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EP0010900A1
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A static inverter with a relatively low-frequency output voltage, and a method for generating this voltage
Assignee: ERA Patents Ltd
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Filing: 1979-10-17
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Granted: —
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Expires: 1999-10-17
Abstract
Abstract in a static inverter for providing a low-frequency output (e.g. 60Hz) from a d.c. supply (Q), the passage of low-frequency currents through the inverter transformer (P) is avoided by producing a train of high-frequency pulses (e.g. 40kHz) which represent, for example by their pulse widths (4), the successive instantaneous amplitudes of the required low-frequency voltage. These pulses cause a train of corresponding pulses (7) to be produced at the secondary of the transformer, and this train is filtered (H) to produce a unidirectional voltage (9) having the desired instantaneous amplitudes. This voltage is fed to a transistor switching bridge (1) which changes the unidirectional voltage into an alternating voltage (12) having the required low-frequency. Means (N, E, L, M) is preferably provided to allow regeneration of power from the load back into the d.c. supply (Q).
Inventors
- 👤 Graham Peter Hicks
- 👤 Michael Charles Carter
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 12:27
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/4807
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
155 words
A static inverter for connection to a d.c. supply to provide a relatively low-frequency alternating voltage output, characterised by means (A) to generate a relatively high-frequency first train of electrical pulses (1); means (B, C, D, F) to cause successive pulses of the first train to represent (4) required successive instantaneous amplitudes of the alternating voltage output to be provided; a transformer (P); means (G) to cause the passage through the transformer primary winding of pulses of current from the d.c. supply (Q) in response to the first pulse train so that a corresponding second pulse train (7) is induced across the transformer secondary winding; means (H) to produce from the second pulse train a unidirectional voltage (9) having the required instantaneous amplitudes; and switching means (I) to which the unidirectional voltage is fed and which cyclically reverses the polarity of the voltage at the relatively low frequency to produce the alternating voltage output (12).
Claim 2
Dependent Claim
155 words
A static inverter for connection to a d.c. supply to provide a relatively low-frequency alternating voltage output, characterised by means (A) to generate a relatively high-frequency first train of electrical pulses (1); means (B, C, D, F) to cause successive pulses of the first train to represent (4) required successive instantaneous amplitudes of the alternating voltage output to be provided; a transformer (P); means (G) to cause the passage through the transformer primary winding of pulses of current from the d.c. supply (Q) in response to the first pulse train so that a corresponding second pulse train (7) is induced across the transformer secondary winding; means (H) to produce from the second pulse train a unidirectional voltage (9) having the required instantaneous amplitudes; and switching means (I) to which the unidirectional voltage is fed and which cyclically reverses the polarity of the voltage at the relatively low frequency to produce the alternating voltage output (12).
Claim 3
Dependent Claim
47 words
An inverter as claimed in Claim 1, characterised in that the means to cause successive pulses of said first train to represent the required successive instantaneous amplitudes (3) comprises a pulse-width modulator (F) whereby the width of each successive pulse (4) represents the corresponding required instantaneous amplitude.
Claim 4
Dependent Claim
63 words
An inverter as claimed in Claim 2, characterised by means (B, C) to generate a reference alternating voltage at the relatively low frequency; and a clock pulse generator (A) circuit to provide said first pulse train and to provide a sawtooth waveform (2) at the relatively high frequency for sampling the instantaneous amplitudes of the reference voltage to control the pulse width modulation.
Claim 5
Dependent Claim
32 words
An inverter as claimed in Claim 3, characterised in that the means (B, C) to generate a reference alternating voltage comprises a sine wave generator (C) connected in a phase-lock loop configuration.
Claim 6
Dependent Claim
56 words
An inverter as claimed in Claim 2, Claim 3 or Claim 4, characterised in that the means (G) to cause the passage of current pulses through the transformer primary winding comprises two switching devices operating in a push-pull configuration, and in that the second pulse train (7) comprises a sequence of alternately positive and negative pulses.
Claim 7
Dependent Claim
35 words
An inverter as claimed in Claim 5, characterised by a rectifier circuit (H) coupled to the transformer secondary winding to convert the sequence of alternately positive and negative pulses into a unidirectional pulse train (8).
Claim 8
Dependent Claim
34 words
An inverter as claimed in Claim 6, characterised by a filter (H) to which the unidirectional pulse train (8) is fed and which thereby produces the unidirectional voltage (9) having the required instantaneous amplitudes.
Claim 9
Dependent Claim
20 words
An inverter as claimed in any preceding claim, characterised in that the switching means comprises a bridge rectifier circuit (I).
Claim 10
Dependent Claim
56 words
An inverter as claimed in Claim 8, characterised by means (N) operative selectively to by-pass the bridge rectifier circuit (I) to provide a reverse path through the inverter from the output to the d.c. supply (Q) in the event of excess power being available at the inverter output due to load conditions existing on said output.
Claim 11
Dependent Claim
86 words
An inverter as claimed in Claim 9, characterised in that the means to provide a reverse path comprises means (E, N, L) responsive to the excess power to produce a train of regeneration pulses which are pulse-width modulated in dependence upon the magnitude of the excess power; inverting means (M) to which the regeneration pulses are fed and which produces an alternating regeneration output; and means (M) to rectify the alternating regeneration output and to feed the resulting d.c. regeneration power to the d.c. supply (Q).
Claim 12
Independent Claim
128 words
A method of producing a relatively low-frequency alternating voltage output from a d.c. supply, characterised by generating a relatively high-frequency first train of electrical pulses (1); causing successive pulses (4) of said first train to represent required successive instantaneous amplitudes of the alternating voltage output which is to be provided; causing the passage through a transformer primary winding of pulses of current from the d.c. supply (Q) in response to said first pulse train so that a corresponding second pulse train (7) is induced across a secondary winding of the transformer; producing from the second pulse train a unidirectional voltage (9) having the required instantaneous amplitudes; and cyclically reversing the polarity of the unidirectional voltage at the relatively low frequency to produce the required alternating voltage output (12).
Claim 13
Independent Claim
128 words
A method of producing a relatively low-frequency alternating voltage output from a d.c. supply, characterised by generating a relatively high-frequency first train of electrical pulses (1); causing successive pulses (4) of said first train to represent required successive instantaneous amplitudes of the alternating voltage output which is to be provided; causing the passage through a transformer primary winding of pulses of current from the d.c. supply (Q) in response to said first pulse train so that a corresponding second pulse train (7) is induced across a secondary winding of the transformer; producing from the second pulse train a unidirectional voltage (9) having the required instantaneous amplitudes; and cyclically reversing the polarity of the unidirectional voltage at the relatively low frequency to produce the required alternating voltage output (12).
References Cited (Backward Citations)
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