Abstract: A novel switching rectifier circuit that combines the conventional three-phase, 6-stepped PWM rectifier/inverter circuit with a simple, low-power switch commutation circuit to provide zero-voltage turn-on for the switches, and soft turn-off for the diodes. The main features of the new circuit include elimination of switching losses on the power switches and reverse recovery problems on the diodes, elimination of the need for any snubbers in the three-phase bridge, possibility of use of slower diodes in the power bridge, constant frequency operation, and no increase in component current and voltage stresses over the conventional PWM rectifier.
September 17, 1993
Date of Patent:
July 11, 1995
The Center for Innovative Technology
Vlatko Vlatkovic, Dusan Borojevic, Fred C. Lee
Abstract: A power supply for use in electronic apparatuses is disclosed, and the power supply is provided with a switching control circuit for controlling the switching operations of a switching device of a rectifying portion, thereby making the switching device more efficiently operate. In the case where an over-voltage is supplied, the switching device is prevented from being damaged. There is added a tertiary coil in the transformer for inducement of a voltage, and a switching circuit is added to it, so that the switching control circuit should be switched in synchronization with a main MOS transistor which is connected to a primary coil of the main transformer. Thus, the switching operations of the switching device is made more efficient, and the switching device is protected, as well as making it possible to carry out a high density design. Therefore the power supply can be applied to all kinds of electronic apparatuses.
Abstract: A power supply circuit limits the voltage on a filter capacitor driven by rectified half-cycles of an input AC waveform. A FET switch in series with the current charging the filter capacitor is opened as soon as the charge on the filter capacitor is adequate. A voltage triggered latch circuit is responsive to the rectified AC input applied through a decoupling diode to the filter capacitor, and supplies a control signal to the FET switch. A further sensing circuit can monitor the current charging the filter capacitor, and can trigger the latch to open the FET switch as needed to limit initial in-rush current during the initial application of AC power. The decoupling diode decouples the rectified peaks provided by the rectifiers from the voltage on the filter capacitor.
Abstract: Instabilities in the output voltage provided from an AC power supply system connected to a power factor correcting load are suppressed by a stabilizer which is connected across the output lines from the power supply system to the load. The stabilizing apparatus includes a rectifier having AC input nodes connected to the power supply system output lines, and DC output nodes at which DC voltage appears. A capacitor and resistor are connected in parallel across the output nodes of the rectifier. During normal operation, where the peak AC voltage from the power supply system is substantially constant, the capacitor charges up to a voltage level near the zero to peak value of the AC voltage waveform, with the charge on the capacitor slowly dissipated through the parallel resistor at a rate that does not substantially dissipate the charge between peaks of the AC voltage waveform.
July 28, 1993
Date of Patent:
June 20, 1995
Best Power Technology, Incorporated
Steven J. Paul, Phillip A. Board, Michael W. Hogan
Abstract: A power supply system of a high reliability and stability capable of suppressing a cross current flow by establishing rapidly synchronism between a power converter and an AC power source in a parallel operation for changing over the power supply sources. The power supply system comprises a current sensor for detecting an AC current supplied from a power converter, a comparator for making decision as to whether the AC current exceeds a predetermined value, and a regulation input means for fetching an active component of the AC power supplied from the power converter in response to an output signal of the comparator, wherein when the AC current exceeds a predetermined value, an output frequency of the power converter is speedily regulated so as to coincide with an output frequency of the AC power source in accordance with a drooping characteristic of the active component of the AC power, while in an isolated operation of the power converter, the output frequency is set at a predetermined value.
Abstract: An HVDC transmission has two converters (SR1, SR2). Each converter is connected between an alternating-voltage network (N1, N2) and a d.c. link (L1, L2) common to the converters. At least one converter is connected to its alternating-voltage network without the use of any full transformer, for example directly, or via an inductor or an autotransformer, or via series capacitors. The transmission has a mutual inductor (IB) which is arranged on the d.c. side of the converter and which has two windings (IB1, IB2) which are each connected to a respective one of the d.c. supply lines of the converter and are magnetically coupled to each other, the inductor being designed and connected so as to exhibit a high impedance to ground mode currents.
August 3, 1993
Date of Patent:
May 9, 1995
Asea Brown Boveri AB
Per-Erik Bjorklund, Bernt Bergdahl, Urban Astrom, John J. Vithayathil
Abstract: An integrated circuit voltage regulator employs a PNP pass transistor to produce a low dropout voltage. Saturation in the pass transistor produces excessive substrate current which appears in the form of wasted current which lowers the regulator efficiency. A current conducted by the sat catcher circuit is employed to avoid pass transistor saturation. The sat catcher is controlled dynamically so the dropout voltage is minimized and the voltage regulator maintains good performance at high regulator output currents.
Abstract: An AC-to-DC converter for providing a step-down output DC voltage from an AC voltage source. The converter includes a rectifier connected to the AC voltage source to provide therefrom a rectified DC voltage to a step-up chopper. The chopper includes an inductor and a switching element which is connected in series with the inductor across the rectifier and which is driven to periodically turn on and off so as to store into the inductor an energy from the rectified DC voltage when the switching element is turned on and to release the energy from the inductor through a blocking diode to a charge-pump circuit when the switching element is turned off. The charge-pump circuit is connected to receive the energy released from the inductor as well as from the rectifier to accumulate a first voltage and provides a divided voltage of the first voltage to charge a smoothing capacitor by the divided voltage so as to develop thereat the step-down output DC voltage for driving a load.
Abstract: A circuit arrangement provided with a switch mode power supply energized with a pulsatory input current generated by means of high-frequency switching of the main switching means HS (3) provided in turn with a drive circuit (6) having at least drive switching means SS (60) and connected to a return current line (7).A self-inductance element (61) is included in the drive circuit, preferably between the main switching means HS and the drive switching means SS. This arrangement results in a rapid level shifter of compact construction.
Abstract: A full wave rectified AC mains supply voltage is produced from an AC mains supply voltage without low-pass filtering. The rectified voltage is developed in a winding of a flyback transformer. The winding of the flyback transformer is also coupled to a switching transistor that generates in the winding a first plurality of current pulses at a frequency that is higher than the frequency of the mains supply voltage. The current pulses energize a load circuit. A capacitor voltage is coupled via a second switching transistor to the winding to produce in the winding a second plurality of current pulses that energize the load circuit during a portion of the period of the mains supply voltage that does not occur in the vicinity of the peak of the mains supply voltage. When the second plurality of current pulses are generated, the mains supply voltage is decoupled from the first winding.
Abstract: In a control device for controlling a CPU 11 in accordance with an input voltage which is applied to the CPU and which results from a power source voltage, a first detecting circuit 16 produces a first detection signal when the power source voltage is lower than a first voltage. Responsive to the first detection signal, a switching circuit 21 stops supply of the input voltage to the CPU and the CPU assumes to a waiting state. A condenser 15 discharges an electric voltage in order to compensate a drop of the input voltage. When the input voltage is lower than a second voltage which is lower than the first voltage, a second detecting circuit 17 produces a second detection signal to make the CPU become a reset or an initial state.
Abstract: An invertor-controlled power unit includes a direct current power source circuit, an invertor circuit, and a pair of output lines. A waveform of voltage appearing between the output lines is detected. There is generated a target output waveform signal having a predetermined frequency. The target output waveform signal is converted into a control signal, which is then supplied to the invertor circuit. The invertor circuit effects switching control of an output from the direct current power source circuit in response to the control signal. There is detected an overvoltage state of the direct current power source circuit. The generation or supply of the control signal is inhibited while there is detected the overvoltage state of the direct current power source circuit. The control signal starts to be supplied again to the invertor circuit at a timing at which the detected waveform of the voltage between the output lines crosses a substantially zero volt level.
Abstract: An improved method for current limiting applications to control the current through MOSFETs or IGBTs. An amplifier having a single, high-frequency pole is used to drive the large gate capacitance of a power MOSFET or IGBT. The current in the power transistor generates a negative feedback voltage in a sensing resistor. This feedback voltage is compared with a reference voltage to determine the output voltage of the amplifier. This provides greater stability for driving IGBT transistors, and the actual frequency response is only dependent upon the poles generated by the power transistor and its load. The current in the transistor ramps up to a value determined by the reference voltage, and then settles to a constant value with little or no overshoot or oscillation.
Abstract: A universal signal converter composed of a first current mirror having a first input terminal adapted to receive a first input signal and a first output terminal. A first common terminal is coupled to a first reference terminal. The signal converter is adapted to receive a second input signal via the first output terminal. The converter further comprises a second current mirror having a second input terminal coupled to a second reference terminal, a second output terminal adapted to supply a first output signal, and a second common terminal coupled to the first output terminal. A third current mirror has a third input terminal coupled to the second reference terminal and a third output terminal adapted to supply a second output signal. A third common terminal is coupled to the first input terminal and a bias current source is coupled between the second and the third input terminal and the second reference terminal.
Abstract: A pulse width modulated (PWM) power supply combines the advantages of pulse width modulator circuitry with linear circuitry to provide power supply operation over an extended input range with no dropout of power supply output and no adverse effect on a load. The PWM circuitry includes input voltage scalers, control logic, mode detectors, an inductor, a diode switch and a capacitor and the linear circuitry includes a transistor, transistor voltage scaling and gate driver logic.
Abstract: A two terminal temperature transducer which controls its operating current to indicate the temperature, by producing a linear response to temperature which can be set to extrapolate to a desired temperature. The transducer including circuitry which controls its operating current to be linearly proportional with temperature. The circuitry operates to produce a first reference voltage which is proportional to absolute temperature, produce a second reference voltage which is complementary to absolute temperature, generate a voltage drop corresponding to the operating current, compare the voltage drop to a temperature sensitive voltage corresponding to the difference between the first reference voltage and the second reference voltage, and adjust the operating current so as to equilibrate the voltage drop and the temperature sensitive voltage.
Abstract: The constant current generating circuit includes a high resistance element for generating a very small current. This very small current is supplied to a first MOS transistor having a sufficiently large gate width to gate length ratio. The gate-source voltage of the first MOS transistor becomes its threshold voltage VTH, and the voltage applied across a resistance connected between the gate of the first MOS transistor and the ground line is set to a constant value VTH. Thus, a constant current is normally passed through the resistance. Since the very small current is supplied from the high resistance element which is normally turned on, regardless of the change of the power supply voltage, a constant current can be generated stably.
Abstract: A voltage reference circuit (2) is provided which includes a 2nd order curvature correction circuit (3) that eliminates undesirable 2nd order polynomial temperature dependency characteristics. A bandgap reference circuit (Q4, Q3, Q2, Q1, R2 and R1) forms a bandgap current (I.sub.X) that is dependent upon absolute temperature. A translinear cell (Q15, Q14, Q13, Q12, Q11 and Q10) transforms this current in a squaring transformation and divides the squared current by a temperature independent current (I.sub.X). A current mirror (Q17 and Q16) adjusts the value of the squared current so that it approximates the value of the 2nd order term of the bandgap reference circuit.
Abstract: A system and method minimizing switching errors in voltages delivered to a resistive load. Switch impedances can be significant when small resistor values are utilized. A system relies on varying the resistance in the switches to compensate for the output voltage errors. The selection of a particular CMOS input transmission gate depends upon which outputs of a resistor divider are selected. In concept, a system is created which replaces each input transmission gate with a resistor and a zero impedance switch. The combination of properly selected CMOS input transmission gates results in output offset voltage errors which are greatly reduced due to the matching impedances of the individual switches.
Abstract: In a non-insulated, self-oscillation type DC-DC converter, a first PNP switching transistor (Q1) has the emitter thereof connected to the emitter of a second switching transistor (Q2) of the same conductivity type as the first switching transistor. The base of the first switching transistor (Q1) is connected to the collector of the second switching transistor (Q2). The base of the first switching transistor (Q1) is connected to the base of the second switching transistor (Q2) through a resistor R2. A feedback circuit (4) is connected between the collector of the first switching transistor (Q1) and the base of the second switching transistor (Q2).