A chopper-type AC to AC voltage converter

Abstract

The application discloses a chopper AC to AC voltage converter, which comprises an AC input module, an input voltage detection circuit, a chopper switch module, a driving circuit, an AC output module, a control circuit and a power supply circuit, wherein the chopper switch module comprises a first switch tube and a second switch tube which are oppositely connected, and the chopper switch module is connected to the control circuit and the power supply circuit through the driving circuit. The first switch tube and the second switch tube are oppositely combined into a switch circuit to replace a thyristor, the first switch tube and the second switch tube are opened to output when the mains voltage is lower than a peak value of 200V, the first switch tube and the second switch tube are closed when the mains voltage is higher than the peak value of 200V, and the first switch tube and the second switch tube are opened again when the mains voltage is lower than the peak value of 200V, so that the output voltage is always lower than the peak value of 200V through the above-mentioned process, and the user's electronic and electrical products are prevented from being burnt due to the excessively high peak voltage.

Description

Technical Field

[0001] This invention relates to the field of voltage converter technology, and specifically to a chopper-type AC to AC voltage converter. Background Technology

[0002] Voltage differences can cause equipment to burn out or malfunction when directly plugged in during international travel or when using imported electrical appliances. Voltage converters were developed to address this issue. They use internal transformers or electronic circuits to convert the input voltage (e.g., 220V) to the required output voltage (e.g., 110V), thus ensuring the safe and stable operation of electrical appliances under different voltage standards.

[0003] Currently, the mainstream transformer products on the market include thyristor phase-shifting transformers, modified sine wave transformers, and pure sine wave transformers. Among them, modified sine wave transformers and pure sine wave transformers have complex circuits and high costs, while thyristor phase-shifting transformers have simple circuits and are inexpensive, but because of their high peak voltage, they are prone to burning out users' electronic and electrical products. For example, Chinese Patent Publication No. CN210007628U discloses a portable voltage converter, which includes: a housing, an AC input terminal, and an output terminal. The housing contains a voltage conversion circuit. AC power is converted by the voltage conversion circuit after passing through the input terminal and then connected to the AC output terminal. The voltage conversion circuit includes a low-power voltage conversion circuit and a high-power voltage conversion circuit. The output terminals of these two circuits are connected in parallel and then connected to the AC output terminal. The low-power voltage conversion circuit includes an iron-core transformer and an overload protector on the main current line. The voltage waveform after voltage conversion is called the first waveform. The high-power voltage conversion circuit includes a thyristor, and the voltage waveform after voltage conversion is called the second waveform. When the connected external load is low-power, the current passes through the low-power voltage conversion circuit and the overload protector to output the first waveform. When the connected external load requires high power, the overload protector reduces the output of the first waveform, causing the second waveform to start and be output.

[0004] In view of the above, the inventors propose the following technical solution. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a chopper-type AC to AC voltage converter.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a chopper-type AC to AC voltage converter, comprising: an AC input module, an input voltage detection circuit, a current detection module, a chopper switch module, a drive circuit, an AC output module, a control circuit, a temperature detection module, and a power supply circuit, wherein the chopper switch module includes a first switch transistor and a second switch transistor connected opposite to each other, and the chopper switch module is connected to the control circuit and the power supply circuit through the drive circuit.

[0007] Furthermore, in the above technical solution, the first and second switching transistors in the chopper switch module include, but are not limited to, any one of IGBT, MOSFET, and transistor, and are combined in opposite directions to form a switching circuit.

[0008] Furthermore, in the above technical solution, the power supply circuit includes a first rectifier and filter module, a power control chip U5, a transformer T1, a +15V output terminal, a +5V output terminal, and a 3.3V voltage regulator U4. The first rectifier and filter module, the power control chip U5, and the transformer T1 are connected in sequence. The input terminal of the first rectifier and filter module is connected to the mains power. The transformer T1 has two output voltages: a +15V output terminal and a +5V output terminal. The 3.3V voltage regulator U4 is connected to the +5V output terminal and stably outputs a +3.3V voltage.

[0009] Furthermore, in the above technical solution, the control circuit includes a main control chip U2, multiple pins of which are connected to the +3.3V voltage of the power supply circuit, and the control circuit is connected to the drive circuit through an optocoupler P1.

[0010] Furthermore, in the above technical solution, the PA3 and PA4 pins of the main control chip U2 are connected to LED1 diodes that can emit red and green colors, the PA14 pin of the main control chip U2 is connected to the IN-CHK pin of the input voltage detection circuit, and the PA12 and PA13 pins of the main control chip U2 are connected to the PI1 and PI2 pins of the current detection module.

[0011] Furthermore, in the above technical solution, the driving circuit includes a dual-channel independent driving chip U1 and switching diodes D1 and D2. Switching diodes D1 and D2 are respectively connected to the first switching transistor and the second switching transistor. The dual-channel independent driving chip U1 is connected to the +15V output terminal of the power supply circuit and is connected to the main control chip U2 of the control circuit through optocoupler P1.

[0012] Furthermore, the above technical solution also includes a current detection module.

[0013] Furthermore, in the above technical solution, the current detection module includes a current sensor U3, which is connected to the N-IN terminal of the chopper switch module and connected to the +3.3V voltage of the power supply circuit via resistor R25.

[0014] Furthermore, the above technical solution also includes a temperature detection module, which is connected to the +3.3V voltage of the power supply circuit via resistor R21.

[0015] Furthermore, in the above technical solution, the input voltage detection circuit includes a second rectifier and filter module and an operational amplifier IC1. The second rectifier and filter module is connected to the mains power and the operational amplifier IC1. The operational amplifier IC1 is powered by the +3.3V voltage of the power supply circuit and connected to the control circuit through the IN-CHK pin.

[0016] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: In the present invention, a switching circuit is formed by combining a first switching transistor and a second switching transistor facing each other to replace the thyristor. When the mains voltage is lower than the peak value of 200V, the first switching transistor and the second switching transistor are turned on to output; when the mains voltage is higher than the peak value of 200V, the first switching transistor and the second switching transistor are turned off; when the mains voltage is lower than the peak value of 200V, the first switching transistor and the second switching transistor are turned on again. This cycle repeats continuously, keeping the output voltage always lower than the peak value of 200V, thus avoiding damage to the user's electronic and electrical products due to excessively high peak voltage. Attached Figure Description

[0017] Figure 1 This is the circuit diagram of the present invention.

[0018] Figure 2 This is a circuit diagram of the driving circuit and the chopper switch module in this invention.

[0019] Figure 3 This is the circuit diagram for input voltage detection in this invention.

[0020] Figure 4 This is a circuit diagram of the current detection module in this invention.

[0021] Figure 5 This is the control circuit diagram in this invention.

[0022] Figure 6 This is the driving circuit diagram in this invention.

[0023] Figure 7 This is the circuit diagram of the 3.3V voltage regulator in this invention.

[0024] Figure 8 This is a circuit diagram of the temperature detection module in this invention. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0026] See Figures 1 to 8 The diagram shows a chopper-type AC-to-AC voltage converter, comprising: an AC input module 1, an input voltage detection circuit 2, a current detection module 3, a chopper switch module 4, a drive circuit 5, an AC output module 6, a control circuit 7, a temperature detection module 8, and a power supply circuit 9. The chopper switch module 4 includes a first switch transistor 41 and a second switch transistor 42 connected opposite each other. This chopper switch module 4 is connected to the control circuit 7 and the power supply circuit 9 via the drive circuit 5. The first switch transistor 41 and the second switch transistor 42 are combined in opposite directions to form a switching circuit to replace the thyristor. When the mains voltage is lower than the peak value of 200V, the first switch transistor 41 and the second switch transistor 42 are turned on to output; when the mains voltage is higher than the peak value of 200V, the first switch transistor 41 and the second switch transistor 42 are turned off; when the mains voltage is lower than the peak value of 200V, the first switch transistor 41 and the second switch transistor 42 are turned on again. This cycle repeats continuously, keeping the output voltage consistently below the 200V peak value, thus preventing damage to the user's electronic appliances due to excessively high peak voltage.

[0027] The first switching transistor 41 and the second switching transistor 42 in the chopper switch module 4 include, but are not limited to, any one of IGBT, MOSFET, and transistor, and are combined in opposite directions to form a switching circuit. In this embodiment, the first switching transistor 41 and the second switching transistor 42 are IGBT Q1 and IGBT Q2, respectively. In this embodiment, switching transistors Q1 and Q2 are used, which can be power transistors with switching properties such as IGBT, MOSFET, and transistor, and are combined in opposite directions to form a switching circuit. The method of controlling the output voltage in this invention is to adjust the duration of the drive switching signal by detecting the input voltage.

[0028] The power supply circuit 9 includes a first rectifier and filter module 91, a power control chip U5, a transformer T1, a +15V output terminal, a +5V output terminal, and a 3.3V voltage regulator U4. The first rectifier and filter module 91, the power control chip U5, and the transformer T1 are connected in sequence. The input terminal of the first rectifier and filter module 91 is connected to the mains power. The transformer T1 has two output voltages: a +15V output terminal and a +5V output terminal. The 3.3V voltage regulator U4 is connected to the +5V output terminal and stably outputs a +3.3V voltage.

[0029] The control circuit 7 includes a main control chip U2. Multiple pins of the main control chip U2 are connected to the +3.3V voltage of the power supply circuit 9, and the control circuit 7 is connected to the driver circuit 5 via an optocoupler P1. Pins PA3 and PA4 of the main control chip U2 are connected to LED1 diodes that emit red and green light respectively. Pin PA14 of the main control chip U2 is connected to the IN-CHK pin of the input voltage detection circuit 2, and pins PA12 and PA13 of the main control chip U2 are connected to pins PI1 and PI2 of the current detection module 3. Two LED1 diodes are used as indicator lights, emitting red and green light respectively. When the output is normal, the green light is on; when the output is abnormal, the red and green lights flash alternately.

[0030] The driving circuit 5 includes a dual-channel independent driving chip U1 and switching diodes D1 and D2. Switching diodes D1 and D2 are respectively connected to the first switching transistor 41 and the second switching transistor 42. The dual-channel independent driving chip U1 is connected to the +15V output terminal of the power supply circuit 9 and is connected to the main control chip U2 of the control circuit 7 through optocoupler P1.

[0031] The voltage converter also includes a current detection module 3, which includes a current sensor U3. The current sensor U3 is connected to the N-IN terminal of the chopper switch module 4 and then connected to the +3.3V voltage of the power supply circuit 9 via resistor R25. The current detection module 3 detects the input / output current and sends the detected current signal to the control circuit 7. When the output load is too heavy or a short circuit occurs, the control circuit 7 shuts off the output based on the signal detected by the current detection module 3, protecting the user's product and the safety of this product.

[0032] The voltage converter also includes a temperature detection module 8, which is connected to the +3.3V voltage of the power supply circuit 9 via resistor R21. This temperature detection module 8 includes a thermistor NTC, which monitors the transformer temperature in real time. The temperature detection module 8 monitors the temperature of the chopper switch module 4 in real time, providing temperature information to the control circuit 7. When the control circuit 7 receives a temperature reading that has risen to a certain maximum value, it will reduce the duration of the drive signal, shortening the switching time of the chopper switch module 4 and reducing the output voltage AVG value, thus lowering the output voltage. Conversely, when an abnormal circuit temperature signal is detected, the control circuit 7 sends a signal via drive circuit 5 to shut down the chopper switch module 4, protecting the product's safety.

[0033] The input voltage detection circuit 2 includes a second rectifier and filter module 21 and an operational amplifier IC1. The second rectifier and filter module 21 is connected to the mains power and the operational amplifier IC1. The operational amplifier IC1 is powered by the +3.3V voltage of the power supply circuit 9 and connected to the control circuit 7 through the IN-CHK pin.

[0034] In summary, the working principle of this invention is as follows:

[0035] First, the AC mains power enters through the AC input module 1, is detected by the voltage detection circuit 2, and the detection signal is sent to the control circuit 7.

[0036] When the detected mains voltage is AC110V / 120V, the control circuit 7 sends a signal, which drives the first switch 41 and the second switch 42 of the chopper switch module 4 to be fully turned on via the drive circuit 5, so that the input AC mains voltage remains unchanged and is directly sent to the AC output module 6.

[0037] When the detected mains voltage is AC 230V, the control circuit 7 sends a time pulse signal, which drives the chopper switch module 4 via the drive circuit 5 to allow voltages below the peak value of 200V and shut down voltages above 200V, so that the peak value of the output AC voltage is always below 200V, ensuring that the peak value of the output AC voltage does not exceed 200V, thereby preventing damage to the user's electronic and electrical products.

[0038] The principle of this invention for adjusting the output voltage is as follows: the output voltage is adjusted by regulating the AGV value of the output voltage, which is essentially the same principle as that of a thyristor. However, this circuit cuts off the high voltage portion in the middle of the AC sine wave, ensuring that the output voltage does not exceed the peak value of 110 / 120V AC voltage, thus guaranteeing the safety of users' electricity use. Furthermore, many electrical products have built-in voltage detection circuits that detect the starting point of the AC voltage, therefore, this invention has a wider range of applications.

[0039] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A chopper-type AC to AC voltage converter, characterized in that, include: The AC input module (1), input voltage detection circuit (2), chopper switch module (4), drive circuit (5), AC output module (6), control circuit (7) and power supply circuit (9) are provided. The chopper switch module (4) includes a first switch transistor (41) and a second switch transistor (42) connected opposite to each other. The chopper switch module (4) is connected to the control circuit (7) and the power supply circuit (9) through the drive circuit (5).

2. A chopper-type AC to AC voltage converter according to claim 1, characterized in that: The first switch (41) and the second switch (42) in the chopper switch module (4) include, but are not limited to, any one of IGBT, MOSFET, and transistor, and are combined in opposite directions to form a switching circuit.

3. A chopper-type AC to AC voltage converter according to claim 1, characterized in that: The power supply circuit (9) includes a first rectifier and filter module (91), a power control chip U5, a transformer T1, a +15V output terminal, a +5V output terminal, and a 3.3V voltage regulator U4. The first rectifier and filter module (91), the power control chip U5, and the transformer T1 are connected in sequence. The input terminal of the first rectifier and filter module (91) is connected to the mains power. The transformer T1 has two output voltages: a +15V output terminal and a +5V output terminal. The 3.3V voltage regulator U4 is connected to the +5V output terminal and outputs a stable +3.3V voltage.

4. A chopper-type AC to AC voltage converter according to claim 3, characterized in that: The control circuit (7) includes a main control chip U2, multiple pins of which are connected to the +3.3V voltage of the power supply circuit (9), and the control circuit (7) is connected to the drive circuit (5) through an optocoupler P1.

5. A chopper-type AC to AC voltage converter according to claim 3, characterized in that: The main control chip U2 has two pins, PA3 and PA4, connected to LED1 diodes that can emit red and green colors. The main control chip U2 has a PA14 pin connected to the IN-CHK pin of the input voltage detection circuit (2). The main control chip U2 has PA12 and PA13 pins connected to the PI1 and PI2 pins of the current detection module (3).

6. A chopper-type AC to AC voltage converter according to claim 4, characterized in that: The driving circuit (5) includes a dual-channel independent driving chip U1 and switching diodes D1 and D2. Switching diodes D1 and D2 are connected to the first switching transistor (41) and the second switching transistor (42) respectively. The dual-channel independent driving chip U1 is connected to the +15V output terminal of the power supply circuit (9) and is connected to the main control chip U2 of the control circuit (7) through optocoupler P1.

7. A chopper-type AC to AC voltage converter according to claim 5, characterized in that: It also includes a current detection module (3).

8. A chopper-type AC to AC voltage converter according to claim 7, characterized in that: The current detection module (3) includes a current sensor U3, which is connected to the N-IN terminal of the chopper switch module (4) and connected to the +3.3V voltage of the power supply circuit (9) via resistor R25.

9. A chopper-type AC to AC voltage converter according to claim 3, characterized in that: It also includes a temperature detection module (8), which is connected to the +3.3V voltage of the power supply circuit (9) via resistor R21.

10. A chopper-type AC to AC voltage converter according to any one of claims 3-9, characterized in that: The input voltage detection circuit (2) includes a second rectifier filter module (21) and an operational amplifier IC1. The second rectifier filter module (21) is connected to the mains power and the operational amplifier IC1. The operational amplifier IC1 is powered by the +3.3V voltage of the power supply circuit (9) and connected to the control circuit (7) through the IN-CHK pin.

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