Inductor zero current detection circuit

Abstract

The utility model relates to an inductor zero current detection circuit, which comprises an input inductor L1, a coupling circuit, a comparator U1 and a working circuit, one end of the input inductor L1 is connected with a direct current voltage, the other end of the input inductor L1 is connected with the input end of the coupling circuit, the output end of the coupling circuit is connected with a pin 2 of the comparator U1, a pin 3 of the comparator U1 is connected with a reference voltage, and the working circuit is connected with the output end of the comparator U1. The first pin of the comparator U1 is an output pin, and the input end of the working circuit is connected with the other end of the input inductor L1. The zero current signal of the input inductor is converted into the comparator through the coupling circuit and the comparator, the zero current signal of the input inductor can be obtained through the output pin of the comparator, the whole circuit structure is simple, excessive elements do not need to be added, and the detection result is more accurate and reliable.

Description

Technical Field

[0001] This utility model relates to the field of power supply circuit technology, and in particular to an inductor zero current detection circuit. Background Technology

[0002] In PFC (Power Factor Corrector) power supplies and LED constant current power supplies, the MOSFET needs to be turned on again when the current in inductor L1 drops to zero. After the MOSFET Q1 is turned off, the current in inductor L1 gradually decreases and eventually reaches zero. Currently, an auxiliary winding is added to inductor L1, and the signal from this auxiliary winding is detected after the voltage is reduced to determine that the current is zero. This solution increases the complexity and cost of the circuit. Summary of the Invention

[0003] This invention provides an inductor zero-current detection circuit, which aims to solve the problem of complex detection circuits in existing technical solutions.

[0004] This utility model provides an inductor zero-current detection circuit, including an input inductor L1, a coupling circuit, a comparator U1, and a working circuit. One end of the input inductor L1 is connected to a DC voltage, and the other end of the input inductor L1 is connected to the input terminal of the coupling circuit. The output terminal of the coupling circuit is connected to pin 2 of the comparator U1, pin 3 of the comparator U1 is connected to a reference voltage, and pin 1 of the comparator U1 is the output pin. The input terminal of the working circuit is connected to the other end of the input inductor L1.

[0005] As a further improvement of this utility model, the working circuit includes a switching transistor Q1, the drain of the switching transistor Q1 is connected to the other end of the input inductor L1, the source of the switching transistor Q1 is connected to one end of the resistor R10, the base of the switching transistor Q1 is connected to one end of the resistor R9, the other ends of the resistor R9 and the other ends of the resistor R10 are both grounded, and the base of the switching transistor Q1 is connected to the PWM signal.

[0006] As a further improvement of this utility model, the working circuit includes a diode D2 and a capacitor C7. The positive terminal of the diode D2 is connected to the other end of the input inductor L1, one end of the capacitor C7 is connected to the negative terminal of the diode D2, and the other end of the capacitor C7 is grounded.

[0007] As a further improvement of this utility model, the coupling circuit includes resistor R11, resistor R12 and capacitor C6. One end of resistor R11 is connected to the other end of input inductor L1, the other end of resistor R11 is connected to one end of capacitor C6, the other end of capacitor C6 is connected to pin 2 of comparator U1, and the two ends of resistor R12 are respectively connected to the two ends of capacitor C6.

[0008] As a further improvement of this utility model, the coupling circuit includes resistor R11, resistor R12 and capacitor C6. One end of resistor R11 is connected to the other end of input inductor L1, the other end of resistor R11 is connected to one end of capacitor C6, the other end of capacitor C6 is connected to pin 2 of comparator U1, one end of resistor R12 is connected to one end of resistor R11, and the other end of resistor R12 is connected to the other end of capacitor C6.

[0009] As a further improvement of this utility model, the coupling circuit also includes a diode D1, the negative terminal of which is connected to the other end of the capacitor C6, and the positive terminal of the diode D1 is grounded.

[0010] As a further improvement of this utility model, pin 4 of the comparator U1 is grounded, pin 5 of the comparator U1 is connected to the negative terminal of diode D3, the positive terminal of diode D3 is connected to pin 2 of the comparator U1, and the negative terminal of diode D3 is connected to a 5V voltage.

[0011] The beneficial effects of this invention are: by using a coupling circuit and a comparator, the zero current detection of the input inductor is converted to the comparator, and the zero current signal of the input inductor can be obtained through the output pin of the comparator. The entire circuit structure is simple, does not require adding too many components, and the detection results are more accurate and reliable. Attached Figure Description

[0012] Figure 1 This is the first embodiment of the circuit connection of this utility model;

[0013] Figure 2 This is the second embodiment of the circuit connection of this utility model;

[0014] Figure 3 This is a waveform diagram of the circuit of this utility model during testing. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0016] This utility model provides an inductor zero-current detection circuit, including an input inductor L1, a coupling circuit, a comparator U1, and a working circuit. One end of the input inductor L1 is connected to a DC voltage, and the other end of the input inductor L1 is connected to the input terminal of the coupling circuit. The output terminal of the coupling circuit is connected to pin 2 of the comparator U1, pin 3 of the comparator U1 is connected to a reference voltage, and pin 1 of the comparator U1 is the output pin. The input terminal of the working circuit is connected to the other end of the input inductor L1.

[0017] As an embodiment of this utility model, the working circuit includes a switching transistor Q1, the drain of the switching transistor Q1 is connected to the other end of the input inductor L1, the source of the switching transistor Q1 is connected to one end of the resistor R10, the base of the switching transistor Q1 is connected to one end of the resistor R9, the other ends of the resistor R9 and the other ends of the resistor R10 are both grounded, and the base of the switching transistor Q1 is connected to the PWM signal.

[0018] In another embodiment of this utility model, the working circuit includes a diode D2 and a capacitor C7. The positive terminal of the diode D2 is connected to the other end of the input inductor L1, one end of the capacitor C7 is connected to the negative terminal of the diode D2, and the other end of the capacitor C7 is grounded.

[0019] like Figure 1 As shown, in another embodiment of the present invention, the coupling circuit includes resistor R11, resistor R12 and capacitor C6. One end of resistor R11 is connected to the other end of input inductor L1, the other end of resistor R11 is connected to one end of capacitor C6, the other end of capacitor C6 is connected to pin 2 of comparator U1, and the two ends of resistor R12 are respectively connected to the two ends of capacitor C6.

[0020] like Figure 2 As shown, in another embodiment of the present invention, the coupling circuit includes resistor R11, resistor R12 and capacitor C6. One end of resistor R11 is connected to the other end of input inductor L1, the other end of resistor R11 is connected to one end of capacitor C6, the other end of capacitor C6 is connected to pin 2 of comparator U1, one end of resistor R12 is connected to one end of resistor R11, and the other end of resistor R12 is connected to the other end of capacitor C6.

[0021] In another embodiment of the present invention, the coupling circuit further includes a diode D1, the negative terminal of which is connected to the other end of the capacitor C6, and the positive terminal of the diode D1 is grounded.

[0022] In another embodiment of this utility model, pin 4 of the comparator U1 is grounded, pin 5 of the comparator U1 is connected to the negative terminal of diode D3, the positive terminal of diode D3 is connected to pin 2 of the comparator U1, and the negative terminal of diode D3 is connected to a 5V voltage.

[0023] This invention provides an inductor zero-current detection circuit. After the Vdc voltage (DC voltage) passes through the input inductor L1, the voltage can reach approximately 400V when the switching transistor Q1 is switched. This voltage signal cannot be directly fed to the microcontroller's I / O pins, otherwise it will burn out the microcontroller. Therefore, a circuit is needed to detect this high-voltage waveform, which must first be stepped down while maintaining its shape.

[0024] Therefore, this solution adds resistor R11, capacitor C6, and resistor R12 to form a coupling circuit. This couples the signal to obtain a low-voltage waveform, the same as the voltage VPH at diode D2, which is the Zin waveform. Diodes D1 and D3 then fix this signal voltage within -0.7V to 5.7V to prevent damage to downstream components from excessive voltage. The signal is then input to pin 2 of comparator U1, and pin 3 of comparator U1 is connected to the reference voltage Vref. Comparator U1 outputs Zout, which is the final signal to be detected. The connection method of resistor R12 can be... Figure 1 or Figure 2 Two circuit structures.

[0025] Figure 3 The waveforms displayed by the instrument during testing are shown below. The intersections of each waveform with the first vertical dashed line, from top to bottom, represent signal values ​​A1, A2, A3, and A4. When the switch Q1 is turned off, the input inductor L1 begins to discharge, and the current gradually decreases. At A1, the current is 0, and the waveform also begins to decline. Simultaneously, waveform A2 is detected at Zin, also beginning to decline. When it drops to A3, below the reference voltage Vref, the Zout signal A4 becomes 0. Therefore, the signal at Zin is related to the zero-current signal of the input inductor L1. When the current of the input inductor is 0, the signal at Zin will be less than the reference voltage Vref, and the Zout signal output from pin 1 of comparator U1 will be 0. Thus, by detecting the Zout signal, it can be determined that VPH has decreased, thereby deducing that the current of the input inductor L1 is 0.

[0026] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the protection scope of the present invention.

Claims

1. An inductor zero-current detection circuit, characterized in that, The system includes an input inductor L1, a coupling circuit, a comparator U1, and a working circuit. One end of the input inductor L1 is connected to a DC voltage, and the other end of the input inductor L1 is connected to the input terminal of the coupling circuit. The output terminal of the coupling circuit is connected to pin 2 of the comparator U1, pin 3 of the comparator U1 is connected to a reference voltage, and pin 1 of the comparator U1 is the output pin. The input terminal of the working circuit is connected to the other end of the input inductor L1.

2. The inductor zero-current detection circuit according to claim 1, characterized in that, The working circuit includes a switching transistor Q1. The drain of the switching transistor Q1 is connected to the other end of the input inductor L1. The source of the switching transistor Q1 is connected to one end of the resistor R10. The base of the switching transistor Q1 is connected to one end of the resistor R9. The other ends of the resistor R9 and the other ends of the resistor R10 are both grounded. The base of the switching transistor Q1 is connected to the PWM signal.

3. The inductor zero-current detection circuit according to claim 1, characterized in that, The working circuit includes a diode D2 and a capacitor C7. The positive terminal of the diode D2 is connected to the other end of the input inductor L1, one end of the capacitor C7 is connected to the negative terminal of the diode D2, and the other end of the capacitor C7 is grounded.

4. The inductor zero-current detection circuit according to claim 1, characterized in that, The coupling circuit includes resistors R11 and R12 and capacitor C6. One end of resistor R11 is connected to the other end of input inductor L1, the other end of resistor R11 is connected to one end of capacitor C6, the other end of capacitor C6 is connected to pin 2 of comparator U1, and the two ends of resistor R12 are connected to the two ends of capacitor C6 respectively.

5. The inductor zero-current detection circuit according to claim 1, characterized in that, The coupling circuit includes resistors R11 and R12 and capacitor C6. One end of resistor R11 is connected to the other end of input inductor L1, the other end of resistor R11 is connected to one end of capacitor C6, the other end of capacitor C6 is connected to pin 2 of comparator U1, one end of resistor R12 is connected to one end of resistor R11, and the other end of resistor R12 is connected to the other end of capacitor C6.

6. The inductor zero-current detection circuit according to claim 1, characterized in that, The coupling circuit also includes a diode D1, the negative terminal of which is connected to the other end of the capacitor C6, and the positive terminal of the diode D1 is grounded.

7. The inductor zero-current detection circuit according to claim 1, characterized in that, The 4th pin of the comparator U1 is grounded, the 5th pin of the comparator U1 is connected to the negative terminal of the diode D3, the positive terminal of the diode D3 is connected to the 2nd pin of the comparator U1, and the negative terminal of the diode D3 is connected to a 5V voltage.

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