Ultra-low-cost high-voltage driving circuit, wide-voltage output power supply and electric energy meter

Abstract

The invention provides an ultra-low-cost high-voltage driving circuit, a wide-voltage output power supply and an electric energy meter, and the circuit comprises a plurality of high-voltage capacitors of a high-voltage stacked circuit which are connected in series, and a plurality of high-voltage resistors are connected in parallel, so that the midpoint output voltage value of a high-voltage capacitor string is kept to be half of the input end voltage of the high-voltage stacked circuit; the switch driving circuit comprises a plurality of megohm-level resistors and a first capacitor, the midpoint output end of the high-voltage capacitor string is connected to the grid electrode of the high-voltage switch tube through the high-resistor string, and the positive electrode of the high-voltage capacitor string is connected with a transformer primary winding of the wide-voltage output power supply and is connected to the drain electrode of the high-voltage switch tube through the transformer primary winding; one end of the first capacitor is connected with the grid electrode of the high-voltage switch tube, and the other end is in common-ground connection with the high-voltage power supply control chip. The stacked circuit design of the high-voltage resistor and the high-voltage capacitor replaces a TVs high-voltage regulator tube, so that the effects of greatly reducing the cost, simplifying the circuit design and improving the circuit compactness and reliability are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage power supplies, and in particular to an ultra-low-cost high-voltage drive circuit, a wide-voltage output power supply, and an electric energy meter. Background Art

[0002] To ensure compatibility with diverse power systems, three-phase energy meters used in industrial environments typically need to operate over a wide input voltage range, encompassing either an equivalent single-phase AC voltage of 49-480Vac or a rectified DC voltage of 70-690Vdc. To meet this stringent requirement, the meter's internal circuitry must incorporate a dedicated AC / DC switching power supply circuit. This circuit's core function is to safely and stably convert the high input three-phase AC voltage into low-voltage DC power, such as 3V, 5V, or 12V, to power the meter's critical internal components. Furthermore, to effectively address the aforementioned 690Vdc input voltage, the industry currently widely adopts a flyback switching power supply topology with integrated stacked high-voltage switching transistors. This topology typically utilizes a TVS high-voltage zener diode, whose primary purpose is to achieve voltage division across the entire switching circuit by limiting the voltage between the switching transistor's gate and source.

[0003] To enhance the power circuit's high-voltage resistance, the core high-voltage power control chip typically has a withstand voltage of less than 700V. To protect the chip and the switching transistor it drives, this structure incorporates a critical protection path between the switch's gate and ground. This path consists of a TVs high-voltage Zener diode connected in series with multiple high-voltage resistors to form a voltage divider. The TVs high-voltage Zener diode's voltage regulation value is set within a range of 400V to 450V. This circuit design ensures that the gate-to-ground voltage of the series-connected FET switches is strictly limited to 400V to 450V. This limiting effect directly protects the subsequent high-voltage power control chip, keeping the voltage stress it experiences within its 400-450V withstand voltage range and preventing damage to the high-voltage power control chip due to voltage fluctuations and overvoltage. It can be seen that the traditional stack design uses the fixed voltage regulation function of the TVs tube to limit the gate voltage of the upper switch tube, thereby limiting the drain voltage of the lower switch tube. The lower switch tube is generally an integrated power control chip of the switch tube, so as to achieve the purpose of always limiting the operating voltage of the lower power chip in each switching cycle of the power supply to enhance the voltage resistance of the switching circuit.

[0004] See also Figure 1Referring to the electrical parameters of a typical P6SMB440A / CA device manufactured by Littelfuse, the regulated voltage error range is 418-462V. Because the circuit-limited voltage of the lower switching tube is entirely dependent on the voltage regulation of the TVS tube, the operating voltage of the lower switching tube in the circuit remains between 418-462V regardless of the front-end power supply input voltage. Therefore, in addition to the circuit's high cost, it is clear that under most operating conditions, the operating voltages of the upper and lower switching tubes in the stack are unbalanced, preventing the circuit from maximizing its overall high-voltage performance.

[0005] Therefore, in the aforementioned stacked switch circuit, the TVs high-voltage Zener diode (hereinafter referred to as the TVs high-voltage diode) is the core component for achieving the voltage limiting function. The cost and reliability of this component almost determine the design cost and long-term reliability of the entire circuit. This stacked switch circuit has the following problems: 1. High cost. Currently, there are few manufacturers capable of producing high-reliability TVs with voltages above 400-500V. Therefore, they are expensive and have limited supply chains, which leads to an increase in the cost of the entire product.

[0006] 2. Long-term reliability issues exist. TVs high-voltage tubes are prone to aging phenomena such as increased leakage current and breakdown voltage drift under long-term high-stress operation, which directly affects the long-term reliability of the power circuit and even the entire electricity meter product.

[0007] 3. There are issues with space occupation and PCB design limitations. To meet high voltage requirements, the stacked switch tube circuit requires a large number of high-voltage resistors and TVs high-voltage tubes. This takes up a lot of space in the PCB design, increases PCB costs, and restricts product miniaturization, making it difficult to meet the market demand for compact structures in modern electricity meters.

[0008] 4. There are thermal management risks and untimely dynamic response issues. During high-voltage transient response, TVs high-voltage tubes may experience localized high temperatures due to power loss. Failure to optimize the heat dissipation path will further exacerbate the risk of device performance degradation. Furthermore, parasitic inductance generated by long lead layouts can weaken the clamping speed of TVs high-voltage tubes, causing the switching tube to experience voltage spikes under extreme operating conditions.

[0009] Therefore, there is an urgent need for a high-voltage drive circuit, a wide-voltage output power supply, and an electric energy meter that can replace TVs high-voltage tubes to avoid the above-mentioned problems. Summary of the Invention

[0010] In order to solve the common problems in the prior art, the purpose of the present invention is to provide an ultra-low-cost high-voltage drive circuit, a wide-voltage output power supply and an electric energy meter. The invention replaces the TVs high-voltage regulator tube with a stacked circuit design based on high-voltage resistors and high-voltage capacitors, thereby achieving the effect of significantly reducing costs, simplifying circuit design, and improving circuit compactness and reliability.

[0011] The present invention achieves the above-mentioned purpose through the following technical solutions: An ultra-low-cost high-voltage drive circuit includes a rectifier and filter circuit, a high-voltage stacking circuit, and a switch drive circuit. The input end of the rectifier and filter circuit is connected to alternating current (AC) for rectifying the AC into DC, and filtering the DC before outputting it to the input end of the high-voltage stacking circuit. The high-voltage stacking circuit includes a plurality of high-voltage capacitors and a plurality of high-voltage resistors. The plurality of high-voltage capacitors are connected in series to form a high-voltage capacitor string, and the midpoint output voltage of the high-voltage capacitor string is maintained at half the voltage of the input end of the high-voltage stacking circuit by connecting the plurality of high-voltage resistors in parallel. The switch drive circuit is used to provide high-voltage drive for a power switch circuit with an upper and lower stacking design, and includes a plurality of mega-ohm resistors and a first capacitor. The plurality of mega-ohm resistors A high resistance string is formed in series, and the midpoint output end of the high-voltage capacitor string is connected to the gate of the high-voltage switch tube stacked on the power switch circuit through the high resistance string; the first capacitor is used to limit the voltage value of the high-voltage power control chip stacked under the power switch circuit; in the conduction cycle of the high-voltage power control chip, the midpoint output voltage of the high-voltage capacitor string drives the high-voltage switch tube to turn on through the high resistance string, and the output voltage of the high-voltage stacked circuit is converted into magnetic energy storage in the primary winding of the transformer; in the off cycle of the high-voltage power control chip, the source voltage of the high-voltage switch tube follows the gate voltage to rise to the midpoint output voltage value of the high-voltage capacitor string, and the stored energy of the primary winding is released to the secondary side output through the transformer.

[0012] According to an ultra-low-cost high-voltage drive circuit provided by the present invention, the rectifier and filter circuit includes a full-bridge high-voltage rectifier circuit and an LC filter circuit. The multiple input ends of the full-bridge high-voltage rectifier circuit are respectively connected to each phase of the alternating current through a current-limiting resistor, and the alternating current is rectified into a high-voltage direct current output using a full-wave rectification method; the LC filter circuit includes a filter capacitor and multiple filter inductors. The filter capacitor is connected to the output end of the full-bridge high-voltage rectifier circuit, and EMC / EMI inductor filtering protection is provided by connecting multiple filter inductors in series.

[0013] According to an ultra-low-cost high-voltage drive circuit provided by the present invention, the full-bridge high-voltage rectifier circuit includes 16 high-voltage diodes, and the 16 high-voltage diodes are connected in a bridge structure to form a full-wave rectifier circuit with a withstand voltage of 3200V.

[0014] In which, the bridge structure includes a positive-pole connected group and a negative-pole connected group, and the positive-pole connected group and the negative-pole connected group each include 4 groups of two high-voltage diodes connected in series. The positive-pole connected group connects the positive pole of each group of high-voltage diodes to the alternating current, and its negative pole is connected in parallel as the first output end of the full-bridge high-voltage rectifier circuit; the negative-pole connected group connects the negative pole of each group of high-voltage diodes to the alternating current, and its positive pole is connected in parallel as the second output end of the full-bridge high-voltage rectifier circuit.

[0015] According to an ultra-low-cost high-voltage drive circuit provided by the present invention, one end of the filter inductor is connected to the first output end of the full-bridge high-voltage rectifier circuit, and the other end is connected to the second output end of the full-bridge high-voltage rectifier circuit; the multiple filter inductors include two differential-mode inductors and one common-mode inductor, and the first output end and the second output end of the full-bridge high-voltage rectifier circuit are respectively connected to the input end of the common-mode inductor through one of the differential-mode inductors, and the output end of the common-mode inductor is connected in series and parallel with the high-voltage capacitor.

[0016] According to an ultra-low-cost high-voltage drive circuit provided by the present invention, the high-voltage stacked circuit uses two electrolytic capacitors with a withstand voltage of 400V. The upper and lower electrolytic capacitors are stacked in series to form the high-voltage capacitor string with an equivalent total withstand voltage of 800V.

[0017] The high-voltage stacking circuit uses 4 SMD-packaged 390Kohm high-voltage resistors, and the withstand voltage of the high-voltage resistors is 200V; every two high-voltage resistors are connected in series and connected in parallel at both ends of the upper and lower electrolytic capacitors, so that the upper and lower stacking circuit voltages of the high-voltage capacitor string are equal.

[0018] According to an ultra-low-cost high-voltage drive circuit provided by the present invention, the switch drive circuit uses two 1Mohm megohm resistors in SMD packages, the withstand voltage of the megohm resistors is 200V, and the two megohm resistors are connected in series to form a 2Mohm high resistance string.

[0019] An ultra-low-cost, wide-voltage output power supply comprises the high-voltage drive circuit, a multi-winding transformer, a power supply power switching circuit, a feedback control circuit, and a low-voltage DC output circuit. The power supply power switching circuit comprises a high-voltage switching tube and a high-voltage power supply control chip. One end of the primary winding of the multi-winding transformer is connected to the positive output end of the high-voltage stack circuit, and the other end is connected to the power output end of the high-voltage power supply control chip through the high-voltage switching tube. The gate of the high-voltage switching tube is connected to the midpoint output end of the high-voltage stack circuit through a megohm resistor, and its source is connected to the interface of the integrated switch drain in the high-voltage power supply control chip, so as to increase the output voltage of the high-voltage stack circuit when the high-voltage power supply control chip is in the off cycle. The pressure is evenly distributed to the high-voltage switching tube and the high-voltage power supply control chip; the total withstand voltage value of the power supply power switching circuit is the sum of the withstand voltage values ​​of the high-voltage switching tube and the high-voltage power supply control chip; the input end of the low-voltage DC output circuit is connected to the secondary winding of the multi-winding transformer, and is used to rectify the induced current on the secondary side into pulsating DC power, and output low-voltage DC power after ripple suppression of the pulsating DC power; the feedback control circuit is connected to the output end of the low-voltage DC output circuit, and is used to collect voltage sampling signals and feed back voltage feedback signals to the control end of the high-voltage power supply control chip, and the high-voltage power supply control chip controls the power supply in real time according to the voltage feedback signal to ensure the continuity and stability of the power supply output.

[0020] According to an ultra-low-cost, wide-voltage output power supply provided by the present invention, the power supply also includes a leakage inductance absorption circuit, which includes a fast recovery diode, a plurality of bleeder resistors, and an absorption capacitor. The primary winding of the transformer and the drain of the high-voltage switch tube are connected in parallel to the anode of the fast recovery diode, the cathode of the fast recovery diode is connected to one end of the absorption capacitor, and the other end of the absorption capacitor is connected to the positive output end of the high-voltage stack circuit. The absorption capacitor is also connected in parallel with the plurality of bleeder resistors connected in series.

[0021] In each switching cycle of the high-voltage power supply control chip, the leakage inductance absorption circuit damps and absorbs the high-voltage spike formed by the leakage inductance of the primary side of the transformer, and limits and absorbs the peak voltage of the power switch circuit.

[0022] According to an ultra-low-cost wide-voltage output power supply provided by the present invention, the feedback control circuit includes a sampling circuit, a reference reference chip and an isolation optocoupler. The sampling circuit is used to collect a sampled voltage signal and output the voltage sampling signal to the reference end of the reference reference chip. The reference reference chip compares the voltage sampling signal with its reference voltage, outputs the voltage feedback signal, and feeds it back to the control end of the high-voltage power supply control chip through the isolation optocoupler.

[0023] An ultra-low-cost electric energy meter includes the wide-voltage output power supply, a microprocessor, a liquid crystal display, a metering circuit, and a communication circuit. The wide-voltage output power supply is used to convert the voltage of an input equivalent single-phase alternating current (AC) within a voltage range of 49 to 480 Vac, or to convert the voltage of a rectified equivalent DC power within a voltage range of 70 to 690 Vdc, and output a low-voltage DC voltage of the corresponding voltage level to the power input terminals of the microprocessor, LCD, metering circuit, and communication circuit to provide the required operating voltage.

[0024] It can be seen that compared with the prior art, the present invention has the following beneficial effects: 1. In the design of driving the stacked high-voltage switching tube, the present invention utilizes a very low-cost, relatively high-reliability high-value resistor to replace the traditional expensive TVS high-voltage, high-power voltage-stabilizing diode, which can save more than 80% of the cost. At the same time, the high-voltage stack capacitor of the original circuit and the structural design of the voltage-equalizing circuit are used to replace the voltage-stabilizing function of the TVS tube, and the large-volume TVS high-voltage diode is replaced by the SMD packaged chip resistor. Compared with the TVS high-voltage, high-power voltage-stabilizing diode, the resistor and capacitor are more mature and simple in product technology, thereby achieving more dynamic voltage balance between the upper and lower stacked switching tubes in terms of performance, thereby improving the long-term reliability of the product.

[0025] 2. The present invention utilizes the original high-voltage capacitor circuit of the circuit, saving the original four high-voltage series resistors, thereby simplifying the number of components required for the existing stacked circuit, making the circuit simpler and more compact, and improving the design reliability; and by using SMD packaged chip resistors to replace large-volume TVs high-voltage diodes, it greatly reduces the PCB area occupied and can critically promote the miniaturization design of products.

[0026] 3. The rectifier and filter circuit of the present invention has wide voltage compatibility. Its full-bridge rectifier structure supports a wide input range of equivalent single-phase AC power with a voltage range of 49~480Vac or equivalent DC power with a rectified voltage range of 70~690Vdc, and suppresses surge current through current-limiting resistors to prevent grid fluctuations from damaging the subsequent circuit; and the LC filter network can attenuate high-frequency switching noise, meet electromagnetic compatibility standards, and reduce external interference; in addition, the full-bridge high-voltage rectifier circuit is low-cost and high-voltage-resistant. It achieves a 3200V voltage resistance by stacking 16 high-voltage diodes in a bridge. A single tube only needs a 200V voltage resistance, which is significantly lower than the cost of dedicated high-voltage rectifier modules.

[0027] 4. The present invention achieves peak voltage suppression through a leakage inductance absorption circuit, adopts a fast recovery diode to quickly conduct leakage inductance energy, and cooperates with an RC network to limit the drain spike of the switch tube to within the withstand voltage value; at the same time, the absorbed energy is converted into heat energy through a bleeder resistor, which reduces the temperature rise of the high-voltage switch tube and thus reduces heat loss, thereby improving the stability of the circuit.

[0028] 5. The present invention uses a feedback reference chip designed through a feedback control circuit to compare the sampled voltage with the reference value, so that the feedback error is less than 1% and the output ripple is controlled within ±2%, thereby achieving precise voltage regulation and blocking the common-mode interference between the primary and secondary sides through optical coupling to achieve safe isolation between high and low voltages.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 These are the electrical parameters of the P6SMB440A / CA device in the prior art of the present invention.

[0031] Figure 2 This is a circuit diagram of an ultra-low-cost high-voltage drive circuit embodiment of the present invention.

[0032] Figure 3 This is a circuit schematic diagram of an ultra-low-cost high-voltage drive circuit embodiment of the present invention.

[0033] Figure 4 This is a circuit diagram of an embodiment of an ultra-low-cost wide-voltage output power supply of the present invention. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0035] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] See also Figure 2-3The present invention provides an ultra-low-cost high-voltage drive circuit, including a rectifier filter circuit 10, a high-voltage stacking circuit 20, and a switch drive circuit 30. The input end of the rectifier filter circuit 10 is connected to an alternating current, and is used to rectify the alternating current into a direct current output to provide the working voltage of a wide-voltage output power supply, and output the direct current to the input end of the high-voltage stacking circuit 20 after filtering; the high-voltage stacking circuit 20 includes a plurality of high-voltage capacitors and a plurality of high-voltage resistors, and the plurality of high-voltage capacitors are connected in series to form a high-voltage capacitor string, and the midpoint output voltage value of the high-voltage capacitor string is maintained at half of the input end voltage of the high-voltage stacking circuit 20 by connecting the plurality of high-voltage resistors in parallel; the switch drive circuit 30 and the power switch circuit 50 of the wide-voltage output power supply are connected. Connection, used to provide high-voltage switch drive for the high-voltage switch tube V201 for the power supply power switch circuit 50, including several megohm resistors and a first capacitor, several of the megohm resistors are connected in series to form a high resistance string, the midpoint output end of the high-voltage capacitor string is connected to the gate of the high-voltage switch tube V201 through the high resistance string, the positive pole of the high-voltage capacitor string is connected to the primary winding of the transformer 40 of the wide voltage output power supply, and is connected to the drain of the high-voltage switch tube V201 through the primary winding of the transformer 40, the source of the high-voltage switch tube V201 is connected to the integrated switch drain of the high-voltage power supply control chip IC200, one end of the first capacitor is connected to the gate of the high-voltage switch tube V201, and the other end is connected to the common ground of the high-voltage power supply control chip IC200.

[0037] Among them, in the conduction cycle of the high-voltage power supply control chip IC200, the midpoint output voltage of the high-voltage capacitor string drives the high-voltage switch tube V201 to turn on through the high-resistance string, and the output voltage of the high-voltage stack circuit 20 is converted into magnetic energy storage in the primary winding of the transformer 40; in the shutdown cycle of the high-voltage power supply control chip IC200, the integrated switch of the high-voltage power supply control chip IC200 is turned off to open the source of the high-voltage switch tube V201, and the source voltage of the high-voltage switch tube V201 follows the gate voltage to rise to the midpoint output voltage value of the high-voltage capacitor string. The first capacitor is used to limit the pressure of the high-voltage power supply control chip IC200 to half of the input voltage of the high-voltage stack circuit 20; the energy stored in the primary winding is released to the secondary side output through the transformer 40.

[0038] Specifically, this embodiment utilizes the high-voltage stack capacitor and its voltage equalizing circuit of the original circuit to replace the voltage stabilizing function of the TVS tube, and uses a high-resistance resistor to replace the traditional expensive TVS high-voltage and high-power voltage stabilizing diode to drive the stacked high-voltage switch tube V201. Therefore, when the high-voltage power supply control chip IC200 is in the on-cycle, the source potential P21 of the high-voltage switch tube V201 will be forced to be close to the reference ground, and then the center point voltage of P2 will be connected to the high-voltage switch tube V201 through the series connection of the two megohm resistors R215 and R216. The gate of 201 charges capacitor C213, thereby forming a turn-on voltage from gate G to source S, turning on the high-voltage switch tube V201. At this time, the gate potential P16 of the high-voltage switch tube V201 is approximately equal to 15V under the voltage regulation protection of the voltage regulator diode D214. Since the high-voltage switch tube V201 is in the on state, its drain D voltage P13 is close to the reference ground. At this time, the input voltage is completely borne by the primary winding of the transformer 40, and the electrical energy is converted into magnetic energy and stored in the primary winding inductance.

[0039] Next, the high-voltage power supply control chip IC200 enters a shutdown cycle. At this time, the integrated switch of the high-voltage power supply control chip IC200 is turned off, the source of the high-voltage switch tube V201 is open, and its source voltage is reverse-conducted by the voltage-stabilizing protection of the voltage-stabilizing diode D214 and the gate. Therefore, the source potential P21 will quickly follow the gate potential P17 and rise rapidly, and eventually approach the neutral point voltage of the equalizing capacitor P2, which is 0.5 times the input voltage. That is, the drain voltage of the high-voltage power supply control chip IC200 is limited to 0.5 times the input voltage. At this time, since the voltage between the gate and the source of the high-voltage switch tube V201 is almost zero, the high-voltage switch tube V201 is forced to enter and quickly be in a closed state, the primary inductor voltage drops, and the stored energy is released to the secondary output end through the transformer 40. The input voltage is almost entirely shared by the drain-source of high-voltage switching transistor V201 in series with the high-voltage power supply control chip IC200. As previously analyzed, the drain of high-voltage power supply control chip IC200 is limited to half the input voltage by the voltage-divider capacitor. Therefore, the off-state upper and lower switching transistors each share half of the input voltage. If the maximum withstand voltage of high-voltage power supply control chip IC200 is 700V, the theoretical total peak withstand voltage of the stacked upper and lower transistors is close to 1400V, achieving the voltage-strengthening effect of the stacked drive switch circuit.

[0040] In this embodiment, the rectifier and filter circuit 10 includes a full-bridge high-voltage rectifier circuit 11 and an LC filter circuit 12. The multiple input ends of the full-bridge high-voltage rectifier circuit 11 are respectively connected to the phases of the alternating current through a current-limiting resistor, and the alternating current is rectified into a high-voltage direct current output using a full-wave rectification method; the LC filter circuit 12 includes a filter capacitor and multiple filter inductors. The filter capacitor is connected to the output end of the full-bridge high-voltage rectifier circuit 11, and EMC / EMI inductor filtering protection is provided by connecting multiple filter inductors in series.

[0041] In this embodiment, the full-bridge high-voltage rectifier circuit 11 includes 16 high-voltage diodes, and the 16 high-voltage diodes are connected in a bridge structure to form a full-wave rectifier circuit with a withstand voltage of 3200V.

[0042] In which, the bridge structure includes a positive-pole connected group and a negative-pole connected group, and the positive-pole connected group and the negative-pole connected group each include 4 groups of two high-voltage diodes connected in series. The positive-pole connected group connects the positive pole of each group of high-voltage diodes to the alternating current, and its negative pole is connected in parallel as the first output end of the full-bridge high-voltage rectifier circuit 11; the negative-pole connected group connects the negative pole of each group of high-voltage diodes to the alternating current, and its positive pole is connected in parallel as the second output end of the full-bridge high-voltage rectifier circuit 11.

[0043] In this embodiment, one end of the filter inductor is connected to the first output end of the full-bridge high-voltage rectifier circuit 11, and the other end is connected to the second output end of the full-bridge high-voltage rectifier circuit 11; the multiple filter inductors include two differential-mode inductors and one common-mode inductor, and the first output end and the second output end of the full-bridge high-voltage rectifier circuit 11 are respectively connected to the input end of the common-mode inductor through one of the differential-mode inductors, and the output end of the common-mode inductor is connected in series and parallel with the high-voltage capacitor.

[0044] Specifically, this embodiment achieves noise frequency suppression through differential mode inductance, blocks high-frequency noise through inductive reactance, and forces the noise current to enter the ground through the parallel capacitor; and achieves current smoothing, reduces current mutations caused by the switching power supply, and reduces conducted interference.

[0045] Specifically, the common-mode inductor of this embodiment adopts a common-mode choke structure to suppress common-mode noise.

[0046] In this embodiment, the high-voltage stack circuit 20 uses two electrolytic capacitors with a withstand voltage of 400V. The upper and lower electrolytic capacitors are stacked in series to form the high-voltage capacitor string with an equivalent total withstand voltage of 800V.

[0047] The high-voltage stack circuit 20 uses four 390Kohm high-voltage resistors in SMD packages, and the withstand voltage of the high-voltage resistors is 200V; every two high-voltage resistors are connected in series and then connected in parallel to the upper and lower electrolytic capacitors, so that the voltages of the upper and lower stack circuits of the high-voltage capacitor string are equal.

[0048] Specifically, the high-voltage stacked circuit 20 structure in this embodiment reduces voltage stress by half. Two 400V electrolytic capacitors connected in series have an equivalent withstand voltage of 800V. The parallel high-voltage resistors force the midpoint voltage to 50% of the input voltage, reducing the stress on subsequent switching transistors by 50%. The parallel high-voltage resistors form a resistor-equalizing network, giving the circuit dynamic balancing capabilities. This resistor-equalizing network suppresses voltage offsets caused by capacitor tolerances, ensuring the voltage difference between the upper and lower stacked capacitors is less than 5%, improving system reliability.

[0049] In this embodiment, the switch driving circuit 30 uses two 1Mohm megaohm resistors in SMD packages, the withstand voltage of the megaohm resistors being 200V, and the two megaohm resistors being connected in series to form a 2Mohm high resistance string.

[0050] Specifically, this embodiment uses two 1Mohm resistors connected in series to form a high-resistance voltage divider path to provide safe high-voltage switch drive, limiting the gate drive current to the μA level and preventing high voltage breakdown in the high-voltage power supply control chip IC200. Furthermore, a first capacitor clamps the source voltage when the high-voltage switch V201 is turned off, limiting the high-voltage power supply control chip IC200 to only 50% of the input voltage, thereby extending the device's service life.

[0051] See also Figure 4, an ultra-low-cost wide-voltage output power supply, including the high-voltage drive circuit, transformer 40, power switch circuit 50, feedback control circuit 60, and low-voltage DC output circuit 70. The power switch circuit 50 includes a high-voltage switch tube V201 and a high-voltage power supply control chip IC200. One end of the primary winding of the transformer 40 is connected to the positive output end of the high-voltage stack circuit 20, and the other end is connected to the power output end of the high-voltage power supply control chip IC200 through the high-voltage switch tube V201; the gate of the high-voltage switch tube V201 is connected to the midpoint output end of the high-voltage stack circuit 20 through a megohm resistor, and its source is connected to the interface of the integrated switch drain in the high-voltage power supply control chip IC200, which is used to turn on the high-voltage stack circuit 20 when the high-voltage power supply control chip IC200 is in the off cycle. The output voltage of 0 is evenly distributed to the high-voltage switch tube V201 and the high-voltage power supply control chip IC200; the total withstand voltage value of the power switch circuit 50 is the sum of the withstand voltage values ​​of the high-voltage switch tube V201 and the high-voltage power supply control chip IC200; the input end of the low-voltage DC output circuit 70 is connected to the secondary winding of the transformer 40, and is used to rectify the induced current on the secondary side into pulsating DC power, and output low-voltage DC power after ripple suppression of the pulsating DC power; the feedback control circuit 60 is connected to the output end of the low-voltage DC output circuit 70, and is used to collect voltage sampling signals and feed back the voltage feedback signals to the control end of the high-voltage power supply control chip IC200. The high-voltage power supply control chip IC200 controls the power supply in real time according to the voltage feedback signal to ensure the continuity and stability of the power supply output.

[0052] Specifically, this embodiment adopts an upper and lower driven stacked high-voltage switch structure, including an upper stacked high-voltage switch tube V201 and a lower stacked high-voltage power supply control chip IC200. By connecting the high-voltage switch tube V201 and the high-voltage power supply control chip IC200 in series, dynamic voltage division is achieved, the total withstand voltage value is superimposed, and the cost of a single device is reduced; and by efficiently transferring the magnetic energy of the primary winding to the secondary side during the switching cycle, energy efficiency optimization is achieved, thereby improving the efficiency of the entire power supply circuit.

[0053] In this embodiment, a leakage inductance absorption circuit is also included, which includes a fast recovery diode, several discharge resistors and an absorption capacitor. The primary winding of the transformer 40 and the drain of the high-voltage switch tube V201 are connected in parallel to the anode of the fast recovery diode, the cathode of the fast recovery diode is connected to one end of the absorption capacitor, and the other end of the absorption capacitor is connected to the positive output end of the high-voltage stack circuit 20. The absorption capacitor is also connected in parallel with several of the discharge resistors connected in series.

[0054] Specifically, this embodiment uses a fast recovery diode to quickly conduct leakage inductance energy, and cooperates with an RC network to limit the drain peak of the switch tube to within the withstand voltage value; at the same time, the absorbed energy is converted into heat energy through a discharge resistor, so that the temperature rise of the high-voltage switch tube V201 is reduced, thereby reducing heat loss and improving the stability of the circuit.

[0055] In each switching cycle of the high-voltage power supply control chip IC200, the leakage inductance absorption circuit damps and absorbs the high-voltage spike formed by the primary leakage inductance of the transformer 40, and limits and absorbs the peak voltage of the power switch circuit 50.

[0056] In this embodiment, the feedback control circuit 60 includes a sampling circuit, a reference reference chip and an isolation optocoupler. The sampling circuit is used to collect a sampled voltage signal and output the voltage sampling signal to the reference end of the reference reference chip. The reference reference chip compares the voltage sampling signal with its reference voltage, outputs the voltage feedback signal, and feeds it back to the control end of the high-voltage power supply control chip IC200 through the isolation optocoupler.

[0057] Specifically, the sampling circuit in this embodiment uses resistor sampling; the reference chip is a TL431 chip. Resistors R218 and R210 are connected to the output voltage, and the lower ends are connected to resistors R291, R277, and R278 to form a voltage divider for sampling. The sampled voltage is input to the reference pin of IC208, and the feedback signal is fed back to the power feedback control pin of IC200 through the optical coupling of the optocoupler, achieving real-time feedback control of the output voltage and ensuring a stable and continuous output voltage.

[0058] Specifically, the low-voltage DC output circuit 70 of this embodiment includes a rectifier diode D210 and capacitors C202 and C232. Capacitors C202 and C232 form a two-pole filter circuit. Capacitor C202 is connected in parallel to the output terminal of the rectifier diode D210 to filter out switching noise >1MHz; capacitor C232 is used for low-pass filtering, smoothing pulsating DC, and storing energy. Rectifier diode D210 is connected to the secondary winding of transformer 40 and periodically outputs primary switching power to capacitors C202 and C232, outputting a 12.5V low-voltage DC output. The low-voltage DC output circuit 70 also includes a transient suppression diode D200, which is connected in series with the output terminal to clamp the voltage to a safe value when an abnormal voltage occurs.

[0059] An ultra-low-cost electric energy meter includes the wide-voltage output power supply, a microprocessor, a liquid crystal display, a metering circuit, and a communication circuit. The wide-voltage output power supply is used to convert the voltage of an input equivalent single-phase alternating current (AC) within a voltage range of 49 to 480 Vac, or to convert the voltage of a rectified equivalent DC power within a voltage range of 70 to 690 Vdc, and output a low-voltage DC voltage of the corresponding voltage level to the power input terminals of the microprocessor, LCD, metering circuit, and communication circuit to provide the required operating voltage.

[0060] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. An ultra-low-cost high-voltage drive circuit, characterized in that: include: A rectifier and filter circuit, a high-voltage stacking circuit, and a switch drive circuit, wherein the input end of the rectifier and filter circuit is connected to alternating current, for rectifying the alternating current into direct current, and filtering the direct current and outputting it to the input end of the high-voltage stacking circuit; the high-voltage stacking circuit includes a plurality of high-voltage capacitors and a plurality of high-voltage resistors, wherein the plurality of high-voltage capacitors are connected in series to form a high-voltage capacitor string, and the midpoint output voltage value of the high-voltage capacitor string is maintained at half of the voltage at the input end of the high-voltage stacking circuit by connecting the plurality of high-voltage resistors in parallel; the switch drive circuit is used to provide high-voltage drive for a power switch circuit with an upper and lower stacking design, and includes a plurality of mega-ohm resistors and a first capacitor, wherein the plurality of mega-ohm resistors are connected in series to form a high resistance string , the midpoint output end of the high-voltage capacitor string is connected to the gate of the high-voltage switch tube stacked on the power switch circuit through the high-resistance string; the first capacitor is used to limit the voltage value of the high-voltage power control chip stacked under the power switch circuit; in the conduction cycle of the high-voltage power control chip, the midpoint output voltage of the high-voltage capacitor string drives the high-voltage switch tube to turn on through the high-resistance string, and the output voltage of the high-voltage stacked circuit is converted into magnetic energy storage in the primary winding of the transformer; in the off cycle of the high-voltage power control chip, the source voltage of the high-voltage switch tube follows the gate voltage to rise to the midpoint output voltage value of the high-voltage capacitor string, and the energy stored in the primary winding is released to the secondary side output through the transformer.

2. The ultra-low-cost high-voltage driving circuit according to claim 1, wherein: The rectifier and filter circuit includes a full-bridge high-voltage rectifier circuit and an LC filter circuit. The multiple input ends of the full-bridge high-voltage rectifier circuit are respectively connected to the phases of the alternating current through a current-limiting resistor, and the alternating current is rectified into a high-voltage direct current output using a full-wave rectification method; the LC filter circuit includes a filter capacitor and multiple filter inductors. The filter capacitor is connected to the output end of the full-bridge high-voltage rectifier circuit, and EMC / EMI inductor filtering protection is provided by connecting multiple filter inductors in series.

3. The ultra-low-cost high-voltage driving circuit according to claim 2, wherein: The full-bridge high-voltage rectifier circuit includes 16 high-voltage diodes, and the 16 high-voltage diodes are connected in a bridge structure to form a full-wave rectifier circuit with a withstand voltage of 3200V; In which, the bridge structure includes a positive-pole connected group and a negative-pole connected group, and the positive-pole connected group and the negative-pole connected group each include 4 groups of two high-voltage diodes connected in series. The positive-pole connected group connects the positive pole of each group of high-voltage diodes to the alternating current, and its negative pole is connected in parallel as the first output end of the full-bridge high-voltage rectifier circuit; the negative-pole connected group connects the negative pole of each group of high-voltage diodes to the alternating current, and its positive pole is connected in parallel as the second output end of the full-bridge high-voltage rectifier circuit.

4. The ultra-low-cost high-voltage driving circuit according to claim 3, wherein: One end of the filter inductor is connected to the first output end of the full-bridge high-voltage rectifier circuit, and the other end is connected to the second output end of the full-bridge high-voltage rectifier circuit; the multiple filter inductors include two differential-mode inductors and one common-mode inductor, and the first output end and the second output end of the full-bridge high-voltage rectifier circuit are respectively connected to the input end of the common-mode inductor through one of the differential-mode inductors, and the output end of the common-mode inductor is connected in series and parallel with the high-voltage capacitor.

5. The ultra-low-cost high-voltage driving circuit according to claim 1, characterized in that: The high-voltage stacking circuit uses two electrolytic capacitors with a withstand voltage of 400V. The upper and lower electrolytic capacitors are stacked in series to form the high-voltage capacitor string with an equivalent total withstand voltage of 800V. The high-voltage stacking circuit uses 4 SMD-packaged 390Kohm high-voltage resistors, and the withstand voltage of the high-voltage resistors is 200V; every two high-voltage resistors are connected in series and connected in parallel at both ends of the upper and lower electrolytic capacitors, so that the upper and lower stacking circuit voltages of the high-voltage capacitor string are equal.

6. The ultra-low-cost high-voltage driving circuit according to claim 1, characterized in that: The switch drive circuit uses two 1Mohm megohm resistors in SMD packages, the withstand voltage of the megohm resistors is 200V, and the two megohm resistors are connected in series to form a 2Mohm high resistance string.

7. An ultra-low-cost wide-voltage output power supply, characterized in that: include: The high-voltage drive circuit, multi-winding transformer, power supply power switching circuit, feedback control circuit, and low-voltage DC output circuit according to any one of claims 1 to 6, wherein the power supply power switching circuit includes a high-voltage switching tube and a high-voltage power supply control chip, one end of the primary winding of the multi-winding transformer is connected to the positive output end of the high-voltage stack circuit, and the other end is connected to the power output end of the high-voltage power supply control chip through the high-voltage switching tube; the gate of the high-voltage switching tube is connected to the midpoint output end of the high-voltage stack circuit through a megohm resistor, and its source is connected to the interface of the integrated switch drain in the high-voltage power supply control chip, and is used to average the output voltage of the high-voltage stack circuit when the high-voltage power supply control chip is in the off cycle. The pressure is distributed to the high-voltage switching tube and the high-voltage power supply control chip; the total withstand voltage value of the power supply power switching circuit is the sum of the withstand voltage values ​​of the high-voltage switching tube and the high-voltage power supply control chip; the input end of the low-voltage DC output circuit is connected to the secondary winding of the multi-winding transformer, and is used to rectify the induced current on the secondary side into pulsating DC power, and output low-voltage DC power after ripple suppression of the pulsating DC power; the feedback control circuit is connected to the output end of the low-voltage DC output circuit, and is used to collect voltage sampling signals and feed back voltage feedback signals to the control end of the high-voltage power supply control chip, and the high-voltage power supply control chip controls the power supply in real time according to the voltage feedback signal to ensure the continuity and stability of the power supply output.

8. The ultra-low-cost wide-voltage output power supply according to claim 7, characterized in that: The device further includes a leakage inductance absorption circuit, the leakage inductance absorption circuit including a fast recovery diode, a plurality of bleeder resistors and an absorption capacitor, the primary winding of the transformer and the drain of the high-voltage switch tube are connected in parallel to the anode of the fast recovery diode, the cathode of the fast recovery diode is connected to one end of the absorption capacitor, the other end of the absorption capacitor is connected to the positive output end of the high-voltage stack circuit, and the absorption capacitor is further connected in parallel to the plurality of bleeder resistors connected in series; In each switching cycle of the high-voltage power supply control chip, the leakage inductance absorption circuit damps and absorbs the high-voltage spike formed by the leakage inductance of the primary side of the transformer, and limits and absorbs the peak voltage of the power switch circuit.

9. The ultra-low-cost wide-voltage output power supply according to claim 7, characterized in that: The feedback control circuit includes a sampling circuit, a reference reference chip and an isolation optocoupler. The sampling circuit is used to collect a sampled voltage signal and output the voltage sampling signal to the reference end of the reference reference chip. The reference reference chip compares the voltage sampling signal with its reference voltage, outputs the voltage feedback signal, and feeds it back to the control end of the high-voltage power supply control chip through the isolation optocoupler.

10. An ultra-low-cost electric energy meter, characterized in that: include: The wide-voltage output power supply, microprocessor, liquid crystal display, metering circuit, and communication circuit according to any one of claims 7 to 9, wherein the wide-voltage output power supply is used to convert the input voltage of an equivalent single-phase alternating current (AC) in the range of 49 to 480 Vac, or to convert the rectified equivalent DC power in the range of 70 to 690 Vdc, and output a low-voltage DC voltage of the corresponding voltage level to the power input terminal of the microprocessor, liquid crystal display, metering circuit, and communication circuit to provide the required operating voltage.

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