Dual-channel ac power supply isolation circuit and power supply system

Abstract

The application discloses a kind of double-channel alternating current source isolation circuits and power supply system, belong to power electronics technical field, the circuit includes first, second channel module of same structure, including rectifier bridge, optoelectronic coupler and thyristor;The positive and negative output terminals of rectifier bridge are connected with the anode and cathode of optoelectronic coupler respectively, and the second output end of optoelectronic coupler is connected with the control end of thyristor;Two alternating current input ends of the rectifier bridge of first, second channel module are connected with input end live wire LI zero line NI, output end live wire LO zero line NO respectively;The first output end of the optoelectronic coupler of first, second channel module and the input end of thyristor are all connected with input end live wire LI, output end live wire LO, and the output end of the thyristor of first, second channel module is connected with the first input live wire of power frequency transformer end respectively, second input live wire.The application has high safety, strong anti-interference ability, fast response, no mechanical contact, long service life, maintenance-free and miniaturization potential.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a dual-channel AC power isolation circuit and power supply system. Background Technology

[0002] In recent years, new energy vehicles have become increasingly popular and have become a common mode of transportation. Currently, new energy vehicle charging stations are unidirectional, meaning they can only charge the vehicle's battery via the power grid. However, in practice, a large number of new energy vehicles remain idle, with their stored electricity sitting unused. Meanwhile, the power grid faces significant pressure during peak electricity demand periods, often resorting to expensive energy storage stations to alleviate this pressure, resulting in resource waste.

[0003] With the development of V2G, the fully high-frequency isolated bidirectional solution has attracted attention from the academic community as its core. Existing fully high-frequency isolated bidirectional solutions employ two AC-DC modules with bidirectional power supply, achieving grid isolation between the output and output via a high-frequency transformer. The topology includes: two AC-side filter circuits, two rectifier bridges, two high-frequency transformers, and a DC-side filter circuit. Existing high-frequency isolated bidirectional solutions suffer from drawbacks such as circuit complexity, numerous components, and the need for additional filtering and shielding designs to address electromagnetic interference. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dual-channel AC power isolation circuit and power supply system, which solves the technical problems of existing high-frequency isolation bidirectional schemes, such as complex circuits, many components, and the need for additional filtering and shielding designs for electromagnetic interference.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a dual-channel AC power isolation circuit, including a first channel module and a second channel module; the first channel module and the second channel module have the same structure, both including a rectifier bridge, an optocoupler and a thyristor; the positive output terminal and the negative output terminal of the rectifier bridge are respectively connected to the anode and cathode of the optocoupler, and the second output terminal of the optocoupler is connected to the control terminal of the thyristor; In this configuration, the two AC input terminals of the rectifier bridge of the first channel module are connected to the input live wire LI and the input neutral wire NI, respectively; the two AC input terminals of the rectifier bridge of the second channel module are connected to the output live wire LO and the input neutral wire NO, respectively; the first output terminal of the optocoupler of the first channel module and the input terminal of the thyristor are both connected to the input live wire LI, and the first output terminal of the optocoupler of the second channel module and the input terminal of the thyristor are both connected to the output live wire LO; the output terminals of the thyristors of the first channel module and the second channel module are respectively connected to the first input live wire LI_F and the second input live wire LO_F of the power frequency transformer.

[0006] Optionally, a thermistor RT1 is connected between the input live wire LI and its rectifier bridge, and a thermistor RT2 is connected between the output live wire LO and its rectifier bridge. The thermistors RT1 and RT2 are used to suppress surge current.

[0007] Optionally, a first resistor-capacitor step-down module is connected between the input live wire LI and its rectifier bridge, and a second resistor-capacitor step-down module is connected between the output live wire LO and its rectifier bridge. The first resistor-capacitor step-down module and the second resistor-capacitor step-down module are used for current limiting and voltage division. The first RC step-down module includes resistors R1 and R2 and capacitor Cr1, wherein capacitors R1 and R2 are connected in series and then connected in parallel with capacitor Cr1; the second RC step-down module includes resistors R6 and R7 and capacitor Cr2, wherein capacitors R6 and R7 are connected in series and then connected in parallel with capacitor Cr2.

[0008] Optionally, a bidirectional transient suppression diode D2 is connected between the input live wire LI and the input neutral wire NI, and a bidirectional transient suppression diode D4 is connected between the output live wire LO and the output neutral wire NO. The bidirectional transient suppression diodes D2 and D4 are used to clamp high voltage spikes.

[0009] Optionally, a shunt resistor module is connected between the positive output terminal of the rectifier bridge and the anode of the optocoupler to fine-tune the current threshold flowing through the light-emitting diode of the optocoupler, thereby setting the sensitivity of zero-crossing detection.

[0010] Optionally, the shunt resistor module of the first channel module includes resistors R4 and R5 connected in parallel; the shunt resistor module of the second channel module includes resistors R9 and R10 connected in parallel.

[0011] Optionally, the first output terminals of the optocouplers of the first channel module and the second channel module are respectively connected to current-limiting resistors R3 and R8.

[0012] Secondly, the present invention provides a power supply system, including the dual-channel AC power isolation circuit as described above.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention provides a dual-channel AC power isolation circuit and power supply system. It employs a dual-channel symmetrical AC power isolation circuit (i.e., a first channel module and a second channel module) to achieve independent acquisition, isolated detection, and drive control of two AC signals without interference. Furthermore, unlike traditional transformer-based step-down sampling or resistor-based direct voltage division sampling, this invention uses a combination architecture of a rectifier bridge, optocoupler, and thyristor. The rectifier bridge converts AC power into pulsating DC power, ensuring that the optocoupler only cuts off near the zero-crossing point, thereby generating a zero-crossing pulse signal at the output that is strictly synchronized with the AC power. This design not only achieves complete electrical isolation between the high-voltage side and the low-voltage control side but also effectively filters out grid harmonic interference, improving the accuracy and noise immunity of zero-crossing detection.

[0014] Signal acquisition and conditioning employ a RC step-down module and a shunt resistor module. The RC step-down module is used for current limiting and voltage division, using capacitive reactance instead of resistors to limit current, effectively avoiding the device overheating problem caused by increased power consumption due to resistors. The shunt resistor module is used to fine-tune the current threshold flowing through the LED of the optocoupler, thereby setting the sensitivity of zero-crossing detection.

[0015] The input stage surge suppression with multiple protections employs a thermistor and a bidirectional transient suppression diode. The thermistor is used to suppress surge current and protect the rectifier bridge and optocoupler, while the bidirectional transient suppression diode is used to clamp high voltage spikes. The combination of the two significantly improves the circuit's survivability and long-term stability in harsh power grid environments.

[0016] The compact drive architecture of optocouplers directly driving bidirectional thyristors eliminates the need for additional transistor amplification stages, simplifying the circuit structure and reducing costs. Simultaneously, the fast response characteristics of the optocoupler, combined with the high current handling capability of the thyristor, enable efficient, contactless control of AC loads. Attached Figure Description

[0017] Figure 1 This is a topological diagram of the first channel module and the second channel module provided in an embodiment of the present invention; Figure 2 This is a topology diagram of a power frequency transformer provided in an embodiment of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0019] Example 1

[0020] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a dual-channel AC power isolation circuit, including a first channel module and a second channel module. The first channel module and the second channel module have the same structure. The first channel module includes a rectifier bridge D1, an optocoupler OP1, and a thyristor U1, and the second channel module includes a rectifier bridge D3, an optocoupler OP2, and a thyristor U2.

[0021] (1) Input protection and sampling level: The live wire LI is connected in series with the thermistor RT1 and the first RC step-down module, and then connected to one AC input terminal of the rectifier bridge D1. The neutral wire NI is directly connected to the other AC input terminal of the rectifier bridge D1.

[0022] The output live wire LO is connected in series with the thermistor RT2 and the second RC step-down module, and then connected to one AC input terminal of the rectifier bridge D3. The output neutral wire NO is directly connected to the other AC input terminal of the rectifier bridge D3.

[0023] Thermistors RT1 and RT2 are used to suppress surge current. They utilize their positive temperature coefficient characteristics of "low resistance in cold state and high resistance in hot state" to "limit current" at the moment the surge is connected and then quickly "give way".

[0024] The first RC step-down module includes resistors R1 and R2 and capacitor Cr1. Capacitors R1 and R2 are connected in series and then in parallel with capacitor Cr1 to form a first RC network. The second RC step-down module includes resistors R6 and R7 and capacitor Cr2. Capacitors R6 and R7 are connected in series and then in parallel with capacitor Cr2 to form a second RC network. The first and second RC step-down modules are used for current limiting and voltage division. Capacitive reactance is used instead of resistors to limit current, effectively avoiding the device overheating problem caused by increased power consumption due to resistors.

[0025] A bidirectional transient suppression diode D2 is connected between the input live wire LI and the input neutral wire NI, and a bidirectional transient suppression diode D4 is connected between the output live wire LO and the output neutral wire NO. The bidirectional transient suppression diodes D2 and D4 are used to clamp high voltage spikes and clamp them to a safe range that the subsequent circuit can withstand.

[0026] The positive and negative output terminals of rectifier bridge D1 are connected to the anode and cathode of optocoupler OP1, respectively; the positive and negative output terminals of rectifier bridge D3 are connected to the anode and cathode of optocoupler OP2, respectively.

[0027] A shunt resistor module is connected between the positive output terminal of the rectifier bridge and the anode of the optocoupler. This module is used to fine-tune the current threshold flowing through the LED of the optocoupler, thereby setting the sensitivity of the zero-crossing detection. The shunt resistor module of the first channel module includes resistors R4 and R5 connected in parallel; the shunt resistor module of the second channel module includes resistors R9 and R10 connected in parallel. The parallel connection of the two resistors facilitates fine-tuning of the current threshold flowing through the LED of the optocoupler.

[0028] (2) Signal isolation and driver stage: The first output terminal of optocoupler OP1 and the input terminal of thyristor U1 are both connected to the input live wire LI via current-limiting resistor R3. The second output terminal of optocoupler OP1 is connected to the control terminal of thyristor U1, and the output terminal of thyristor U1 is connected to the first input live wire LI_F of the power frequency transformer. The first output terminal of optocoupler OP2 and the input terminal of thyristor U2 are both connected to the output live wire LO via current-limiting resistor R8. The second output terminal of optocoupler OP2 is connected to the control terminal of thyristor U2, and the output terminal of thyristor U2 is connected to the second input live wire LO_F of the power frequency transformer.

[0029] (3) Workflow and logic, taking the first channel module as an example: Step 1: Voltage Transformation and Conditioning When AC power is input from the live wire LI and the neutral wire NI, it first passes through the thermistor RT1 to suppress inrush current and is filtered out by the transient suppression diode D2 to remove high-frequency interference. Subsequently, the AC power is current-limited and voltage-divided by resistors R1 and R2 and capacitor Cr1 before entering the rectifier bridge D1, where it is converted into pulsating DC power, forming a current signal suitable for the operation of the optocoupler OP1. Resistors R4 and R5 act as shunt resistors, used to fine-tune the current threshold flowing through the LED of the optocoupler OP1, thereby setting the zero-crossing detection sensitivity.

[0030] Step 2: Zero-crossing signal generation The optocoupler OP1 changes its output state according to the magnitude of the input current.

[0031] Non-zero crossing region: When the AC voltage is near the peak, the rectified voltage is high, and the current flowing through the LED of the optocoupler OP1 is greater than its turn-on threshold, the optocoupler OP1 is turned on and outputs a high level.

[0032] Zero-crossing region: When the AC voltage approaches 0V, the rectified voltage is lower than the forward voltage drop of the LED in optocoupler OP1, causing optocoupler OP1 to turn off and the output state to flip. As a result, a pulse square wave signal synchronized with the AC frequency is generated at the output of optocoupler OP1, with its falling or rising edge precisely corresponding to the zero-crossing point of the AC current.

[0033] Step 3: Power Execution After receiving the zero-crossing signal output by optocoupler OP1, thyristor U1 sends a trigger signal to the gate of thyristor U1.

[0034] When the gate of thyristor U1 receives a trigger current, thyristor U1 conducts, and AC power flows from the input live wire LI through the thermistor RT1 to the first input live wire LI_F of the power frequency transformer, and the load is energized and works.

[0035] When the AC current crosses zero again, the thyristor U1 automatically turns off, waiting for the next trigger to enable AC conduction.

[0036] The workflow and logic of the second channel module are completely consistent with those of the first channel module. The output live wire (LO) and the output neutral wire (NO) are the second AC input, and LO_F is the second load output. The two channels work independently and do not interfere with each other, which can achieve safe isolation between the two AC power supplies.

[0037] Example 2

[0038] This invention provides a power supply system, including a dual-channel AC power isolation circuit as described in Embodiment 1 above.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dual-channel AC power isolation circuit, characterized in that, It includes a first channel module and a second channel module; the first channel module and the second channel module have the same structure, both including a rectifier bridge, an optocoupler and a thyristor; the positive and negative output terminals of the rectifier bridge are respectively connected to the anode and cathode of the optocoupler, and the second output terminal of the optocoupler is connected to the control terminal of the thyristor; In this configuration, the two AC input terminals of the rectifier bridge of the first channel module are connected to the input live wire LI and the input neutral wire NI, respectively; the two AC input terminals of the rectifier bridge of the second channel module are connected to the output live wire LO and the input neutral wire NO, respectively; the first output terminal of the optocoupler of the first channel module and the input terminal of the thyristor are both connected to the input live wire LI, and the first output terminal of the optocoupler of the second channel module and the input terminal of the thyristor are both connected to the output live wire LO; the output terminals of the thyristors of the first channel module and the second channel module are respectively connected to the first input live wire LI_F and the second input live wire LO_F of the power frequency transformer.

2. The dual-channel AC power isolation circuit according to claim 1, characterized in that, A thermistor RT1 is connected between the input live wire LI and its rectifier bridge, and a thermistor RT2 is connected between the output live wire LO and its rectifier bridge. The thermistors RT1 and RT2 are used to suppress surge current.

3. The dual-channel AC power isolation circuit according to claim 1, characterized in that, A first resistor-capacitor (RC) step-down module is connected between the input live wire LI and its rectifier bridge, and a second RC step-down module is connected between the output live wire LO and its rectifier bridge. The first RC step-down module and the second RC step-down module are used for current limiting and voltage division. The first RC step-down module includes resistors R1 and R2 and capacitor Cr1, wherein capacitors R1 and R2 are connected in series and then connected in parallel with capacitor Cr1; the second RC step-down module includes resistors R6 and R7 and capacitor Cr2, wherein capacitors R6 and R7 are connected in series and then connected in parallel with capacitor Cr2.

4. The dual-channel AC power isolation circuit according to claim 1, characterized in that, A bidirectional transient suppression diode D2 is connected between the input live wire LI and the input neutral wire NI, and a bidirectional transient suppression diode D4 is connected between the output live wire LO and the output neutral wire NO. The bidirectional transient suppression diodes D2 and D4 are used to clamp high voltage spikes.

5. The dual-channel AC power isolation circuit according to claim 1, characterized in that, A shunt resistor module is connected between the positive output terminal of the rectifier bridge and the anode of the optocoupler. This module is used to fine-tune the current threshold flowing through the LED of the optocoupler, thereby setting the sensitivity of the zero-crossing detection.

6. The dual-channel AC power isolation circuit according to claim 5, characterized in that, The shunt resistor module of the first channel module includes resistors R4 and R5 connected in parallel; the shunt resistor module of the second channel module includes resistors R9 and R10 connected in parallel.

7. The dual-channel AC power isolation circuit according to claim 1, characterized in that, The first output terminals of the optocouplers of the first channel module and the second channel module are respectively connected to current-limiting resistors R3 and R8.

8. A power supply system, characterized in that, Includes the dual-channel AC power isolation circuit as described in any one of claims 1-7.

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