# US 5,349,270 A · Transformerless fluorescent lamp operating circuit, particularly for a compact fluorescent lamp, with phase-shifted inverter control

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- Number: US 5,349,270 A
- Document ID: US5349270A
- Status: Granted
- Kind: A
- Application number: 07/935,004
- Filed: 1992-08-25
- Granted: 1994-09-20
- Earliest claimed: 1991-09-04
- Assignees: Patent-Treuhand-Gesellschaft F. Elektrische Gluehlampen mbH
- Inventors: Ulrich Roll; Werner Bernhard; Ludwig Reiser
- Web page: https://patentgrep.com/patent/US5349270A

## CPC

- H02M 7/538: in a push-pull configuration (H02M7/5375 takes precedence {; with oscillating arrangements H02M7/53832, H02M7/53846})
- H02M 3/338: in a self-oscillating arrangement (H02M3/337 takes precedence)
- H02M 7/53832: {in a push-pull arrangement}
- H03K 17/04123: {in field-effect transistor switches}
- H05B 41/2825: {by means of a bridge converter in the final stage (H05B41/285 takes precedence)}
- Y02B 20/00: Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
- Y10S 315/07: Starting and control circuits for gas discharge lamp using transistors
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

To eliminate the necessity for a saturated or air gap inductance to provide feedback circuit for a self-exciting oscillator including two active electronic switches (T1, T2) , for example MOSFETs, an auxiliary winding (HW1, HW2, . . . HW11) is inductively coupled to the resonance inductance (L2) present in the circuit for the discharge lamp (LP) anyway; and a pulse shaping - phase shifting network (R3, C3; R4, C4 . . . ) , devoid of inherent resonance, coupling the auxiliary winding to the active switching elements. The pulse shaping - phase shifting network is formed of a one or multiple-stage RC low-pass circuit, connected serially between the auxiliary winding and the control input, for example the gate, of the active switching element. The RC network can be constructed with variable elements, for example including PTC resistors, a varistor or the like, and may include a current source, protective circuits to protect against voltage peaks including Zener diodes. The low-pass characteristics of the pulse shaping - phase shifting network permits switching of the active semiconductor switches after the maximum current flow.

## Claims

### Claim 1

For combination with a low-pressure discharge lamp (LP),
an operating circuit for high-frequency operation of the lamp, said operating circuit comprising
a power network rectifier (GL including a filter (C1) for providing d-c output electrical energy, and connected thereto;
a self-excited osillator circuit connected to said rectifier having at least one active switching element (T1, T2);
and a lamp supply circuit including
a resonance circuit coupled to the lamp and having at least one resonance inductance (L2) and at least one capacitative element (C8, C9) connected to said oscillator circuit, and
wherein the oscillator circuit includes, in accordance with the invention,
a feedback circuit which comprises at least one auxiliary winding (HW1, HW2, . . . HW11) inductively coupled to the resonance inductance (L2); and
a pulse shaping - phase shifting network (R3, C3; R4, C4; R10, C10, R11, C11; R12, C12) devoid of inherent resonance, coupling the auxiliary winding to the active switching element.

### Claim 2 (depends on 1)

The operating circuit of claim 1, wherein the pulse shaping - phase shifting network devoid of inherent resonance comprises a low-pass RC circuit having at least one circuit stage.

### Claim 3 (depends on 2)

The operating circuit of claim 2, wherein said RC low-pass circuit comprises a plurality of low-pass circuit stages.

### Claim 4 (depends on 2)

The operating circuit of claim 2, wherein the RC pulse shaping and phase shifting network is coupled in series with respect to the auxiliary winding (HW1 . . . HW11) and the control input of the at least one active switching element.

### Claim 5 (depends on 1)

The operating circuit of claim 1, wherein the at least one switching element comprises a field effect transistor, optionally a metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT).

### Claim 6 (depends on 1)

The operating circuit of claim 1, wherein the pulse shaping - phase shifting network comprises at least one variable impedance element.

### Claim 7 (depends on 6)

The operating circuit of claim 6, wherein the pulse shaping - phase shifting network comprises a resistor component and a capacitor component network; and
wherein the resistor component comprises, at least in part, a positive temperature coefficient (PTC) resistor (KL2, KL3).

### Claim 8 (depends on 7)

The operating circuit of claim 7, wherein the resistor component of the pulse shaping - phase shifting network comprises (FIG. 5) a resistor (R13) serially connected with the auxiliary winding (HW6) and further, serially connected therewith, an ohmic resistor (R14) and a PTC resistor (KL3) connected in parallel to said ohmic resistor (R14).

### Claim 9 (depends on 6)

The operating circuit of claim 6, wherein (FIG. 6) the resistor component of the pulse shaping - phase shifting network comprises an active element (TR1) and circuit elements (D4-D9, R16) connected to said active element.

### Claim 10 (depends on 1)

The operating circuit of claim 1, wherein (FIG. 7) said pulse shaping - phase shifting network includes a further pulse shaping circuit branch, said pulse shaping - phase shifting network comprising a resistor (R17), serially connected with said auxiliary winding (HW8), and a capacitor (C16) connected across the series connection of said resistor (R17) and said auxiliary winding;
wherein said further pulse shaping current branch comprises a further resistor (R18) connected to a junction between said capacitor (C16) and said resistor (R17); and
a series circuit comprising an additional resistor (R19) and a diode (D10) connected between the terminal of said further resistor (R18) remote from said junction and a further junction between said resistor (R17) and said auxiliary winding.

### Claim 11 (depends on 1)

The operating circuit of claim 1, wherein (FIG. 8) said pulse shaping - phase shifting network comprises a resistor (R20) serially connected with said auxiliary winding (HW9); and
a varistor (V1) connected across the series circuit formed by said resistor and auxiliary winding.

### Claim 12 (depends on 1)

The operating circuit of claim 1, further including (FIGS. 9, 10) a charge carrier removal network (A) coupled to the at least one active switching element (T11, T12).

### Claim 13 (depends on 12)

The operating circuit of claim 12, wherein the pulse shaping - phase shifting network comprises a resistor element - capacitor element circuit;
and wherein the charge carrier removal network (A) comprises a transistor (TR2, TR3) having its collector-emitter path connected in parallel to the capacitor element (C17, C18) of the pulse shaping and phase shifting network (R21, C17; R23, C18), and is connected between the capacitor element (C17, C18) and the control input of the active switching element (T11, T12).

### Claim 14 (depends on 5)

The operating circuit of claim 5, further including overvoltage protective circuit elements connected to the control terminal of the active switching element to protect insulation of the control terminal with respect to overvoltage during ignition of the lamp.

### Claim 15 (depends on 14)

The operating circuit of claim 14, wherein said active switching element comprises a transistor (T6, T7, T11, T12) and said control terminal comprises the gate or base terminal of the transistor.

### Claim 16 (depends on 14)

The operating circuit of claim 14, wherein the protective circuit elements comprise Zener diodes (Z1-Z5).

### Claim 17 (depends on 1)

The operating circuit of claim 1, wherein said operating circuit includes an isolating transformer (TT), or a low power - economy operation transformer;
said resonance inductance (L3) being inductively coupled to said isolating or economy operation transformer, and the auxiliary winding (HW12, HW13) is coupled to the secondary of said transformer.

### Claim 18 (depends on 17)

The operating circuit of claim 17, wherein the resonance inductance (L3) is physically integrated with the structure of said transformer.