Direct current circuit with transformer isolation
By using technical means such as transformer isolation and full-bridge chopping units in DC circuits, the problem that existing isolation circuits are difficult to achieve efficient electrical isolation and flexible output adjustment in high-power applications is solved, and the safety and efficient power processing of high-voltage and high-power systems are achieved.
Patent Information
- Application Number
- CN202421183063.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-28
- Publication Date
- 2025-03-11
- Estimated Expiration
- 2034-05-28
AI Technical Summary
Existing isolation circuits are difficult to meet the needs of efficient electrical isolation, power processing and output regulation in high-power applications, and lack flexibility and adaptability.
The DC circuit with transformer isolation is adopted, including a full-bridge chopping unit, a transformer, a rectifier unit and a voltage regulation output unit, is electrically isolated through the transformer, and the power processing capability and output regulation flexibility are improved through the full-bridge chopping unit and a voltage regulation output unit.
It realizes the safety and reliability of high-voltage and high-power systems, expands the scope of application of the circuit, improves power processing capabilities and conversion efficiency, and has flexible output regulation capabilities.
Smart Images
Figure CN222602278U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of power electronics, in particular to a direct current circuit with transformer isolation. Background Art
[0002] In the field of power electronics, electrical isolation is usually required between the DC power supply and the load to meet safety and reliability requirements. The isolation circuit can prevent direct electrical connection between the DC power supply and the load while achieving energy transmission.
[0003] However, existing isolation circuit technology has some shortcomings. First, traditional isolation circuits are mostly only suitable for low-power applications and cannot meet the growing demand for high-power applications. In high-power applications, isolation circuits not only need to reliably achieve electrical isolation, but also need to have high power handling capabilities and conversion efficiency, and existing isolation circuits often fail in this regard.
[0004] Secondly, existing isolation circuits usually lack sufficient flexibility and adaptability. They cannot flexibly adjust the output voltage and current range of the subsequent stage according to actual needs, and can only adapt to the full power output of a small range of loads. This limits the applicability of isolation circuits and cannot meet diverse application needs.
[0005] In addition, although many isolation circuits have achieved electrical isolation, they do not effectively regulate and control the output voltage and current, resulting in unstable and inaccurate output. In some occasions where high power quality requirements are required, this may affect the normal operation of the load equipment.
[0006] In view of the above problems, a new type of isolation circuit technology is urgently needed, which can meet the needs of high-power applications while achieving reliable electrical isolation, and improve power handling capacity and conversion efficiency. At the same time, the new isolation circuit should also have a wide range of applicability and flexible output adjustment capabilities to adapt to different load requirements and application scenarios. Utility Model Content
[0007] The purpose of the utility model is to provide a DC circuit with transformer isolation to solve the above problems existing in the prior art.
[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0009] A DC circuit with transformer isolation comprises a full-bridge chopper unit, a transformer, a rectifier unit and a voltage regulating output unit; the output end of the full-bridge chopper unit is connected to the primary of the transformer, and the input end of the full-bridge chopper unit is connected to the DC voltage; the secondary of the transformer is connected to the input end of the rectifier unit, the output end of the rectifier unit is connected to the input end of the voltage regulating output unit, and the output end of the voltage regulating output unit is used to connect a load.
[0010] Preferably, the secondary turns of the transformer are adjustable.
[0011] Preferably, the full-bridge chopper unit includes a first capacitor, a first MOS transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor, the drain of the first MOS transistor and the source of the third MOS transistor are respectively connected to the two ends of the first capacitor, the two ends of the capacitor are also connected to a DC voltage input, the source of the first MOS transistor is connected to the drain of the third MOS transistor; the drain of the second MOS transistor is connected to the drain of the first MOS transistor, the source of the second MOS transistor is connected to the drain of the fourth MOS transistor, and the source of the fourth MOS transistor is connected to the source of the third MOS transistor.
[0012] Preferably, one end of the primary of the transformer is connected between the source of the first MOS transistor and the drain of the third MOS transistor, and the other end of the primary of the transformer is connected between the source of the second MOS transistor and the drain of the fourth MOS transistor.
[0013] Preferably, the full-bridge chopper unit also includes four first driving modules, the first driving module includes a first diode, a second diode and a first resistor; the cathode of the first diode is connected to the cathode of the second diode, and the anode of the first diode and the anode of the second diode are connected to the two ends of the first resistor; the four first driving modules correspond to the first MOS transistor, the second MOS transistor, the third MOS transistor and the fourth MOS transistor, respectively, and the two ends of the first resistor in each first driving module are respectively connected to the gate and source of the corresponding MOS transistor.
[0014] Preferably, the rectifier unit includes a third diode, a fourth diode, a fifth diode, and a sixth diode, wherein the cathode of the third diode is connected to the cathode of the fourth diode, the anode of the fifth diode is connected to the anode of the sixth diode, the anode of the third diode is connected to the cathode of the fifth diode, and the anode of the fourth diode is connected to the cathode of the sixth diode. The cathode of the third diode is connected to the cathode of the fourth diode as the first output terminal of the rectifier unit; the anode of the fifth diode is connected to the anode of the sixth diode as the second output terminal of the rectifier unit.
[0015] Preferably, the rectifier unit also includes a filtering module, which includes a second capacitor and a second resistor; one end of the second capacitor is connected to the second resistor, and the other end is connected to the anode of the fourth diode and the cathode of the sixth diode, and the other end of the second resistor is connected to the anode of the third diode and the cathode of the fourth diode.
[0016] Preferably, the voltage regulating output unit includes a third capacitor, a fourth capacitor, a fifth MOS transistor, a seventh diode and a first inductor; one end of the third capacitor is connected to the drain of the fifth MOS transistor and the other end is connected to the anode of the seventh diode, the source of the fifth MOS transistor is connected to the cathode of the seventh diode and one end of the first inductor, the anode of the seventh diode is connected to one end of the fourth capacitor, and the other end of the first inductor is connected to the other end of the fourth capacitor; both ends of the fourth capacitor are also connected to the load.
[0017] Preferably, the voltage regulating output unit also includes a second driving module, which includes an eighth diode, a ninth diode and a third resistor; the cathode of the eighth diode is connected to the cathode of the ninth diode, the anode of the eighth diode and the anode of the ninth diode are connected to the two ends of the third resistor, and the two ends of the third resistor are also respectively connected to the gate and source of the fifth MOS transistor.
[0018] The utility model has the following beneficial effects:
[0019] The use of transformers for electrical isolation improves the safety and reliability of high-voltage and high-power systems. The number of turns of the transformer secondary is adjustable, which expands the scope of application of the circuit and can adapt to different high-power output voltage requirements. The introduction of the full-bridge chopper unit improves the utilization rate of the DC voltage and is suitable for high-voltage and high-power applications. The design of the rectifier unit and the voltage regulation output unit simplifies the circuit structure and improves the efficiency. The use of high-voltage and high-power devices meets the needs of high-voltage and high-power applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a schematic diagram of a circuit structure of a DC circuit with transformer isolation in one embodiment of the utility model;
[0021] Figure 2 This is a schematic diagram of the structure of a transformer T1 in an embodiment of the utility model;
[0022] Figure 3 1 is a schematic diagram of the circuit structure of a full-bridge chopper unit in one embodiment of the utility model;
[0023] Figure 4 It is a schematic diagram of the circuit structure of a rectifier unit and a voltage regulating output unit in one embodiment of the utility model;
[0024] Figure 5 It is a schematic diagram of the output waveform of the full-bridge chopper unit in one embodiment of the utility model. DETAILED DESCRIPTION
[0025] The utility model is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that these embodiments are only used to explain the technical principles of the utility model and cannot be understood as limitations on the claims of the utility model. Those skilled in the art can make various modifications or variations to the utility model based on the inspiration of these embodiments, and these modifications and deformations still belong to the protection scope of the utility model. In the following description, in order to better understand the utility model, a preferred implementation will be described in detail. However, the protection scope of the utility model is not limited to this, and any technician familiar with the technical field can modify or replace the enlightenment of the preferred implementation without departing from the scope of the technical solution of the utility model, and these modifications and replacements should also fall within the protection scope of the utility model. At the same time, the circuit structure and components involved in the embodiments of the utility model are not limited to those described in the text, and ordinary technicians in the field can make appropriate selections and adjustments according to actual needs to achieve optimal working performance.
[0026] This embodiment provides a DC circuit with transformer isolation, which is suitable for electrical isolation between a high-voltage and high-power DC power supply and a high-voltage and high-power load. Compared with the traditional low-voltage and low-power isolation circuit, the isolation circuit of this embodiment has a higher voltage withstand level and power handling capability, and can meet the needs of high-voltage and high-power applications.
[0027] like Figure 1 As shown, this embodiment provides a DC circuit with transformer isolation, including a full-bridge chopper unit, a transformer T1, a rectifier unit and a voltage regulation output unit. Figure 1 This is a complete schematic diagram of this embodiment. Figure 2 This is the schematic diagram of transformer T1. Figure 3 It is the schematic diagram of the full-bridge chopper unit. Figure 4 It is a schematic diagram of the rectifier unit and the voltage regulation output unit.
[0028] refer to Figure 1 and Figure 3 The full-bridge chopper unit includes four capacitors C4-C7 (first capacitors), a first MOS transistor Q2, a second MOS transistor Q3, a third MOS transistor Q4, and a fourth MOS transistor Q5 connected in parallel. The drain of the first MOS transistor Q2 and the source of the third MOS transistor Q4 are respectively connected to the two ends of the capacitors C4-C7, and the two ends of the capacitors C4-C7 are also connected to the DC voltage input, the source of the first MOS transistor Q2 is connected to the drain of the third MOS transistor Q4; the drain of the second MOS transistor Q3 is connected to the drain of the first MOS transistor Q2, the source of the second MOS transistor Q3 is connected to the drain of the fourth MOS transistor Q5, and the source of the fourth MOS transistor Q5 is connected to the source of the third MOS transistor Q4.
[0029] like Figure 2 and Figure 3 As shown, the transformer is a 30kV high voltage transformer. One end of the primary winding of the transformer T1 is connected between the source of the first MOS transistor Q2 and the drain of the third MOS transistor Q4, and the other end of the primary winding of the transformer T1 is connected between the source of the second MOS transistor Q3 and the drain of the fourth MOS transistor Q5. The number of turns of the secondary winding of the transformer T1 is adjustable to meet different output voltage requirements.
[0030] refer to Figure 3 , the full-bridge chopper unit also includes 4 first drive modules. The first first drive module includes a first diode D3, a second diode D6 and a first resistor R2; the second first drive module includes a first diode D2, a second diode D7 and a first resistor R3; the third first drive module includes a first diode D9, a second diode D13 and a first resistor R5; the fourth first drive module includes a first diode D10, a second diode D12 and a first resistor R6. In each first drive module, the cathode of the first diode is connected to the cathode of the second diode, and the anode of the first diode and the anode of the second diode are connected to the two ends of the first resistor; the four first drive modules correspond to the first MOS transistor Q2, the second MOS transistor Q3, the third MOS transistor Q4 and the fourth MOS transistor Q5 respectively, and the two ends of the first resistor in each first drive module are connected to the gate and source of the corresponding MOS transistor respectively.
[0031] refer to Figure 4 The rectifier unit includes a dual diode D1 (third and fourth diodes) and a dual diode D11 (fifth and sixth diodes). The cathode of the dual diode D1 (cathode of the third and fourth diodes) is connected as the first output end of the rectifier unit, the anode of the dual diode D11 (anode of the fifth and sixth diodes) is connected as the second output end of the rectifier unit, the anode of the dual diode D1 (anode of the third diode) is connected to the cathode of the dual diode D11 (cathode of the fifth diode), and the cathode of the dual diode D1 (anode of the fourth diode) is connected to the anode of the dual diode D11 (cathode of the sixth diode).
[0032] The rectifier unit further includes a filter module, which includes a second capacitor C1 and a second resistor R4. One end of the second capacitor C1 is connected to the second resistor R4, and the other end is connected to the cathode of the dual diode D1 (the anode of the fourth diode) and the anode of the dual diode D11 (the cathode of the sixth diode), and the other end of the second resistor R4 is connected to the anode of the dual diode D1 (the anode of the third diode) and the cathode of the dual diode D1 (the cathode of the fourth diode).
[0033] The voltage regulating output unit includes a third capacitor C2, a fourth capacitor C3, a fifth MOS transistor Q1, a seventh diode D8 and a first inductor L1. One end of the third capacitor C2 is connected to the drain of the fifth MOS transistor Q1, and the other end is connected to the anode of the seventh diode D8, the source of the fifth MOS transistor Q1 is connected to the cathode of the seventh diode D8 and one end of the first inductor L1, the anode of the seventh diode D8 is connected to one end of the fourth capacitor C3, and the other end of the first inductor L1 is connected to the other end of the fourth capacitor C3. Both ends of the fourth capacitor C3 are also connected to the load.
[0034] The voltage regulating output unit further includes a second driving module, which includes an eighth diode D4, a ninth diode D5 and a third resistor R1. The cathode of the eighth diode D4 is connected to the cathode of the ninth diode D5, the anode of the eighth diode D4 and the anode of the ninth diode D5 are connected to the two ends of the third resistor R1, and the two ends of the third resistor R1 are also connected to the gate and source of the fifth MOS transistor Q1 respectively.
[0035] The working principle of this embodiment is as follows:
[0036] like Figure 1 As shown, the connected DC power is filtered by capacitors C4 to C7 and then enters the full-bridge chopper circuit. The four MOS transistors Q2 to Q5 are divided into two groups, Q2 and Q5 are in one group, and Q3 and Q4 are in another group. When Q2 and Q5 are turned on, the positive voltage will be input to end 1 of the primary winding of the transformer T1, and the negative voltage will be input to end 2 of the primary winding of the transformer T1; when Q2 and Q5 are turned off and Q3 and Q4 are turned on, the positive voltage will be input to end 2 of the primary winding of the transformer T1, and the negative voltage will be input to end 1 of the primary winding of the transformer T1. By quickly switching the two groups of MOS transistors, the DC power is converted into AC power in the shape of a square wave. In this embodiment, a switching frequency of 80kHz is selected. Increasing the switching frequency can reduce the ripple of the output of the post-stage rectifier. As shown Figure 5 As shown in the figure, when the input DC voltage is 400 V, the full-bridge chopper circuit outputs a square wave AC voltage, whose amplitude switches between positive and negative 400 V. By changing the switch combination of MOS transistors Q2 to Q5, the polarity of the voltage across the primary winding can be controlled, thereby realizing the conversion of DC voltage to AC voltage.
[0037] The AC signal is electrically isolated through transformer T1, and the energy is transferred from the primary winding of transformer T1 to the secondary winding. In the early stage of design, the final output voltage range can be adjusted by changing the turns ratio of the primary and secondary. The secondary turns of transformer T1 can be adjusted by switches S1, S2, and S3, so as to achieve quick adjustment of the output voltage range. The secondary output of transformer T1 is connected to the rectifier circuit, and the AC signal is rectified into a DC signal through two dual diodes D1 and D11. In order to suppress the leakage inductance and interference generated during the transformer transmission process, a filter circuit composed of resistor R4 and capacitor C1 is added to the secondary to prevent interference from damaging the rectifier diode and the subsequent circuit.
[0038] The rectified DC signal is connected to the post-stage voltage regulation output circuit. This circuit is a DC-DC converter based on the principle of inductive energy storage. By controlling the input duty cycle variable PWM wave to switch the on and off state of MOS transistor Q1, the input DC voltage is converted into an adjustable output voltage. The operation of the voltage regulation output circuit is divided into three stages:
[0039] On stage: When MOS transistor Q1 is turned on, inductor L1 stores electrical energy and capacitor C3 is charged.
[0040] Turn-off phase: When the MOS transistor Q1 is turned off, the energy stored in the inductor L1 and the capacitor C3 is transferred to the load. At this time, the current in the inductor L1 still exists and it will continue to flow to the load.
[0041] Oscillation stage: After the current in the inductor L1 flows to the load, the MOS transistor Q1 is turned off. At this time, the current in the inductor L1 cannot disappear immediately, so the energy in the inductor will be transmitted back to the switch tube Q1, driving the diode D8 to turn on. This process is called oscillation.
[0042] At the same time, in order to ensure a stable output voltage, the voltage regulation output circuit adopts negative feedback control. The output voltage is sampled and fed back to the microcontroller (not shown in the figure), and then the microcontroller adjusts the duty cycle of the output PWM wave and controls the on time and off time of the MOS transistor Q1, so that the output voltage remains within the predetermined range.
[0043] This embodiment uses a 30kV high-voltage transformer T1 for electrical isolation, which greatly improves the safety and reliability of the high-voltage and high-power system. The full-bridge chopper unit uses multiple high-voltage MOS transistors in series and parallel, such as Q2 to Q5, which are suitable for high-voltage and high-power applications and improve the utilization rate of DC voltage. The secondary turns of transformer T1 can be flexibly adjusted by switches S1, S2, and S3, which can adapt to different high-power output voltage requirements and expand the scope of application of the circuit. The rectifier unit uses high-voltage dual diodes D1 and D11, and the voltage regulation output unit uses high-voltage MOS transistor Q1 and inductor L1 to meet the needs of high-voltage and high-power output. At the same time, the design of the rectifier unit and the voltage regulation output unit simplifies the circuit structure and improves efficiency. The filter capacitors C1, C2, and C3 are selected with higher voltage ratings and capacities, which further improves the reliability and stability of the circuit under high voltage and high power.
[0044] Those skilled in the art can make various modifications and variations to the technical solution of the utility model to meet different application requirements. As long as these modifications and variations do not deviate from the spirit and scope of the utility model, they shall fall within the scope of protection of the claims of the utility model. The scope of protection of the utility model shall be based on the claims, and any technical solution or its equivalent that does not deviate from the technical solution recorded in the claims shall be deemed to fall within the scope of protection of the utility model.
Claims
1. A DC circuit with transformer isolation, characterized in that: It includes a full-bridge chopper unit, a transformer, a rectifier unit and a voltage regulating output unit; The output end of the full-bridge chopper unit is connected to the primary of the transformer, and the input end of the full-bridge chopper unit is connected to a DC voltage; The secondary of the transformer is connected to the input end of the rectifier unit, the output end of the rectifier unit is connected to the input end of the voltage regulating output unit, and the output end of the voltage regulating output unit is used to connect to a load.
2. The DC circuit with transformer isolation according to claim 1, characterized in that: The secondary turns of the transformer are adjustable.
3. The DC circuit with transformer isolation according to claim 1, characterized in that: The full-bridge chopper unit includes a first capacitor, a first MOS transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor, wherein the drain of the first MOS transistor and the source of the third MOS transistor are respectively connected to two ends of the first capacitor, and the two ends of the capacitor are also connected to a DC voltage input, and the source of the first MOS transistor is connected to the drain of the third MOS transistor; The drain of the second MOS transistor is connected to the drain of the first MOS transistor, the source of the second MOS transistor is connected to the drain of the fourth MOS transistor, and the source of the fourth MOS transistor is connected to the source of the third MOS transistor.
4. The DC circuit with transformer isolation according to claim 3, characterized in that: One end of the primary of the transformer is connected between the source of the first MOS transistor and the drain of the third MOS transistor, and the other end of the primary of the transformer is connected between the source of the second MOS transistor and the drain of the fourth MOS transistor.
5. The DC circuit with transformer isolation according to claim 3, characterized in that: The full-bridge chopper unit further includes four first driving modules, wherein the first driving module includes a first diode, a second diode and a first resistor; the cathode of the first diode is connected to the cathode of the second diode, and the anode of the first diode and the anode of the second diode are connected to both ends of the first resistor; The four first driving modules correspond to the first MOS transistor, the second MOS transistor, the third MOS transistor and the fourth MOS transistor respectively, and two ends of the first resistor in each of the first driving modules are respectively connected to the gate and source of the corresponding MOS transistor.
6. The DC circuit with transformer isolation according to claim 1, characterized in that: The rectifier unit includes a third diode, a fourth diode, a fifth diode, and a sixth diode, the cathode of the third diode is connected to the cathode of the fourth diode, the anode of the fifth diode is connected to the anode of the sixth diode, the anode of the third diode is connected to the cathode of the fifth diode, and the anode of the fourth diode is connected to the cathode of the sixth diode; the cathode of the third diode and the cathode of the fourth diode are connected as the first output end of the rectifier unit; the anode of the fifth diode and the anode of the sixth diode are connected as the second output end of the rectifier unit.
7. The DC circuit with transformer isolation according to claim 6, characterized in that: The rectifier unit also includes a filtering module, which includes a second capacitor and a second resistor; one end of the second capacitor is connected to the second resistor, and the other end is connected to the anode of the fourth diode and the cathode of the sixth diode, and the other end of the second resistor is connected to the anode of the third diode and the cathode of the fourth diode.
8. The DC circuit with transformer isolation according to claim 1, characterized in that: The voltage regulating output unit includes a third capacitor, a fourth capacitor, a fifth MOS transistor, a seventh diode and a first inductor; one end of the third capacitor is connected to the drain of the fifth MOS transistor, and the other end is connected to the anode of the seventh diode, the source of the fifth MOS transistor is connected to the cathode of the seventh diode and one end of the first inductor, the anode of the seventh diode is connected to one end of the fourth capacitor, and the other end of the first inductor is connected to the other end of the fourth capacitor; the two ends of the fourth capacitor are also connected to the load.
9. The DC circuit with transformer isolation according to claim 8, characterized in that: The voltage regulation output unit also includes a second driving module, which includes an eighth diode, a ninth diode and a third resistor; the cathode of the eighth diode is connected to the cathode of the ninth diode, the anode of the eighth diode and the anode of the ninth diode are connected to the two ends of the third resistor, and the two ends of the third resistor are also respectively connected to the gate and source of the fifth MOS transistor.