US 4,164,785 A · Multiphase to single phase and frequency converter system

Abstract

A multiphase to single phase electrical energy converter wherein the frequency is converted from a relatively high frequency, in order of 1,000 hertz, to a relatively low frequency, as for example, normal household frequency of 60 hertz. A three-phase alternator is driven by an internal combustion engine, the output of the alternator being fed to a full-wave bridge circuit and finally to an inverter. The output of the bridge circuit is acted on by a resolver. The resolver is utilized to control the delivery of energy from the alternator to the inverter to provide an average current or power to the inverter which increases and decreases in a unipolar sinusoidal form at a frequency which is twice the desired output frequency. The inverter is utilized to invert every other cycle of the output from the resolver. Thus, the power from the inverter will take the form of an alternating sinusoidal waveform at 60 hertz. An arc suppressor circuit is provided to protect the resolver and inverter from arcing during switching for non-resistive loads. A current detector circuit senses the inductive ring current at the load and protects the alternator from application of improper loads and a thermal breaker protects the alternator from load faults.

Claims31

Dependent claims

An energy conversion system for converting a high frequency alternating output potential from an alternator to a single phase, low frequency, alternating output for a load, including rectifying means connected to the output from the alternator to produce a unidirectional output, means connected with said rectifying means for controlling said rectifying means to provide a plurality of unidirectional waves, inverter means for inverting alternate ones of said waves whereby an alternating output wave is provided, arc suppressor circuit means connected to the load for providing a low impedance shunt path around said rectifying means and said inverter means at a preselected time after each of said unidirectional waves, and spike detector means connected to the load and responsive to a condition indicative of an excessive voltage condition for disabling the alternator, said spike detector means comprising a breakdown device connected across the load and having a bipolar breakdown characteristic for breaking down in response to potentials of a preselected high magnitude, a positive temperature coefficient resistor having a sharp resistance rise characteristic being physically connected to said breakdown device and responding to the temperature rise of said breakdown device during breakdown for providing a sharp change in resistance and actuating means responsive to said sharp change in resistance for opening said field and shutting down said alternator.

An energy conversion system for converting a high frequency alternating output potential from an alternator to a single phase, low frequency, alternating output for a load, including rectifying means connected to the output from the alternator to produce a unidirectional output, means connected with said rectifying means for controlling said rectifying means to provide a plurality of unidirectional waves, inverter means for inverting alternate ones of said waves whereby an alternating output wave is provided, and arc suppressor circuit means connected to the load for providing a low impedance shunt path around said rectifying means and said inverter means at a preselected time after each of said unidirectional waves, said arc suppressor circuit means comprising a first controlled conduction device having first principal electrodes and a first control electrode actuable to render said first principal electrodes conductive in response to a first trigger signal, said first principal electrodes located in said shunt path, whereby said shunt path is closed when said first principal electrodes are conductive and opened when said first principal electrodes are nonconductive, sensing means sensing the magnitude of current through said brush and slip ring assembly for providing said first trigger signal as the magnitude of current through said brush and slip ring assembly drops whereby said first principal electrodes are rendered conductive and said shunt path is closed.

In an energy conversion system for converting a three phase, high frequency alternating output potential from an alternator to a single phase, low frequency alternating output for a load, the improvement comprising:

rectifying means connected to the output of the alternator for providing a rectified output through each phase, resolver means connected to said rectifying means and controlling said rectifying means for providing a pulse width modulated rectified output defined by continuously repetitive unidirectional pulses having similar wave shapes, said resolver means comprising three resolver switches, with one of said resolver switches being operable with said rectified output for each phase, said resolver switches being operable on said rectified output to provide a modified rectified output and being actuable to closed and open positions in a preselected sequence, a first of said switches being actuated closed prior to the remaining two for transmitting said rectified output for the first phase, a second of said switches being actuated closed approximately 30.degree. after said first switch, for transmitting said rectified output for the second phase, and a third of said switches being actuated closed approximately 60.degree. after said first switch for transmitting said rectified output for the third phase, each of said switches being closed for approximately 90.degree. whereby said first switch opens with said second and third switches closed, said second switch opens with said third closed, and said third switch opens with said first and second opened, each of said unidirectional pulses comprising the composite output from said resolver switches for a period including when said first switch was actuated closed to when said third switch was actuated open, inverter means connected to said resolver means for receiving said modified rectified output and for inverting alternate ones of said unidirectional waves whereby an alternating voltage output is provided, said inverting means comprising an inverter switch operable for inverting the polarity of alternate ones of said unidirectional waves, each of said resolver switches comprising a brush and resolver ring structure, said inverter switch comprising three brushes and an inverter ring structure, said resolver ring structure and said inverter ring structure being located on a common rotor and said resolver switches and said inverter switch being located on a common stator, reducer means connecting said common rotor with the alternator whereby said rotor is rotated at a preselected speed less than the alternator speed such that the frequency of the resultant alternating output from said inverting means is 60 Hz, said resolver ring structure comprising a pair of diametrically opposed resolver insulating portions extending circumferentially for apporoximately 90.degree. and being spaced apart by a pair of diametrically opposed resolver conductive portions with each said resolver brush adapted to engage said resolver insulating and conductive portions, each said resolver brush being located 30.degree. electrically from an adjacent said resolver brush, said inverter ring structure comprising a 360.degree. continuous conductive portion electrically connected to a first less than 180.degree. conductive portion and a second less than 180.degree. conductive portion circumferentially in line with and extending equally circumferentially with said first conductive portion, a pair of inverter insulating portions located between said first and second conductive portions and extending circumferentially slightly greater than the width of associated ones of said inverter brushes whereby said first and secoond conductive portions extend circumferentially substantially further than said inverter insulating portions, two of said inverter brushes spaced 180.degree. apart for sequential engagement with said first and second conductive portions and said inverter insulating portions and a third of said inverter brushes located for engagement with said 360.degree. continuous conductive portions, said second less than 180.degree. conductive portion being electrically connected with said resolver conductive portions, said brush for said third resolver switch adapted to engage said resolver insulating portions and open the circuit therethrough prior to said two of said inverter brushes engaging said inverter insulating portions and opening the circuit therethrough, are suppressor circuit means connected to the load for providing a low impedance shunt path around said resolver means prior to said third resolver switch opening and opening said shunt path prior to said inverter switch opening, said suppressor circuit means comprising a first unidirectional solid state controlled conductive device having a first principal circuit and a first gate circuit with said first principal circuit being rendered conductive in response to a first gate signal at said first gate circuit, first sensing means for sensing a change in current through said third resolver switch indicative of an incipient open condition for providing said gate signal whereby said first principal circuit is rendered conductive closing said shunt path, timing means responsive to said first principal circuit being closed for providing a second signal a preselected time interval after said first principal circuit is closed, commutating means connected to said first principal circuit for rendering said first principal circuit non-conductive in response to said second signal, said preselected time interval being of a selected duration terminating prior to two of said inverter brushes opening the circuit therethrough whereby said shunt path is opened prior to said two of said inverter brushes opening, ring current level detection means electrically connected to the load and responsive to a voltage having a preselected rate of rise for disabling the alternator, said ring current level detection means comprising time delay means for delaying the disabling for a preselected time greater than the time for one cycle, and spike detector means connected to the load and responsive to a condition indicative of an excessive voltage condition for disabling the alternator, and regulating means for regulating the alternator whereby said modulated rectified output is regulated.

An energy conversion system for converting multiphase, high frequency energy to single phase, low frequency energy, and providing the single phase energy to a load, the improvement comprising an alternating current alternator for generating the alternating current multiphase energy at a selected high frequency, rectifying means connected to the output from said alternator to produce a unidirectional output from said rectifying means control switch means connected with said rectifying means for controlling said rectifying means to provide a plurality of pulse width modulated unidirectional waves having a preselected frequency less than said selected high frequency, and inverter means for inverting alternate ones of said modulated waves whereby an alternating output wave is provided, one of said control switch means and said inverter means comprising circuit switch means for opening the circuit to the load and including a brush and slip ring assembly operable at least at some time to provide an open circuit between the said rectifying means and load, and arc suppressor circuit means for providing a low impedance shunt path around said switch means prior to said switch means providing said open circuit whereby arcing of said brush and slip ring is inhibited.

An energy conversion system for converting multiphase, high frequency energy to single phase, low frequency energy, and providing the single phase energy to a load, the improvement comprising an alternating current alternator for generating the alternating current multiphase energy at a selected high frequency said alternator having a field, rectifying means connected to the output from said alternator to produce a unidirectional output from said rectifying means control switch means connected with said rectifying means for controlling said rectifying means to provide a plurality of pulse width modulated unidirectional waves having a preselected frequency less than said selected high frequency, and inverter means for inverting alternate ones of said modulated waves whereby an alternating output wave is provided, one of said control switch means and said inverter means comprising circuit switch means for opening the circuit to the load, and spike detector means for detecting voltage across the load and for opening the circuit to said field in response to voltage spikes of a preselected magnitude for shutting said alternator down.

Dependencies are inferred from the claim text.

Multiphase to single phase and frequency converter system

Life of this patent

Multiphase to single phase and frequency converter system

Life of this patent

Abstract

Claims31