179 results about "Switching frequency control" patented technology

A resonant switched power converter having switching frequency controlled in response to an output voltage thereof achieves over-current protection such as at start-up or under short circuit conditions using a resonant tank circuit which provides a notch filter in addition to a band pass filter. A additional band pass filter provided in the resonant tank circuit achieves increased power transfer to a load and reduced circulating resonant currents and conduction losses. The inductances of the preferred LCLCL tank circuit or other tank circuit with two pass band filters and a notch filter may be integrated into a single electrical component.

A frequency-controlled load driver circuit includes a steady-state and a transient operational mode. A switching driver switches a load current to a solenoid at a set switching frequency during a steady-state operational mode. An analog-to-digital converter (ADC) oversamples a sense resistor voltage an integer number of times within each period of the switching frequency. A control circuit sets the switching frequency of the driver during the steady-state operational mode by providing predetermined switching times. The control circuit disables switching during the transient mode. Dither can be applied during the steady-state mode.

A heat-fixing apparatus is provided that enables a rise in temperature of a heating member to be closely tracked, and an excessive rise in temperature of the heating member to be obviated, a simple configuration and irrespective of differences in the operating mode, such as immediately after a rise in temperature or during continuous operation. Different threshold values are set in accordance with different modes, such as a warm-up mode and a fixing operation mode. Threshold decisions on a switching frequency controlled by a frequency control section are made using different threshold values, according to the mode. A switching frequency of switching elements are varied so that power necessary in each mode is supplied to an exciting coil. An excessive rise in temperature is prevented in each mode by halting a switching element drive in accordance with the threshold decision.

A switching power supply circuit ready for worldwide use is disclosed which suppresses a variation of a pulse voltage to be fed back when the alternating-current input varies. The switching power supply circuit includes a composite resonance type converter of a switching frequency control scheme wherein a voltage resonance pulse voltage generated in a primary side voltage resonance converter is fed back to a rectification diode through a high speed diode and an inductance or a transformer. An active clamp circuit is provided on the primary side to clamp the voltage resonance pulse voltage.

A fly-back power converter has a current-estimating control loop that senses the primary output current in a transformer to control the secondary output. A primary-side control circuit switches primary current through the transformer on and off. A discharge time when a secondary current through an auxiliary winding of the transformer is flowing is generated by sampling a voltage divider on an auxiliary loop for a knee-point. A normalized duty cycle is calculated by multiplying the discharge time by a current that is proportional to the switching frequency and comparing to a sawtooth signal having the switching frequency. The peak of a primary-side voltage is sensed from the primary current loop and converted to a current and multiplied by the normalized duty cycle to generate an estimated current. An error amp compares the estimated current to a reference to adjust the oscillator frequency and peak current to control primary switching.

Provided is a power control apparatus for high frequency dielectric heating, which is not affected by magnetron types, fluctuations of characteristics, power supply voltages and the like. The power control apparatus is provided with input current detecting sections (71, 72) for detecting an input current to an inverter circuit (10), which rectifies (31) an alternating current power supply voltage (20) and converts it into high-frequency power by performing high-frequency switching. A switching frequency control signal (92) wherein input current waveform information (90) from the input current detecting section and power control information (91) are mixed, is converted into a drive signal of semiconductor switching elements (3, 4) of the inverter circuit.

The present invention provides a power supply circuit performing constant voltage control by switching frequency control and achieving minimization of a necessary control range of the switching frequency control and implementation of a configuration ready for a wide range. A switching power supply circuit includes a switching circuit, a switching driving unit, an insulating converter transformer, a primary side series resonance circuit, a secondary side series resonance circuit, a secondary side DC output voltage production unit, a constant voltage control circuit, and a composite coupling coefficient setting mechanism.

A power control unit for a high-frequency dielectric heating not affected by variations in the magnetron type or characteristic, and power supply voltage fluctuation, etc., is provided. The power control unit for a high-frequency dielectric heating has an input current detection section 71, 72 for detecting input current of an inverter 10 for rectifying 31 an AC power supply voltage 20, performing high-frequency switching of the voltage, and converting the voltage to high-frequency power. The power control unit for a high-frequency dielectric heating converts a switching frequency control signal 92 provided by mixing input current waveform information 90 and power control information 91 into a drive signal of a semiconductor switching element 3, 4 of the inverter.

A direct current (DC) to DC power converter includes a first bus converter for converting a first DC bus voltage into a first high frequency AC voltage and a second bus converter for converting a second high frequency alternating current (AC) voltage into a second DC bus voltage. The DC to DC converter also includes a resonant circuit for coupling the first bus converter and the second bus converter and a controller for providing switching signals to the first bus converter and the second bus converter to operate the power converter in a soft switching mode. The controller includes a switching frequency controller for determining a switching frequency signal for the power converter based on a reference output current and a phase shift controller for determining a phase shift signal for the power converter. When the reference output current is lower than the a first load current value the switching frequency signal is maintained at a first switching frequency and the phase shift is determined according to the reference output current. Further, when the reference output current is above a second load current value the switching frequency signal is maintained at a second switching frequency and the phase shift is determined according to the reference output current. When the reference output current is between the first load current value and the second load current value, the switching frequency signal is adjusted according to a value of the reference output current and the phase shift is determined based on the switching frequency, the reference output current and perturbations in the output current.

A power supply circuit is disclosed which performs constant voltage control by switching frequency control and is ready for a wide range while the necessary control range of the switching frequency control is reduced. The circuit includes a primary side series resonance circuit forming a current resonance type converter, and a secondary side series resonance circuit formed from secondary windings and secondary side series resonance capacitors while a coupling type resonance circuit by electromagnetic coupling of an insulating converter transformer is formed. To obtain a single-humped characteristic from the coupling type resonance circuit, a gap of approximately 1.6 mm is formed in the core of the insulating converter transformer so as to achieve a coupling coefficient of 0.65 or less. A secondary side DC output voltage is produced from outputs of the secondary windings so as to cope with a heavy load condition.

A system for power conversion includes a power converter having switching elements, a detector, and a controller is provided. The detector detects a parameter and provides electrical signals indicative of the parameter. The controller receives the electrical signals transmitted from the detector, and sends commands to instruct the power converter to perform power conversion by operating the switching elements in accordance with switching signals at a different frequency in response to a detection of the system condition. A method for operating the system is also provided.

A thermal controller for driving a gate control unit of a gate-driven semiconductor switching device, the thermal controller comprising a junction temperature estimation module for generating an estimated junction temperature for the switching device, a gate voltage control module for modifying a gate voltage of the switching device, a switching frequency control module for modifying a switching frequency of the switching device, and a duty cycle control module for modifying the duty cycle of the switching device. In use, the thermal controller is adapted to activate one of the gate voltage control module, switching frequency control module and duty cycle control module dependent upon the estimated junction temperature in order to maintain the actual junction temperature below a pre-determined limit.