WO2023116398A1

WO2023116398A1 - Energy-saving control method for csr high-frequency pwm rectifier circuit

Info

Publication number: WO2023116398A1
Application number: PCT/CN2022/136405
Authority: WO
Inventors: 薛洛良
Original assignee: 薛洛良
Priority date: 2021-12-21
Filing date: 2022-12-03
Publication date: 2023-06-29
Also published as: CN114244159A

Abstract

Disclosed is an energy-saving control method for a CSR high-frequency PWM rectifier circuit, comprising: enabling two pulse wave edges of two phases of three-phase alternating current to be overlapped according to the numerical value change of the voltage of each line of the three-phase alternating current in a rectifier circuit and a characteristic that the rectifier circuit works at a high frequency, wherein the overlapping comprises that the overlapping time of the two pulse wave edges is equal to the sum of the turn-on time and the turn-off time of switching tubes, so that one pulse front edge or rear edge of a switching signal is in a soft switching state or in a state that low voltage is cut off, and thus, loss during the switching of the switching tubes is reduced. According to the energy-saving control method, the switching loss can be reduced, the cost is reduced, the energy consumption is reduced, the service life is prolonged, and the present invention is safe and reliable.

Description

Energy saving control method of CSR high frequency PWM rectifier circuit

technical field

The invention relates to the technical field of CSR high-frequency PWM rectifier circuits, in particular to an energy-saving control method for CSR high-frequency PWM rectifier circuits.

Background technique

The CSR high-frequency PWM rectifier circuit is a current source step-down rectifier circuit (also called Buck rectifier circuit). The high-power rectifier circuit uses a three-phase input power supply. As shown in Figure 1, the circuit has a PFC function that can make the input power factor greater than 0.99. , At the same time, the harmonic generated by the circuit is very small, and the output power control precision is high. High-frequency PWM rectifier circuits are widely used in rectifier circuits. The CSR circuit realizes high-frequency operation through high-power switching tubes, and the switching tubes use devices such as insulated gate bipolar transistors (IGBTs) in high-voltage applications. The on-off control of the switching tube is completed by adjusting the on-pulse width PWM according to the needs of the load size. The determination of the pulse width is obtained by modulating the triangular wave carrier with a sine wave. Because the power supply is a sine wave, in order to improve the power factor, a sine wave is used. The wave is used as a modulation wave, so that the harmonics generated by the circuit are the smallest. It is also called SPWM high-frequency rectification. S stands for sine wave, which is represented by PWM below.

technical problem

Now high-power rectifiers are controlled by DSP digital signals, and various algorithms are used to generate PWM control signals. The principle is the same as that of triangular wave modulation. The loss of the rectifier circuit is mainly the loss during the IGBT switching process and conduction, and the loss in the switching process accounts for the majority. The most serious power consumption is in the transient process of switching off the switching tube. Therefore, reducing the loss in the switching process is the main task of the present invention. .

technical solution

In view of this, the present invention provides a safe and reliable energy-saving control method for a CSR high-frequency PWM rectifier circuit that can reduce switching loss, reduce cost, save energy consumption, and prolong service life.

In order to realize the object of the present invention, the following technical solutions can be taken:

An energy-saving control method for a CSR high-frequency PWM rectifier circuit. According to the numerical change of each line voltage of the three-phase alternating current in the rectifying circuit and the characteristics of the high-frequency operation of the rectifying circuit, the edges of the two pulse waves of the two phases of the three-phase alternating current are Overlap; the overlap includes that the overlapping time of two pulse wave edges is equal to the sum of the on-time and off-time of the switch tube, so that the leading or trailing edge of a pulse of the switching signal is in a soft switching state, or in a cut-off low voltage state.

Beneficial effect

The beneficial effects of the present invention are: 1) The present invention makes use of the characteristics of each line voltage of the three-phase alternating current in the rectification circuit to change in value every moment and the circuit works at a high frequency, so that the two pulse wave edges of the two line voltages Overlapping, so that one front or rear edge of the switch is in the soft switching state, or in the low-voltage cut-off state, so as to reduce the switching process loss of the switching tube; 2) The present invention greatly reduces the cost, saves energy consumption, and prolongs the service life; 3) The present invention is a technical upgrade of the prior art and is suitable for general promotion.

Description of drawings

Fig. 1 is the circuit diagram of the CSR high-frequency PWM rectifier circuit of the energy-saving control method of the CSR high-frequency PWM rectifier circuit of the embodiment of the present invention;

2 is a sine wave modulation diagram of an energy-saving control method for a CSR high-frequency PWM rectifier circuit according to an embodiment of the present invention;

3 is a sine wave decomposition modulation diagram of an energy-saving control method for a CSR high-frequency PWM rectifier circuit according to an embodiment of the present invention;

Fig. 4 is the overlapping modulation diagram of the front and rear edges of two pulses of the energy-saving control method of the CSR high-frequency PWM rectifier circuit according to the embodiment of the present invention;

5 is a sine wave and pulse overlapping modulation diagram of the energy-saving control method of the CSR high-frequency PWM rectifier circuit according to the embodiment of the present invention.

Embodiments of the present invention

Detailed ways

The invention will be further described in detail below in conjunction with the drawings and embodiments of the invention.

Example 1

The commutation of the three-phase CSR PWM high-frequency rectifier of the present invention is carried out between the upper and lower bridge arm switching tubes of adjacent phases, referring to Fig. 1, wherein V1, V2, V3 are A, B, C three-phase upper bridge arms Switch tubes, V4, V5, and V6 are A, B, and C three-phase lower bridge arm switch tubes.

For example, when V1 of the upper bridge arm is turned on and the lower bridge arm is turned on, V5 or V6 is turned on, and the actions of other tubes can be deduced by analogy. Due to the structural characteristics of the CSR circuit, the control waveform of the three-level PWM must be used, so as to form a current path.

The general PWM energy-saving modulation is shown in Figure 2. The uppermost figure a in Figure 2 is a three-phase sine wave, and Ua, Ub, and Uc represent three-phase voltages. In Figure 2, V1, V2, V3, V4, V5, and V6 are horizontal The figure represents the schematic diagram of the turn-on of the six switch tubes according to PWM modulation. In order to reduce the loss of the switch tubes, the corresponding switch tubes in the 60° degree area where the absolute value of each phase voltage is the largest remain on. In the range of 240° to 300°, the upper bridge arm tube V1 remains normally on, and the lower bridge arm tubes V5 and V6 of the B and C phases are respectively turned on according to PWM modulation to form a current path; in the range of 240° to 300° The bridge arm tube V4 remains normally on, and the upper bridge arm tubes V2 and V3 of the B and C phases are respectively turned on according to the PWM modulation to form a current path; this reduces the number of actions of the V1 and V4 switch tubes, that is, reduces the switching process loss. The operation situation in the interval of 60° of the maximum absolute value of the absolute value of each tube voltage of the two phases B and C can be deduced by analogy. As shown in Figure 2, the conduction diagram of V1, V5, and V6 in the interval from 60° to 120°, in the figure, the switches of V5 and V6 are independent of each other.

Referring to Figures 1 to 5, this energy-saving control method for a CSR high-frequency PWM rectifier circuit, according to the numerical change of each line voltage of the three-phase AC in the rectifier circuit and the characteristics of the rectifier circuit working at high frequency, makes the three-phase AC The edges of the two pulse waves of the two phases overlap; the overlap includes the overlapping time of the edges of the two pulse waves being equal to the sum of the turn-on time and the turn-off time of the switch tube, so that the leading edge or trailing edge of a pulse of the switching signal is in a soft switching state, Or it is in the state of cutting off the low voltage to reduce the loss of the switching process of the switching tube.

Referring to Fig. 2, in this embodiment, any point D on the abscissa in the three-phase AC voltage diagram, the line voltage values passing through point D are respectively: AB line voltage Uab is the absolute value from point F to point G; BC line voltage Ubc It is the absolute value from point E to point G; the AC line voltage Uca is the absolute value from point E to point F.

In the rectifier circuit, the AC line voltage value at point D is small, and it does not work if it does not deliver power to the load, so there is no need to discuss it. In Figure 2, in point D, the B-phase lower bridge arm tube V5 is continuously connected, and the A and C two-phase upper bridge arm tubes V1 and tube V3 near point D are respectively turned on in time-sharing, which is controlled according to the PWM principle. The conduction voltage is shown as V1, V3, and V5 in Fig. 3 .

Referring to Figure 3, in the lowermost voltage coordinate system U in Figure 3, the Uab height represents the voltage value between AB lines, that is, the absolute value from point F to point G, and the width represents the current conduction time between AB phases; the height of Ubc represents BC The line-to-line voltage value, that is, the absolute value from point E to point G, and the width represents the conduction time of the current between the BC phases. The invention overlaps and modulates two pulses together, utilizes the characteristic of three-phase voltage variation, completes a rising or falling edge soft switching process of a switching tube or reduces the switching voltage amplitude.

Referring to Fig. 4, this Fig. 4 shows the two-phase voltage pulse values near the point D on the abscissa of Fig. 3, the low pulse represents the voltage Uab, and the high pulse represents the voltage Ubc. According to the normal energy-saving modulation, at this point, the switch tube V5 of the lower bridge arm of the B phase is always on, and the upper bridge arm tube V3 of the C phase at point X in Figure 4 is turned on, and the turn-on voltage value is the height shown by the line segment 1. The upper bridge arm tube V1 is turned on, because the voltage value Ubc is greater than Uab at this point, although the tube V1 is turned on but there is no current, it is a soft turn-on without loss, and the tube V3 starts to turn off when it reaches the Z point. When the Z point V3 is turned off, it only bears the line segment 3 The voltage, the voltage value is less than the value of line segment 1, forming a soft turn-off, reducing the turn-off power loss and voltage stress. At the end of the Uab voltage pulse, the switch tube V1 only bears the voltage value of the line segment 4, avoiding the voltage value of the line segment 1.

The maximum power consumption of the switching tube characteristics is in the turn-off transient process, so the two intersecting pulse voltages are arranged with the high one in front and the low one in the back. The high pulse also has the effect of reducing loss, but the effect is not as good as the protection of the switching tube after the low pulse. Therefore, in the switching process, the characteristics of different amplitudes of the three-phase voltage at different times are used to complete soft switching or low-voltage switching to reduce losses. In this process, the pulse width of Uab and Ubc modulation conduction is modulated according to the PWM principle.

In this embodiment, the symmetry of the above-mentioned loop operation is not very good, and because the high-voltage IGBT tube operating frequency is low, thus affecting the input power factor of the loop and increasing harmonics, in order to solve these two problems, the operating frequency of the loop can be increased, The problem of input power factor and harmonics is solved when the frequency is greater than 20 kHz.

In order to increase the operating frequency of the entire circuit, the mature CSR high-frequency SPWM rectifier circuit parallel superposition technology is used to improve the power factor, reduce harmonics, and increase power output. In addition, it can be seen from the three-phase voltage changes in Figure 2 that every 30° is a cycle of voltage change control. After analyzing the working method of the 30° switch tube, it can be cycled every 30° in the future.

The present invention makes use of the characteristics of each line voltage of the three-phase alternating current in the rectification circuit to change in value every moment and the circuit works at a high frequency, so that the edges of the two pulse waves of the two line voltages overlap, so that a front or back of the switch The edge is in the soft switching state, or it is in the low voltage state to reduce the switching process loss of the switching tube.

Referring to Fig. 5, a in Fig. 5 shows the 60° three-phase voltage variation, select point D, b in the figure shows two voltage pulse values at point D, the low pulse represents the voltage Uab, and the high pulse represents the voltage Ubc. At point X in Figure 5b, the switch tube V5 of the lower bridge arm of phase B is in the long-on state, the switch tube V3 of the upper bridge arm of phase C is turned on, and the turn-on voltage value is the height shown by line segment 1. At point Y, let the upper bridge arm of phase A The switch tube V1 is turned on, the voltage value Ubc at this point is greater than Uab, and there is no current during the turn-on process of the upper bridge arm tube V1 of phase A, forming a soft turn-on of V1, which saves the turn-on loss. At point Z, the switch tube V3 of the upper bridge arm of the C phase is turned off, because there is already a Uab voltage, as shown in line segment 2, the turn-off voltage value is reduced by the amplitude of line segment 3 to form a soft turn-off, and the switch tube V3 reduces the power loss when it is turned off. Therefore, during the switching process, the characteristics of different amplitudes of the three-phase voltage at different times are used to complete soft switching or low-voltage switching to reduce the loss of the rectifier circuit.

In this embodiment, preferably, the overlapping of the edges of the two pulse waves includes overlapping the trailing edge of a preceding pulse and the leading edge of a trailing pulse of the switch signal.

The commutation of the three-phase CSR PWM high-frequency rectifier of the present invention is carried out between the upper and lower bridge arm switch tubes of adjacent phases. In this embodiment, the edges of the two pulse waves of the two line voltages are overlapped so that the trailing edge of the previous pulse overlaps with the leading edge of the latter pulse, and a soft switching state appears at the overlapping point, or it is in a state of breaking low voltage to reduce loop loss .

The above is only a preferred embodiment of the present invention, and does not therefore limit the patent scope of the present invention. Under the inventive concept of the present invention, the equivalent structural transformation made by using the description of the present invention and the contents of the accompanying drawings, or direct/indirect use All other relevant technical fields are included in the patent protection scope of the present invention.

Claims

An energy-saving control method for a CSR high-frequency PWM rectifier circuit, which is characterized in that: according to the numerical change of each line voltage of the three-phase alternating current in the rectifying circuit and the characteristics of the rectifying circuit working at high frequency, the two phases of the three-phase alternating current The overlapping of two pulse wave edges; the overlap includes the overlapping time of two pulse wave edges is equal to the sum of the switch on time and the off time, so that the leading or trailing edge of a pulse of the switching signal is in the soft switching state, or in the cut-off state low voltage state.