CN109831187B - Variable-frequency triangular carrier generation circuit - Google Patents

Abstract

The invention discloses a frequency-variable triangular carrier generating circuit, which comprises: an inverted sine wave generating circuit and a carrier generating circuit connected to each other; wherein, the inverted sine wave generating circuit is used to generate an inverted sine wave current at an output end; The circuit is used to generate a triangular carrier corresponding to an inverted sine wave current. The frequency-variable triangular carrier generating circuit of the present invention has the ability to cope with the voltage fluctuation of the power grid, and when used in the triangular carrier of the single-phase power factor corrector, the switching loss of the used power switch can be reduced, and the efficiency of the whole machine can be improved.

Description

A frequency variable triangular carrier generator circuit

technical field

The invention relates to the technical field of power electronic conversion, in particular to a frequency-variable triangular carrier generating circuit.

Background technique

In the power electronic converter, the driving signal of the switching device is usually generated by comparing the modulating wave and the triangular carrier, and the frequency of the carrier directly determines the switching frequency of the switching device. Taking a single-phase active power factor corrector (APFC) as an example, the carrier frequency in a common APFC circuit is generally fixed, which leads to a significant increase in the switching loss of the device near the peak of the grid voltage. The triangular carrier generator circuit.

After searching for the prior art of the frequency variable triangular carrier generating circuit, it is found that there are some defects in the existing circuit:

The application number published in 2006 by Yang Xijun et al. is: 200610023250.2, titled: A triangular wave generation circuit with periodic modulation of switching frequency is proposed in the patent of the triangular wave generation circuit with periodic modulation of switching frequency. The design is complicated and the development cost is high; the application number published by Xing Kaipeng et al in 2017 is: 201610651536.9, named: A pulse frequency modulation carrier generation circuit The patent proposes a pulse frequency modulation carrier generation circuit, using The hardware circuit implements a triangular carrier with variable frequency, but it cannot work normally when the grid voltage drops, and its applicability is low; another application number published by Xing Kaipeng et al in 2017 is: 201610651641.2, named: for pulse frequency The patent for modulated carrier generation circuit proposes a carrier generation circuit for pulse frequency modulation. It also uses a hardware circuit to realize a triangular carrier with variable frequency. The same doesn't work when descending.

To sum up, in practice, digital control is generally used to realize the change of switching frequency, which requires the use of digital controllers such as DSP. The structure is complex, the design process is cumbersome, the cost is high, and it is not easy to achieve rapid system construction. However, the existing frequency-variable carrier generating circuit using analog devices cannot work normally when the grid voltage fluctuates.

SUMMARY OF THE INVENTION

Aiming at the problems existing in the above-mentioned prior art, the present invention proposes a frequency-variable triangular carrier generating circuit, which uses hardware to build a frequency-variable carrier generating circuit, which saves hardware costs and algorithm design overhead; the carrier frequency is inverse sine The wave change law reduces the switching frequency when the grid voltage is high, and the switching loss is reduced in view of the high grid current when the grid voltage is high.

In order to solve the above-mentioned technical problems, the present invention is achieved through the following technical solutions:

The present invention provides a frequency-variable triangular carrier generating circuit, comprising: an inverted sine wave generating circuit and a carrier generating circuit connected to each other; wherein,

The inverted sine wave generating circuit is used to generate an inverted sine wave current at the output end;

The carrier wave generating circuit is used for generating a triangular carrier wave corresponding to the inverse sine wave current.

Preferably, the inverted sine wave generating circuit includes: a rectifier circuit, a subtractor circuit and a constant current source circuit; wherein,

The rectifier circuit includes: a DC source circuit and a full-wave rectifier circuit; the DC source circuit is used to rectify and filter the input AC voltage to obtain a DC voltage, and then sample and input it to the subtractor circuit; the full-wave rectifier circuit For rectifying the input AC voltage to obtain a full-wave sinusoidal voltage; then sampling and inputting it to the subtractor circuit;

The subtractor circuit is connected to the rectifier circuit, and is used for subtracting the sine full-wave voltage obtained by the full-wave rectifier circuit from the DC voltage obtained by the DC source circuit to obtain an inverted sine wave voltage;

The constant current source circuit is connected to the subtractor circuit, and is used for converting the inverse sine wave voltage obtained by the subtractor circuit into an inverse sine wave current.

Preferably, the DC source circuit includes an AC power supply us, diodes D1, D2, D3, D4, resistors R1, R2, R3, R4, a capacitor C1 and a junction field effect transistor T1; the full-wave rectifier circuit includes an AC Power supply us, diodes D5, D6, D7, D8, resistors R5, R6 and junction field effect transistor T2; the subtractor circuit includes resistors R7, R8, R9, R10 and an operational amplifier OP1; the constant current source circuit includes Resistors R11, R12, Zener diode ZD1 and transistor Q1; among them,

The anodes of the diodes D1 and D3 are respectively connected to the two ends of the AC power supply us, the cathode of the diode D2 is connected to the anode of the diode D1, the cathode of the diode D4 is connected to the anode of the diode D3, The cathodes of the diodes D1 and D3 are connected to one end of the capacitor C1, the anodes of the diodes D2 and D4 are connected to the other end of the capacitor C1, and are grounded at the same time; the resistors R1 and R2 are connected in series, and the resistor R1 The other end of the resistor R2 is connected to the cathode connection point of the diodes D1 and D3, the other end of the resistor R2 is connected to the anode connection point of the diodes D2 and D4, and the connection point of the resistors R1 and R2 is connected to the junction The gates of the field effect transistors T1 and T2 are connected; the resistors R3 and R4 are connected in series, the other end of the resistor R3 is connected to the cathode connection point of the diodes D1 and D3, and the other end of the resistor R4 is connected to the junction. The drain of the junction field effect transistor T1 is connected, the source of the junction field effect transistor T1 is grounded, the connection point of the resistors R3 and R4 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to The non-inverting input end of the operational amplifier OP1 is connected to one end of the resistor R7 at the same time, and the other end of the resistor R7 is grounded; the anodes of the diodes D5 and D7 are respectively connected to the two ends of the AC power supply us, and the diodes The cathode of D6 is connected to the anode of the diode D5, the cathode of the diode D8 is connected to the anode of the diode D7, the cathodes of the diodes D5 and D7 are connected, the anodes of the diodes D6 and D8 are connected, and the resistor R5 and R6 are connected in series, the other end of the resistor R5 is connected to the connection point of the diodes D5 and D7, the other end of the resistor R6 is connected to the drain of the junction field effect transistor T2, the junction field The source of the effect transistor T2 is connected to the anodes of the diodes D6 and D8 and grounded, the connection point of the resistors R5 and R6 is connected to one end of the resistor R9, and the other end of the resistor R9 is connected to the operational amplifier The inverting input terminal of OP1 is connected to one end of the resistor R10 at the same time, the other end of the resistor R10 is connected to the output terminal of the operational amplifier OP1, and the output terminal of the operational amplifier OP1 is respectively connected to the resistor R11, One end of R12 is connected, the other end of the resistor R11 is connected to the base of the transistor Q1, and at the same time is connected to the cathode of the Zener diode ZD1, the anode of the Zener diode ZD1 is grounded, and the other end of the resistor R12 is connected to the ground. One end is connected to the emitter of the triode Q1.

Preferably, the carrier generation circuit includes: an internal current source I1, an internal reference voltage Vr1, a switching device T3, a capacitor C2, a Zener diode ZD2 and a hysteresis comparator OP2; wherein,

The anode of the zener diode ZD2 is connected to one end of the capacitor C2 and is grounded at the same time, and the cathode of the zener diode ZD2 is connected to the other end of the capacitor C2, and is simultaneously connected to the collector of the transistor Q1 and the other end of the capacitor C2. The source of the switching device T3 is connected to the non-inverting input terminal of the hysteresis comparator OP2, the output terminal of the hysteresis comparator OP2 is connected to the gate of the switching device T3, and the junction field effect transistor T1 The drain of the chip is grounded, the internal current source I1 of the chip is connected to the source of the switching device T3, the inverting input terminal of the hysteresis comparator OP2 is connected to the internal reference voltage Vr1, and the two terminals of the capacitor C2 The terminal voltage is the output of the carrier generation circuit.

Compared with the prior art, the present invention has the following advantages:

(1) The frequency-variable triangular carrier generating circuit of the present invention adopts hardware to build a frequency-variable carrier generating circuit, which saves hardware cost and algorithm design overhead compared with the general use of a microcontroller to generate the same carrier;

(2) In the frequency-variable triangular carrier generating circuit of the present invention, the carrier frequency shows an inverse sine wave variation law. When used for the triangular carrier of the single-phase power factor corrector, the switching frequency when the power grid is high voltage is reduced. When the network voltage is higher, the network flow is also higher, which reduces the switching loss;

(3) In the frequency-variable triangular carrier generating circuit of the present invention, the carrier frequency changes with the magnitude of the power grid voltage, which belongs to the comprehensive modulation of pulse width and pulse frequency modulation, and the center frequency is fully diffused, so that the interference frequency presents a broadband distribution, eliminating the high interference point, which helps to reduce EMI;

(4) Compared with the frequency variable carrier generation circuit built by the existing analog device, the frequency variable triangular carrier generating circuit of the present invention adopts the related circuit of the junction field effect transistor. When the network voltage drops, the junction field The on-resistance of the effect transistor increases, changing the voltage dividing ratio of the voltage dividing branch, so as to make up for the overall decrease of the carrier frequency caused by the drop of the grid voltage to the greatest extent, and increase the ability to resist grid voltage fluctuations, the scope of application is expanded, and the stability improve.

Of course, it is not necessary for any product embodying the present invention to achieve all of the advantages described above simultaneously.

Description of drawings

Embodiments of the present invention are further described below in conjunction with the accompanying drawings:

1 is a schematic structural diagram of a frequency-variable triangular carrier generating circuit according to an embodiment of the present invention;

2 is a schematic structural diagram of a frequency-variable triangular carrier generating circuit according to a preferred embodiment of the present invention;

3 is a circuit schematic diagram of a frequency-variable triangular carrier generating circuit according to an embodiment of the present invention;

FIG. 4 is an output voltage waveform diagram of a full-wave rectifier circuit composed of D5 to D8 according to an embodiment of the present invention;

FIG. 5 is a waveform diagram of the output terminal voltage of the operational amplifier OP1 according to an embodiment of the present invention;

FIG. 6 is a voltage waveform diagram across the capacitor C2 according to an embodiment of the present invention.

Label description: 11-inverted sine wave generating circuit, 12-carrier generating circuit;

111-rectifier circuit, 112-subtractor circuit, 113-constant current source circuit;

1111-DC source circuit, 1112-full-wave rectifier circuit.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following implementation. example.

The frequency-variable triangular carrier generating circuit of the present invention includes: an inverted sine wave generating circuit 11 and a carrier generating circuit 12 connected to each other; wherein, the inverted sine wave generating circuit 11 is used to generate an inverted sine wave current at the output end; the carrier generating circuit 12 Used to generate a triangular carrier corresponding to an inverted sine wave current.

In a preferred embodiment, the inverted sine wave generating circuit 11 includes a rectifier circuit 111 , a subtractor circuit 112 and a constant current source circuit 113 . The rectifier circuit 111 includes: a DC source circuit 1111 and a full-wave rectifier circuit 1112; the DC source circuit 1111 is used to rectify and filter the input AC voltage to obtain a DC voltage, which is then sampled and input to the subtractor circuit 112; the full-wave rectifier circuit 1112 It is used to rectify the input AC voltage to obtain a sine full-wave voltage; and then sample the input to the subtractor circuit 112 . The subtractor circuit 112 is connected to the rectifier circuit 111, and is used for subtracting the sine full-wave voltage obtained by the full-wave rectifier circuit 1112 from the DC voltage obtained by the DC source circuit 1111 to obtain an inverted sine wave voltage. The constant current source circuit 113 is connected to the subtractor circuit 112, and is used for converting the inverse sine wave voltage obtained by the subtractor circuit 112 into an inverse sine wave current.

FIG. 3 is a schematic circuit diagram of a frequency-variable triangular carrier generating circuit according to an embodiment of the present invention.

Please refer to FIG. 3 . In this embodiment, the inverted sine wave generating circuit is shown in part 1 in FIG. 3 , and the carrier generating circuit is shown in parts 2 and 3 in FIG. 3 . The third part is the internal module of the chip IR1155S. The DC source circuit includes an AC power supply us, diodes D1, D2, D3, D4, resistors R1, R2, R3, R4, a capacitor C1 and a junction field effect transistor T1; the full-wave rectifier circuit includes an AC power supply us, diodes D5, D6, D7, D8, resistors R5, R6 and junction field effect transistor T2; the subtractor circuit includes resistors R7, R8, R9, R10 and operational amplifier OP1; the constant current source circuit includes resistors R11, R12, Zener diode ZD1 and transistor Q1 . Among them, the anodes of diodes D1 and D3 are respectively connected to the two ends of the AC power supply us, the cathode of diode D2 is connected to the anode of diode D1, the cathode of diode D4 is connected to the anode of diode D3, and the cathodes of diodes D1 and D3 are connected to capacitor C1 One end of the diodes D2 and D4, the anodes of the diodes D2 and D4 are connected to the other end of the capacitor C1 and grounded; the resistors R1 and R2 are connected in series, the other end of the resistor R1 is connected to the cathode connection point of the diodes D1 and D3, and the other end of the resistor R2 is connected to the diode The anode connection point of D2 and D4, the connection point of resistors R1 and R2 are connected to the gates of the junction field effect transistors T1 and T2; the resistors R3 and R4 are connected in series, and the other end of the resistor R3 is connected to the cathode connection point of the diodes D1 and D3. , the other end of the resistor R4 is connected to the drain of the junction field effect transistor T1, the source of the junction field effect transistor T1 is grounded, the connection point of the resistors R3 and R4 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to The non-inverting input terminal of the operational amplifier OP1 is connected to one end of the resistor R7 at the same time, and the other end of the resistor R7 is grounded; the anodes of the diodes D5 and D7 are respectively connected to the two ends of the AC power supply us, and the cathode of the diode D6 is connected to the anode of the diode D5. The cathode of diode D8 is connected to the anode of diode D7, the cathodes of diodes D5 and D7 are connected, the anodes of diodes D6 and D8 are connected, resistors R5 and R6 are connected in series, the other end of resistor R5 is connected to the junction of diodes D5 and D7, and the resistor R6 The other end of the junction field effect transistor T2 is connected to the drain, the source of the junction field effect transistor T2 is connected to the anodes of the diodes D6 and D8 and grounded, and the connection points of the resistors R5 and R6 are connected to one end of the resistor R9. The other end of R9 is connected to the inverting input terminal of the operational amplifier OP1, and at the same time is connected to one end of the resistor R10, the other end of the resistor R10 is connected to the output terminal of the operational amplifier OP1, and the output terminal of the operational amplifier OP1 is respectively connected with the resistor R11, R12. One end is connected, the other end of the resistor R11 is connected to the base of the transistor Q1, and at the same time is connected to the cathode of the Zener diode ZD1, the anode of the Zener diode ZD1 is grounded, and the other end of the resistor R12 is connected to the emitter of the transistor Q1.

In addition, the carrier generation circuit of this embodiment includes: an internal current source I1, an internal reference voltage Vr1, a switching device T3, a capacitor C2, a Zener diode ZD2, and a hysteresis comparator OP2; wherein the anode of the Zener diode ZD2 and the capacitor One end of C2 is connected to the ground at the same time, and the cathode of the zener diode ZD2 is connected to the other end of the capacitor C2, and at the same time is connected to the collector of the transistor Q1, the source of the switching device T3 and the non-inverting input of the hysteresis comparator OP2. The output terminal of the loop comparator OP2 is connected to the gate of the switching device T3, the drain of the junction field effect transistor T1 is grounded, the internal current source I1 of the chip is connected to the source of the switching device T3, and the reverse input of the hysteresis comparator OP2 The terminal is connected to the internal reference voltage Vr1, and the voltage across the capacitor C2 is the output of the carrier generating circuit.

The third part in Figure 3 is the internal module of the APFC analog control chip IR1155S, which connects the capacitor C2 and the cathode connection point of the Zener diode ZD2 to the No. 2 pin FREQ of the IR1155S.

The selection of the above components in this example:

Input AC voltage us: 220V, 50Hz;

Diodes D1-D8: 500V, 10A/100℃;

Capacitor C1: 500V, 1μF;

Capacitor C2: 50V, 40pF;

Resistor R1: 400kΩ

Resistor R2: 20kΩ

Resistor R3: 298kΩ

Resistor R4: 12kΩ

Resistor R5: 308kΩ

Resistor R6: 5kΩ

Resistor R7: 10kΩ

Resistor R8: 10kΩ

Resistor R9: 10kΩ

Resistor R10: 10kΩ

Resistor R11: 4.7kΩ

Resistor R12: 470kΩ

Transistor Q1: PNP, 50V;

Zener diodes ZD1, ZD2: 5V, 1N4733;

Operational amplifier OP1: LM358;

Junction field effect transistors T1, T2: J2N3819.

When the circuit is working: the DC source circuit in the rectifier circuit rectifies and filters the input AC voltage to obtain a DC voltage, which is sampled and input to the subtractor by the resistor R4 and the junction field effect transistor T1. The voltage is rectified to obtain a sine full-wave rectified voltage. As shown in Figure 4, it is sampled and input to the subtractor by the resistor R6 and the junction field effect transistor T2. After subtracting the full-wave rectified voltage from the DC voltage, the inverted sine wave voltage waveform is obtained, as shown in the figure 5 shown. The inverted sine wave voltage signal is connected to the constant current source circuit to obtain the inverted sine wave output current. This current and the internal current source of the IR1155S chip together charge the capacitor C2. When the capacitor voltage rises to Vr1, the output of the hysteresis comparator OP2 is positive, so that the switching device T3 is turned on, and the capacitor C2 is discharged. When the capacitor C2 is 0V, the OP2 Reset, C2 starts charging again. In this way, a triangular carrier with an inverted sine wave frequency is formed. As shown in Figure 6, when the grid voltage drops, the rectified output voltage decreases, and the voltage on the resistor R2 decreases, that is, the junction field effect transistor T1 , The gate voltage of T2 decreases, and the on-resistance of T1 and T2 increases, so as to keep the voltage sampled on R4 and T1, R6 and T2 approximately unchanged, so that the Zener diode ZD1 can work normally in the reverse phase breakdown state, Ensure the operation effect of the circuit when the grid voltage fluctuates.

The invention adopts the hardware circuit to build a frequency-variable triangular carrier generating circuit with the ability to resist power grid voltage fluctuations, and can be applied to single-phase active power factor correctors and single-phase active power filters. Compared with the present invention, the cost of the present invention is lower, and due to the change of switching frequency, the hardware circuit designed by the present invention reduces EMI. The inverted sine wave circuit used makes the carrier frequency low when the voltage is high, which reduces the loss of the switching device.

Only preferred embodiments of the present invention are disclosed herein, and the present specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present invention, rather than limiting the present invention. Any modifications and changes made by those skilled in the art within the scope of the description should fall within the protection scope of the present invention.

Claims (1)

1. a frequency-variable triangular carrier generating circuit, is characterized in that, comprises: the inverse sine wave generating circuit and the carrier wave generating circuit that are connected to each other; Wherein, the inverse sine wave generating circuit is used for making the output terminal produce the inverse sine wave current ; The carrier generating circuit is used to generate a triangular carrier corresponding to the inverse sine wave current; The inverted sine wave generating circuit includes: a rectifier circuit, a subtractor circuit and a constant current source circuit; wherein, The rectifier circuit includes: a DC source circuit and a full-wave rectifier circuit; the DC source circuit is used to rectify and filter the input AC voltage to obtain a DC voltage, and then sample and input it to the subtractor circuit; the full-wave rectifier circuit For rectifying the input AC voltage to obtain a full-wave sinusoidal voltage; then sampling and inputting it to the subtractor circuit; The subtractor circuit is connected to the rectifier circuit, and is used for subtracting the sine full-wave voltage obtained by the full-wave rectifier circuit from the DC voltage obtained by the DC source circuit to obtain an inverted sine wave voltage; The constant current source circuit is connected with the subtractor circuit, and is used for converting the inverse sine wave voltage obtained by the subtractor circuit into an inverse sine wave current; The DC source circuit includes an AC power supply us, diodes _D1 , D2, D3, D4, resistors R1, R2, R3, R4, a capacitor C1 and a junction field effect transistor T1; the full-wave _rectifier circuit includes an AC power supply us , diodes D5, D6, D7, D8, resistors R5, R6 and junction field effect transistor T2; the subtractor circuit includes resistors R7, R8, R9, R10 and an operational amplifier OP1; the constant current source circuit includes a resistor R11 , R12, Zener diode ZD1 and transistor Q1; among them, The anodes of the diodes D1 and D3 are respectively connected to the two ends of the AC power supply us, the cathode of the diode D2 is connected to the anode of the diode D1, the cathode of the diode D4 is connected to the anode of the diode D3, The cathodes of the diodes D1 and D3 are connected to one end of the capacitor C1, the anodes of the diodes D2 and D4 are connected to the other end of the capacitor C1, and are grounded at the same time; the resistors R1 and R2 are connected in series, and the resistor R1 The other end of the resistor R2 is connected to the cathode connection point of the diodes D1 and D3, the other end of the resistor R2 is connected to the anode connection point of the diodes D2 and D4, and the connection point of the resistors R1 and R2 is connected to the junction The gates of the field effect transistors T1 and T2 are connected; the resistors R3 and R4 are connected in series, the other end of the resistor R3 is connected to the cathode connection point of the diodes D1 and D3, and the other end of the resistor R4 is connected to the junction. The drain of the junction field effect transistor T1 is connected, the source of the junction field effect transistor T1 is grounded, the connection point of the resistors R3 and R4 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to The non-inverting input end of the operational amplifier OP1 is connected to one end of the resistor R7 at the same time, and the other end of the resistor R7 is grounded; the anodes of the diodes D5 and D7 are respectively connected to the two ends of the AC power supply us, and the diodes The cathode of D6 is connected to the anode of the diode D5, the cathode of the diode D8 is connected to the anode of the diode D7, the cathodes of the diodes D5 and D7 are connected, the anodes of the diodes D6 and D8 are connected, and the resistor R5 and R6 are connected in series, the other end of the resistor R5 is connected to the connection point of the diodes D5 and D7, the other end of the resistor R6 is connected to the drain of the junction field effect transistor T2, the junction field The source of the effect transistor T2 is connected to the anodes of the diodes D6 and D8 and grounded, the connection point of the resistors R5 and R6 is connected to one end of the resistor R9, and the other end of the resistor R9 is connected to the operational amplifier The inverting input terminal of OP1 is connected to one end of the resistor R10 at the same time, the other end of the resistor R10 is connected to the output terminal of the operational amplifier OP1, and the output terminal of the operational amplifier OP1 is respectively connected to the resistor R11, One end of R12 is connected, the other end of the resistor R11 is connected to the base of the transistor Q1, and at the same time is connected to the cathode of the Zener diode ZD1, the anode of the Zener diode ZD1 is grounded, and the other end of the resistor R12 is connected to the ground. One end is connected to the emitter of the triode Q1; The carrier generation circuit includes: an internal current source I1 of the chip, an internal reference voltage Vr1, a switching device T3, a capacitor C2, a Zener diode ZD2 and a hysteresis comparator OP2; wherein, The anode of the zener diode ZD2 is connected to one end of the capacitor C2 and is grounded at the same time, and the cathode of the zener diode ZD2 is connected to the other end of the capacitor C2, and is simultaneously connected to the collector of the transistor Q1 and the other end of the capacitor C2. The source of the switching device T3 is connected to the non-inverting input terminal of the hysteresis comparator OP2, the output terminal of the hysteresis comparator OP2 is connected to the gate of the switching device T3, and the junction field effect transistor T1 The drain of the chip is grounded, the internal current source I1 of the chip is connected to the source of the switching device T3, the inverting input terminal of the hysteresis comparator OP2 is connected to the internal reference voltage Vr1, and the two terminals of the capacitor C2 The terminal voltage is the output of the carrier generation circuit.

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