A system and method for combining power from DC power sources. Each power source is coupled to a converter. Each converter converts input power to output power by monitoring and maintaining the input power at a maximum power point. Substantially all input power is converted to the output power, and the controlling is performed by allowing output voltage of the converter to vary. The converters are coupled in series. An inverter is connected in parallel with the series connection of the converters and inverts a DC input to the inverter from the converters into an AC output. The inverter maintains the voltage at the inverter input at a desirable voltage by varying the amount of the series current drawn from the converters. The series current and the output power of the converters, determine the output voltage at each converter.

Distributed Power Harvesting Systems Using DC Power Sources

A monitoring system and method for monitoring performance of individual powers sources in a distributed power source system A monitoring module is coupled to each of the power sources, or to each string of serially connected power sources, to monitor and collect data regarding current, voltage, temperature and other environmental factors at the power source The collected data is transmitted over a power line to a central analysis station for analysis Data collected from each source indicates malfunction or degradation at the source Comparison of data collected from adjacent sources filters for environmental factors impacting neighboring sources such as cloudy days for a solar panel Comparison of data collected from the same source at different times indicates soiling or degradation of the source with time or periodic events such as a moving shade from an adjacent building

Monitoring of Distributed Power Harvesting Systems Using DC Power Sources

A CCFL power converter circuit is provided using a high-efficiency zero-voltage-switching technique that eliminates switching losses associated with the power MOSFETs. An optimal sweeping-frequency technique is used in the CCFL ignition by accounting for the parasitic capacitance in the resonant tank circuit. Additionally, the circuit is self-learning and is adapted to determine the optimum operating frequency for the circuit with a given load. An over-voltage protection circuit can also be provided to ensure that the circuit components are protected in the case of open-lamp condition.

High-efficiency adaptive DC/AC converter

Method for distributed power harvesting using DC power sources

The output current value of a direct-current power source obtained by low-frequency, minute modulation of the input voltage of a switching converter is detected in a circuit having an amplification factor switching function that switches the amplification factor between definite magnitudes synchronizing with the modulation, and by using a signal obtained by demodulating in a discriminator circuit the output of this circuit synchronizing with the modulation to control the switching converter, the power point of the switching converter can be tracked to the maximum power point by following the change in state of the direct current power source.

Maximum power point tracking method and device

A solar cell power source device is disclosed which optimizes the power output of the solar cell by detecting a maximum power point of the solar cell and controlling the duty cycle of a switching transistor in a switching power converter such that the output current of the solar cell follows the maximum power point. Also shown is a pulse width modulation controller which multiplies the output voltage of the solar cell by the output current of the solar cell to obtain a power detecting signal, samples the power detecting signal during two different sample periods to determine if the power output is decreasing, and modulating the pulses output to the switching transistor of the switching power converter in order to maintain the power output of the solar cell at the maximum power point.

Solar cell power source device

A controller for performing a zero voltage switching using a resonance mode converter, and an electronic ballast adopting the same, includes a power controller, a shutdown protection circuit and a brownout circuit, and performs a switching when voltage of a switching element is zero, thereby preventing excessive power consumption, enhancing efficiency and decreasing noise.

Zero voltage switching controller of resonance mode converter and electronic ballast using the same

A maximum power point detecting circuit is disclosed including: a power detector for generating a power detecting signal responsive to an output voltage and an output current of a solar cell; a comparator for comparing a previous power average value with a current power average value according to the power detecting signal for a constant time; and a discriminator for latching an output signal of the comparing means immediately after a current constant time, setting an output immediately before a previous constant time, and judging that an output power of the solar cell decreases when the current power average value is smaller than the previous power average value to generate a discriminating signal.

Maximum power point detecting circuit

A time-compensated overcurrent detection circuit shuts off a D.C. motor during large overcurrent conditions caused by actual constraints on the motor. The circuit prevents premature motor shut off by establishing a minimum activation time for shutting off the D.C. motor. An overcurrent time compensator establishes a minimum time period for activating a motor reset signal after sensing an overcurrent condition. The circuitry uses a relatively small capacitor that provides quick response to overcurrent conditions.

Time-compensated overcurrent detection circuit for DC motor

An overcurrent-detecting device for a DC motor includes a converter for changing a current signal to a voltage signal in a motor; an integrator for comparing an input signal from the convertor with a first reference voltage, and for integrating an excessive value of the reference voltage; and a detector for comparing an input signal from the integrator with a second reference voltage, sensing an overcurrent when the input signal is smaller than the second reference voltage, and outputting a resultant signal. In detecting an overcurrent of the DC motor, the device integrates a higher voltage than a reference voltage, and then detects an overcurrent when the DC motor is constrained. This overcurrent-detecting device, therefore, can be exactly operated by a small-capacity capacitor without incorrect operation with respect to noise and abrupt overload, while not permitting forced operation in the initial operation, and also can be operated quickly in response to an actual mechanical constraint having a reasonable overcurrent.

Hyun-min Jo

Papers

Solar cell power source device

Zero voltage switching controller of resonance mode converter and electronic ballast using the same

Maximum power point detecting circuit

Time-compensated overcurrent detection circuit for DC motor

Overcurrent detecting device for a DC motor