An ultra-low-cost high-voltage drive circuit, a wide-voltage output power supply and an electric energy meter

Abstract

The application provides a kind of ultra-low cost high-voltage drive circuit, wide voltage output power supply and electric energy meter, including a plurality of high-voltage capacitors in series of high-voltage stacked circuit, and the midpoint output voltage value of high-voltage capacitor string is kept as half of high-voltage stacked circuit input voltage by connecting a plurality of high-voltage resistors in parallel; switch drive circuit a plurality of mega-ohm resistors and first capacitor, the midpoint output end of high-voltage capacitor string is connected to the gate of high-voltage switch tube through high resistance string, the anode of high-voltage capacitor string is connected to the primary winding of wide voltage output power supply transformer, and is connected to the drain of high-voltage switch tube through the primary winding of transformer, one end of first capacitor is connected to the gate of high-voltage switch tube, and the other end is connected to high-voltage power supply control chip common ground. The application replaces TV high-voltage stabilizing tube by high-voltage resistance and high-voltage capacitor stacked circuit design, achieves the effect of greatly reducing cost, simplifying circuit design, improving circuit compactness and reliability.

Description

Technical Field

[0001] This invention relates to the field of high-voltage power supply technology, specifically to an ultra-low-cost high-voltage drive circuit, a wide-voltage output power supply, and an energy meter. Background Technology

[0002] In three-phase energy meters used in industrial environments, to ensure compatibility with various power systems, their operating voltage range typically needs to cover a wide input voltage range, including equivalent single-phase AC voltage of 49~480Vac or equivalent DC voltage after rectification of 70~690Vdc. To meet this stringent requirement, the internal circuit design of the energy meter must be equipped with a dedicated AC / DC switching power supply circuit. The core function of this circuit is to safely and stably convert the high-input three-phase AC voltage into low-voltage DC voltage, such as 3V, 5V, or 12V, thereby providing power support for the key internal components of the energy meter. Furthermore, to effectively address the aforementioned input withstand voltage challenge of up to 690Vdc, the industry widely adopts a flyback switching power supply topology with integrated stacked high-voltage switching transistors. This structure generally uses a solution based on TVs (voltage regulators), and its main purpose is to achieve voltage division of the entire switching circuit by limiting the voltage between the gate and source of the switching transistor.

[0003] To enhance the high-voltage withstand capability of the power supply circuit, in the high-voltage switching circuit section, since the core high-voltage power control chip's own withstand voltage is typically below 700V, a critical protection path is incorporated between the gate and ground of the switching transistors to protect the chip and its driven switching transistors. This protection path consists of a voltage divider and regulator circuit formed by a TVs (voltage regulator diode) connected in series with multiple high-voltage resistors. The TVs (voltage regulator diode) has a voltage regulation value set in the range of 400V to 450V. This circuit design ensures that the gate-to-ground voltage of the series-connected FET switching transistors is strictly limited to 400V to 450V. This limitation directly protects the downstream high-voltage power control chip, ensuring that the voltage stress it withstands is always clamped within the 400V to 450V withstand voltage range, preventing damage to the high-voltage power control chip due to voltage fluctuations and overvoltage. As can be seen, the traditional stacked design limits the gate voltage of the upper switching transistor by using the fixed voltage regulation function of TVs, thereby limiting the drain voltage of the lower switching transistor. The lower switching transistor is generally a power control chip that integrates the switching transistor, so as to limit the operating voltage of the lower power chip in each switching cycle of the power supply, thereby enhancing the voltage withstand capability of the switching circuit.

[0004] See Figure 1Referring to the electrical parameters of a typical Littelfuse P6SMB440A / CA device, its regulated voltage error range is 418~462V. Since the voltage limit of the lower-side switching transistor depends entirely on the voltage regulation of the TVS diode, the operating voltage of the lower-side switching transistor remains between 418~462V regardless of the input power supply voltage. Therefore, besides the high cost of the circuit, it is clear that under most operating conditions, the unbalanced operating voltages of the upper and lower-side switching transistors in the stacked circuit cannot maximize the overall high-voltage withstand capability of the circuit.

[0005] Therefore, in the above-mentioned stacked switching transistor circuit, the TVs high-voltage regulator diode (hereinafter referred to as TVs high-voltage diode) is the core component for realizing 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 switching transistor circuit has the following problems:

[0006] 1. High cost. Currently, there are not many manufacturers capable of producing high-reliability TVs high-voltage tubes of 400~500V and above, so their prices are high and the supply chain is limited, which leads to an increase in the cost of the whole product.

[0007] 2. Long-term reliability issues exist. Under long-term high-stress operation, TVs high-voltage tubes are prone to aging phenomena such as increased leakage current and breakdown voltage drift, which directly affects the long-term reliability of the power supply circuit and even the entire electricity meter product.

[0008] 3. Space occupation and PCB design limitations exist. To meet high voltage withstand requirements, stacked switching transistor circuits require a significant number of high-voltage resistors and TVs, which takes up considerable space in the PCB design, increases PCB costs, and restricts product miniaturization design, making it difficult to meet the market demand for compact structures in modern energy meters.

[0009] 4. Potential issues with thermal management and untimely dynamic response. During high-voltage transient response, TVs may generate localized high temperatures due to power loss. If their heat dissipation path is not optimized, the risk of device performance degradation will be further aggravated. In addition, parasitic inductance generated by long lead layouts may weaken the clamping speed of TVs, causing the switching transistor to be subjected to voltage spikes under extreme operating conditions.

[0010] Therefore, there is an urgent need for a high-voltage drive circuit, a wide-voltage output power supply, and an energy meter that can replace TVs high-voltage tubes to avoid the above problems. Summary of the Invention

[0011] To address the common problems in existing technologies, the present invention aims to provide an ultra-low-cost high-voltage drive circuit, a wide-voltage output power supply, and an energy meter. This invention replaces TVs (voltage regulators) with a stacked circuit design based on high-voltage resistors and high-voltage capacitors, thereby significantly reducing costs, simplifying circuit design, and improving circuit compactness and reliability.

[0012] The present invention achieves the above objectives through the following technical solutions:

[0013] 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 of the rectifier and filter circuit is connected to AC power to rectify it into DC power, and the filtered DC power is then output to the input of the high-voltage stacking circuit. The high-voltage stacking circuit includes several high-voltage capacitors and several high-voltage resistors. The high-voltage capacitors are connected in series to form a high-voltage capacitor string, and the output voltage at the midpoint of the high-voltage capacitor string is maintained at half the input voltage of the high-voltage stacking circuit by several high-voltage resistors connected in parallel. The switch drive circuit provides high-voltage drive for a power switch circuit with a stacked design and includes several megohm-level resistors and a first capacitor. A high-resistance string is formed by connecting the high-voltage capacitors in series. The midpoint output terminal of the high-voltage capacitor string is connected to the gate of the high-voltage switching transistor stacked on the power switch circuit through the high-resistance string. The first capacitor is used to limit the voltage withstand value of the high-voltage power control chip stacked under the power switch circuit. During the conduction cycle of the high-voltage power control chip, the midpoint output voltage of the high-voltage capacitor string drives the high-voltage switching transistor to conduct through the high-resistance string. The output voltage of the high-voltage stack circuit is converted into magnetic energy and stored in the primary winding of the transformer. During the shutdown cycle of the high-voltage power control chip, the source voltage of the high-voltage switching transistor rises to the midpoint output voltage value of the high-voltage capacitor string following the gate voltage. The energy stored in the primary winding is released to the secondary side output through the transformer.

[0014] According to the present invention, an ultra-low cost high-voltage drive circuit is provided, wherein the rectifier and filter circuit includes a full-bridge high-voltage rectifier circuit and an LC filter circuit. The multiple input terminals of the full-bridge high-voltage rectifier circuit are respectively connected to each phase of the AC power through a current-limiting resistor, and the AC power is rectified into high-voltage DC power 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 terminal of the full-bridge high-voltage rectifier circuit, and EMC / EMI inductor filtering protection is provided by connecting multiple filter inductors in series.

[0015] According to the present invention, an ultra-low cost high voltage drive circuit is provided, 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.

[0016] The bridge structure includes a positive terminal connected group and a negative terminal connected group. Both the positive terminal connected group and the negative terminal connected group include four sets of two high-voltage diodes connected in series. The positive terminal connected group connects the positive terminal of each high-voltage diode to the AC power, and its negative terminal is connected in parallel as the first output terminal of the full-bridge high-voltage rectifier circuit. The negative terminal connected group connects the negative terminal of each high-voltage diode to the AC power, and its positive terminal is connected in parallel as the second output terminal of the full-bridge high-voltage rectifier circuit.

[0017] According to the present invention, an ultra-low cost high-voltage drive circuit is provided, wherein one end of the filter inductor is connected to the first output terminal of the full-bridge high-voltage rectifier circuit, and the other end is connected to the second output terminal of the full-bridge high-voltage rectifier circuit; the plurality of filter inductors include two differential-mode inductors and one common-mode inductor, the first output terminal and the second output terminal of the full-bridge high-voltage rectifier circuit are respectively connected to the input terminal of the common-mode inductor through one of the differential-mode inductors, and the output terminal of the common-mode inductor is connected in series and parallel with the high-voltage capacitor.

[0018] According to the present invention, an ultra-low cost high voltage driving circuit is provided, wherein the high voltage stacking circuit uses two 400V electrolytic capacitors, and the upper and lower electrolytic capacitors are stacked in series to form a high voltage capacitor string with an equivalent total withstand voltage of 800V.

[0019] The high-voltage stacking circuit uses four 390Kohm high-voltage resistors in SMD packages, each with a withstand voltage of 200V. Every two high-voltage resistors are connected in series and then connected in parallel across the upper and lower electrolytic capacitors, so that the voltage of the upper and lower stacked circuits of the high-voltage capacitor series is equal.

[0020] According to the present invention, an ultra-low cost high voltage driving circuit is provided, wherein the switching driving circuit uses two SMD packaged 1Mohm megohm resistors, the megohm resistors have a withstand voltage of 200V, and the two megohm resistors are connected in series to form a 2Mohm high resistance string.

[0021] An ultra-low-cost wide-voltage output power supply includes a high-voltage drive circuit, a multi-winding transformer, a power switching circuit, a feedback control circuit, and a low-voltage DC output circuit. The power switching circuit includes a high-voltage switching transistor and a high-voltage power control chip. One end of the primary winding of the multi-winding transformer is connected to the positive output terminal of the high-voltage stacking circuit, and the other end is connected to the power output terminal of the high-voltage power control chip via the high-voltage switching transistor. The gate of the high-voltage switching transistor is connected to the midpoint output terminal of the high-voltage stacking circuit via a megohm resistor, and its source is connected to the interface of the integrated switch drain in the high-voltage power control chip. This connection is used to control the output voltage of the high-voltage stacking circuit when the high-voltage power control chip is in its off-cycle. The voltage is evenly distributed across the high-voltage switching transistor and the high-voltage power control chip; the total withstand voltage of the power switching circuit is the sum of the withstand voltages of the high-voltage switching transistor and the high-voltage power control chip; the input terminal of the low-voltage DC output circuit is connected to the secondary winding of the multi-winding transformer, used to rectify the induced current on the secondary side into pulsating DC current, and output low-voltage DC current after ripple suppression; the feedback control circuit is connected to the output terminal of the low-voltage DC output circuit, used to collect voltage sampling signals and feed back the voltage feedback signals to the control terminal of the high-voltage power control chip, and the high-voltage power control chip performs real-time control of the power supply according to the voltage feedback signals to ensure the continuity and stability of the power output.

[0022] According to the present invention, an ultra-low cost wide voltage output power supply further includes a leakage inductance absorption circuit, which includes a fast recovery diode, several bleed resistors, and an absorption capacitor. The primary winding of the transformer and the drain of the high-voltage switching transistor 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 terminal of the high-voltage stacking circuit. Several bleed resistors connected in series are also connected in parallel to the absorption capacitor.

[0023] In each switching cycle of the high-voltage power control chip, the leakage inductance absorption circuit dampens and absorbs the high-voltage spikes generated by the leakage inductance of the transformer primary side, and limits and absorbs the peak voltage of the power switching circuit.

[0024] According to the present invention, an ultra-low cost wide voltage output power supply is provided. The feedback control circuit includes a sampling circuit, a reference chip, and an isolation optocoupler. The sampling circuit is used to acquire a sampled voltage signal and output the voltage sampled signal to the reference terminal of the reference chip. The reference chip compares the voltage sampled signal with its reference voltage, outputs the voltage feedback signal, and feeds it back to the control terminal of the high voltage power supply control chip through the isolation optocoupler.

[0025] An ultra-low-cost electricity meter includes a wide-voltage output power supply, a microprocessor, an LCD display, a metering circuit, and a communication circuit. The wide-voltage output power supply is used to convert the input voltage range of 49~480Vac equivalent single-phase AC power into voltage, or to convert the rectified voltage range of 70~690Vdc equivalent DC power into voltage, and outputs a low-voltage DC voltage of the corresponding voltage level to the power input terminals of the microprocessor, LCD display, metering circuit, and communication circuit to provide the required operating voltage.

[0026] Therefore, compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. In the design of driving stacked high-voltage switching transistors, this invention utilizes a high-resistance value, which is very inexpensive and has relatively high reliability, to replace the traditional expensive TVS high-voltage high-power Zener diodes, thereby saving more than 80% of the cost. At the same time, it uses the high-voltage stacked capacitor and its voltage equalization circuit structure design of the original circuit to replace the voltage regulation function of the TVS transistors, and replaces the bulky TVS high-voltage diodes with SMD packaged surface mount resistors. The resistor and capacitor are more mature and simpler in terms of product process than TVS high-voltage high-power Zener diodes, thereby achieving a more dynamic voltage balance between the upper and lower stacked switching transistors and improving the long-term reliability of the product.

[0028] 2. This invention utilizes the existing high-voltage capacitor circuit, saving the original four high-voltage series resistors, thereby simplifying the number of components required for existing stacked circuits, making the circuit simpler and more compact, and improving design reliability; and by using SMD packaged surface mount resistors to replace large-volume TVs high-voltage diodes, the PCB footprint is significantly reduced, while also enabling key advancements in product miniaturization design.

[0029] 3. The rectifier and filter circuit of this invention has wide voltage compatibility. Its full-bridge rectifier structure supports a wide input range of equivalent single-phase AC voltage of 49~480Vac or equivalent DC voltage of 70~690Vdc after rectification. It also suppresses surge current through current-limiting resistors to prevent grid fluctuations from damaging downstream circuits. In addition, the LC filter network can attenuate high-frequency switching noise, meet electromagnetic compatibility standards, and reduce external interference. Furthermore, the full-bridge high-voltage rectifier circuit is low-cost and high-voltage, achieving a withstand voltage of 3200V through a bridge stack of 16 high-voltage diodes. Each diode only needs a withstand voltage of 200V, which significantly reduces the cost compared to dedicated high-voltage rectifier modules.

[0030] 4. This invention achieves peak voltage suppression through a leakage inductance absorption circuit. It uses a fast recovery diode to quickly conduct leakage inductance energy, and an RC network to limit the drain peak of the switching transistor to within the withstand voltage value. At the same time, the absorbed energy is converted into heat energy through a bleed resistor, which reduces the temperature rise of the high-voltage switching transistor and thus reduces heat loss, thereby improving the stability of the circuit.

[0031] 5. This invention uses a feedback reference chip designed with 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. Furthermore, it uses optocouplers to block common-mode interference between the primary and secondary sides, achieving safe isolation between high and low voltage.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0033] Figure 1 These are the electrical parameters of the P6SMB440A / CA device in the prior art of this invention.

[0034] Figure 2 This is a circuit diagram of an embodiment of an ultra-low-cost high-voltage drive circuit according to the present invention.

[0035] Figure 3 This is a circuit schematic diagram of an embodiment of an ultra-low-cost high-voltage drive circuit according to the present invention.

[0036] Figure 4 This is a circuit schematic diagram of an embodiment of an ultra-low cost wide voltage output power supply according to the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] See Figure 2-3This invention provides an ultra-low-cost high-voltage drive circuit, including a rectifier and filter circuit 10, a high-voltage stacking circuit 20, and a switch drive circuit 30. The input terminal of the rectifier and filter circuit 10 is connected to AC power to rectify the AC power into DC power for providing a wide-voltage output power supply operating voltage. The DC power is then filtered and output to the input terminal of the high-voltage stacking circuit 20. The high-voltage stacking circuit 20 includes several high-voltage capacitors and several high-voltage resistors. The high-voltage capacitors are connected in series to form a high-voltage capacitor string, and the output voltage at the midpoint of the high-voltage capacitor string is maintained at half the input voltage of the high-voltage stacking circuit 20 by several high-voltage resistors connected in parallel. The switch drive circuit 30 is connected to the power switch circuit 50 of the wide-voltage output power supply. A connection is provided for the power switching circuit 50 to drive the high-voltage switching transistor V201. It includes several megohm-level resistors and a first capacitor. The megohm-level resistors are connected in series to form a high-resistance string. The midpoint output terminal of the high-voltage capacitor string is connected to the gate of the high-voltage switching transistor V201 through the high-resistance string. The positive terminal of the high-voltage capacitor string is connected to the primary winding of the transformer 40 of the wide-voltage output power supply and to the drain of the high-voltage switching transistor V201 through the primary winding of the transformer 40. The source of the high-voltage switching transistor V201 is connected to the integrated switch drain of the high-voltage power control chip IC200. One end of the first capacitor is connected to the gate of the high-voltage switching transistor V201, and the other end is connected to the common ground of the high-voltage power control chip IC200.

[0040] During the conduction cycle of the high-voltage power control chip IC200, the midpoint output voltage of the high-voltage capacitor string drives the high-voltage switching transistor V201 to conduct through the high-resistance string, and the output voltage of the high-voltage stacking circuit 20 is converted into magnetic energy and stored in the primary winding of the transformer 40. During the shutdown cycle of the high-voltage power control chip IC200, the integrated switch of the high-voltage power control chip IC200 is turned off, opening the source of the high-voltage switching transistor V201. The source voltage of the high-voltage switching transistor V201 rises with the gate voltage to the midpoint output voltage value of the high-voltage capacitor string. The first capacitor is used to limit the voltage of the high-voltage power control chip IC200 to half of the input voltage of the high-voltage stacking circuit 20. The energy stored in the primary winding is released to the secondary output through the transformer 40.

[0041] Specifically, this embodiment utilizes the existing high-voltage stacked capacitors and their voltage equalization circuit to replace the voltage regulation function of the TVS transistor, and replaces the traditional expensive TVS high-voltage high-power Zener diode with a high-resistance resistor to drive the stacked high-voltage switching transistor V201. Thus, when the high-voltage power control chip IC200 is in its conduction cycle, the source potential P21 of the high-voltage switching transistor V201 is forcibly pulled close to the reference ground. The voltage at the center point of P2, through the series connection of the megohm-level resistors R215 and R216, affects the voltage of the high-voltage switching transistor V201. The gate of V201 is charged by capacitor C213, thereby forming a gate-to-source turn-on voltage, which turns on the high-voltage switch V201. At this time, the gate potential P16 of the high-voltage switch V201 is about 15V under the voltage regulation protection of the Zener diode D214. Since the high-voltage switch V201 is in the conducting state, its drain voltage P13 is close to the reference ground. At this time, the input voltage is completely borne by the primary winding of transformer 40, and the electrical energy is converted into magnetic energy and stored in the inductance of the primary winding.

[0042] Next, the high-voltage power control chip IC200 enters the shutdown cycle. At this time, the integrated switch of the high-voltage power control chip IC200 is turned off, the source of the high-voltage switching transistor V201 is open, and its source voltage is reverse-conducted with the gate through the voltage regulation protection of the Zener diode D214. Therefore, the source potential P21 will quickly rise with the gate potential P17, eventually approaching the neutral point voltage of the equalizing capacitor P2 by 0.5 times the input voltage. That is, the drain voltage of the high-voltage power control chip IC200 is limited to 0.5 times the input voltage. At this time, since the voltage between the gate and source of the high-voltage switching transistor V201 is almost zero, the high-voltage switching transistor V201 is forced to enter and quickly turn off. The primary inductor voltage drops, and the stored energy is released to the secondary output terminal through the transformer 40. The input voltage is almost entirely shared by the drain and source of the high-voltage switching transistor V201 and the high-voltage power control chip IC200 in series. As analyzed above, the drain of the high-voltage power control chip IC200 is limited to half of the input voltage by the voltage-dividing capacitor. Therefore, the upper and lower switching transistors in the off state each share half of the input voltage. If the maximum withstand voltage of this high-voltage power control chip IC200 is 700V, then theoretically, the total peak withstand voltage after stacking the upper and lower transistors is close to 1400V, achieving the voltage withstand enhancement effect of stacked drive switching circuit.

[0043] In this embodiment, the rectifier-filter circuit 10 includes a full-bridge high-voltage rectifier circuit 11 and an LC filter circuit 12. The multiple input terminals of the full-bridge high-voltage rectifier circuit 11 are respectively connected to each phase of the AC power through a current-limiting resistor, and the AC power is rectified into high-voltage DC power 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 terminal of the full-bridge high-voltage rectifier circuit 11, and provides EMC / EMI inductor filtering protection by connecting multiple filter inductors in series.

[0044] In this embodiment, the full-bridge high-voltage rectifier circuit 11 includes 16 high-voltage diodes, which are connected in a bridge structure to form a full-wave rectifier circuit with a withstand voltage of 3200V.

[0045] The bridge structure includes a positive terminal connected group and a negative terminal connected group. Both the positive terminal connected group and the negative terminal connected group include four sets of two high-voltage diodes connected in series. The positive terminal connected group connects the positive terminal of each high-voltage diode to the AC power, and its negative terminal is connected in parallel as the first output terminal of the full-bridge high-voltage rectifier circuit 11. The negative terminal connected group connects the negative terminal of each high-voltage diode to the AC power, and its positive terminal is connected in parallel as the second output terminal of the full-bridge high-voltage rectifier circuit 11.

[0046] In this embodiment, one end of the filter inductor is connected to the first output terminal of the full-bridge high-voltage rectifier circuit 11, and the other end is connected to the second output terminal of the full-bridge high-voltage rectifier circuit 11; the plurality of filter inductors include two differential-mode inductors and one common-mode inductor, the first output terminal and the second output terminal of the full-bridge high-voltage rectifier circuit 11 are respectively connected to the input terminal of the common-mode inductor through one of the differential-mode inductors, and the output terminal of the common-mode inductor is connected in series and parallel with the high-voltage capacitor.

[0047] Specifically, this embodiment uses a differential-mode inductor to suppress noise frequency, uses the inductor's inductive reactance to block high-frequency noise, and forces the noise current to ground through a parallel capacitor; it also achieves current smoothing, reduces current surges caused by the switching power supply, and reduces conducted interference.

[0048] Specifically, in this embodiment, the common-mode inductor uses a common-mode choke structure to suppress common-mode noise.

[0049] In this embodiment, the high-voltage stacking circuit 20 uses two 400V electrolytic capacitors, and the upper and lower electrolytic capacitors are stacked in series to form a high-voltage capacitor string with an equivalent total withstand voltage of 800V.

[0050] The high-voltage stacking circuit 20 uses four SMD packaged 390Kohm high-voltage resistors, each with a withstand voltage of 200V. Every two high-voltage resistors are connected in series and then connected in parallel across the upper and lower electrolytic capacitors, so that the voltage of the upper and lower stacked circuits of the high-voltage capacitor series is equal.

[0051] Specifically, the high-voltage stacked circuit 20 structure in this embodiment halves the voltage stress. Two 400V electrolytic capacitors connected in series have an equivalent withstand voltage of 800V. Combined with a parallel high-voltage resistor, the midpoint voltage is forced to be 50% of the input voltage, reducing the voltage across the subsequent switching transistor by 50%. Furthermore, a resistor voltage equalization network is formed by the parallel high-voltage resistor, enabling the circuit to have dynamic balance capabilities. The resistor voltage equalization network can suppress voltage deviation caused by capacitor tolerance, ensuring that the voltage difference between the stacked capacitors is less than 5%, thus improving system reliability.

[0052] In this embodiment, the switch driving circuit 30 uses two SMD packaged 1Mohm megohm resistors. The megohm resistors have a withstand voltage of 200V, and the two megohm resistors are connected in series to form a 2Mohm high resistance string.

[0053] 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 from damaging the high-voltage power supply control chip IC200. Furthermore, the first capacitor clamps the source voltage when the high-voltage switch V201 is turned off, ensuring that the high-voltage power supply control chip IC200 only withstands 50% of the input voltage, thus extending the device's lifespan.

[0054] See Figure 4A low-cost, wide-voltage output power supply includes a high-voltage drive circuit, a transformer 40, a power switch circuit 50, a feedback control circuit 60, and a low-voltage DC output circuit 70. The power switch circuit 50 includes a high-voltage switching transistor V201 and a high-voltage power control chip IC200. One end of the primary winding of the transformer 40 is connected to the positive output terminal of the high-voltage stacked circuit 20, and the other end is connected to the power output terminal of the high-voltage power control chip IC200 via the high-voltage switching transistor V201. The gate of the high-voltage switching transistor V201 is connected to the midpoint output terminal of the high-voltage stacked circuit 20 via a megohm resistor, and its source is connected to the interface of the integrated switch drain in the high-voltage power control chip IC200. This connection is used to activate the high-voltage stacked circuit 20 when the high-voltage power control chip IC200 is in its off cycle. The output voltage of 0 is evenly distributed across the high-voltage switching transistor V201 and the high-voltage power control chip IC200. The total withstand voltage of the power switching circuit 50 is the sum of the withstand voltages of the high-voltage switching transistor V201 and the high-voltage power control chip IC200. The input terminal of the low-voltage DC output circuit 70 is connected to the secondary winding of the transformer 40 to rectify the induced current on the secondary side into pulsating DC power, and outputs low-voltage DC power after ripple suppression. The feedback control circuit 60 is connected to the output terminal of the low-voltage DC output circuit 70 to collect voltage sampling signals and feed back the voltage feedback signals to the control terminal of the high-voltage power control chip IC200. The high-voltage power control chip IC200 performs real-time control of the power supply based on the voltage feedback signals to ensure the continuity and stability of the power output.

[0055] Specifically, this embodiment adopts a stacked high-voltage switch structure with upper and lower drives, including a high-voltage switch transistor V201 stacked on the upper side and a high-voltage power control chip IC200 stacked on the lower side. By connecting the high-voltage switch transistor V201 and the high-voltage power control chip IC200 in series, dynamic voltage division is achieved, so that the total withstand voltage value is superimposed, reducing the cost of a single device. Furthermore, by efficiently transferring the magnetic energy of the primary winding to the secondary side during the switching cycle, energy efficiency is optimized, thereby improving the efficiency of the entire power supply circuit.

[0056] In this embodiment, a leakage inductance absorption circuit is also included. The leakage inductance absorption circuit includes a fast recovery diode, several bleed resistors, and an absorption capacitor. The primary winding of the transformer 40 and the drain of the high-voltage switching transistor 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. The other end of the absorption capacitor is connected to the positive output terminal of the high-voltage stacking circuit 20. Several bleed resistors connected in series are also connected in parallel to the absorption capacitor.

[0057] Specifically, in this embodiment, the leakage inductance energy is quickly conducted through a fast recovery diode, and the drain peak of the switching transistor is limited to within the withstand voltage value by an RC network. At the same time, the absorbed energy is converted into heat energy through a bleed resistor, which reduces the temperature rise of the high-voltage switching transistor V201 and thus reduces heat loss, thereby improving the stability of the circuit.

[0058] In each switching cycle of the high-voltage power control chip IC200, the leakage inductance absorption circuit dampens and absorbs the high-voltage spikes formed by the leakage inductance of the primary side of the transformer 40, and limits and absorbs the peak voltage of the power switching circuit 50.

[0059] In this embodiment, the feedback control circuit 60 includes a sampling circuit, a reference chip, and an isolation optocoupler. The sampling circuit is used to acquire a sampling voltage signal and output the voltage sampling signal to the reference terminal of the reference chip. The reference chip compares the voltage sampling signal with its reference voltage, outputs the voltage feedback signal, and feeds it back to the control terminal of the high-voltage power control chip IC200 through the isolation optocoupler.

[0060] Specifically, in this embodiment, the sampling circuit uses resistor sampling; the reference chip is a TL431 chip. Resistors R218 and R210 are connected to the output voltage, forming a voltage divider with the lower resistors R291, R277, and R278 for sampling. The sampled voltage is input to the reference pin of IC208, and the feedback signal is transmitted through the power feedback control pin of the optocoupler IC200 to achieve real-time feedback control of the output voltage, ensuring a stable and continuous output voltage.

[0061] Specifically, the low-voltage DC output circuit 70 in this embodiment includes a rectifier diode D210, capacitors C202 and C232. Capacitors C202 and C232 form a diode filter circuit. Capacitor C202 is connected in parallel to the output terminal of 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, periodically outputting primary-side switching energy to capacitors C202 and C232, providing 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 at the output terminal to clamp the voltage to a safe value when abnormal voltage occurs.

[0062] An ultra-low-cost electricity meter includes a wide-voltage output power supply, a microprocessor, an LCD display, a metering circuit, and a communication circuit. The wide-voltage output power supply is used to convert the input voltage range of 49~480Vac equivalent single-phase AC power into voltage, or to convert the rectified voltage range of 70~690Vdc equivalent DC power into voltage, and outputs a low-voltage DC voltage of the corresponding voltage level to the power input terminals of the microprocessor, LCD display, metering circuit, and communication circuit to provide the required operating voltage.

[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.

[0064] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A low-cost high-voltage drive circuit, characterized in that, include: The system includes a rectifier and filter circuit, a high-voltage stacking circuit, and a switch driver circuit. The input of the rectifier and filter circuit is connected to AC power to rectify it into DC power, which is then filtered and output to the input of the high-voltage stacking circuit. The high-voltage stacking circuit includes several high-voltage capacitors and several high-voltage resistors. The high-voltage capacitors are connected in series to form a high-voltage capacitor string, and several high-voltage resistors are connected in parallel to maintain the midpoint output voltage of the high-voltage capacitor string at half the input voltage of the high-voltage stacking circuit. The switch driver circuit provides high-voltage drive for power switching circuits with a stacked design and includes several megohm-level resistors and a first capacitor. The megohm-level resistors are connected in series to form a high-resistance string. The midpoint output terminal of the high-voltage capacitor string is connected to the gate of the high-voltage switching transistor stacked on the power switch circuit through the high-resistance string; the first capacitor is used to limit the voltage withstand value of the high-voltage power control chip stacked under the power switch circuit; during the conduction cycle of the high-voltage power control chip, the midpoint output voltage of the high-voltage capacitor string drives the high-voltage switching transistor to conduct through the high-resistance string, and the output voltage of the high-voltage stack circuit is converted into magnetic energy and stored in the primary winding of the transformer; during the shutdown cycle of the high-voltage power control chip, the source voltage of the high-voltage switching transistor rises to the midpoint output voltage value of the high-voltage capacitor string following the gate voltage, 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 drive circuit according to claim 1, characterized in that: The rectifier and filter circuit includes a full-bridge high-voltage rectifier circuit and an LC filter circuit. The multiple input terminals of the full-bridge high-voltage rectifier circuit are respectively connected to each phase of the AC power through a current-limiting resistor, and the AC power is rectified into high-voltage DC power 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 terminal of the full-bridge high-voltage rectifier circuit, and provides EMC / EMI inductor filtering protection by connecting multiple filter inductors in series.

3. The ultra-low cost high-voltage drive circuit according to claim 2, characterized in that: The full-bridge high-voltage rectifier circuit includes 16 high-voltage diodes, which are connected in a bridge structure to form a full-wave rectifier circuit with a withstand voltage of 3200V. The bridge structure includes a positive terminal connected group and a negative terminal connected group. Both the positive terminal connected group and the negative terminal connected group include four sets of two high-voltage diodes connected in series. The positive terminal connected group connects the positive terminal of each high-voltage diode to the AC power, and its negative terminal is connected in parallel as the first output terminal of the full-bridge high-voltage rectifier circuit. The negative terminal connected group connects the negative terminal of each high-voltage diode to the AC power, and its positive terminal is connected in parallel as the second output terminal of the full-bridge high-voltage rectifier circuit.

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

5. The ultra-low cost high-voltage drive circuit according to claim 1, characterized in that: The high-voltage stacking circuit uses two 400V electrolytic capacitors, and the upper and lower electrolytic capacitors are stacked in series to form a high-voltage capacitor string with an equivalent total withstand voltage of 800V. The high-voltage stacking circuit uses four 390Kohm high-voltage resistors in SMD packages, each with a withstand voltage of 200V. Every two high-voltage resistors are connected in series and then connected in parallel across the upper and lower electrolytic capacitors, so that the voltage of the upper and lower stacked circuits of the high-voltage capacitor series is equal.

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

7. A low-cost, wide-voltage output power supply, characterized in that, include: The high-voltage drive circuit, multi-winding transformer, power switching circuit, feedback control circuit, and low-voltage DC output circuit as described in any one of claims 1-6, wherein the power switching circuit includes a high-voltage switching transistor and a high-voltage power control chip, one end of the primary winding of the multi-winding transformer is connected to the positive output terminal of the high-voltage stacking circuit, and the other end is connected to the power output terminal of the high-voltage power control chip through the high-voltage switching transistor; the gate of the high-voltage switching transistor is connected to the midpoint output terminal of the high-voltage stacking circuit through a megohm resistor, and its source is connected to the interface of the integrated switch drain in the high-voltage power control chip, for distributing the output voltage of the high-voltage stacking circuit evenly to the power output of the high-voltage power control chip during the off cycle of the high-voltage power control chip. The high-voltage switching transistor and the high-voltage power control chip are subjected to voltage; the total withstand voltage of the power switching circuit is the sum of the withstand voltages of the high-voltage switching transistor and the high-voltage power control chip; the input terminal of the low-voltage DC output circuit is connected to the secondary winding of the multi-winding transformer, used to rectify the induced current on the secondary side into pulsating DC current, and output low-voltage DC current after ripple suppression of the pulsating DC current; the feedback control circuit is connected to the output terminal of the low-voltage DC output circuit, used to collect voltage sampling signals and feed back the voltage feedback signals to the control terminal of the high-voltage power control chip, and the high-voltage power control chip performs real-time control of the power supply according to the voltage feedback signals to ensure the continuity and stability of the power output.

8. The ultra-low cost wide voltage output power supply according to claim 7, characterized in that: It also includes a leakage inductance absorption circuit, which includes a fast recovery diode, several bleed resistors and an absorption capacitor. The primary winding of the transformer and the drain of the high-voltage switching transistor 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 terminal of the high-voltage stacking circuit. The absorption capacitor is also connected in parallel with several bleed resistors connected in series. In each switching cycle of the high-voltage power control chip, the leakage inductance absorption circuit dampens and absorbs the high-voltage spike energy formed by the leakage inductance of the primary side of the transformer, and limits and absorbs the peak voltage of the power switching 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 chip, and an isolation optocoupler. The sampling circuit is used to acquire the sampling voltage signal and output the voltage sampling signal to the reference terminal of the reference chip. The reference chip compares the voltage sampling signal with its reference voltage, outputs the voltage feedback signal, and feeds it back to the control terminal of the high-voltage power supply control chip through the isolation optocoupler.

10. An ultra-low cost electricity meter, characterized in that, include: The wide-voltage output power supply, microprocessor, liquid crystal display, metering circuit, and communication circuit as described in any one of claims 7-9, wherein the wide-voltage output power supply is used to perform voltage conversion on the equivalent single-phase AC power with an input voltage range of 49~480Vac, or to perform voltage conversion on the equivalent DC power with a rectified voltage range of 70~690Vdc, and outputs 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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