for dissipating unused energy (derived from leakage inductance of current limit transformer  8  and power transformer  9 ) during MOSFET  11  off time, mosfet driver  6  for driving proper MOSFET  11  gate voltage, open collector three buffer inverter circuitry  25 , open collector two buffer inverter circuitry  26 , micro controller  2  for controlling system energy and monitoring system information, voltage detector  3  for detecting voltage levels at several system locations, computer interface  4  for interfacing with computer, manual interface  5  for interfacing with manual controller and temperature sensor  35  for sensing system temperature. 
         [0016]    Micro controller  2  includes V_IO interface for interfacing with voltage detector  3 , CON 1  interface for interfacing with computer interface  4 , CON 2  interface for interfacing with manual interface  5 , Temp pin for sensing temperature from temperature sensor  35 , I_IN pin for sensing system current information from current sensor  1 , RELAY  15  pin for driving mechanical relay  15 , PWMHF pin for generating high frequency pulse width modulation signal, CYL_LIM pin for generating maximum dutycycle of high frequency pulse width modulation signal, PWMLF pin for generating low frequency pulse width modulation signal, IV_LIM pin for generating over current or over voltage logic level state and PWME pin for detecting PWM signal enable or disable status. 
         [0017]    Open collector two buffer inverter circuitry  26  includes low frequency PWM buffer  21  for buffering between PWMLF and PWME pin of micro controller  2 , iv limit  18  for buffering between IV_LIM and PWME pin of micro controller  2  and pull up resistor 3   24   c  for activating open collector inverter logic level. 
         [0018]    Open collector three buffer inverter circuitry  25  includes high frequency PWM bufferl  19  for inverting logic level of micro controller  2  PWMHF pin output signal, high frequency PWM buffer 2   20  for inverting logic level of high frequency PWM bufferl  19  output signal, dutycycle limit buffer inverter  17  for inverting logic level of micro controller  2  CYL_LIM pin output signal, pull up resistorl  24   a  and pull up resistor 2   24   b  for activating open collector inverter logic level. 
         [0019]    Snubber circuitry  23  includes snubber resistor  27  for dissipating and returning unused energy to source, snubber capacitor  29  for temporary storing unused energy, snubber diode  28  for guiding unused energy direction flow and over voltage protection diode  30  for limiting over voltage. 
         [0020]    Series parallel resonance tank  22  includes current limit transformer  8 , power transformer  9 , primary resonance capacitor  10  for providing primary capacitive reactance (XCr) and secondary resonance capacitor  13  for providing secondary capacitive reactance (XCs). 
         [0021]    Current limit transformer  8  includes current limit transformer primary winding  31  for limiting over current during MOSFET  11  on time and providing series inductive reactance (XLr), current limit transformer secondary winding  32  for dissipating unused energy during MOSFET  11  off time. 
         [0022]    Power transformer  9  includes power transformer primary winding  33  for providing parallel inductive reactance (XLm) and power transformer secondary winding  34  for transferring energy to load  14  by turn ratio (N) of power transformer  9 . 
         [0023]    In order to maintain system stability and high efficiency, series parallel resonance tank  22  is defined by the following equations: 
         [0000]      XLm˜2 ohm
 
         [0000]      XLr˜XLm*Pi
 
         [0000]      XCr˜2.5*XLm
 
         [0000]      XCr*N̂2˜XCs
 
         [0024]    Where 
         [0025]    XLm=inductive reactance of power transformer primary winding  33 . 
         [0026]    XLr=inductive reactance of current limit transformer primary winding  31 . 
         [0027]    Pi=3.142. 
         [0028]    XCr=primary capacitive reactance of primary resonance capacitor  10 . 
         [0029]    N=turn ratio of power transformer  9 . 
         [0030]    XCs=secondary capacitive reactance of secondary resonance capacitor  13 . 
         [0031]    Typically, all the fundamental parameters characterizing the system operative conditions are included in micro controller  2 . These parameters are: voltage levels, current levels, isolation condition, user instruction, system temperature, PWM generators and emergency shutdown. 
         [0032]    Operationally, the initial step in the system is micro controller  2  initialization sequence for deciding whether system is under normal operating condition or not. Micro controller  2  initialization sequence includes normal start up source voltage levels check for collecting initial source voltage value, snubber voltage level check for collecting initial snubber voltage value, current level check for collecting initial current value, system temperature level check for collecting system temperature value and compare with pre programmed respective EEPROM values to determine system condition. Mechanical relay  15  is switched from open to close position only when the system is normal operating condition. The next step is micro controller  2  normal operation sequence for operating system normal condition. Micro controller  2  normal operation sequence includes user interfacing for cooperating with user instructions through out the computer interface  4  or manual interface  5 , variable source voltage level generator for generating user desired source voltage level controlled by micro controller  2  V_IO interface via voltage detector  3 , variable current level generator for generating user desired pulse current level controlled by PWMHF pin and/or PWMLF pin of micro controller  2 , over limit shutdown for terminating voltage generator and/or current generator via CYL_LIM or IV_LIM pins of micro controller  2  during exceeding user setting levels and power process for calculating system power consumption and system efficiency based on voltage, current and temperature values. 
         [0033]    The arrangement of open collector three buffer inverter circuitry  25  provides for maintaining to turn off MOSFET  11  during the system power up sequence. For example, both PWMHF and CYL_LIM pins of micro controller  2  logic states high or low will generate logic low state on open collector three buffer inverter circuitry  25  output. 
         [0034]    Referred to  FIG. 2 , W 1  shown high frequency variable pulse width modulation signal generating by micro controller  2  PWMHF pin, W 2  shown high frequency maximum pulse width limiting signal generating by micro controller  2  CYL_LIM pin, W 3  shown high frequency pulse width modulation signal generating by open collector three buffer inverter circuitry  25  output, W 4  shown low frequency variable pulse width modulation signal generating by micro controller  2  PWMLF pin, W 5  shown over limit shutdown signal generating by micro controller  2  IV_LIM pin and W 6  shown combination logic state output of PWMLF and IV_LIM pins which also controlled PWMHF pin logic state. Truth tables had shown respective curves relationship. 
         [0035]    Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. 
         [0036]    Having thus described the invention, what is desired to be protected by Letters Patent is presented in the subsequently appended claims.