Abstract: A microsource is provided, which includes an energy storage device, a power generation device, and a controller. The energy storage device is operably coupled for power transfer to a load through a first power bus. The power generation device is operably coupled for power transfer to the load through a second power bus. The controller determines a mode of operation for the energy storage device and the power generation device based on an energy level of the energy storage device and on the load; determines minimum power set points and maximum power set points for the energy storage device and the power generation device based on the determined mode of operation, on a storage output power measured at the first power bus, and on a generation output power measured at the second power bus; and controls an output power of the energy storage device and an output power of the power generation device based on the determined minimum and maximum power set points.

Abstract: An apparatus comprises a matrix of thermoelectric devices for applying thermal gradients across an electronic component mounted in a PCB substrate within an enclosed housing. A matrix of thermosensitive devices are placed around the perimeter of the electronic component to measure thermal gradients associated with the component. A controller controls the matrix of thermoelectric devices based on the thermal gradients measured by the matrix of thermosensitive devices with a matrix of thermocouple coefficients.

Abstract: A system includes a first communication module to be coupled to a first transmission medium for distributing power using a voltage waveform having a first amplitude; and a second communication module to be coupled to a second transmission medium for distributing power using a voltage waveform having a second amplitude different from the first amplitude, the second transmission medium being coupled to the first transmission medium. Each of the first and second communication modules is configured to use signals that propagate between the first and second transmission media.

Abstract: A system and method of regulating the voltage of the power supplied to a plurality of power customers via a power distribution system that includes low voltage power lines and medium voltage power lines is provided. In one embodiment, the method includes measuring the voltage of a plurality of low voltage power lines at a plurality locations in the power distribution system with a plurality of voltage monitoring devices; with the plurality of voltage monitoring devices, transmitting voltage data in real time to a remote computer system; receiving, with the computer system, the real time voltage data of the voltage measured from the voltage monitoring devices; comparing, with the computer system, the real time voltage data with a first threshold value; and if the real time voltage data is beyond the first threshold value, transmitting with the computer system a first voltage adjustment instruction to a voltage control device configured to adjust the voltage supplied to a low voltage power line.

Abstract: The aim of the invention is to be able to adapt an item of visualization or optimization software with the least possible amount of effort made on any electrostatic filter configurations. To this end, the invention provides that the electrostatic filter, the high-voltage supply units, and the auxiliary functional units can be used by the software modules in the server component as objects with characteristic features and with characteristic methods, that are capable of being accessed as information, which only exists in the server component, for the client modules via data interfaces.

Abstract: A system for improving dynamic response in a power supply includes a mainframe module having a memory and a mainframe microprocessor, the mainframe processor configured to calculate a plurality of tables in which each table represents a current/voltage (I/V) characteristic curve for the power supply, at least two power supply modules coupled to the mainframe module, each power supply module having a random access memory element, the random access memory element configured to receive and store a first table and a second table, wherein the mainframe microprocessor transfers the first table to each power supply module, and wherein each power supply module executes a respective first table while the mainframe processor calculates the second table for each power supply module and while the mainframe processor transfers the second table to each power supply module.

Abstract: In the present invention, at each of the plurality of points in a wide area, the phase of voltage at a power supply outlet is detected. Data including the phase information and time information are sent to a data server. With one end of the system used as a phase angle reference, the data server observes phase differences at the other end and at the center of the system. The data server then extracts an inter-system fluctuation component from an obtained fluctuation, and constructs an expanded combined vibration model for data sets obtained through first-order and second-order differentiations of the component. The expanded combined vibration model is obtained by expanding a combined vibration model to include a known model of a PSS provided for a generator of interest.

Abstract: A system and method of use for self-tuning a PID controller utilized with an exciter and generator is disclosed. The system includes a power source, an exciter electrically connected to the power source, a generator that is electrically energized by the exciter, and a processor that provides a PID controller that calculates an estimated exciter time constant and an estimated generator time constant using particle swarm optimization (“PSO”) to control exciter field voltage. The particle swarm optimization (“PSO”) technique includes increasing the voltage reference by a predetermined percentage over a predetermined time period, initializing each particle position of exciter time constant and generator time constant, calculating generator voltage, performing a fitness evaluation and then obtaining and updating best values. This is followed by repeating the steps of determining the generator voltage, the fitness evaluation, and the best values over a predetermined number of iterations.

Abstract: A data acquiring unit (122) acquires external factor data such as day of the week, date and time, or weather together with electric power data in a house, and stores the data in a storage unit (114). A classification/learning unit (124) reads the electric power data and the external factor data stored in the storage unit (114), and classifies/learns the read data. A scheduling unit (126) predicts a house power demand on the basis of the classified/learned data, and plans the charge/discharge of a vehicle according to the result of prediction. A command generating/outputting unit (128) generates a charge/discharge command of the vehicle according to the charge/discharge schedule.

Abstract: The invention describes combination I/O modules for automation. Various combinations of inputs and output with different electrical interfaces are offered providing greater flexibility in controller hardware selection.

Abstract: A method and a system for controlling LED with power line carrier are disclosed. The system contains a host controller, an electric power conductor, and at least a luminous device, and the luminous device further containing an environmental data collection module. The method comprises the steps of providing a power line carrier module to both the host controller and the luminous devices; the luminous devices detecting a set of environmental data by the environmental data collection module; the luminous devices transmitting the set of environmental data to the host controller; the host controller recording and analyzing the set of environmental data; and the host controller sending a control signal to the luminous devices according to the analysis. Therein the control signal and the set of environmental data are transmitted by the power line carrier module through the electric power conductor.

Abstract: A two-wire load control device for control of power delivered to an electrical load from a source of AC voltage, comprising a first controllably conductive device adapted to be operatively coupled to the source of AC voltage and to the electrical load for controlling the power delivered to the load; a microprocessor coupled to the first controllably conductive device for controlling the first controllably conductive device; and a power supply adapted to be coupled to the source of AC voltage and coupled to the microprocessor for generating a DC voltage to power the microprocessor, the power supply including an energy storage element and a second controllably conductive device for controllably storing energy in the energy storage element; wherein the microprocessor is operatively coupled to the second controllably conductive device to control the second controllably conductive device.

Abstract: A State and Topology Processor (STP) may be communicatively coupled to one or more intelligent electronic devices (IEDs) communicatively coupled to a electrical power system to obtain one or more current measurements, voltage measurements, and dynamic topology data therefrom. The STP may receive the measurement data and may determine a current topology and a voltage topology therefrom. A current processor may use the current topology and the current measurements to refine the measurements, perform KCL, unbalance, symmetrical component, and consistency checks on the electrical power system. The voltage processor may use the voltage topology and the voltage measurements to perform similar checks on the electrical power system. One or more alarms may be generated responsive to the checks. The data may be displayed to a user in a display of a human machine interface and/or may be transmitted to a user programmable task module, and/or an external control unit.

Abstract: There is provided a digital controller which can generate no oscillation even if sensing a load side and enables control of supplying a desired voltage to the load. In an power amplifier which supplies an output voltage vo to the load connected via a load connecting line, a load voltage vL and the output voltage vo are periodically sampled to calculate a manipulating variable ?1 from the output voltage vo, the load voltage vL and an arbitrary target value r. Based on the manipulating variable ?1 calculated, a control signal is output to the power amplifier. As a result, when connecting an LC filter with a load device 9 of the power amplifier intended for a control target and besides the load connecting line is long, a robust digital controller without generating oscillation even if sensing the load side is performed can be realized.

Abstract: A semiconductor device 2 has a plurality of elements. It also has an F-V table storing unit for low voltage threshold cells 31 for storing an F-V table TB11 of an oscillation frequency f1 relying on the plurality of elements and a power supply voltage EV to be supplied to the plurality of elements. It has a process sensor block 12 having at least one of the plurality of elements, for monitoring the oscillation frequency f1 relying on at least one element. It further has a selector 33 for setting the power supply voltage EV associated with the oscillation frequency f1, as the supply voltage to be supplied to the semiconductor device 2 by selecting according to the F-V table TB11. The F-V table TB11 is obtained by mutually relating the combinations of random number models ?n between an F-? table TB20 and an ?-V table TB30.

Abstract: Provided are methods for controlling operation of a voltage regulator of a single-phase of a three-phase power system to regulate a measured voltage. One of the methods includes recording a first elapsed time between detecting a first excursion of the measured voltage from an in-band area to an out-of-band area, and a first return of the measured voltage to the in-band area. The method also includes recording a second elapsed time period (dip period) between detecting the first return and a second excursion of the measured voltage from the in-band area to an out-of-band area. If the second elapsed time period is less than a predetermined dip time period, causing a tap position change of the voltage regulator upon expiration of a countdown period initiated upon detecting the first excursion, thereby adjusting the measured voltage to the in-band area while allowing a voltage drop of limited length.

Abstract: A device for adaptively controlling a voltage supplied to circuitry in substantially close proximity to the device, comprising a processing module, a first tracking element coupled to the processing module and producing a first value indicative of a first estimated speed associated with the circuitry, and a second tracking element coupled to the processing module and producing a second value indicative of a second estimated speed associated with the circuitry. The processing module compares each of the first and second values to a target value and causes a voltage output to be adjusted based on said comparison.

Abstract: An adaptive power managing device for an IC chip or a circuit system comprises a tunable voltage generator, a data generator, a data processing unit, a data checking unit and a control unit; the tunable voltage generator is used for providing the IC chip or the circuit system with an operating voltage; the data generator is used for generating a series of predetermined data to the data processing unit; the data processing unit is used for processing the series of predetermined data and then outputting a series of output data associated with the series of predetermined data; and the data checking unit is used for checking the validity of the series of output data; wherein if the series of output data is checked to be invalid, the control unit outputs a control signal for tuning up the operating voltage; if the series of output data is checked to be valid, the operating voltage is maintained or the control unit outputs another control signal for tuning down the operating voltage whereby efficiently achieving th

Abstract: A method of performing loadflow calculations for controlling voltages and power flow in a power network by reading on-line data of given/specified/scheduled/set network variables/parameters and using control means, so that no component of the power network is overloaded as well as there is no over/under voltage at any nodes in the network following a small or large disturbances.

Abstract: A device for controlling at a fault condition. An apparatus is connected by a connection line to a grid point of a transmission net in an electric power network. A voltage raising apparatus includes a first branch connected to the grid point including a switching element and a second branch including a current resisting means. The voltage raising apparatus includes a computer for signal processing of a sensed fault condition on the network and for affecting the operation of the switching element such that on a fault condition at least part of the current is diverted through the voltage raising apparatus and for evaluation of further actions.

Abstract: In a motor driving control device, a high-frequency alternating voltage or rotation voltage (having a frequency of ?h) is applied to a motor so that magnetic saturation occurs in the motor, thereby extracting, from a ?-axis current, a high-frequency second-harmonic component (a frequency component of 2×?h) that is obtained by attenuating at least a direct-current component of the ?-axis current. The polarity checker detects the polarity of the magnetic pole of the rotor based on the difference, caused by magnetic saturation, between the positive and negative amplitudes of the high-frequency second-harmonic component.

Abstract: A microsource is provided, which includes a generator, a prime mover, and a controller. The prime mover includes a shaft connected to drive the generator to generate power at a frequency controlled by a rotation rate of the shaft. The controller calculates an operating frequency for the generator based on a comparison between a power set point and a measured power flow. A requested shaft speed for the prime mover is calculated by combining a maximum frequency change, a minimum frequency change, and the calculated operating frequency A shaft speed adjustment is calculated for the prime mover based on a comparison between the requested shaft speed and a measured shaft speed of the prime mover. A fuel command for the prime mover is calculated based on the shaft speed adjustment. A rotation rate of the shaft of the prime mover is adjusted based on the calculated fuel command to control the frequency.

Abstract: Power supplies include digital supervisory circuits that detect faults and control power supply operation. The supervisory control algorithms are user programmable so that the supervisory function can be easily manipulated by the power supply user for different applications of the power supply.

Abstract: A transfer switch includes first terminals adapted to input power from a first power source, second terminals adapted to input power from a second power source, third terminals adapted to output power to a first load, and a transfer mechanism adapted to selectively electrically connect the one of the first or second terminals to the third terminals. A control mechanism cooperates with the first and second terminals and the transfer mechanism to electrically connect one of the first and third terminals or the second and third terminals. A control circuit and a relay include normally closed contacts and normally open contacts. The relay is de-energized responsive to the first and third terminals being electrically connected, and energized responsive to the second and third terminals being electrically connected. The normally closed contacts shed corresponding second loads and the normally open contacts enable corresponding third loads when the relay is energized.

Abstract: An electronic system comprises a plurality of circuit paths. Each path in the plurality of circuit paths is coupled to receive a system voltage from a voltage supply. The system further comprises a first circuit for providing a first value indicating a first potential capability of operational speed of at least one path in the plurality of circuit paths and a second circuit for providing a second value for indicating a second potential capability of operational speed of the at least one path in the plurality of circuit paths. The system further comprises circuitry for adjusting the system voltage, as provided by the voltage supply, in response to a relation between the first value and the second value.

Abstract: A device for adaptively controlling a voltage supplied to circuitry in close proximity to the device, comprising a processing module and a first tracking element coupled to the processing module. The first tracking element produces a first value indicative of a first estimated speed associated with the circuitry. The device also comprises a second tracking element coupled to the processing module. The second tracking element produces a second value indicative of a second estimated speed associated with the circuitry. The processing module compares each of the first and second values to respective target values and causes a voltage output to be adjusted based on the comparisons. The first and second tracking elements comprise a plurality of transistors, at least some of the transistors selectively provided with a transistor bias voltage to adjust transistor speed.

Abstract: A closed loop power converter circuit of a UPS or other power supply includes a pulse width modulator circuit in a forward path of the closed loop power circuit. A compensation circuit provides pulse width commands to the pulse width modulator at a first rate. A feedback circuit digitally filters samples of an output of the closed loop power converter at a second rate greater the first rate and that provides the filtered samples to the compensation circuit. In some embodiments, the compensation circuit may be operative to compensate for the phase lag associated with a low pass output filter.

Abstract: An intelligent demand controller protects the local customer premises supply transformer from overload and senses conditions on the transformer. The intelligent demand control system utilizes a communications network with a plurality of load control units having a unique address and residing at a plurality of customer premises. A demand controller monitors the voltages and frequency of electricity provided to the customer premises as well as the instantaneous current required by the operating loads of the customer premises. Each of the plurality of demand controllers may be associated with one or more of a plurality of load control units and configured to receive data related to the state of the power supplied to the plurality of controlled loads and generate a transmit message using a predefined communication protocol. When certain programmable conditions are met, a load control unit is signaled to remove power from one or more of its monitored loads.

Abstract: A digitally controlled hybrid power module is controlled by a programmable controller. The hybrid power module includes a digitally controlled switching supply with an output coupled to an input of a digitally controlled linear voltage regulator. Independent control of switching supply and the linear regulator is provided by the programmable controller, which may be a field programmable gate array (FPGA), microcontroller, or digital signal processor (DSP). The programmable controller may independently control one or more power modules. Each power module may also include enable switching and an associated current clamp for capacitive loads. An output voltage transient suppressor may also be used to control transients, such as those produced under fast switching conditions.

Abstract: A multivariable control system provides regulation for a plurality of control variables of interest based on selecting a particular one of the variables for regulation relative to a corresponding setpoint, while continuing to monitor the other variables and switching regulation control over to another one of the variables as needed to maintain all of them within their allowed ranges. The system includes one or more PID regulators that tune themselves for the particular variables selected for regulation control. In an exemplary embodiment, the control system is configured for controlling an alternative energy system, wherein it includes one or more power flow devices that control power flow between electrical energy storage devices (EESDs) and a common dc bus and/or power flow between the dc bus and an external ac electrical system.

Abstract: In sensorless vector control performed through use of a rotation speed of a synchronous motor 6 and the position of a rotor, a positive current is caused to flow to a ? axis on the assumption that a “d” axis serving as a true magnetic axis is out of phase with the ? axis by only an angle of load ?e, whereby torque which is proportional to i? sin ?e and directed toward the ? axis arises in the magnetic axis. Accordingly, a deviation between a d-q axis serving as a true magnetic axis and a ?-? axis serving as a control axis is eliminated. Even if load is exerted on the motor, the ? axis serving as a control axis is constantly aligned with the “d” axis serving as the magnetic axis of the synchronous motor, thereby enabling excellent vector control.

Abstract: A voltage margin testing blade is adapted for use in a bladed server having at least one internal adjustable power supply. The testing blade is further adapted to provide a control signal to the power supply indicative of any desire to modify the output voltage of the power supply. The testing blade senses the output voltage of the power supply and compares it to a desired power supply voltage. The control signal is generated in response to this comparison in order to control the actual power supply voltage at or about the desired power supply voltage.

Abstract: Electrical appliance energy consumption control methods and electrical energy consumption systems are described. In one aspect, an electrical appliance energy consumption control method includes providing an electrical appliance coupled with a power distribution system, receiving electrical energy within the appliance from the power distribution system, consuming the received electrical energy using a plurality of loads of the appliance, monitoring electrical energy of the power distribution system, and adjusting an amount of consumption of the received electrical energy via one of the loads of the appliance from an initial level of consumption to an other level of consumption different than the initial level of consumption responsive to the monitoring.

Abstract: A system to manage energy may include a plurality of energy storage modules. Each energy storage module may include a power converter couplable to a link and a power converter controller to control operation of the power converter. Each energy storage module may also include at least one energy storage unit connected only to the power converter. The system may also include a power management controller to control power delivery from each of the plurality of energy storage modules to the link and to control power delivery to each of the plurality of energy storage modules.

Abstract: Reactive power (VAR) consumption in a power plant or facility having synchronous machines is adaptively controlled in an automated manner. Electrical parameters of the plant are dynamically monitored during plant operation, and the overall plant power system is brought to an optimum operating point under control of a microprocessor-based power measurement system. The microprocessor-based power measurement system adaptively changes the excitation system of synchronous machines in the plant based on results of monitoring. The excitation systems of the synchronous machines may be adjusted to be constant bus voltage, constant reactive power, or constant power factor, according to optimum system performance requirements. The power measurement system also assists in avoiding problems in voltage regulation during increased load demand conditions, such as when starting large electrical motors or energizing large transformers in the system.

Abstract: One embodiment of the present invention provides a system that facilitates reducing static power consumption of a processor. During operation, the system receives a signal indicating that instruction execution within the processor is to be temporarily halted. In response to this signal, the system halts an instruction-processing portion of the processor, and reduces the voltage supplied to the instruction-processing portion of the processor. Full voltage is maintained to a remaining portion of the processor, so that the remaining portion of the processor can continue to operate while the instruction-processing portion of the processor is in reduced power mode.

Abstract: A control system (10) actively limits the power drawn from a main power distribution bus (20) by one or more electric loads (30). The system (10) includes circuitry (14) for determining a maximum permissible current magnitude that may be supplied to the loads (30) based on a signal representative of the voltage magnitude supplied to the loads (30). Additional circuitry (18, 34) limits the power drawn from the main power distribution bus (20) to the maximum permissible current magnitude from exceeding a predetermined maximum power level. As a result, the required design capacity of power generation components and the power distribution system can be reduced in size, weight, and cost.

Abstract: A power control apparatus for controlling charging and discharging of a plurality of storage means (101a, . . . ) has voltage measuring means (102a, . . . ) for measuring voltages of said storage means respectively, current measuring means (103a, . . . ) for measuring currents flowing through said storage means respectively, a status detecting means (104) for detecting the operating status of each storage means from values measured by said voltage measuring means and said current measuring means, and a charging/discharging controlling means (105) for controlling currents, voltages, or power according to the operating status of each storage means detected by said status detecting means to charge or discharge said storage means.

Abstract: Interleaved converter and method for controlling such inverter are provided. The converter includes a plurality of phasing stages. The converter further includes a calculator configured to calculate a duty cycle value of the converter. A processor is configured to receive the calculated duty cycle value. A rulebase is coupled to the processor and includes a set of phase-selection rules configured to select a respective phase number based on the: calculated duty cycle value.

Abstract: The present invention is a system and method for variable base load demand-side energy management. The system of the present invention includes a power reduction device receiving electrical power from an electrical power source and outputting electrical power to a load. The system of the present invention can control the power delivered to one or more devices in a single facility or to multiple facilities. The system of the present invention can control the power delivered to one or more devices located in one or more facilities by sending control signals over various kinds of networks using various communication methods simultaneously, such as a modem, a LAN, or a WAN such as the Internet.

Abstract: For an internal circuit having a first operation mode consuming a first operational current and a second operation mode consuming a second operational current, which is smaller than the first operational current, a first power source regulator for stepping down a predefined output power supply voltage from an input power supply voltage and having a current supply ability corresponding to the first operational current of the internal circuit and a second power source gulator having a current supply ability corresponding to the second operational current are combined in order to, under the control of a power supply control unit, operate the first step-down type regulator in response to a first control signal instructing the first operation mode in the internal circuit and to operate the second step-down type regulator in response to a second control signal instructing the second operation mode.

Abstract: The present invention may be embodied in an apparatus, and related method, for monitoring an individual cell in a fuel cell in an electrical power source. The monitoring apparatus includes a plurality of individual cells, a first switch network, a capacitor, a second switch network, and a voltage measurement circuit. The plurality of individual cells electrically may be stacked in series. The first switch network is coupled between the plurality of cells and the capacitor for momentarily coupling a selected cell to the capacitor. The second switch network is coupled between the capacitor and the measurement circuit for momentarily coupling the capacitor to the measurement circuit for permitting measurement of the voltage across the capacitor for monitoring selected cells. The capacitor may be a floating capacitor that is electrically isolated from a reference voltage of the monitoring apparatus when not coupled by the second network to the measurement circuit.

Abstract: Device miniaturization is made possible by building a battery protection circuit in a microcomputer. A secondary battery protection device comprises a voltage detection means 7 that detects a voltage of a power supply circuit 6 including a secondary battery 1, a current detection means 8 that detects a current of the power supply circuit, and a battery protection circuit 10 that shuts off the power supply circuit 6 based on a signal representing a detection made by the voltage detection means 7 or the current detection means 8 of an excess current that is generated in the power supply circuit 6, wherein the protection circuit 10 is built in a microcomputer 13.

Abstract: The modular switch instrument card has a single or double slot card frame having a front panel. The card frame has module receiving areas for receiving selected switch modules. Each switch module is configured to provide a particular switching function. One or more switch modules may be positioned into the module receiving areas such that switch connectors on the switch modules extend through the front panel and are available for connection to an automated test system. The switch modules may be fixedly mounted within the card frame or may be removably coupled. Each switch module couples to an interconnect bus backplane enabling all installed switch modulars to communicate to a switch interface. The switch interface provides a communication interface to the VXI backplane, thereby providing a uniform and consistent programming interface independent of which switch modules are presently installed into the module receiving areas.

Abstract: A modular architecture for electronic equipment. Data-concentration modules, processing modules and display devices are interconnected by data-transmitters with sensors, measuring instruments and detectors. The data-concentration modules concentrate only the data which is not critical for the industrial process. This data is transmitted to other modules by a multi-receiver serial bus. The other modules directly receive the critical data which is routed by separate, respective serial digital links between, on the one hand, display devices and functions controlling the processes which are distributed in the process modules, and, on the other hand, sensors, measuring instruments and actuators.

Abstract: An apparatus for regulating voltage and power in a computer system is disclosed. The voltage and power regulation is performed by voltage regulation circuitry on a voltage regulator module. The voltage regulator module is a detachable unit which interfaces with the motherboard through a socket connector. The socket connector has a fixed pin definition which allows a variety of voltage regulator modules programmed to regulate voltages and power at different levels to be implemented on the motherboard.

Abstract: A system including a component (e.g., a processor) with a clock and a thermal management controller that monitors a temperature in the system. The thermal management controller varies the component between different performance states (e.g., cycles the processor between a high and a low performance state) when an over-temperature condition is detected. The thermal management controller further throttles the clock of the component while in the low performance state until the over-temperature condition is removed.

Abstract: An electronic device employed in a system where packets are sent and received between a plurality of electronic devices connected by a bus, with a bias voltage not being outputted to the bus in a first operating mode operated in from when a power supply is thrown until an internal initialization process is complete and a bias voltage is outputted to the bus in a second operating mode operated in after the initialization process is complete so that communication system hang-ups at the time of throwing the power supply can be avoided.

Abstract: A method and apparatus for detecting leakage current in the coolant of a fuel cell stack. The invention eliminates the use of a conductivity sensor by using a voltmeter to measure the voltage across the coolant. If the coolant voltage is at or below a predetermined level, an excessive level of conductivity in the coolant exists, and the presence of leakage current is reported. The invention can also compare the coolant voltage to two different predetermined voltage levels, the second one higher than the first. A coolant voltage at or below the lower voltage level could signal a shut down of the stack, while a coolant voltage at or below the higher voltage level could signal an alarm or another diagnostic. The invention can optionally use a second voltmeter to measure the voltage across the stack and calculate the resistivity and conductivity of the coolant.

Abstract: A frequency reference is employed to correct a frequency error in a signal synthesizer. The frequency reference provides a reference frequency with a parts per million deviation from the reference's nominal frequency. The reference frequency parts per million deviation is equal in magnitude to the parts per million deviation of the frequency error from a desired signal synthesizer output frequency. The deviation in the reference frequency offsets the deviation from the desired output frequency to significantly reduce the frequency error. The frequency reference includes a voltage controlled oscillator, programmable voltage generator, and voltage control engine. The reference frequency is set by the voltage controlled oscillator in response to a frequency setting voltage from the programmable voltage generator. The voltage control engine is coupled to the programmable voltage generator to provide a voltage setting value that controls the frequency setting voltage.