Phase frequency detector with increased phase error gain
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IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G01R-025/00
H03D-013/00
출원번호
US-0084537
(2002-02-27)
발명자
/ 주소
Xin-LeBlanc, Jane
출원인 / 주소
National Semiconductor Corporation
대리인 / 주소
Vedder, Price, Kaufman & Kammholz, P.C.
인용정보
피인용 횟수 :
9인용 특허 :
6
초록▼
A phase-frequency detector (PFD) with increased phase error gain during acquisition of phase lock when used in a phase-locked loop (PLL). The reference and feedback signals are time-multiplexed into N pairs of input signals. Each pair of input signals is detected by one of N phase-frequency detector
A phase-frequency detector (PFD) with increased phase error gain during acquisition of phase lock when used in a phase-locked loop (PLL). The reference and feedback signals are time-multiplexed into N pairs of input signals. Each pair of input signals is detected by one of N phase-frequency detectors, which produce N pairs of detection signals indicative of phase differences between the reference and feedback signals. These N pairs of detection signals are combined in separate logical-OR operations to produce a frequency increase control signal and a frequency decrease control signal indicative of when the feedback signal frequency is lower and higher, respectively, than the reference signal frequency. These control signals have respective substantially nonzero signal values that vary in respective relations to the difference between the reference and feedback signal phases when such phase difference is less than 2π radians, and repeat with patterns having phase difference intervals of 2Nπ radians when such phase difference is greater than 2π radians.
대표청구항▼
A phase-frequency detector (PFD) with increased phase error gain during acquisition of phase lock when used in a phase-locked loop (PLL). The reference and feedback signals are time-multiplexed into N pairs of input signals. Each pair of input signals is detected by one of N phase-frequency detector
A phase-frequency detector (PFD) with increased phase error gain during acquisition of phase lock when used in a phase-locked loop (PLL). The reference and feedback signals are time-multiplexed into N pairs of input signals. Each pair of input signals is detected by one of N phase-frequency detectors, which produce N pairs of detection signals indicative of phase differences between the reference and feedback signals. These N pairs of detection signals are combined in separate logical-OR operations to produce a frequency increase control signal and a frequency decrease control signal indicative of when the feedback signal frequency is lower and higher, respectively, than the reference signal frequency. These control signals have respective substantially nonzero signal values that vary in respective relations to the difference between the reference and feedback signal phases when such phase difference is less than 2π radians, and repeat with patterns having phase difference intervals of 2Nπ radians when such phase difference is greater than 2π radians. to provided to the DC--DC converter to regulate the output voltage thereof. 10. A motor controller, comprising: a position sensor for detecting the rotor position of a switched reluctance (SR) motor; a position decoder operatively coupled to the position sensor; an angular velocity calculator operatively coupled to the position decoder; a look-up table for storing a plurality of control parameters; an interpolator, operatively coupled to the look-up table and the angular velocity calculator, for outputting a reference voltage and phase indicator; a DC--DC converter for receiving the reference voltage and a DC supply voltage; and an inverter operatively coupled to one or more phase windings of the SR motor and the outputs of the DC--DC converter. 11. The motor controller of claim 10, further comprising: a capacitor connected to the outputs of the DC--DC converter. 12. The motor controller of claim 10, wherein the DC--DC converter is selected from the group consisting of a buck converter, a boost converter, and a buck-boost converter. 13. The motor controller of claim 10, wherein the inverter includes: a first transistor having a first node connected to a first output of the DC--DC converter and a second node for connecting to a phase winding of the SR motor; and a second transistor having a first node connected to a second output of the DC--DC converter and a second node for connecting to the phase winding of the SR motor. 14. The motor controller of claim 13, further comprising: a freewheeling diode connected to the second node of the first transistor. 15. The motor controller of claim 13, further comprising: a freewheeling diode connected to the second node of the second transistor. 16. The motor controller of claim 13, wherein the first and second transistors are insulated gate bipolar transistors. preset level; a DC/DC converter for sourcing power from the stack and providing a converted output voltage; a load switch for receiving the control signal and the converted output voltage; and a main load coupled to the load switch, the load switch responsive to the control signal for switching in and out the main load. 8. The fuel cell system of claim 7, further comprising a secondary load providing fuel cell support circuitry coupled to the DC/DC converter. 9. A fuel cell system, comprising: a plurality of fuel cells connected in series and coupled to a load; a controller for determining individual fuel cell voltage level and providing a control signal based on the individual fuel cell voltage levels, the control signal indicating whether fuel cell operation is in or out of negative dP/dI region; and a load switch coupled between the plurality of fuel cells and the main load, the load switch disconnecting the load from the fuel cells in response to the control signal to prevent operation of the fuel cell system in the negative dP/dI region. 10. A fuel cell system, including: a stack of fuel cells coupled in series; a controller coupled to the stack; a load operatively coupled to the fuel cells; and the controller monitoring each fuel cell voltage, comparing each fuel cell voltage to a reference voltage, and generating a control signal for disconnecting and reconnecting the main load. 11. The fuel cell system of claim 10, further comprising a first DC/DC converter powered by the stack of fuel cells and turned on or off by the control signal, the DC/DC converter for powering the main load when turned on by the control signal. 12. The fuel cell system of claim 11, further comprising: a second DC/DC converter powered by the stack of fuel cells; a second load comprising fuel cell support circuitry coupled to the fuel cells; and wherein the second DC/DC converter generates a converted voltage output for powering the fuel cell support circuitry. 13. The fuel cell system of claim 10, further comprising: a DC/DC converter powered by the stack of fuel cells and generating a converted output voltage; and a load switch for receiving the control signal from the controller and for receiving the converted output voltage from the DC/DC converter, the load switch for connecting and disconnecting the main load to the converted output voltage in response to the control signal. 14. A method of protecting a fuel cell system, comprising: providing a stack of fuel cells connected in series and coupled to a load; monitoring the voltage of more than one cell within the stack; comparing the monitored voltage to a preset level; switching the load off in response to the voltage falling below the preset level; and switching the load on in response to the voltage rising above the preset level. 15. The method of claim 14, wherein the step of monitoring the voltage of more than one cell comprises monitoring the voltage of the stack. 16. The method of claim 14, wherein the step of monitoring the voltage of more than one cell comprises monitoring the voltage of a group of cells within the stack. 17. A method of protecting a fuel cell system, comprising: providing a stack of fuel cells connected in series and coupled to a load; monitoring the voltage of the stack; tracking power drawn by the load; determining slope of the power versus voltage; switching the load off if the slope is zero or positive; and switching the load on in response to the slope being negative. 18. The method of claim 17, wherein the step of tracking power comprises measuring total cell current and total cell voltage and calculating the product as the power. 19. A method of protecting a fuel cell system, comprising: providing a stack of fuel cells connected in series and coupled to a load; monitoring the current of the stack; tracking power drawn by the load; determining a slope of the power versus current; switching the load off, in response to the slope being zero or negative; and switching the load on, in response to the slope being positive. 20. The method of claim 19, wherein the step of tracking the power comprises measuring total cell current and total cell voltage and calculating the product as the power. 21. A method of protecting a fuel cell system, comprising: providing a stack of fuel cells coupled in parallel and coupled to a load; monitoring a current of each fuel cell; comparing each monitored current to a preset level; switching the load off in response to the current rising above the preset level; and switching the load on in response to the current falling below the preset level. 22. The method of claim 21, wherein switching the load off further includes maintaining the load switched off for a predetermined amount of time after the current falls below the preset level. 23. A fuel cell system, including: a stack of fuel cells; a controller coupled to the stack; a load operatively coupled to the fuel cells; and the controller monitoring a fuel cell parameter, comparing the fuel cell parameter to a preset level, and generating a control signal for disconnecting and reconnecting the load depending on the fuel cell parameter. 24. A method of protecting a fuel cell system, comprising: providing a stack of fuel cells with a load operatively coupled thereto; monitoring at least one parameter of one or more of the fuel cells; comparing the parameter to a preset parameter level; and disconnecting or reconnecting the load in response to the fuel cell parameter. 25. The method of claim 24, wherein the stack of fuel cells are coupled in parallel and the at least one parameter is current. 26. The method of claim 24, wherein the stack of fuel cells are coupled in series and the at least one parameter is voltage. 27. The method of claim 24, wherein the stack of fuel cells is coupled in series and the at least one parameter is current through the stack. 28. The method of claim 24, wherein the step of monitoring at least one parameter comprises monitoring current and voltage and the stack of fuel cells are coupled with a combination of series and parallel coupling. 29. A method of protecting a fuel cell system, comprising: providing a stack of fuel cells operatively coupled to a load; monitoring a parameter of the stack; tracking power drawn by the load; determining slope of the power versus parameter; switching the load off on or off in response to the slope having a predetermined characteristic. 30. The method of claim 29, wherein the parameter is voltage and the load is switched off if the slope is zero or positive. 31. The method of claim 29, wherein the parameter is current and the load is switched off if the slope is zero or negative. 32. The method of claim 30, wherein the stack of fuel cells comprises a plurality of fuel cells coupled in series. 33. The method of claim 31, wherein the stack of fuel cells comprises a plurality of fuel cells coupled in parallel.
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