Energy-saving control method of CSR high-frequency PWM rectifier circuit

Abstract

The application discloses an energy-saving control method of a CSR high-frequency PWM rectifier circuit. According to the value change of each line voltage of three-phase alternating current in a rectifier circuit and the characteristic that the rectifier circuit works at a high frequency, the two pulse wave edges of two phases of the three-phase alternating current are overlapped. The overlapping time of the overlapping of the two pulse wave edges is equal to the sum of the turn-on time and the turn-off time of a switching tube, so that the front edge or the rear edge of a pulse of a switching signal is in a soft switching state or in a cut-off low voltage state, thereby reducing the switching process loss of the switching tube. The application provides the energy-saving control method of the CSR high-frequency PWM rectifier circuit, which can reduce switching loss, reduce cost, save energy, prolong service life and is safe and reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of CSR high-frequency PWM rectifier circuit, and particularly relates to an energy-saving control method of CSR high-frequency PWM rectifier circuit. BACKGROUND

[0002] The CSR high-frequency PWM rectifier circuit is a current source step-down rectifier circuit (also called Buck rectifier circuit), and a three-phase input power supply is used in a high-power rectifier circuit. Figure 1 As shown in the figure, the circuit has a PFC function, can make the input power factor greater than 0.99, and the harmonic generated by the circuit is small, and the output power control precision is high. The high-frequency PWM rectifier circuit is widely used in rectifier circuits. The CSR circuit is realized by a high-power switching tube to realize high-frequency operation, and the switching tube is used in a high-voltage field. The on-off control of the switching tube is completed by adjusting the on-off pulse width PWM according to the size of the load, and the determination of the pulse width is obtained by modulating the triangular wave carrier by the sine wave. Because the power supply is a sine wave, in order to improve the power factor, the sine wave is used as the modulation wave, so that the harmonic generated by the circuit is minimized. It is also called SPWM high-frequency rectification, and S represents the sine wave. Hereinafter, PWM is used.

[0003] Now the control of the high-power rectifier is realized by using DSP digital signal control, and various algorithms are used to generate PWM control signals, and the principle is the same as the triangular wave modulation. The loss of the rectifier circuit is mainly the loss of the IGBT switching process and the conduction time. The switching process loss accounts for a large part, and the most serious power consumption is in the switching-off transient process of the switching tube. Therefore, reducing the switching process loss is the main task of the present application. SUMMARY

[0004] Therefore, the present application provides an energy-saving control method of CSR high-frequency PWM rectifier circuit, which can reduce switching loss, reduce cost, save energy, prolong service life, and is safe and reliable.

[0005] In order to achieve the purpose of the present application, the following technical solutions can be adopted:

[0006] An energy-saving control method of CSR high-frequency PWM rectifier circuit, according to the value change of each line voltage of three-phase alternating current in the rectifier circuit and the characteristics that the rectifier circuit works at high frequency, the two pulse wave edges of two phases of three-phase alternating current are overlapped; the overlap includes that the overlap time of the two pulse wave edges is equal to the sum of the turn-on time and the turn-off time of the switching tube, so that the front edge or the rear edge of one pulse of the switching signal is in a soft switching state or in a cut-off low voltage state.

[0007] The beneficial effects of this invention are: 1) This invention utilizes the characteristic that the line voltage of each three-phase AC power changes every moment in the rectifier circuit and that the circuit operates at a high frequency, so that the edges of the two pulse waves of the two line voltages overlap, so that one leading edge or trailing edge of the switch is in a soft-switching state or in a low-voltage cutoff state, thereby reducing the switching losses of the switching tube; 2) This invention greatly reduces costs, saves energy, and extends service life; 3) This invention is a technical upgrade of the prior art and is suitable for widespread promotion. Attached Figure Description

[0008] Figure 1 The circuit diagram of the CSR high-frequency PWM rectifier circuit is shown in the embodiment of the energy-saving control method of the CSR high-frequency PWM rectifier circuit of the present invention.

[0009] Figure 2 This is a sinusoidal modulation diagram of the energy-saving control method of the CSR high-frequency PWM rectifier circuit in an embodiment of the present invention;

[0010] Figure 3 This is a sinusoidal decomposition modulation diagram of the energy-saving control method of the CSR high-frequency PWM rectifier circuit in an embodiment of the present invention;

[0011] Figure 4 This is a diagram showing the overlapping modulation of the leading and trailing edges of two pulses in the energy-saving control method of the CSR high-frequency PWM rectifier circuit according to an embodiment of the present invention.

[0012] Figure 5 The diagram shows the sinusoidal wave and pulse overlap modulation of the energy-saving control method for the CSR high-frequency PWM rectifier circuit in this embodiment of the invention. Detailed Implementation

[0013] The invention will now be described in further detail with reference to the accompanying drawings and embodiments thereof.

[0014] Example 1

[0015] The commutation of the three-phase CSR PWM high-frequency rectifier described in this invention is performed between the upper and lower bridge arm switches of adjacent phases, see [link / reference]. Figure 1 V1, V2, and V3 are the upper bridge arm switches for phases A, B, and C, respectively, while V4, V5, and V6 are the lower bridge arm switches for phases A, B, and C.

[0016] For example, if V1 of the upper bridge arm is turned on, then V5 or V6 of the lower bridge arm will be turned on, and the operation of other transistors follows the same principle. Due to the structural characteristics of the CSR circuit, a three-level PWM control waveform must be used to form a current path.

[0017] General PWM energy-saving modulation, such as Figure 2 As shown, the Figure 2 The top diagram, a, shows a three-phase sine wave, where Ua, Ub, and Uc represent the three-phase voltages.Figure 2 V1, V2, V3, V4, V5, V6 transverse pattern represents six switch tubes according to PWM modulation opening situation diagram, in order to reduce the switch tube loss, in every phase voltage absolute value maximum 60 ° area corresponding switch tube keeps on, such as A phase in 60 ° to 120 ° interval upper bridge arm tube V1 keeps on, B, C two phase lower bridge arm tube V5, V6 respectively according to PWM modulation to on, constitute current path; In 240 ° to 300 ° interval A phase lower bridge arm tube V4 keeps on, B, C two phase upper bridge arm tube V2, V3 respectively according to PWM modulation to on, constitute current path; This reduces the V1, V4 switch tube action frequency, that is to reduce the switching process loss. B, C two phase each tube voltage absolute value maximum amplitude 60 ° interval action case is similar. Such as Figure 2 V1 and V5, V6 in 60 ° to 120 ° interval on-off diagram, V5, V6 in the figure are not involved in each other.

[0018] Referring to Figures 1 to 5 , the energy saving control method of the CSR high frequency PWM rectifier circuit, according to the value change of each line voltage of three-phase alternating current in the rectifier circuit and the characteristics of the rectifier circuit working at high frequency, the two pulse wave edges of two phases of three-phase alternating current are overlapped; The overlap includes that the overlap time of the two pulse wave edges is equal to the sum of the turn-on time and the turn-off time of the switch tube, so that the front edge or the rear edge of the switch signal is in soft switching state or in cut-off low voltage state, so as to reduce the switching process loss of the switch tube.

[0019] Referring to Figure 2 , in the embodiment, the voltage value of the line voltage through the optional point D on the horizontal coordinate in the three-phase alternating voltage diagram is: the AB line voltage Uab is the absolute value from F point to G point; The BC line voltage Ubc is the absolute value from E point to G point; The AC line voltage Uca is the absolute value from E point to F point.

[0020] The AC line voltage value of D point in the rectifier circuit is small and does not work to deliver power to the load, so it is not discussed. Figure 2 , in a, D point B phase lower bridge arm tube V5 long on, D point near A, C two phase upper bridge arm tube V1 and tube V3 are turned on respectively, which is controlled according to the PWM principle, and the specific on voltage condition is shown in Figure 3 V1, V3, V5.

[0021] Referring to Figure 3 , in the Figure 3In the lowest voltage coordinate system U, the height of Uab represents the voltage value between lines AB, i.e., the absolute value from point F to point G, and the width represents the current conduction time between phases AB; the height of Ubc represents the voltage value between lines BC, i.e., the absolute value from point E to point G, and the width represents the current conduction time between phases BC. This invention overlaps and modulates two pulse portions together, utilizing the characteristic of three-phase voltage magnitude changes to complete a soft-switching process of a rising or falling edge of the switching transistor or reduce the switching voltage amplitude.

[0022] See Figure 4 ,Should Figure 4 for Figure 3 The two-phase voltage pulse values ​​near point D on the horizontal axis represent voltage Uab (lower pulse) and voltage Ubc (higher pulse). Under normal energy-saving modulation, at this point, the lower phase B bridge arm switch V5 is always on. Figure 4 At point X, phase C upper arm transistor V3 is turned on with an on-state voltage value shown in line segment 1. At point Y, phase A upper arm transistor V1 is turned on. Since the voltage value Ubc at this point is greater than Uab, transistor V1 conducts but has no current, resulting in a soft turn-on with no losses. At point Z, transistor V3 begins to turn off. When V3 is off at point Z, it only bears the voltage of line segment 3, which is less than the value of line segment 1, thus forming a soft turn-off, reducing turn-off power loss and voltage stress. At the end of the Uab voltage pulse, transistor V1 only bears the voltage value of line segment 4, avoiding the voltage value of line segment 1.

[0023] The switching transistor experiences the greatest power consumption during the turn-off transient. Therefore, two intersecting voltage pulses are arranged, with the higher pulse preceding the lower one. While placing the higher pulse later also reduces losses, it's not as effective as placing the lower pulse later for protecting the switching transistor. Therefore, the characteristic of varying amplitudes of the three-phase voltages at different times during the switching process is utilized to achieve soft switching or low-voltage switching, reducing losses. In this process, the pulse widths of Uab and Ubc modulation for conduction are modulated according to PWM principles.

[0024] In this embodiment, the symmetry of the circuit is not very good, and the low operating frequency of the high-voltage IGBT affects the circuit input power factor and increases harmonics. To solve these two problems, the operating frequency of the circuit can be increased. When the frequency is greater than 20 kHz, the input power factor and harmonic problems are solved.

[0025] To increase the operating frequency of the entire circuit, the mature CSR high-frequency SPWM rectifier circuit parallel superposition technology is adopted to improve the power factor, reduce harmonics, and increase power output. Additionally, from... Figure 2 It can be seen from the three-phase voltage change that every 30° is a cycle of voltage change control. After analyzing the working method of the switching transistor at 30°, the operation can be repeated in this way every 30°.

[0026] The application is characterized by the fact that the value of each line voltage in the rectifier circuit changes every moment and the circuit works at high frequency, so that the two pulse wave edges of two line voltages overlap, one leading edge or trailing edge of the switch is in soft switch state or in low voltage state, so as to reduce the switching process loss of the switch tube.

[0027] Referring to Figure 5 , the Figure 5 a shows the 60° three-phase voltage variation, and a point D is selected, and b shows the two voltage pulse values of the point D, the low pulse represents the voltage Uab, and the high pulse represents the voltage Ubc. Figure 5 At the X point of b, the lower bridge arm switch tube V5 of the B phase is in long-through state, the upper bridge arm switch tube V3 of the C phase is turned on, the turn-on voltage value is shown by the height of the line segment 1, and the upper bridge arm switch tube V1 of the A phase is turned on at the Y point, the voltage value Ubc is greater than Uab, and the upper bridge arm switch tube V1 of the A phase is turned on without current, so that the V1 soft turn-on is formed, and the turn-on loss is saved. To the Z point, the upper bridge arm switch tube V3 of the C phase is turned off, because there is already the Uab voltage, which is shown by the line segment 2, the turn-off voltage value is reduced to the amplitude of the line segment 3, so that the soft turn-off is formed, and the switching tube V3 reduces the turn-off power loss. Therefore, the characteristics of the different values of the three-phase voltage at different moments are used to complete the soft switch or low voltage switch in the switching process, so as to reduce the loss of the rectifier circuit.

[0028] In the embodiment, preferably, the two pulse wave edges overlapping includes overlapping the trailing edge of a leading pulse with the leading edge of a trailing pulse of the switch signal.

[0029] The commutation of the three-phase CSR PWM high-frequency rectifier of the application is performed between the upper and lower bridge arm switch tubes of adjacent phases. In the embodiment, the two pulse wave edges of two line voltages overlap, the trailing edge of a leading pulse overlaps with the leading edge of a trailing pulse, the soft switch state appears at the overlapping position, or is in the low voltage state, so as to reduce the circuit loss.

[0030] The above only describes the preferred embodiments of the application, and does not limit the patent scope of the application, and any equivalent structural transformation, direct / indirect application in other related technical fields, or the like made according to the application concept of the application and the contents of the specification and drawings are included in the patent protection scope of the application.

Claims

1. An energy-saving control method for a CSR high-frequency PWM rectifier circuit, characterized in that: The commutation of the three-phase CSR PWM high-frequency rectifier is carried out between the switching tubes of the upper and lower bridge arms of adjacent phases, and is modulated according to the PWM principle; according to the characteristics that the value of each line voltage of the three-phase alternating current changes every moment in the rectifier circuit and the rectifier circuit works at a high frequency, the two pulse wave edges of two line voltages of the three-phase alternating current are overlapped, and one leading edge or trailing edge of the switching signal is in a soft switching state or a cut-off low-voltage state; wherein the overlapping of the two pulse wave edges includes that the overlapping time of the overlapping of the two pulse wave edges is equal to the sum of the turn-on time and the turn-off time of the switching tube, the two pulse wave edges of the two line voltages are overlapped, the trailing edge of one leading pulse and the leading edge of a trailing pulse of the switching signal are overlapped, the soft switching state appears at the overlapping position, or the switching signal is in the cut-off low-voltage state.

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