Isolation high-voltage power supply circuit
Through the separated rectifying filter circuit and conversion and discharge control circuit, combined with the LT8304-1 converter and field effect tube, the load capacity and large volume of the high-voltage isolation power supply circuit are solved, and efficient and safe high-voltage discharge protection is achieved, and the power conversion efficiency and accuracy are improved.
Patent Information
- Application Number
- CN202422515522.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-17
- Publication Date
- 2025-08-15
- Estimated Expiration
- 2034-10-17
AI Technical Summary
The load current capacity of existing high-voltage isolation power supply circuits is insufficient, the product is large in size, low in efficiency, and lacks safe high-voltage discharge protection.
The separation rectifying filter circuit and the conversion and discharge control circuit are adopted, and the LT8304-1 isolated optical flyback converter is used for high-voltage conversion and output voltage detection, and high-voltage discharge is realized through the field effect tube, and a safe and high-voltage discharge is combined with the switch control circuit and the isolation auxiliary power supply circuit for safe and high-speed high-voltage discharge.
Improves the load capacity and conversion efficiency of the power supply, reduces product volume, and provides safe high-voltage discharge protection, achieving output voltage accuracy of 2% to 3% and ultra-high conversion efficiency of 90.5%.
Smart Images
Figure CN223231078U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of electronic circuits, in particular to an isolated high-voltage power supply circuit. Background Art
[0002] There are various implementation methods for high-voltage isolated power supplies, and the flyback topology is widely used in high-voltage, low-power applications. The commonly used flyback topology in the market converts the output high voltage through voltage doubling rectification technology. At the output, a voltage-divider resistor network, along with a shunt voltage regulator and an optocoupler, is used for output voltage detection and isolated feedback to achieve output voltage control. However, the use of voltage-doubling rectification technology limits the output load current capability and requires rectifier diodes and filter capacitors with higher voltage ratings. The use of a voltage-divider resistor network, a shunt voltage regulator, and an optocoupler for output voltage detection and isolated feedback requires multiple large-package resistors (the voltage rating of a single resistor is limited by the corresponding package size) to form the voltage-divider network, which increases the product size. Furthermore, the overall efficiency of this power supply circuit is low, typically between 50% and 80%. Utility Model Content
[0003] The purpose of the utility model is to provide an isolated high-voltage power supply circuit which effectively improves the load capacity and conversion efficiency of the power supply while reducing the product volume and has a safe and high-speed high-voltage discharge protection function.
[0004] The utility model is achieved in this way:
[0005] An isolated high-voltage power supply circuit includes a conversion detection circuit for high-voltage conversion and output voltage detection, wherein the output end of the conversion detection circuit is electrically connected to a separate rectifier and filter circuit for rectification and filtering, the separate rectifier and filter circuit is connected in parallel with a high-voltage discharge circuit, and the control end of the high-voltage discharge circuit is electrically connected to a conversion discharge control circuit for isolation control, one control end of the conversion discharge control circuit is connected to the high-voltage discharge circuit, and the other control end is connected to the conversion detection circuit.
[0006] Furthermore, the conversion detection circuit includes a conversion chip for high-voltage conversion, the detection end of the conversion chip is connected in series with a detection resistor, the other end of the detection resistor is connected to the voltage output end of the conversion chip, the voltage output end of the conversion chip is electrically connected to the multiple separation rectification and filtering circuits, and the control end of the conversion chip is connected to a control end of the conversion discharge control circuit.
[0007] Furthermore, the conversion chip adopts an isolated lightless flyback converter model LT8304-1.
[0008] Furthermore, the separate rectifier and filter circuit includes a transformer whose primary end is connected to the output end of the conversion detection circuit, and the secondary end of the transformer is a plurality of separate output winding units, and the plurality of separate output winding units are connected in series, and any one of the separate output winding units includes a secondary winding and a high-voltage output diode and a high-voltage output capacitor connected in series with the secondary winding.
[0009] Furthermore, the high-voltage discharge circuit includes a field effect transistor whose gate is connected to the conversion and discharge control circuit, and the source of the field effect transistor is connected in series with a discharge resistor and then connected in parallel with the separate rectifier and filter circuit.
[0010] Furthermore, the conversion and discharge control circuit includes a first switch control circuit for controlling the conversion of the conversion detection circuit, a second switch control circuit for controlling the discharge of the high-voltage discharge circuit, and an isolated auxiliary power supply circuit for powering the second switch control circuit. The control input end of the first switch control circuit is connected to the control input end of the second switch control circuit, the control output end of the first switch control circuit is connected to the conversion detection circuit, the control output end of the second switch control circuit is connected to the high-voltage discharge circuit, and the isolated auxiliary power supply circuit is respectively connected to the high-voltage power supply end of the conversion detection circuit and the second switch control circuit.
[0011] Furthermore, the first switch control circuit includes a first transistor whose base is electrically connected to the control input terminal, whose collector is electrically connected to the control terminal of the conversion detection circuit, and whose emitter is grounded.
[0012] Furthermore, the second switch control circuit includes a second transistor whose base is electrically connected to the control input terminal, the collector of the second transistor is connected to an input terminal of the optocoupler chip, the emitter of the second transistor is connected to the ground, and the two output terminals of the optocoupler chip are respectively connected to the isolated auxiliary power supply circuit and the high-voltage discharge circuit.
[0013] Furthermore, the isolated auxiliary power supply circuit includes a charging resistor, a rectifier diode and an energy storage capacitor connected in series at the output end of the conversion detection circuit, the anode of the rectifier diode is connected to the charging resistor, and the cathode of the rectifier diode is respectively connected to one end of the energy storage capacitor and the high-voltage power supply end of the second switch control circuit.
[0014] Compared with the prior art, the beneficial effects of the present invention are:
[0015] In practical applications, the output voltage detection is realized by detecting the primary side waveform through the conversion detection circuit. The separate rectifier filter circuit includes multiple separate winding rectifier filter units connected in series. The separate rectifier filter circuit is used to output high voltage after rectification, which is conducive to obtaining more optional output diodes and output capacitors. At the same time, it also avoids the problem of insufficient load capacity caused by voltage doubling rectification, and effectively improves the conversion efficiency; the conversion detection circuit and the high-voltage discharge circuit are controlled separately by the conversion discharge control circuit to realize the integration of primary side isolation control high-voltage fast discharge function, which can completely isolate the control signal and high-voltage output, realize safe and high-speed high-voltage discharge, and effectively ensure the safety of the devices at the load end; this application effectively improves the load capacity and conversion efficiency of the power supply, while reducing the product volume, and has a safe and high-speed high-voltage discharge protection function. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.
[0017] Figure 1 This is a circuit structure diagram of the utility model;
[0018] Figure 2 It is a circuit principle diagram of the utility model;
[0019] Figure 3 This is a load regulation performance curve diagram of the circuit of the utility model under different input voltages;
[0020] Figure 4 This is an efficiency curve diagram of the circuit of the utility model under different input voltages;
[0021] Figure 5 This is a load voltage discharge curve diagram corresponding to different resistance values of the discharge resistors of the circuit of the utility model. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the utility model for which protection is sought, but merely represents the selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0023] See also Figure 1 , an isolated high-voltage power supply circuit, including a conversion detection circuit for high-voltage conversion and output voltage detection, the output end of the conversion detection circuit is electrically connected to a separate rectifier and filter circuit for rectification and filtering, the separate rectifier and filter circuit is connected in parallel with a high-voltage discharge circuit, the control end of the high-voltage discharge circuit is electrically connected to a conversion discharge control circuit for isolation control, one control end of the conversion discharge control circuit is connected to the high-voltage discharge circuit, and the other control end is connected to the conversion detection circuit.
[0024] In practical applications, the output voltage detection is realized by detecting the primary side waveform through the conversion detection circuit. The separate rectifier filter circuit includes multiple separate winding rectifier filter units connected in series. The separate rectifier filter circuit is used to output high voltage after rectification, which is conducive to obtaining more optional output diodes and output capacitors. At the same time, it also avoids the problem of insufficient load capacity caused by voltage doubling rectification, and effectively improves the conversion efficiency; the conversion detection circuit and the high-voltage discharge circuit are controlled separately by the conversion discharge control circuit to realize the integration of primary side isolation control high-voltage fast discharge function, which can completely isolate the control signal and high-voltage output, realize safe and high-speed high-voltage discharge, and effectively ensure the safety of the devices at the load end; this application effectively improves the load capacity and conversion efficiency of the power supply, while reducing the product volume, and has a safe and high-speed high-voltage discharge protection function.
[0025] See also Figure 1 and Figure 2 The conversion detection circuit includes a conversion chip for high-voltage conversion, a detection resistor is connected in series to the detection end of the conversion chip, the other end of the detection resistor is connected to the voltage output end of the conversion chip, the voltage output end of the conversion chip is electrically connected to the multiple separation rectification and filtering circuits, and the control end of the conversion chip is connected to a control end of the conversion discharge control circuit.
[0026] In this embodiment, the input voltage is converted to high voltage by a converter chip. The output voltage is detected by detecting the voltage change of the detection resistor caused by the change in the voltage output terminal of the converter chip. The converter chip controls the conversion through the conversion discharge control circuit. Traditionally, the regulation feedback loop requires a bulky high-voltage divider to directly detect the high output voltage. Because 1206 resistors can only handle 200V at most, to detect 1000V, at least six 1206 resistors are required, plus a small bottom resistor. At the same time, an optocoupler is required to transmit the feedback information back through the isolation barrier. Figure 3 Without using an output voltage divider resistor network, a parallel voltage regulator, or an optocoupler, this application can achieve an output voltage accuracy of 2% to 3% over the full input voltage range and full load range. It can detect the output voltage through the primary-side waveform, thereby eliminating the need for adding a bulky high voltage divider and eliminating the need for an optocoupler, effectively reducing the product size.
[0027] See also Figure 2 The conversion chip adopts the isolated lightless flyback converter model LT8304-1.
[0028] In this embodiment, the FRB terminal of the isolated light-free flyback converter, model LT8304-1, serves as a detection terminal, and the SW terminal serves as a voltage output terminal. Detection resistors R9 and R10 are connected in series between the FRB terminal and the SW terminal. Output voltage detection is achieved by detecting voltage changes across detection resistors R9 and R10 caused by waveform changes output from the SW terminal. The isolated light-free flyback converter, model LT8304-1, features a small number of components and can support a 15mA load. Its output current capability increases with increasing input voltage, reaching 13mA when the input voltage is greater than 24V. The LT8304-1 can detect the output voltage by detecting the waveform on the primary side of a transformer connected to the output terminal, thereby eliminating the need for a bulky high voltage divider and eliminating the need for an optocoupler.
[0029] See also Figure 2 The separate rectifier and filter circuit includes a transformer whose primary end is connected to the output end of the conversion detection circuit, and the secondary end of the transformer is a plurality of separate output winding units. The plurality of separate output winding units are connected in series, and any of the separate output winding units includes a secondary winding and a high-voltage output diode and a high-voltage output capacitor connected in series with the secondary winding.
[0030] In this embodiment, three separate rectifier and filter units are connected in series to output high voltage. The 1000V output solution uses a transformer with three separate output windings on the secondary side. The transformer has a primary-to-secondary turns ratio of 1:10:10:10, rather than a single secondary winding with a 1:30 turns ratio. The 1:10:10:10 transformer allows the output voltage stress to be shared among three high-voltage output diodes and three high-voltage output capacitors. The voltage rating of each component only needs to be 1 / 3 of the total voltage, which facilitates a wider selection of output diodes and output capacitors. At the same time, the load current capability of the high-voltage output is also improved in this form. Figure 4 The conversion efficiency of this circuit is generally high within the full input voltage and full load range. At 0.5mA load, the efficiency has reached more than 65%, and the highest conversion efficiency can reach 90.5%.
[0031] See also Figure 2 The high-voltage discharge circuit includes a field-effect transistor whose gate is connected to the conversion and discharge control circuit, and whose source is connected in series with a discharge resistor and then in parallel with the separate rectifier and filter circuit.
[0032] In this embodiment, when the conversion discharge control circuit outputs a high level to the gate of the field effect tube, the field effect tube is turned on, and the discharge resistor releases the high voltage energy stored in the separate rectifier filter circuit and the load end capacitor in time, forming a protection function for the load end circuit; by selecting a suitable switch MOS and discharge resistor, a high voltage discharge time of microseconds can be achieved. For the high voltage discharge curve of this design, please refer to Figure 5 .
[0033] See also Figure 1 and Figure 2 The conversion and discharge control circuit includes a first switch control circuit for controlling the conversion of the conversion detection circuit, a second switch control circuit for controlling the discharge of the high-voltage discharge circuit, and an isolated auxiliary power supply circuit for supplying power to the second switch control circuit. The control input end of the first switch control circuit is connected to the control input end of the second switch control circuit, the control output end of the first switch control circuit is connected to the conversion detection circuit, and the control output end of the second switch control circuit is connected to the high-voltage discharge circuit. The isolated auxiliary power supply circuit is respectively connected to the high-voltage power supply ends of the conversion detection circuit and the second switch control circuit.
[0034] In this embodiment, when the system is used, when the system detects a fault at the high-voltage output load end or receives a related instruction to shut down the high-voltage output, a high level is applied to the common control input end of the first switch control circuit and the second switch control circuit to control the shutdown conversion detection circuit to switch, and at the same time, the high-voltage discharge circuit is controlled to release the high-voltage electrical energy stored in the output high-voltage filter capacitor and the load-end capacitor through the discharge circuit in a timely manner, thereby forming a protection function for the load-end circuit, and the isolated auxiliary power supply circuit provides the high-voltage end of the second switch control circuit with the voltage required for controlling the shutdown.
[0035] See also Figure 2 The first switch control circuit includes a first transistor whose base is electrically connected to the control input terminal, the collector of the first transistor is electrically connected to the control terminal of the conversion detection circuit, and the emitter of the first transistor is grounded.
[0036] In this embodiment, the CTRL terminal is a control input terminal. When the CTRL terminal applies a high level to the base of the first transistor, the first transistor is turned on, and the control terminal voltage of the conversion detection circuit is pulled low, thereby shutting down the conversion.
[0037] See also Figure 2 The second switch control circuit includes a second transistor whose base is electrically connected to the control input terminal, the collector of the second transistor is connected to an input terminal of the optocoupler chip, the emitter of the second transistor is connected to the ground, and the two output terminals of the optocoupler chip are respectively connected to the isolated auxiliary power supply circuit and the high-voltage discharge circuit.
[0038] In this embodiment, the CTRL terminal is a control input terminal. When the CTRL terminal applies a high level to the base of the second transistor, the second transistor is turned on, driving the optocoupler chip to turn on. The isolated auxiliary power supply circuit and the high-voltage discharge circuit are connected in series through the optocoupler chip. The high-voltage discharge circuit is driven by the isolated auxiliary power supply circuit to release high voltage in time to protect the system.
[0039] See also Figure 2 The isolated auxiliary power supply circuit includes a charging resistor, a rectifier diode and an energy storage capacitor connected in series at the output end of the conversion detection circuit. The anode of the rectifier diode is connected to the charging resistor, and the cathode of the rectifier diode is respectively connected to one end of the energy storage capacitor and the high-voltage power supply end of the second switch control circuit.
[0040] In this embodiment, the cathode of the rectifier diode is the voltage output end of the isolated auxiliary power supply circuit. During normal operation of the system, the rectifier diode is turned on, and the energy storage capacitor is charged and stored through the charging resistor. When the CTRL end is at a high level, the first switch control circuit controls the conversion detection circuit to turn off, the rectifier diode is cut off, and the energy storage capacitor is discharged. Under the control of the second switch control circuit, the high-voltage discharge circuit is driven to discharge the high voltage.
[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.
Claims
1. An isolated high-voltage power supply circuit, characterized in that: It includes a conversion detection circuit for high-voltage conversion and output voltage detection, the output end of the conversion detection circuit is electrically connected to a separate rectifier and filter circuit for rectification and filtering, the separate rectifier and filter circuit is connected in parallel with a high-voltage discharge circuit, the control end of the high-voltage discharge circuit is electrically connected to a conversion discharge control circuit for isolation control, one control end of the conversion discharge control circuit is connected to the high-voltage discharge circuit, and the other control end is connected to the conversion detection circuit.
2. The isolated high-voltage power supply circuit according to claim 1, characterized in that: The conversion detection circuit includes a conversion chip for high-voltage conversion, a detection resistor is connected in series to the detection end of the conversion chip, the other end of the detection resistor is connected to the voltage output end of the conversion chip, the voltage output end of the conversion chip is electrically connected to the multiple separate rectifier and filter circuits, and the control end of the conversion chip is connected to a control end of the conversion discharge control circuit.
3. The isolated high-voltage power supply circuit according to claim 2, characterized in that: The conversion chip adopts an isolated lightless flyback converter model LT8304-1.
4. The isolated high-voltage power supply circuit according to claim 1, characterized in that: The separate rectifier and filter circuit includes a transformer whose primary end is connected to the output end of the conversion detection circuit, and the secondary end of the transformer is a plurality of separate output winding units. The plurality of separate output winding units are connected in series, and any one of the separate output winding units includes a secondary winding and a high-voltage output diode and a high-voltage output capacitor connected in series with the secondary winding.
5. The isolated high-voltage power supply circuit according to claim 1, characterized in that: The high-voltage discharge circuit includes a field effect tube whose gate is connected to the conversion and discharge control circuit, and the source of the field effect tube is connected in series with a discharge resistor and then connected in parallel with the separate rectifier and filter circuit.
6. The isolated high-voltage power supply circuit according to claim 1, characterized in that: The conversion and discharge control circuit includes a first switch control circuit for controlling the conversion of the conversion detection circuit, a second switch control circuit for controlling the discharge of the high-voltage discharge circuit, and an isolated auxiliary power supply circuit for powering the second switch control circuit. The control input end of the first switch control circuit is connected to the control input end of the second switch control circuit, the control output end of the first switch control circuit is connected to the conversion detection circuit, the control output end of the second switch control circuit is connected to the high-voltage discharge circuit, and the isolated auxiliary power supply circuit is respectively connected to the high-voltage power supply end of the conversion detection circuit and the second switch control circuit.
7. The isolated high-voltage power supply circuit according to claim 6, characterized in that: The first switch control circuit includes a first transistor whose base is electrically connected to the control input terminal, a collector of the first transistor is electrically connected to the control terminal of the conversion detection circuit, and an emitter of the first transistor is grounded.
8. The isolated high-voltage power supply circuit according to claim 6, characterized in that: The second switch control circuit includes a second transistor whose base is electrically connected to the control input terminal, the collector of the second transistor is connected to an input terminal of the optocoupler chip, the emitter of the second transistor is connected to the ground, and the two output terminals of the optocoupler chip are respectively connected to the isolated auxiliary power supply circuit and the high-voltage discharge circuit.
9. The isolated high-voltage power supply circuit according to claim 6, characterized in that: The isolated auxiliary power supply circuit includes a charging resistor, a rectifier diode and an energy storage capacitor connected in series at the input end of the separate rectifier and filter circuit, the anode of the rectifier diode is connected to the charging resistor, and the cathode of the rectifier diode is respectively connected to one end of the energy storage capacitor and the high-voltage power supply end of the second switch control circuit.