Power supply system and method of handling fault in non-earthed apparatus

Abstract

To provide a power supply system with built-in fault detection.SOLUTION: A power supply system 200 with built-in fault detection includes: a transformer 201 with a primary side 209 to which an input voltage 204 is supplied; one or more switching elements 222 connected to the primary side of the transformer 201; a controller 205 configured to control switching of the one or more switching elements 222 to control an output voltage on a secondary side of the transformer 201; an isolation capacitor 207 connected between the secondary side of the transformer 201 and the primary side of the transformer 201; and fault circuitry 208 connected to the isolation capacitor 207 and configured to detect a switching pattern propagated through a short circuit between the primary side and secondary side of the transformer 201 and further propagated through the isolation capacitor 207. Furthermore, an electrical apparatus 100 including the power supply system 200, and a method of handling a fault in a non-earthed electrical apparatus are provided.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure relates to a power supply system incorporating fault detection. Further, the present disclosure relates to a method for handling faults in non-grounded devices.

Background Art

[0002] Power over Ethernet (PoE) and regulatory safety standards require electrical insulation between the signals in the Ethernet cable and all accessible metal parts of the product. In an electrical device having an internal power supply system, the internal power supply system often comprises a flyback connection configuration. The flyback connection configuration is a type of switching power supply circuit that uses a transformer, a switching element, a feedback loop, and a controller to control the flow of current through the primary winding of the transformer to convert one voltage level to another voltage level. When the switch element is turned on, current passes through the primary winding of the transformer, and the energy from the primary side is transferred to the secondary winding. The voltage across both ends of the secondary winding is determined by the turns ratio of the transformer that enables voltage conversion.

[0003] In this type of internal power supply system, there is a possibility of high voltage spikes that need to be carefully managed to prevent damage to components and the risk of exposing users to high voltages. For example, when the primary winding of the transformer is switched off, a voltage spike may occur on the primary side. In some electronic devices where the load on the secondary side of the transformer and perhaps the user are only allowed to operate at relatively low voltages, the peak voltage may cause pain or injury to the user. For example, according to the safety standard IEC62368, a peak voltage exceeding 50V can be considered at a level that can cause pain or injury.

[0004] Safety specifications require that the product be safe even if a component fails somewhere in the product. If the transformer fails in such a way that the peak voltage is transmitted to the chassis of the electrical device via the secondary side, the chassis is exposed to the peak voltage and can no longer be safely touched. This type of failure is not easily detected in electrical devices having an internal power supply system based on a transformer. Therefore, there is a risk that the internal power supply system continues to operate in such a situation, exposing the user to the peak voltage.

[0005] There is a solution to this problem. A common and straightforward solution is to add a protective ground to the chassis of the electrical device. However, this adds cost and complexity to the device and equipment. Another solution is to cover the chassis with plastic or another non-conductive material. However, this can lead to other disadvantages or problems such as a decrease in heat dissipation capacity and the overall appearance and robustness of the product. This solution may not be possible if the electrical device has external connections. SUMMARY OF THE INVENTION

[0006] The present disclosure relates to a power supply system incorporating failure detection that does not rely on an electrical device with a protective ground.

[0007] According to a first embodiment, the present disclosure is a power supply system incorporating failure detection, comprising: a transformer having a primary side and a secondary side, the primary side and the secondary side being electrically insulated from each other, and an input voltage being supplied to the primary side; one or more switching elements connected to the primary side of the transformer; a controller configured to control the switching of the one or more switching elements to control the output voltage of the secondary side of the transformer; an insulating capacitor connected between the secondary side of the transformer and the primary side of the transformer; a failure circuit connected to the insulating capacitor and configured to detect a switching pattern that propagates through a short circuit between the primary side and the secondary side of the transformer and further propagates through the insulating capacitor Relates to a power supply system comprising...

[0008] One advantage of a power supply system based on a transformer such as a flyback converter is that it can provide electrical insulation between the primary side and the secondary side of the transformer. In fact, this means that the electrical device of which the power supply system is a part can have two insulated parts. When the part of the device that uses the output voltage operates at a voltage level such that it does not cause pain or injury to the user, generally, the specific risk of a fault on the secondary side of the power supply system can be manageable.

[0009] However, for example, if the transformer fails in such a way that the low side of the primary winding of the transformer shorts to the low side of the secondary winding which may be connected to the chassis of the device, the user may be directly exposed to the peak voltage from the primary side of the transformer, i.e., a quite high voltage that can be, for example, 100V or more. Since the primary side and the secondary side are insulated, it is not possible to detect on either the primary side or the secondary side that there is a short circuit to the secondary side and thus it is necessary to immediately stop the energy transfer.

[0010] The power supply system of the present disclosure comprises an insulating capacitor connected between the secondary side of the transformer and the primary side of the transformer. Insulating capacitors are generally used, for example, to block DC and allow AC, which can be useful, for example, in certain audio and telecommunications applications and can be useful for reducing electromagnetic interference. The inventors of the present invention have realized that by connecting the secondary side of the transformer to the primary side of the power supply system by means of an insulating capacitor and using a fault circuit on the primary side of the power supply system to detect the switching pattern that propagates through the short circuit between the primary side and the secondary side of the transformer and further propagates back to the primary side through the insulating capacitor, it is possible to obtain an efficient and reliable way to detect and stop the continuation of the operation of the power supply system. Figure 1A shows an example of an embodiment of a power supply system incorporating fault detection. In particular, it can be noted that the insulating capacitor is connected from the secondary side of the transformer to the fault circuit on the primary side of the power supply system.

[0011] The isolation capacitor can function like a communication element in the sense that it can transmit a switching pattern from the secondary side to the primary side across the insulation barrier. On the primary side, a diode can be used to rectify the propagated signal. An additional switch that turns off the current in the primary winding of the transformer can be used to disable the switching of one or more switching elements when a short circuit between the primary side and the secondary side is detected upon detection of a fault. This can be implemented, for example, using a pull-down or pull-up resistor as shown in Figure 1C. Some controllers of switching power supplies have high / low input pins for controlling the operation of the power supply, which can be utilized for the same purpose.

[0012] The power supply system incorporating the fault detection of the present disclosure provides a solution that is efficient and not overly conspicuous compared to existing solutions. This solution eliminates the need to add a protective ground to the chassis of the electrical device and the need to cover the chassis with a non-conductive material.

[0013] Furthermore, the present disclosure is a method for handling faults in non-grounded electrical equipment, comprising a transformer having a primary side and a secondary side, the primary side and the secondary side being electrically insulated from each other and an input voltage being supplied to the primary side, one or more switching elements connected to the primary side of the transformer, and an isolation capacitor connected between the secondary side of the transformer and the primary side of the transformer providing a step of providing a non-grounded electrical equipment comprising a power supply system comprising the above; a step of controlling the output voltage of the secondary side of the transformer by operating the transformer by controlling the switching of one or more switching elements; a step of detecting, on the primary side of the isolation capacitor, a switching pattern that propagates through a short circuit between the primary side and the secondary side of the transformer and further propagates through the isolation capacitor and relates to a method including the above.

[0014] A person skilled in the art will understand that the method of the present disclosure for handling failures of non-grounded electrical equipment can be implemented using any embodiment of the power supply system of the present disclosure and / or any embodiment of the electrical equipment equipped with the power supply system of the present disclosure, and vice versa.

[0015] Hereinafter, various embodiments will be described with reference to the drawings. The drawings are examples of embodiments and are intended to show some of the features of the power supply system incorporating the failure detection of the present disclosure.

Brief Description of the Drawings

[0016]

Fig. 1A

Fig. 1B

Fig. 1C

Fig. 1D

Fig. 2

Fig. 3

Modes for Carrying Out the Invention

[0017] The present disclosure relates to a power supply system incorporating fault detection. The power supply system includes a transformer having a primary side and a secondary side, with the primary side and the secondary side being electrically insulated from each other. The power supply may further include one or more switching elements connected to the primary side of the transformer and a controller configured to control the switching of the one or more switching elements to control the output voltage of the secondary side of the transformer. As is generally known to those skilled in the art, a controller typically requires a feedback loop for adjusting the output voltage. The power supply system may further include an isolation capacitor connected directly or indirectly from the secondary side of the transformer to the primary side of the transformer, and a fault circuit connected to the isolation capacitor and configured to detect a switching pattern that propagates through a short circuit between the primary side and the secondary side of the transformer and further propagates through the isolation capacitor. Generally, the primary side and the secondary side of the transformer can refer not only to each part of the transformer itself but also to the two insulated sides of the power supply system. Thus, in this regard, the fault circuit is part of the primary side of the power supply system. The fact that the isolation capacitor is "connected between the secondary side of the transformer and the primary side of the transformer" does not necessarily mean that the isolation capacitor is directly connected to the primary side of the transformer. As described above, the isolation capacitor is connected to the fault circuit and the fault circuit can control the transformer. The fault circuit may be a separate unit or may be integrated into the controller. In particular, upon detection of a fault, the controller can stop the operation of the transformer by directly or indirectly disabling the switching of the one or more switching elements. The power supply system may include additional isolation capacitors used for other purposes other than fault detection.

[0018] FIG. 1A shows a non-limiting example of one embodiment of a power supply system 200 incorporating fault detection. As can be seen, an input voltage 204 is supplied to the primary side of a transformer 201. The input voltage 204 can be understood as the voltage to the transformer 201, and preferably can be understood as a DC voltage that is switched on and off by opening and closing a switching element 222. Since the primary side 209 and the secondary side 210 are insulated, both sides have their own respective grounds. In the example of FIG. 1A, the primary side ground is shown as GND1 while the secondary side ground is shown as GND2.

[0019] The electrical device can receive an input voltage for device 100. The electrical device 100 can have, for example, an input voltage terminal in the form of a power receiving device interface towards the corresponding power supply facility interface. More specifically, the interface can be a Power over Ethernet (PoE) interface. Thus, the power supply can be a power supply facility such as a PoE midspan or a network switch having PoE functionality. The power supply system can be configured to communicate with the PoE power supply facility, for example, by detecting the PoE power supply facility and perform power negotiation and the like. A person skilled in the art is generally considered to be proficient in implementing such functions. The power supply can provide a DC voltage, but since the input DC voltage can have a reversible polarity, rectifying the input voltage to the electrical device can still be useful. In the examples of FIGS. 1A - 1C, the input rectifying circuit 216 rectifies the input voltage to the electrical device 100. The power supply system 200 of the present disclosure may or may not include a rectifying circuit. The rectifying circuit 216 can include a passive diode rectifying bridge or an active rectifying bridge such as an active rectifying bridge based on FET transistors. The controller 205 or an additional circuit can be configured to detect the PoE PSE and communicate with the PoE PSE. The power supply system may further include an output rectifying circuit on the secondary side. A person skilled in the art is generally considered to be proficient in various implementations of such rectifying circuits. The "input voltage supplied to the primary side of the transformer" can refer to the voltage directly applied to the transformer, but alternatively, for example, when a rectifying circuit is present, it can also refer to the input voltage indirectly applied to the primary side of the transformer through such a rectifying circuit.

[0020] The power supply system may be an insulated power supply system comprising a primary winding and a secondary winding separated by a non-conductive insulating material, with the non-conductive insulating material constituting an insulating barrier. When the power supply system is part of an electrical device, it is common to design the power supply system and / or the electrical device such that the high voltage side cannot come into contact with the chassis or any accessible conductive part. This can be done, for example, by means of a barrier, insulating material, and / or a gap. The power supply system and / or the electrical device of the present disclosure may be divided into a high voltage side and a low voltage side. The input voltage may be a voltage in the range of 37 to 57V. The output voltage may be a voltage in the range of 3.3 to 24V. This is under operation where there are no faults, i.e., no voltage spikes are included. These voltage levels may be useful in applications including a PoE midspan supplying input power to an electrical device or a network switch having a PoE function. The load may be, for example, a surveillance camera or a power-consuming part of a surveillance camera system.

[0021] In one embodiment of the power supply system of the present disclosure incorporating fault detection, the power supply system is a power supply system for an electrical device powered by PoE. Accordingly, the power supply system may comprise a controller or additional circuitry configured to communicate with a PoE PSE. Such an embodiment may comprise a rectifier circuit. Preferably, the power supply system is configured to process an input voltage in the range of 37 to 57V.

[0022] The concepts of the high voltage side and the low voltage side are shown in FIGS. 1A - 1D (high voltage side 209, low voltage side 210). Note that the high voltage side 209 and the low voltage side 210 each have their own ground or reference level, which can also be referred to as high voltage side ground and low voltage side ground respectively. More generally, the two sides can also be referred to as the primary side and the secondary side. Thus, the high voltage side ground and the low voltage side ground can also be referred to as the primary side ground (GND1) and the secondary side ground (GND2). The primary side may be, but is not necessarily, the high voltage side. The secondary side may be, but is not necessarily, the low voltage side. The power system may be a system that converts an input voltage to a higher output voltage. When the transformer fails and shorts, there may still be a risk that a voltage spike is transmitted from the primary side to the secondary side. Both the transformer 201 and the insulating capacitor 207 preferably provide electrical insulation between the two sides. In one embodiment of the power system and / or electrical equipment of the present disclosure, the primary components or circuits connected to the primary side of the transformer are insulated from the secondary components or circuits connected to the secondary side of the transformer.

[0023] As described, there is a possibility of high voltage spikes on the primary side of the power system. When the primary winding of the transformer is switched off, a voltage spike may occur. For example, if the primary side of the transformer 201 includes at least one primary winding, the secondary side of the transformer 201 includes at least one secondary winding, and there is a short circuit between the low side of the primary winding and the low side of the secondary winding, there may be a voltage peak on the secondary side, more specifically on the low side of the secondary winding. Such a point may be connected to the chassis 101 to provide a common ground or reference level on the secondary side. A short circuit between the insulated primary and secondary sides of the transformer can be caused by several factors, including, for example, insulation failure, physical damage, and manufacturing defects. For example, when the insulating material is heated beyond its tolerance, it may lose its insulating ability.

[0024] The power supply system further includes an isolation capacitor connected between the secondary side of the transformer and the primary side of the transformer. The isolation capacitor is generally used, for example, to block DC and allow AC, which can be useful, for example, in certain audio and telecommunications applications and can be useful for reducing electromagnetic interference. In the power supply system of the present disclosure, the isolation capacitor can transmit a fault signal from the secondary side to the primary side across its insulation barrier. Due to a short circuit between the primary side and the secondary side in the transformer, the switching pattern originating from the primary side also exists on the secondary side. The switching pattern normally exists on the primary side of the transformer under normal operation, but is transmitted to the secondary side when there is a short circuit between the primary side and the secondary side of the transformer. Here, the switching pattern represents a fault signal when it exists on the secondary side of the shorted transformer. The isolation capacitor transmits the switching pattern when there is a short circuit between the primary side and the secondary side of the transformer. The isolation capacitor, which can be said to bridge the primary side and the secondary side of the transformer, transfers the switching pattern to the primary side, enabling detection of the switching pattern by the fault circuit. The fault circuit, which may optionally be part of the primary side controller, is configured to detect a switching pattern including one or more propagation pulses. The power supply system can include a current sensing element connected to the primary side of the transformer. The current sensing element can be connected between the primary side of the transformer and the primary side ground. Alternatively, the current sensing element can be connected between the negative side (or low side) of the secondary side of the transformer and the secondary side ground. The current sensing element can include, for example, one or more resistors. The controller may be configured to measure the current in the current sensing element / the voltage across the current sensing element. In the example of FIGS. 1A - 1D, the current sensing element 223 exists connected between the negative side (or low side) of the primary side winding 202 of the transformer 201 and the ground of the primary / high voltage side 209. The fault circuit can be configured to detect the potential difference between the primary side ground and the secondary side ground. The potential difference between the primary side ground and the secondary side ground during observation of the switching pattern serves as an indicator of the presence of a short circuit between the primary side and the secondary side in the transformer.The difference in potential can typically be understood as the difference of the AC signals since the insulating capacitor blocks DC but allows AC.

[0025] FIG. 1A shows an example of an embodiment of a power supply system 200 incorporating fault detection. In this example, a fault circuit 208 connected to an insulating capacitor 207 is configured to detect a propagated switching pattern. In this example, the fault circuit 208 controls a fault switching element 215. The fault switching element 215 may be implemented as a generalized on / off switch element as shown in FIG. 1A in one embodiment. The fault switching element 215 is closed during normal operation. In a situation where the fault circuit 208 detects a fault signal in the form of a propagated switching pattern via the insulating capacitor 207, the fault circuit 208 opens the fault switching element 215 and cuts off the current passing through the primary winding 202 of the transformer 201.

[0026] FIG. 1B shows a further example of an embodiment of a power supply system 200 incorporating fault detection. In this example, a fault circuit 208 connected to an insulating capacitor 207 is configured to detect a propagated switching pattern. In this example, the fault circuit 208 can indirectly cut off the current passing through the primary winding 202 of the transformer 201 via a controller 205. This can be done in several ways. Some controllers have on / off pins for controlling the operation of the power supply system. The fault circuit 208 can provide an enable signal that controls such a pin on the controller 205, and as a result, the controller switches off the operation of the power supply system, for example, by controlling a switching element 222 to be cut off / released when a fault is detected. It is also possible to integrate the fault circuit 208 into the controller 205, and again as a result, the controller switches off the operation of the power supply system, for example, by controlling a switching element 222 to be cut off / released when a fault is detected.

[0027] Therefore, the controller 205 can have several functions. In addition to controlling the switching of one or more switching elements to control the output voltage on the secondary side of the transformer in normal operation, it is possible to make it impossible to transfer energy from the primary side to the secondary side by the transformer when a short circuit between the primary side and the secondary side is detected.

[0028] Furthermore, the fault circuit 208 can be configured to prevent energy transfer from the primary side to the secondary side by the transformer when a short circuit between the primary side and the secondary side is detected. This can be done, for example, by disabling the switching of one or more switching elements when a short circuit between the primary side and the secondary side is detected. The fault circuit may be configured or implemented such that a pulse of a specific magnitude is detected and / or used to turn off the operation of the transformer. According to a specific example, the fault circuit includes a diode connected to the isolation capacitor, and a pull-up or pull-down resistor connected to the diode and also connected to a fault switching element such as a control transistor, and can disable the switching of one or more switching elements when a short circuit between the primary side and the secondary side is detected. Such a solution can optionally include an inverter between the diode and the fault switching element. As can be understood by those skilled in the art, the fault switching element may be implemented using any suitable type of switch. As described above, some controllers of the switching power supply have high / low input pins for controlling the operation of the power supply. The fault circuit may be configured to provide a signal for switching off the operation of the transformer. Thus, the fault circuit may be configured to control an input to the controller that makes it impossible to transfer energy from the primary side to the secondary side by the transformer. The signal from the isolation capacitor can be rectified and / or amplified to provide an appropriate control signal for turning off the operation of the power supply when a pulse having a peak voltage greater than a predetermined voltage threshold is present. Alternatively, or in combination, the fault circuit may include a pulse detection circuit. The pulse detection circuit may be further configured to disable the operation of the transformer when a first pulse in the switching pattern is detected.

[0029] FIG. 1C includes a specific example of the fault circuit 208. In this example, the isolation capacitor 207 is connected in series with the fault circuit diode 212, the fault circuit diode 212 is further connected in series with the fault circuit inverter 213, and the fault circuit inverter 213 controls a fault switching element 215 implemented here as a control transistor (having a pull-down resistor 214 connected to ground) that can cut off the current passing through the primary winding 202 of the transformer 201. As described above, other embodiments of the fault circuit are also possible.

[0030] The power supply system may be, but is not strictly limited to, a flyback transformer power supply system or a forward transformer power supply system, and / or a push-pull converter.

[0031] FIG. 1A shows an example of an embodiment of a power supply system 200 with built-in fault detection within an electrical device 100 having a chassis 101. The power supply system 200 has a power receiving device interface 217 in the form of a PoE connector in this particular example. The input voltage to the electrical device 100 is rectified by an input rectifier circuit 216. The output voltage of the input rectifier circuit 216 is the input voltage 204 to the transformer 201 of the power supply system 200. The power supply system 200 includes a transformer 201 having a primary winding 202 and a secondary winding 203, and a switching element 222. A controller 205 is configured to control the switching of the switching element 222 to control the output voltage on the secondary side of the transformer 201. The power supply system 200 further includes output rectification in the form of an output rectifier diode 218 and an output smoothing capacitor 219. The output voltage 206 can be supplied to a component or system that consumes current, for example, by a voltage supply connection 221. An isolation capacitor 207 is connected between the secondary side of the transformer and the primary side of the transformer, and more specifically, is connected from the low side of the secondary winding 203 to a fault circuit 208. The fault circuit can open a fault switching element 215 when a fault is detected. FIG. 1B is the same as FIG. 1A except that in FIG. 1B, the fault circuit 208 is connected to a controller 205 that can make it impossible to transfer energy from the primary side to the secondary side by the transformer 201 when a fault is detected.

[0032] Furthermore, the present disclosure relates to an electrical device comprising any embodiment of the power supply system of the present disclosure.

[0033] The electrical device may have an electrically insulated high-voltage side and a low-voltage side, and includes a power supply system. The power supply system includes a primary side and a secondary side, where the primary side and the secondary side are electrically insulated from each other. The power supply system includes a transformer to which an input voltage is supplied on the primary side, one or more switching elements connected to the primary side of the transformer, a controller configured to control the switching of the one or more switching elements to control the output voltage on the secondary side of the transformer, an insulating capacitor connected between the high-voltage side and the low-voltage side, and a fault circuit connected to the insulating capacitor and configured to detect a switching pattern that propagates through a short circuit between the primary side and the secondary side of the transformer and further propagates through the insulating capacitor.

[0034] The electrical device may include a chassis such as a conductive chassis. Typically, the chassis is a metal housing in which the device is housed. In some devices, the chassis can function as the internal ground or reference of the device. The chassis of the electrical device of the present disclosure may be a non-grounded chassis. Thus, the secondary side of the transformer may be directly or indirectly connected to the chassis. The electrical device may have an electrically insulated high-voltage side and a low-voltage side. In such a device, it is common for the primary side of the transformer to be electrically insulated from the chassis under fault-free operation. However, if a short circuit exists in the transformer, the aforementioned voltage peak may propagate to the low-voltage side of the electrical device.

[0035] The electrical device may include a power receiving device interface such as a Power over Ethernet (PoE) interface that provides an input voltage to the electrical device. A power feeding facility such as a midspan or a network switch with PoE function enables PoE support by an existing network. The power feeding facility that adds power to the Ethernet cable may be arranged between the network switch and the power receiving device. The input voltage to the electrical device of the present disclosure may be a voltage from a PoE midspan or a network switch with PoE function.

[0036] The electrical device may be any electrical device that can benefit from the power supply system of the present disclosure. The electrical device typically includes one or more components that use current. Such components may be loads of the power supply system. As an example, a surveillance camera or a surveillance camera system includes components that require power supply by a local power supply system. There may be a need to control the camera itself, and additional circuits may exist for acquiring, storing, processing, communicating, etc. images from the camera. As would be understood by those skilled in the art, the electrical device may include, for example, one or more processing units, one or more memories that may be used to store instructions that may be executed by any of the processing units, internal and external network interfaces, input and / or output ports, a module for wirelessly transmitting and receiving data, and a communication interface that enables transferring software and / or data between the system and external devices.

[0037] FIG. 2 shows an example of an electrical device 100 including a power supply system 200 and a power receiving device subsystem 300. The power supply system 200 receives an input voltage from a power receiving device interface 217 and delivers an output voltage to the power receiving device subsystem 300 via a voltage supply connection 221. The electrical device 100, such as a camera, has a chassis 101. The power receiving device subsystem 300 includes functional power consumption entities 301, such as, for example, the optical and / or electric components of the camera, a processing circuit 302, and further peripheral components 303.

[0038] FIG. 3 shows an example of a flowchart of a method 400 of the present disclosure for handling faults in ungrounded electrical equipment. The method of FIG. 3 includes a power supply system with built-in fault detection. The power supply system includes a primary side and a secondary side, where the primary side and the secondary side are electrically insulated from each other, and a transformer to which an input voltage is supplied to the primary side, one or more switching elements connected to the primary side of the transformer, and an insulating capacitor connected between the secondary side of the transformer and the primary side of the transformer. The method includes step 401 of providing an ungrounded electrical equipment, step 402 of operating the transformer of the power supply system with built-in fault detection by controlling the output voltage of the secondary side of the transformer by controlling the switching of one or more switching elements, and step 403 of detecting a switching pattern propagated through the insulating capacitor on the primary side of the transformer. The switching pattern propagates through a short circuit between the primary side and the secondary side of the transformer and further propagates through the insulating capacitor. This method may be executed by any processing circuit.

[0039] The method may further include step 404 of making it impossible for the transformer to transfer energy from the primary side to the secondary side when detecting a short circuit between the primary side and the secondary side. This can be achieved using any embodiment of the power supply system and / or electrical equipment of the present disclosure. This step is an optional step.

[0040] In one embodiment, the power supply system with built-in fault detection includes a transformer having a primary side and a secondary side, where the primary side and the secondary side are electrically insulated from each other, and an input voltage is supplied to the primary side, one or more switching elements connected to the primary side of the transformer, a controller configured to control the switching of the one or more switching elements to control the output voltage of the secondary side of the transformer, and a fault circuit configured to detect a switching pattern propagated through a short circuit between the primary side and the secondary side of the transformer and includes The power supply system includes an insulating capacitor connected between the secondary side of the transformer and the primary side of the transformer. The fault circuit is connected to the insulating capacitor, and the switching pattern further propagates through the insulating capacitor. The primary component or circuit connected to the primary side of the transformer is insulated from the secondary component or circuit connected to the secondary side of the transformer.

[0041] The primary side can include at least one primary winding. The secondary side can include at least one secondary winding.

[0042] The fault circuit does not necessarily have to be arranged on the primary side. A short circuit in the transformer can be propagated from the primary side to the secondary side through the insulating capacitor. Figure 1D shows an example of such an embodiment. The power supply system 200 in Figure 1D is conceptually the same as the embodiments of Figures 1A - 1C, but has a fault circuit on the secondary side. It can be seen that the primary side 209 and the secondary side 210 each have their own ground GND1 and GND2. When there is a short circuit between the primary winding 202 and the secondary winding 203, the switching pattern becomes available on both sides of the transformer 201. The switching pattern propagates through the insulating capacitor 207 and can be detected by the fault circuit 208 there.

[0043] Generally, in embodiments having a fault circuit on the primary side, the insulating capacitor can be connected to the secondary winding of the transformer. The insulating capacitor can be directly and / or indirectly connected to the low side of the secondary winding, or the high side of the secondary winding, and / or both the low side and the high side of the secondary winding.

[0044] In the non - limiting example shown in Figure 1A, the insulating capacitor 207 is directly connected to the low side of the secondary winding 203. In this example, the insulating capacitor 207 is also indirectly connected to the high side of the secondary winding 203 via the output smoothing capacitor 219 and the output rectifying diode 218. As described above, other connections to the second winding are also possible.

[0045] In an embodiment having a fault circuit on the primary side, the isolation capacitor may be connected to the primary winding, typically via a current sensing element. In the non-limiting example shown in FIG. 1D, the isolation capacitor 207 is connected to the primary winding 202 via a current sensing element 223.

[0046] The isolation capacitor may be connected to the fault circuit. This typically applies to both embodiments having a fault circuit on the primary side and embodiments having a fault circuit on the secondary side.

[0047] The power system can have a primary side ground and a secondary side ground. The primary side ground and the secondary side ground may be separate grounds for each side. In the examples shown in FIGS. 1A - 1D, the primary side ground is shown as GND1 while the secondary side ground is shown as GND2.

[0048] On the secondary side, the secondary side ground may be connected to, for example, a node connected to the isolation capacitor. On the primary side, the primary side ground may be connected to a node connected to the isolation capacitor.

[0049] In an embodiment having a fault circuit on the primary side, the primary side fault circuit may be connected to the primary side ground and / or may use the primary side ground as a reference voltage. In an embodiment having a fault circuit on the secondary side, the secondary side fault circuit may be connected to the secondary side ground and / or may use the secondary side ground as a reference voltage.

[0050] In one embodiment, the primary side ground is connected to the primary winding via a current sensing element. This is shown, for example, in FIGS. 1A, 1B, 1C, and 1D.

[0051] The transformer can operate using a switching frequency. The switching frequency may be in the dimension of kHz, such as at least 10 kHz or at least 100 kHz, depending on the application. The transformer may typically be configured to convert an input voltage to a higher output voltage or a lower output voltage. If there is a fault in the transformer in the form of a short circuit between the primary side and the secondary side of the transformer, as a result, the potentials of the primary side and the secondary side of the transformer become the same.

[0052] In an embodiment having a fault circuit on the primary side, the secondary winding of the transformer may be connected to an insulating capacitor on the secondary side. The insulating capacitor may be configured to propagate an AC signal between the primary side and the secondary side in case of a fault. Thus, the switching pattern can be propagated through the short circuit between the primary side and the secondary side of the transformer and then further propagated through the insulating capacitor between the secondary side and the primary side. The fault circuit on the primary side can detect the propagated switching pattern as the potential difference across the current sensing element on the primary side. In an embodiment having a fault circuit on the primary side, the propagation of the switching pattern is conceptually the same. In case of a fault in the transformer, there is not only the propagation across the transformer but also the propagation in the form of an AC signal between the primary side and the secondary side through the insulating capacitor.

[0053] The fault circuit may be configured to detect the physical connection between the primary side ground and the secondary side ground caused by a fault in the transformer. The fault circuit may be configured to detect the switching pattern propagated through the short circuit between the primary side and the secondary side of the transformer and further propagated through the insulating capacitor.

[0054] In one embodiment, the primary side ground is connected to the primary winding via a current sensing element.

[0055] The power supply system of the present disclosure may be configured to disconnect the transformer when a fault is detected. This can be done, for example, by an embodiment in which a fault circuit is connected to a controller. In such an embodiment, the fault circuit can provide an enable / disable signal that controls a pin on the controller. This can be used to turn off the operation of the power supply system.

[0056] Alternatively, the fault circuit can have a separate switch for disconnecting the current to the primary winding. An example of such a fault switching element 215 is shown in FIG. 1A. Note that the fault switching element can be part of the fault circuit or a separate part connected to the fault circuit.

[0057] One embodiment of the power supply system of the present disclosure is configured to be able to select whether to turn off the operation of the transformer (using a controller, for example), or to disconnect or short-circuit the input connection, or a combination of these.

[0058] Further options for interrupting the operation of the power supply system when a fault is detected include short-circuiting a connection from the input connection, such as a connection from the input rectifier circuit. This typically causes a fuse to blow. Alternatively, the current from the input connection can be disconnected. An example of this is shown in FIG. 1B, where the fault circuit controls two current switches 224 to disconnect the input connection when a fault is detected. It is believed that this embodiment, or an embodiment in which the input connection is short-circuited, can also be applied to the embodiments of FIGS. 1A and 1C. In an embodiment having a fault circuit on the secondary side, such as the embodiment shown in FIG. 1D, the current switch 224 can be arranged, for example, somewhere between the secondary winding and the output terminal to cut off the current in case of a fault.

[0059] In an embodiment having a fault circuit on the primary side, it is understood that the fault circuit can be used with reference to the primary side ground when detecting the propagated switching pattern. In an embodiment having a fault circuit on the secondary side, it is understood that the fault circuit can be used with reference to the secondary side ground when detecting the propagated switching pattern.

[0060] The transformer may fail in such a manner that the primary side is short-circuited to the secondary side. As can be understood by those skilled in the art, the fault may cause a short circuit from the primary winding to the secondary winding in several conceivable ways. For example, the low side of the primary winding of the transformer may be short-circuited to the low side of the secondary winding. For example, the high side of the primary winding of the transformer may also be short-circuited to the low side of the secondary winding, and the low side of the primary winding of the transformer may also be short-circuited to the high side of the secondary winding. The present invention is not limited to one type of short circuit in the transformer.

[0061] The primary side may be, but is not necessarily, the high voltage side. The secondary side may be, but is not necessarily, the low voltage side. The power system may be a system that converts an input voltage to a higher output voltage. When the transformer is short-circuited due to a fault, there may still be a risk that a voltage spike is transmitted from the primary side to the secondary side.

[0062] In one embodiment, a power system incorporating fault detection is comprising a primary side and a secondary side, the primary side comprising at least one primary winding, the secondary side comprising at least one secondary winding, the primary side and the secondary side being electrically insulated from each other, a transformer to which an input voltage is supplied to the primary side, and one or more switching elements connected to the primary side of the transformer, and a controller configured to control the switching of the one or more switching elements to control the output voltage of the secondary side of the transformer and The power supply system includes an insulating capacitor connected between the secondary side of the transformer and the primary side of the transformer. The secondary winding is connected to an insulating capacitor further connected to a fault circuit. The fault circuit is connected to the insulating capacitor, and the switching pattern propagates through the insulating capacitor further. The fault circuit is configured to detect a switching pattern that propagates through a short circuit between the primary side and the secondary side of the transformer and further propagates to the fault circuit. The primary component or circuit connected to the primary side of the transformer is insulated from the secondary component or circuit connected to the secondary side of the transformer.

[0063] In one embodiment, the insulating capacitor is connected to the fault circuit, the fault circuit is connected to the primary side ground, and the primary side ground is connected to the low side of the primary winding via a current sensing element. Or The insulating capacitor is connected to the fault circuit, the fault circuit is connected to the controller, and the primary side ground is connected to one or more switching elements via a current sensing element.

Description of Reference Numerals

[0064] 100 Electrical equipment 101 Chassis 200 Power supply system 201 Transformer 202 Primary winding 203 Secondary winding 204 Input voltage 205 Controller 206 Output voltage 207 Insulating capacitor 208 Fault circuit 209 Primary side 210 Secondary side 211 Non-conductive insulating material 212 Fault circuit diode 213 Fault circuit inverter 214 Fault circuit pull resistor 215 Fault switching element 216 Input rectifier circuit 217 Power receiving device interface 218 Output rectifying diode 219 Output smoothing capacitor 221 Voltage supply connection part 222 Switching element 223 Current sensing element 224 Current switch 300 Power receiving device subsystem 301 Functional power consumption entity 302 Processing circuit 303 Further peripheral components 400 Method for handling faults in non - grounded electrical equipment 401 Provide a non - grounded electrical device with a power supply system 402 Operate the transformer of the power supply system 403 Detect the switching pattern propagated through the isolation capacitor 404 Make it impossible to transfer energy by the transformer

Claims

1. A power supply system incorporating a fault detection, comprising: A transformer having a primary side and a secondary side, wherein the primary side and the secondary side are electrically insulated from each other, and an input voltage is supplied to the primary side; One or more switching elements connected to the primary side of the transformer; A controller configured to control the switching of the one or more switching elements to control the output voltage of the secondary side of the transformer; An insulating capacitor connected between the secondary side of the transformer and the primary side of the transformer; A fault circuit connected to the insulating capacitor and configured to detect a switching pattern that propagates through a short circuit between the primary side and the secondary side of the transformer and further propagates through the insulating capacitor A power supply system comprising.

2. The power supply system is an insulated power supply system in which the transformer includes a primary winding and a secondary winding separated by a non-conductive insulating material, and the non-conductive insulating material constitutes an insulating barrier. The power supply system according to claim 1.

3. The primary component or circuit connected to the primary side of the transformer is insulated from the secondary component or circuit connected to the secondary side of the transformer. The power supply system according to claim 1.

4. The insulating capacitor bridges the primary side and the secondary side of the transformer. The power supply system according to claim 1.

5. The fault circuit is configured to detect one or more propagation pulses within the switching pattern. The power supply system according to claim 1.

6. Comprising a current sensing element, and the fault circuit is configured to detect a potential difference between a primary ground and a secondary ground across the current sensing element. The power supply system according to claim 1.

7. The fault circuit is further configured to prevent energy transfer from the primary side to the secondary side by the transformer when a short circuit between the primary side and the secondary side is detected. The power supply system according to claim 1.

8. The fault circuit is configured to prevent switching of the one or more switching elements when a short circuit between the primary side and the secondary side is detected. The power supply system according to claim 7.

9. The power supply system according to claim 1, wherein the failure circuit is configured to control the input to the controller so as to make it impossible to transfer energy from the primary side to the secondary side by the transformer.

10. The power supply system according to claim 1, wherein the primary side of the transformer includes at least one primary winding, the secondary side of the transformer includes at least one secondary winding, and the short circuit is a short circuit between the low side of the primary winding and the low side of the secondary winding.

11. The power supply system according to claim 1, wherein the power supply system is a flyback transformer power supply system or a forward transformer power supply system.

12. An electrical device including the power supply system according to any one of claims 1 to 11.

13. The electrical device according to claim 12, including a chassis such as a non-grounded chassis, and the secondary side of the transformer is directly or indirectly connected to the chassis.

14. The electrical device according to claim 13, wherein the primary side of the transformer is electrically insulated from the chassis during normal operation without failure.

15. A method for handling a failure of a non-grounded electrical device, comprising: providing a non-grounded electrical device including a power supply system including a transformer having a primary side and a secondary side, the primary side and the secondary side being electrically insulated from each other, and an input voltage being supplied to the primary side; controlling the output voltage of the secondary side of the transformer by operating the transformer by controlling the switching of one or more switching elements connected to the primary side of the transformer; detecting, at the primary side of the isolation capacitor, a switching pattern that propagates through a short circuit between the primary side and the secondary side of the transformer and further propagates through the isolation capacitor. Including the method. ​ ​ ​

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