TW200412826A - Ballast circuit having enhanced output isolation transformer circuit - Google Patents

Abstract

The present invention is related to a kind of ballast circuit having enhanced output isolation transformer circuit. The invention includes one isolation output transformer, which is provided with one primary winding, and the first and the second secondary terminals connected to the terminal opposite to the ballast lamp tube so as to add the electric potential of the primary winding and the electric potentials of the first and the second secondary windings to the entire lamp tube through a summation manner for restricting the grounding malfunction voltage. The circuit can include one close loop feedback path from a certain load to one feedback rectifier to promote the linear operation of one input rectifier.

Description

200412826 发明 Description of the invention (The description of the invention should state: the technical field, the prior art, the content, the embodiments, and the drawings of the invention are briefly explained. Circuit. [Prior art] 5 There are many types of circuits that supply power to a load. One of them is a resonant inverting circuit, which receives, for example, a direct current (DC) signal from a rectifier and outputs an alternating current (AC) signal. Resonant inverter circuits can be used in a wide variety of devices, such as lamp ballasts. The AC output can be coupled to a load, such as a fluorescent tube, or to a rectifier to form an AC / DC converter. Resonant inverter circuits are available in a variety of configurations. For example, a half-bridge inverter circuit includes first and second switching elements, such as transistors, coupled in a half-bridge configuration. A full bridge circuit includes four switching elements coupled in a full bridge configuration. Full-bridge and half-bridge inverse circuits are usually driven by a resonance characteristic frequency determined by the impedance values of various circuit elements including resonant 15-vibration inductance elements. A conventional current stabilization circuit generally includes an output transformer inductively coupled to a resonant inductive element in order to isolate the lamp from the resonant conversion circuit. The configuration of this output transformer is a well-known and meets the applicable UL (U.S. Underwriters Laboratories 20) lamp ballast ground fault standards. Generally speaking, the current from the terminal of the constant current lamp is limited to a predetermined level in terms of grounding. With this method of limiting the current, people will not be electrocuted if they come into contact with the lamp terminals so that a path to ground is formed through the human body. Econtinuation page (if the invention description page is insufficient, please note and use the continuation page) -4- 200412826

The first figure is a typical conventional current stabilization circuit, which is provided with a conventional separate output transformer 12. The rectifier / filter 14 is connected to the first and second input terminals 16a, b to receive an AC input signal, and provides positive and negative voltage rails 18,20. Inductive coupling inductors Ll-A, Ll-B can be set on the positive and negative voltages 18 and 20, respectively. The first and second switching elements 22, 24 are coupled across the voltage in a well-known half-bridge configuration. The separated output transformer has a primary winding 26, such as 1.5 mH 50 turns, combined with a resonant capacitor 28 to form a parallel resonant conversion circuit. The transformer has another secondary winding 30, such as 100 turns, 10 for exciting the first and second lamps LP1, LP2, each of which is coupled in parallel with the corresponding lamp capacitors CL1, CL2. In this well-known configuration, the secondary winding 30 of the transformer isolates the lamp terminal from the harmonic circuit, thereby limiting the ground fault current. If a technician accidentally touches the lamp terminal and provides a current path to ground, the current through the technician's body will be limited to a safe level to prevent injury. UL has set standards for accepting the level of a ground fault circuit for a ballast. Although this kind of separated output transformer can provide safety, its size is so large that it needs to occupy a considerable space on the current-stabilizing circuit board. In addition, the power consumed by this type of transformer is also high. Furthermore, the performance of the transformer is adversely affected by the corona effect in some applications. For example, in the so-called instant start current stabilizer, because a higher voltage, such as 500 VRMS, is applied to the lamp terminal to cause current to flow through the lamp, the transformer must provide this voltage in order to trigger the lamp . However, after a period of this voltage, the operating characteristics of the transformer are impaired. 200412826 Invention Description Continued Page Therefore, it is desirable to provide a current-stabilizing circuit with enhanced output isolation configuration. [Summary of the Invention] 5 The main object of the present invention is to provide a current stabilization circuit with an enhanced separation output transformer circuit, which includes a resonant inverter provided with a more efficient and reliable output isolation transformer circuit. In general, the output isolation transformer includes at least one secondary winding combined with the primary winding to provide the required lamp trigger voltage, while limiting the ground fault current 10 from the lamp terminals. With this configuration, the required voltage can be effectively applied to the lamp to start the current without sacrificing safety, for example, in compliance with applicable safety ballast safety standards. Although the present invention is mainly shown and explained in conjunction with a current stabilization circuit, the present invention is also applicable to other circuits that are suitable for isolating loads and limiting ground fault current, such as power supplies and electric motors. 15 An aspect of the present invention is to provide a resonance conversion circuit including a separate output transformer, the transformer being provided with a first secondary winding coupled to one of the lamp terminals. The primary winding of the transformer provides a circuit path in series with the first secondary winding, so that a node for AC (alternating current) grounding is located between the first secondary winding and the primary winding. In addition, an inductor is provided in the primary winding of the separated output transformer to form a part of the resonance conversion circuit. If necessary, a secondary winding can be added. In one embodiment, a second secondary winding is coupled between the primary winding and the tube. The voltage across the entire first secondary winding is applied to one end of the tube, and the voltage across the entire second secondary and primary windings is applied to the other end of the tube. The ground fault voltage from the first lamp terminal is equivalent to the voltage of the first secondary winding, and the voltage from the second lamp terminal is equivalent to the combined voltage of the second secondary winding and the primary winding. Another aspect of the present invention is to provide a circuit including a feedback path starting from a point near the 5 lamp tube for reducing harmonic distortion and increasing overall efficiency. In one embodiment, the circuit includes a feedback path from a closed-circuit current loop provided with a transformer winding to a high-frequency rectifier to facilitate linear operation of a low-frequency input rectifier. 10 [Embodiment] The present invention will be described in detail below with reference to examples and drawings, wherein: the first diagram is a schematic block diagram of a conventional current stabilization circuit; the second diagram is constructed in accordance with the present invention and has A circuit diagram of a separate output transformer 15 for an embodiment of the resonant conversion circuit for limiting the ground fault current; the third diagram is constructed in accordance with the present invention and has a separate output transformer for the resonant conversion circuit for limiting the ground fault current. The circuit diagram of the example; The fourth diagram is a circuit diagram of a total of 20 oscillation conversion circuits with a load feedback path constructed according to the present invention; the one shown in the fifth diagram is a graphical description of the rectifier diode operation provided by the circuit of the fourth diagram . The second figure shows an embodiment of a lamp current stabilizer 100 circuit having an enhanced output isolation transformer 102 configured in accordance with the present invention. Generally, 200412826

The separate output transformer 102 provides efficient and flexible operation while limiting the ground fault current to a safe level. In particular, the first and second windings L2-B and L2-A of the separated output transformer are coupled to the lamp terminals, so as to provide the intended trigger voltage and limit the voltage level of the lamp to the ground. Details will be explained later. The current stabilizer 100 includes a rectifier 104 having a full bridge configuration provided by a bridge diode DR1-4. The first and second input terminals 106a, b are used to receive an AC (alternating current) input signal, such as a standard 110 VRMS, 60 Hz signal. A conventional filter 108 includes electrically inductively coupled first and second inductive elements L1-A, L1-B, a filter capacitor C0, and first and second bridge capacitors CB1, CB2 coupled as shown. . If cross-conduction occurs, that is, when the switching elements Ql, Q2 conduct simultaneously, the first and second inductance elements Ll-A, Ll-B will operate to limit the current. The first and second switching elements Q1, Q2 belonging to the transistor shown in 15 are coupled across the inverter's positive and negative voltage rails 110, 112 in a conventional half-bridge configuration. The conduction states of the first and second switching elements Q1, Q2 are controlled by the first and second control circuits 114, 116, respectively. In one embodiment, the first control element 114 includes an inductive element L2-D that is inductively coupled to the L2-A primary winding of the output transformer 102 that is resonantly separated. This inductive element L2-D operates in conjunction with a capacitor CQ1 and a resistor RQ1 to periodically deflect the first switching element Q1 to a conductive state so as to achieve the operation of the resonant conversion circuit. The configuration of the second control circuit 116 may be the same as that of the first control circuit 114. Those skilled in the art are well aware of the configuration of this control 200412826 circuit. In addition, it is obvious to those skilled in the art that there are various alternative control circuits. The operation of the resonant inverter is also well understood by those skilled in the art. The primary winding L2-A of the separated output transformer 102 is coupled in parallel with a resonant capacitor C1 to form a parallel resonant inverting circuit configuration. The first secondary winding L2-B of the separated output transformer 102 has a first terminal 120 coupled to the primary winding L2-A, and a second terminal 122 coupled to a series of lamp terminals LTA1-N. The lamp terminals LTA1-N, together with the lamp terminals provided at the opposite ends of these lamps LP1-N. 10 LTB1-N, can be used to provide electrical connection to the lamps inserted in these lamp terminals. During operation, the first secondary winding L2-B and the primary winding L2-A jointly provide a voltage sufficient to immediately start the lamp operation, such as 500 VRMS, while limiting the voltage of a lamp terminal to ground. In particular, the trigger voltage applied to all of the lamps LP1-N can be budgeted between the primary winding L2-A and the first secondary winding L2-B, for example, roughly split evenly. Those skilled in the art know that about half of the trigger voltage is not enough to trigger the ionization of the lamp. Therefore, if that voltage is applied to the lamp, the lamp current is limited to a safe value. When the voltage of the transformer is split, the potential from the tube terminal 20 to the AC ground node A is equivalent to the potential on the winding connected between that lamp terminal and node A. This configuration limits the ground fault current of the lamp terminals, and at the same time can safely generate a relatively high trigger voltage for starting the lamp. In the embodiment shown in the third figure, the circuit includes a second secondary winding L2-C which can further allocate the available electricity. In one embodiment, the second secondary winding L2-C of the transformer has a first terminal 124 coupled to the other end of the transformer primary winding L2-A, and a second terminal coupled to each of the lamp capacitors CL1-N. 126, the capacitors are coupled in series with each of the lamps 5 LP1-N. The first node A provides AC ground from one side of the transformer primary winding L2-A. The potential from the first lamp terminal LTA1 to the first node A (AC ground) is equivalent to the voltage applied to the entire first secondary winding L2-B. Similarly, the potential | J. 10 from the second lamp terminal LTB1 to the AC ground (node A) corresponds to the voltage applied to the entire second secondary winding L2-C and the primary winding L2-A. In an embodiment (not shown), the polarity of the second secondary winding L2-C may be reversed so as to reduce the voltage applied to the lamps from the primary winding L2-A. 15 It will be apparent to those skilled in the art that other secondary windings of the intended polarity can be provided throughout the circuit to meet the needs of a particular application. In addition, those skilled in the art also know that the primary winding can be divided into more than two windings, so that various secondary windings can be coupled to it. Generally, because the winding voltage is applied to each lamp in an additive manner, the turns ratio of the first and second secondary windings L2-A, L2-B and the primary winding L2-A can be selected as needed Prepare a budget for lamp trigger voltage. Therefore, the separate output transformer circuit of the present invention provides the flexibility to control the voltage generated by the windings. For example, a total of 750 VRMS potential can be generated on the primary and secondary windings to trigger an eight-foot tube. Once at -10- 200412826

Separate the voltage from the secondary winding with AC ground to safely generate 75 VRMS. It is understood that the trigger voltage can be distributed among the windings as required. In addition, compared to the conventional circuit shown in the first figure, this transformer can provide 750 VRMS with extremely low corona discharge effect. Table 1 shows examples of circuit characteristics of various circuit components shown in the third figure. It ’s understood that those skilled in the art can easily change the characteristics of these circuits under the circumstances of this violation. 1 To meet the needs of specific applications

It is understood that those skilled in the art know that

-1K 10 412826 Description of the invention® wing; in addition, additional additional secondary windings are connected to each tube and / or basin. It has additional primary windings to meet the needs of specific applications. In addition, the present invention can be applied to various circuits and devices that want to provide effective and flexible wheel-out isolation. Examples of circuits and devices include a steady-state 5-state electric motor for a lamp, and a power supply. In another aspect of the present invention, the resonant conversion circuit includes a feedback path from the load to the multi-bridge rectifier to enhance the power factor (PF) and total harmonic distortion (THD) performance of the circuit. In general, a closed-loop circuit path from the transformer winding and load to a point in the multi-bridge rectifier can facilitate linear operation of the 10-input rectifier diode. The fourth figure shows an example of a resonance conversion circuit 200 with power feedback according to the present invention. The multi-bridge rectifier 201 includes several pairs (DF11, DF12), (DF21, DF22), ... (DF1Sil, DFN2) end-to-end light-weighted rectifier diodes. The top 202 of the multi-bridge rectifier 200 is coupled to the bottom 202 of a low-frequency input rectifier 204, and the bottom 206 is coupled to the negative rail 208 of the inverter. The top of the input rectifier 210 is coupled to the inverter 212. In one embodiment, the provided resonant conversion circuit 200 is a resonant inverting circuit having a topology similar to that shown in the third figure, in which the same components are assigned the same reference numbers. This circuit further includes a first series load path extending from the first secondary winding terminal 122 to the second secondary winding terminal 126. The first series load path further includes first and second feedback capacitors CF11, CF12 and a plurality of terminals coupled in a DC-blocking configuration for exciting a first load, such as the first lamp tube LP1. -12- 200412826

The circuit 200 may include similar load paths with paired feedback capacitors (CH1, CF22), ... (CFN1, CFN2) on the right stem, respectively, for exciting other lamp tubes LP2,... LPN. The first feedback path FP1 extends from a point 250a between the first and second feedback capacitors cFU, 5 CF12 to a point 252a between the first pair of diodes DF11, DF12 of the multi-bridge rectifier 201. Similarly, other feedback circuits FP2 '... FPN can extend from the corresponding points 250b-N between the paired feedback capacitors to the corresponding points 252b-N between the paired diodes of the multi-bridge rectifier 201. 10 During operation, the total voltage drop of the entire primary primary winding L2B and the first feedback capacitor at point A of the AC ground is applied between the primary and secondary pairs of the multi-bridge rectifier 001 and the one-pole DF11 and DF12 Point 252a. The higher frequency constant amplitude signal on the first feedback path will periodically deflect the first pair of diodes (DF11, DF12) to a conductive state, which in turn causes a pair of 15-input rectifier diodes, For example, DR 1, DR3 is deflected to a conductive state. As shown in the fifth figure, via the multi-bridge rectifier 201, the high-frequency signal on the first feedback path FP1 periodically causes the first pair of diodes DR1 of the input rectifier 204 during the positive half cycle PHC of the lower-frequency input signal IS. DR3 is deflected to the conduction state. Similarly, during the negative half cycle NHC 20 of the input signal IS, the second pair of diodes DR2, DR4 of the input rectifier 204 will also conduct periodically. With this configuration, the first storage capacitor C01 can be effectively excited during the positive half cycle PHC of the input signal IS, and the second storage capacitor C02 can be excited during the negative half cycle NHC of the input signal IS. So, -13- 200412826

The linear operation of this input rectifier diode provides a more efficient circuit if compared to a circuit without linear diode operation. In addition, depending on whether there are active lamps, each feedback path FP1-N provides independent power feedback. In other words, if the first 5 lamp LP1 is stored and operating, the first feedback path FP1 provides substantial feedback energy. If the first lamp is not stored or is not functioning, the first feedback signal is generally equivalent to the energy of the first secondary winding L2B of the transformer. However, it is understood that a large amount of feedback energy comes from the lamps in operation. Therefore, this circuit provides an automatic optimization signal so that this feedback can be based on whether there is a load corresponding to 10 or not. In a conventional circuit having a feedback path to facilitate the operation of a linear diode, a feedback signal usually exists regardless of whether a load is present. If the feedback energy is injected into the circuit under no load condition, the circuit may withstand stress and degrade performance. 15 Although the feedback circuit of the present invention has been shown and described in conjunction with a specific circuit topology, it is understood that this feedback configuration is applicable to a wide variety of resonance conversion circuits having a closed-circuit current path from a primary winding transformer. That is to say, if, for example, when using a conventional separate output transformer as shown in the first figure, the load is not isolated from the resonance conversion circuit. 20 In addition, the independent feedback circuit configuration enables the circuit to excite a wide variety of loads with different operating characteristics. For example, the circuit 200 may excite lamps having different lengths. Each feedback path provides "appropriate" feedback energy that improves power factor (PF) and total harmonic distortion (THD) performance. Although the bipolar transistor system shown is used as an example for the examples contained herein -14- 200412826

It is understood that a variety of switching elements and switching control circuits can be used without departing from the spirit of the present invention. Exemplary switching elements include transistors such as bipolar junction transistors and field effect transistors, and silicon controlled rectifiers (SCRs). 5 It is also understood that, depending on the requirements of a particular application, various inverter configurations are available. For example, half-bridge, full-bridge, single switching elements, and other inverter configurations known to those skilled in the art. The above examples are only used to illustrate the present invention, and are not intended to limit the scope of the present invention. For example, various modifications or changes that do not violate the spirit of the present invention are within the scope of the present application for patent. -15- 200412826

[Brief description of the diagram] The first diagram is a schematic block diagram of a conventional current stabilization circuit; the second diagram is a circuit diagram of an embodiment of a resonant conversion circuit constructed according to the present invention with a separate output transformer for limiting ground fault current 5 The third diagram is a circuit diagram of another embodiment of a resonant conversion circuit having a separate output transformer for limiting ground fault current constructed according to the present invention; the fourth diagram is constructed according to the present invention and has a load feedback path The circuit diagram of the resonance conversion circuit; 10 The diagram shown in the fifth diagram is a graphical illustration of the rectifier diode operation provided by the circuit in the fourth diagram. 15 20 [Representative symbols] Current stabilizer 100 Rectifier 104 Second input terminal 106b Filter capacitor C0 Second switching element Q2 Second control circuit 116 Multi-bridge rectifier 201 Low-frequency input rectifier 204 Bottom 206 Inverter positive rail 212 Output type Isolation transformer 102 First input terminal 106a Filter 108 First switching element Q1 First control circuit 114 Resonance conversion circuit 200 Top 202 Bottom 202 Inverter negative 208 -16-

Claims (1)

200412826 (1) Patent application Fanqi 1. A resonance conversion circuit, comprising: a transformer provided with a primary winding and a first secondary winding, wherein the first primary winding is located between the first secondary winding and the primary One node of the AC (alternating current) ground between the windings is electrically connected to the primary winding, so that the potential on the primary winding and the potential on the first secondary winding are combined to excite a load. 2. The circuit described in item 1 of the scope of patent application, further comprising a second secondary winding, wherein the primary winding and the first and second secondary windings provide 10 series circuit paths. 3. The circuit according to item 1 of the scope of the patent application, wherein the first ground fault potential of the first load terminal is provided by the potential across the entire first secondary winding. 4. The circuit according to item 2 of the scope of the patent application, wherein the second ground fault potential of the second load terminal is provided by the potential across the entire second secondary winding and the primary winding. 5. The circuit according to item 1 of the patent application range, wherein the circuit includes a resonant inverter circuit. 6. The circuit according to item 5 of the scope of patent application, wherein the primary winding of the transformer 20 corresponds to a resonant inductive element of a resonant inverter. 7. The circuit according to item 5 of the scope of patent application, wherein the inverting circuit has a half-bridge configuration. 8. The circuit according to item 5 of the scope of patent application, wherein the first and second secondary windings can be used to excite a lamp. Continued; man page (failed to apply for patent application, please! Please use the continuation page for the award> 200412826 Patent Application Scope Continued 9. If the Patent Application Scope is No.! In the circuit described in the item, the secondary winding has a younger end coupled to Ac-corrected point d and a second end connected to the first end of the load. QT 10 · The circuit described in item 9 of the scope of the patent application, and the second secondary winding 'where the second secondary winding has _shaft connected to-the first end of the winding and -the first The second end of the two ends. If you declare the circuit described in item 10 of the patent scope, it includes a 10 I2 from the first secondary winding to the ground node of Ac after the way. The circuit described in item 11 of the scope of patent application, where the second place The P early path includes a path across the second secondary winding and the secondary winding to the AC grounded node. 13. The circuit described in item 丨 of the scope of the patent application, further comprising an input rectifier for receiving AC input signals, a feedback rectifier for Xingmahe to the input 15 input and two, and a feedback rectifier from the load to the The wheeled rectifier supplies energy to facilitate linear operation of the diodes in the input rectifier. 14. The circuit according to item 13 of the scope of patent application, wherein the first feedback path further includes the energy supplied by the first secondary winding. 20 15 · The circuit according to item 14 of the patent application scope, wherein the first feedback path further comprises the energy supplied by the capacitor excited by the current through the load. 0 16 · The circuit according to item 13 of the patent application scope, wherein The first feedback path is from -18-200412826 between a pair of diodes coupled end-to-end in the feedback rectifier. The scope of the patent application extends from a point of the stomach to a point in series with the load. 17. The circuit according to item 13 of the scope of the patent application, further including a feedback path extending from other loads to points between other paired diodes in the feedback rectifier. 5 18. The circuit according to item 17 of the scope of patent application, wherein the first feedback path and other feedback paths are independent of each other. 19. A method for providing ground fault protection in an AC circuit, comprising: setting an AC ground between a primary winding and a first secondary winding to separate a 10 load voltage between the primary winding and the secondary winding. 20. The method described in item 19 of the scope of patent application, further comprising coupling the secondary winding and the primary winding at opposite ends of the load. 21. The method described in item 20 of the scope of the patent application, which additionally includes other secondary windings in the circuit suitable for allocating the available voltage budget. 15 22. The method according to item 19 of the scope of patent application, further comprising providing a feedback path from the load to a multi-bridge rectifier to facilitate linear operation of an input rectifier. 23. A current stabilization circuit comprising: a resonant inverter; 20 a transformer provided with a primary winding and a first secondary winding, wherein the primary winding is equivalent to a resonant inductive element of a resonant inverter, and The primary and secondary windings are electrically coupled to opposite ends of the primary winding, so that the voltages on the primary winding and the first and second secondary windings can be applied to an entire lamp tube in an additive manner. -19- 200412826 Patent Application Continued 24. The circuit as described in Item 23 of the Patent Application, wherein a node between the primary winding and the first secondary winding is equivalent to AC ground. 25. The circuit according to item 23 of the patent application, wherein the primary winding and the second secondary winding provide a series circuit path. 5 26. The circuit according to item 23 of the scope of patent application, wherein a first ground fault path extends from a first lamp terminal across the first secondary winding to AC ground. 27. The circuit described in item 26 of the scope of patent application, wherein a second ground fault path extends from a second lamp terminal across the second secondary winding 10 and the primary winding to AC ground. 28. The circuit described in item 23 of the scope of patent application, wherein the current stabilizer provides instant start operation. 29. A method for providing ballast ground fault protection, comprising: providing a spectrum oscillator inverter including a transformer 15 provided with a primary winding; first and second transformers of the transformer The secondary winding is electrically coupled to the primary winding, so that the voltages on the first and second secondary windings and the primary winding are applied to an entire lamp tube in an additive manner. 30. The method described in item 29 of the patent application, further comprising setting an AC ground node between the first end of the primary winding 20 group and the first end of the first secondary winding. 31. The method described in claim 30, further comprising forming a series circuit path through the primary winding and the first and second secondary windings. 32. A circuit including: -20-200412826 patent application scope $ 1 first rectifier; a resonance conversion circuit coupled to the first rectifier, the resonance conversion circuit includes a transformer, and the transformer is provided with a power A primary winding coupled to a secondary winding; 5 a second rectifier coupled to a first rectifier and a resonant conversion circuit; and a second point from the resonant conversion circuit to a second rectifier for promoting linear operation of the first rectifier Feedback path. 33. The circuit of claim 32, wherein the first rectifier includes first and second pairs of diodes coupled end-to-end to rectify an AC output signal. 34. The circuit of claim 32, wherein the second rectifier includes a first pair of diodes coupled end-to-end between the first rectifier and the negative voltage rail. 15 35. The circuit of claim 32, wherein the circuit includes other feedback paths to provide energy from each load to the second rectifier. 36. The circuit described in item 35 of the scope of the patent application, wherein the other loads excited by the second rectifier to the circuit include 20 other pairs of diodes coupled end-to-end. 37. The circuit described in item 36 of the scope of patent application, wherein the first feedback path and the other feedback paths are each independent. 38. The circuit described in item 37 of the scope of patent application, wherein the first feedback path and other feedback paths are automatically optimized. 21- 200412826 Patent Application Continued Page 39. The circuit described in Item 32 of the Patent Application Scope also includes an AC ground between the primary winding and the secondary winding, so that the voltage applied to a load is between the primary winding and the The secondary windings are separated. 40. The circuit of claim 32, wherein the first and second secondary windings have a first end coupled to the AC ground node and a second end available for coupling to the first end of a load. 41. The circuit according to item 40 of the scope of patent application, further comprising a second secondary winding, wherein the second secondary winding has a first end which is light-closed to the primary winding and a second end which can be coupled to a load. End of the second end. 10 42. The circuit according to item 41 of the scope of patent application, wherein one of the first ground fault paths includes a path from the first secondary winding to the AC ground node. 43. The circuit as described in item 42 of the scope of the patent application, wherein a second ground fault path includes a path across the second secondary winding and the primary winding and 15 to the AC grounded node. 44. The circuit according to item 32 of the scope of patent application, wherein the feedback path extends from a point where a load current flows on the resonance conversion circuit to the first and second dipoles in the second rectifier which are coupled end-to-end. A point between the bodies. 20 45. The circuit according to item 44 of the scope of patent application, wherein the first diode system in the second rectifier is coupled to the first rectifier, and the second diode in the second rectifier is coupled to the inverting Device's negative rail. 46. The circuit of claim 45, wherein the feedback path provides energy from the second winding and the load to the second rectifier. -22- 200412826 Patent Application Scope, Continued 47. The circuit described in Item 46 of the Patent Application Scope, in which the feedback path is provided by a capacitor coupled in series with the load. -twenty three-