摘要:
A power generation system includes photovoltaic (PV) modules for generating power and power converters coupled to receive power from the PV modules. The power generation system further includes converter controllers to control the power converters, each converter controller includes a maximum power point tracking control element. A master controller in the power generation system is configured to coordinate power outputs of the power converters by controlling the timing and numbers of power converters having power-voltage (P-V) curves sweeping between maximum power points and power points off the maximum power points.
摘要:
A method of operating a system having a coil includes providing a switched amplified current to the coil, and adding a second current to the switched amplified current, wherein the second current is substantially out of phase with the switched amplified current such that the coil receives current with substantially no switching frequency ripple.
摘要:
A boost inductor value reduction circuit is integrated into a traditional boost power converter to greatly reduce undesirable high frequency harmonics from being fed back to the input side of the boost power converter. The boost inductor value reduction circuit is very small when compared with traditional filter techniques, is less costly than traditional filter techniques, and does not degrade the boost power converter control performance. It can also be used to reduce the size of the boost inductor without compromising the converter performance for use in energy efficient sensitive applications such as photovoltaic inverters.
摘要:
A circuit for driving the current for inductive loads such as an electron beam deflection coil for an x-ray generator system. The circuit includes two selectable voltage levels provided by a high level and a low level source. A plurality of switches selects the voltage level and determines the polarity of the current through the coil. The high level source is selected when the load is charging or discharging. The low level source is selected when the load is operating in a constant current mode, where a high frequency switching device controls the voltage through the load by switching the low level source to generate a PWM waveform according to a reference current duty cycle. A feedback loop monitors the current through the load to adjust the duty cycle of the PWM waveform to more accurately control the current through the load.
摘要:
In one embodiment, a system includes a gradient coil driver configured to supply electrical signals to a gradient coil of a magnetic resonance imaging system. The gradient coil driver includes an electronic circuit. The electronic circuit includes a first H-bridge circuit electrically coupled to a power source. The first H-bridge includes a plurality of metal-oxide-semiconductor field-effect transistor (MOSFET) switches; and a plurality of diodes electrically coupled in parallel with each MOSFET switch. Each diode of the plurality of diodes is configured to conduct current to cause zero voltage potential across a source and a drain of one of the plurality of MOSFET switches. The first H-bridge also includes a load configured to regulate currents flowing through each of the plurality of diodes and each MOSFET switch of the plurality of MOSFET switches.
摘要:
A gradient amplifier system is presented. An embodiment of a gradient amplifier system that includes a power stage having a plurality of bridge amplifiers, where each of the plurality of bridge amplifiers operates at a first switching frequency. The gradient amplifier system further includes a gradient coil coupled to an output terminal of the power stage and configured to produce a magnetic field proportional to a coil current signal supplied by the power stage. In addition, the gradient amplifier system includes a controller stage coupled to an input terminal of the power stage and configured to generate a pulse width modulated gate signal based on the coil current signal and a reference current signal, where the pulse width modulated gate signal is generated at a second switching frequency upon occurrence of a slew rate associated with the reference current signal is below a determined threshold rate and an amplitude level associated with the reference current signal is above a determined level. Further, the controller stage is configured to apply the generated pulse width modulated gate signal to the power stage for changing an operating frequency of each of the plurality of bridge amplifiers from the first switching frequency to the second switching frequency.
摘要:
A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.
摘要:
One embodiment is a gate drive circuitry for switching a semiconductor device having a non-isolated input, the gate drive circuitry having a first circuitry configured to turn-on the semiconductor device by imposing a current on a gate of the semiconductor device so as to forward bias an inherent parasitic diode of the semiconductor device. There is a second circuitry configured to turn-off the semiconductor device by imposing a current on the gate of the semiconductor device so as to reverse bias the parasitic diode of the semiconductor device wherein the first circuitry and the second circuitry are coupled to the semiconductor device respectively through a first switch and a second switch.
摘要:
A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.
摘要:
Embodiments of the present disclosure include a magnetic resonant imaging (MRI) system including a gradient driver configured to deliver a pulse sequence to gradient coils in the MRI system. The gradient driver may be interleaved, and may include two or more interleaved drivers, such that a high amplitude pulse may be output by operating the two interleaved parts of the gradient driver while spreading the electrical loss and maintaining the thermal stability of the system. In one embodiment, each interleaved driver may be rated to output approximately half a maximum amplitude of a current utilized by the gradient coil, and only one interleaved driver may be in operation if only one interleaved driver is sufficient for delivering a necessary pulse to the coils. Further, the interleaved drivers may alternate in operation to maintain thermal stability in the switching semiconductors of the gradient driver.