A low-loss high-power high-order harmonic AC power supply and its modulation method

Abstract

To ensure the high-efficiency operation and accurate testing of a high-order harmonic high-frequency AC power supply, it is necessary to select a circuit topology with lower losses, ensure that the occurrence frequency of high-order harmonics is not restricted, and at the same time ensure that the AC power supply has a high efficiency. The present invention proposes a low-loss high-power high-order harmonic AC power supply and its modulation method, belonging to the field of power electronics technology. It includes an AC power supply circuit and a switch part control circuit. The switch tubes of the AC power supply circuit are driven to conduct or turn off through the drive signals in the switch part control circuit, sinusoidally shaping the linear tube bus voltage, and greatly reducing the losses of the linear power tubes.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and particularly to a low-loss high-power high-order harmonic AC power supply and its modulation method. Background Art

[0002] The mainstream products in the current test power supply industry, such as AC test power supplies, feedback-type grid simulators, and AC source-load integrated machines, all have the basic functions of AC power supplies and also have the functions of AC test power supplies. With the wide application of power electronic devices and the increasing complexity of the grid structure, the harmonic problems in the grid have become increasingly serious, posing a significant challenge to the stability of the power system and the normal operation of equipment. Therefore, testing and analyzing high-order harmonics is of great significance for ensuring the safe and efficient operation of the power system. Harmonics refer to voltage or current components in the power system with frequencies higher than the fundamental frequency (usually 50 Hz or 60 Hz). These harmonic components may be generated by various power electronic devices, such as rectifiers, frequency converters, inverters, etc. High-order harmonics, especially high-order odd harmonics, have a more significant impact on the power system due to their higher frequencies, and may cause problems such as equipment overheating, insulation aging, and communication interference. To study the performance of the power supply, one important function is to test by superimposing harmonics and inter-harmonics on the fundamental frequency.

[0003] In the high-order harmonic high-frequency AC power supply simulation test circuit, the loss of linear tubes is a key issue. Since high-order harmonics usually require higher frequencies and more complex waveforms, and may be accompanied by higher voltage and current fluctuations, these will cause more heat and loss in linear tubes. When the loss of the linear tube is too high, its working performance and efficiency will be severely affected. This loss will not only reduce the efficiency of the linear tube, but may also cause its performance to be unstable, or even lead to failures. In addition, high losses may also limit the working range of the linear tube. Under high-frequency and high-order harmonic conditions, the linear tube may not be able to effectively process or transmit signals, resulting in distorted or limited output.

[0004] This means that if the loss of the linear tube is too high, it may not be able to support the generation and transmission of higher-frequency high-order harmonics. Therefore, in order to ensure the normal operation and accurate testing of the high-order harmonic high-frequency AC power supply simulation test circuit, it is necessary to reduce the loss of the linear tube through technical means to ensure high power output and unrestricted occurrence frequencies of high-order harmonics. Summary of the Invention

[0005] The object of the present invention is to provide a low-loss high-power high-order harmonic AC power supply and its modulation method, which can not only reasonably utilize the excellent high-frequency characteristics of linear devices, but also effectively reduce the loss of linear devices.

[0006] To achieve the above object, the present invention is realized through the following technical solutions:

[0007] A low-loss high-power high-order harmonic AC power supply, characterized in that it includes: an AC power supply circuit, a switch part control circuit;

[0008] The AC power supply circuit includes: bus power supplies V1 and V2, switching tubes T1 and T2, filter inductor L, diodes D3 and D4, capacitors C1 and C2, linear tubes Q1 and Q2, load resistor RL. The bus power supplies V1 and V2 are connected in series, the negative pole of V1 is connected to the positive pole of V2 at point COM. The first end of switching tube T1 is connected to the positive pole of V1, the second end of T1 is connected to the first end of switching tube T2, and the second end of T2 is connected to the negative pole of V2. The connection point of switching tubes T1 and T2 is connected to the first end of filter inductor L. The second end of filter inductor L is respectively connected to the positive pole of diode D3 and the negative pole of diode D4. The negative pole of D3 is connected to the first end of capacitor C1, the second end of capacitor C1 is connected to the first end of C2 at point COM, the positive pole of D4 is connected to the second end of capacitor C2, the first end of linear tube Q1 is connected to the first end of C1, the second end of linear tube Q2 is connected to the second end of C2, and the second end of Q1 is connected to the first end of Q2 at point S. A load resistor RL is connected between connection point S and connection point COM;

[0009] The switch part control circuit outputs drive signals S1 and S2, S1 drives switching tube T1, and S2 drives switching tube T2.

[0010] Further, the switch part control circuit includes: resistors R21, R22 and R23, capacitor C23, operational amplifier U2; the inverting input terminal of the operational amplifier U2 is connected to resistor R22, the non-inverting input terminal is connected to resistor R21, and a series of resistor R23 and capacitor C23 are connected between the inverting input terminal and the output terminal. The output terminal outputs modulation signals S1 and S2 through carrier modulation.

[0011] A control method for a low-loss high-power high-order harmonic AC power supply, based on the above low-loss high-power high-order harmonic AC power supply, the carrier modulation includes a positive carrier uc1, a load wave uc2, and a modulation wave Uv_REF. The modulation wave Uv_REF is compared with the carriers uc1 and uc2 to generate drive signals S1 and S2.

[0012] Further, when Uv_REF>uc1, S1 = 1, T1 is turned on, otherwise, S1 = 0, T1 is turned off. When Uv_REF<uc2, S2 = 1, T2 is turned on, otherwise, S2 = 0, T2 is turned off.

[0013] Further, it includes four modes: the positive half-cycle T1 tube on mode, the positive half-cycle T1 tube off mode, the negative half-cycle T2 tube on mode, and the negative half-cycle T2 tube off mode. During the positive half-cycle, the signal controls the linear tube Q1 to conduct linearly, and Uo operates in the positive half-wave. During the negative half-cycle, the signal controls the linear tube Q2 to conduct linearly, and Uo operates in the negative half-wave.

[0014] Further, the positive half-cycle T1 tube on mode is as follows:

[0015] T1 conducts, and the current flows from the bus power supply V1 through T1, through the filter inductor L. The voltage across the inductor V1 - VC1 charges the inductor, then flows through the diode D3 and the capacitor C1, and then back to the negative terminal of the bus power supply V1. At this time, the linear tube Q1 conducts linearly correspondingly, flows back to the lower end of C1 after passing through the load, VC1 is the voltage across the capacitor C1, and Uo operates in the positive half-wave;

[0016] The positive half-cycle T1 tube off mode is as follows:

[0017] T1 turns off, the bus power supply V1 stops outputting energy, the filter inductor L discharges by freewheeling, flows through the diode D3 and the capacitor C1, then flows into the positive terminal of the bus power supply V2, and flows back to the other end of the inductor L through the body diode of the switching tube T2. At this time, the linear tube Q1 conducts linearly correspondingly, flows back to the lower end of C1 after passing through the load, and Uo operates in the positive half-wave;

[0018] The negative half-cycle T2 tube on mode is as follows:

[0019] T2 conducts, and the current flows from the bus power supply V2 through the capacitor C2, through D4 and the filter inductor L, and then back to the negative terminal of the bus power supply V2 through T2. At this time, the linear tube Q2 conducts linearly correspondingly, the current flows from the upper end of the capacitor C2 through the negative terminal of the load to the positive terminal of the load, and then through Q2 back to the lower end of C2, VC2 is the voltage between the upper and lower ends of the capacitor C2, and Uo operates in the negative half-wave;

[0020] The negative half-cycle T2 tube off mode is as follows:

[0021] T2 turns off, the bus power supply V2 stops outputting energy, the filter inductor L discharges by freewheeling, flows through the body diode of the switching tube T1 and the bus power supply V1, then flows into the upper end of the capacitor C2, and flows back to the other end of the inductor L through the diode D4. At this time, the linear tube Q2 conducts linearly correspondingly, the voltage VC2 flows from the upper end of the capacitor C2, through the negative terminal of the load to the positive terminal, and then through Q2 back to the lower end of C2, and Uo operates in the negative half-wave.

[0022] The advantages of the present invention are as follows: It provides a high-order harmonic and high-efficiency AC power circuit topology. By using modulation technology, the bus voltage of the linear tube is sinusoidized, greatly reducing the loss of the linear power tube. By optimizing the circuit topology and reducing the loss, the application of the linear tube in high-power AC power supplies becomes more practical and feasible. Description of the Drawings

[0023] Figure 1 This is the circuit diagram of the present invention;

[0024] Figure 2 This is the on-mode of T1 tube in the positive half cycle of the present invention;

[0025] Figure 3 This is the off-mode of T1 tube in the positive half cycle of the present invention;

[0026] Figure 4 This is the on-mode of T2 tube in the negative half cycle of the present invention;

[0027] Figure 5 This is the off-mode of T2 tube in the negative half cycle of the present invention. Detailed Embodiment

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0029] Embodiment 1

[0030] This embodiment discloses a low-loss high-power high-order harmonic AC power supply, including an AC power supply circuit and a switching part control circuit. The switching part control circuit outputs driving signals S1 and S2, where S1 drives switching tube T1 and S2 drives switching tube T2.

[0031] The AC power supply circuit includes: bus power supplies V1 and V2, switching tubes T1 and T2, filter inductor L, diodes D3 and D4, capacitors C1 and C2, linear tubes Q1 and Q2, load resistor RL. The bus power supplies V1 and V2 are connected in series, the negative pole of V1 is connected to the positive pole of V2 at point COM. The first end of switching tube T1 is connected to the positive pole of V1, the second end of T1 is connected to the first end of switching tube T2, and the second end of T2 is connected to the negative pole of V2. The connection point of switching tubes T1 and T2 is connected to the first end of filter inductor L. The second end of filter inductor L is respectively connected to the positive pole of diode D3 and the negative pole of diode D4. The negative pole of D3 is connected to the first end of capacitor C1, the second end of capacitor C1 is connected to the first end of C2 at point COM, the positive pole of D4 is connected to the second end of capacitor C2, the first end of linear tube Q1 is connected to the first end of C1, the second end of linear tube Q2 is connected to the second end of C2, the second end of Q1 is connected to the first end of Q2 at point S, and a load resistor RL is connected between connection point S and connection point COM;

[0032] The switching part control circuit includes: resistors R21, R22 and R23, capacitor C23, operational amplifier U2; the inverting input terminal of the operational amplifier U2 is connected to resistor R22, the non-inverting input terminal is connected to resistor R21, a series connection of resistor R23 and capacitor C23 is connected between the inverting input terminal and the output terminal, and the output terminal outputs modulation signals S1 and S2 through carrier modulation.

[0033] Example 2

[0034] This embodiment discloses a control method for the power supply circuit described in Embodiment 1. Based on the above-mentioned low-loss high-power high-order harmonic AC power supply, the carrier modulation includes a positive carrier uc1, a load carrier uc2, and a modulation wave Uv_REF. The modulation wave Uv_REF is compared with the carriers uc1 and uc2 to generate drive signals S1 and S2.

[0035] The comparison logic is as follows: When Uv_REF > uc1, S1 = 1 and T1 conducts; otherwise, S1 = 0 and T1 turns off. When Uv_REF < uc2, S2 = 1 and T2 conducts; otherwise, S2 = 0 and T2 turns off.

[0036] Figure 2 For the positive half-cycle T1 tube on mode:

[0037] T1 conducts, and the current flows from the bus power supply V1 through T1, through the filter inductor L. The voltage across the inductor V1 - VC1 charges the inductor, then flows through the diode D3 and the capacitor C1 and returns to the negative pole of the bus power supply V1. At this time, the linear tube Q1 conducts linearly, flows through the load and then returns to the lower end of C1. VC1 is the voltage across the capacitor C1, and Uo operates in the positive half-wave.

[0038] Figure 3 For the positive half-cycle T1 tube off mode:

[0039] T1 turns off, the bus power supply V1 stops outputting energy, the filter inductor L discharges by freewheeling, flows through the diode D3 and the capacitor C1, then flows into the positive pole of the bus power supply V2, and returns to the other end of the inductor L through the body diode of the switch tube T2. At this time, the linear tube Q1 conducts linearly, flows through the load and then returns to the lower end of C1, and Uo operates in the positive half-wave.

[0040] Figure 4 For the negative half-cycle T2 tube on mode:

[0041] T2 conducts, and the current flows from the bus power supply V2 through the capacitor C2, through D4 and the filter inductor L, and then returns to the negative pole of the bus power supply V2 through T2. At this time, the linear tube Q2 conducts linearly, the current flows from the upper end of the capacitor C2 through the negative pole of the load to the positive pole of the load, and then returns to the lower end of C2 through Q2. VC2 is the voltage between the upper and lower ends of the capacitor C2, and Uo operates in the negative half-wave.

[0042] Figure 5 For the negative half-cycle T2 tube off mode:

[0043] When T2 is turned off, the bus power supply V2 stops outputting energy, and the filter inductor L discharges by freewheeling. The current flows through the body diode of the switching transistor T1 and the bus power supply V1, and then flows into the upper end of the capacitor C2, and returns to the other end of the inductor L through the diode D4. At this time, the linear transistor Q2 conducts linearly. The voltage VC2 flows from the upper end of the capacitor C2, through the negative pole of the load to the positive pole, and then returns to the lower end of C2 through Q2. Uo operates in the negative half-wave.

[0044] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A low-loss, high-power, high-harmonic AC power supply, characterized in that: Comprising: An AC power supply circuit and a switching part control circuit; The AC power supply circuit includes: bus power supplies V1 and V2, switching transistors T1 and T2, a filter inductor L, diodes D3 and D4, capacitors C1 and C2, linear transistors Q1 and Q2, and a load resistor RL. The bus power supplies V1 and V2 are connected in series, the negative pole of V1 is connected to the positive pole of V2 at point COM. The first end of switching transistor T1 is connected to the positive pole of V1, the second end of T1 is connected to the first end of switching transistor T2, and the second end of T2 is connected to the negative pole of V2. The connection point of switching transistors T1 and T2 is connected to the first end of the filter inductor L. The second end of the filter inductor L is respectively connected to the positive pole of diode D3 and the negative pole of diode D4. The negative pole of D3 is connected to the first end of capacitor C1, the second end of capacitor C1 is connected to the first end of C2 at point COM, the positive pole of D4 is connected to the second end of capacitor C2. The first end of linear transistor Q1 is connected to the first end of C1, the second end of linear transistor Q2 is connected to the second end of C2, and the second end of Q1 is connected to the first end of Q2 at point S. A load resistor RL is connected between the connection point S and the connection point COM; The switching part control circuit outputs drive signals S1 and S2, where S1 drives switching transistor T1 and S2 drives switching transistor T2.

2. The low-loss, high-power, high-harmonic AC power supply according to claim 1, characterized in that: The switching part control circuit includes: resistors R21, R22, and R23, a capacitor C23, and an operational amplifier U2. The inverting input terminal of the operational amplifier U2 is connected to resistor R22, the non-inverting input terminal is connected to resistor R21. A series connection of resistor R23 and capacitor C23 is connected between the inverting input terminal and the output terminal. The output terminal outputs modulation signals S1 and S2 through carrier modulation.

3. A low-loss, high-power, high-order harmonic AC power supply control method, based on the low-loss, high-power, high-order harmonic AC power supply of claim 2, characterized in that: The carrier modulation includes a positive carrier uc1, a negative carrier uc2, and a modulation wave Uv_REF. The modulation wave Uv_REF is compared with the carriers uc1 and uc2 to generate drive signals S1 and S2.

4. The low-loss, high-power, high-order harmonic AC power supply control method according to claim 3, characterized in that: When Uv_REF > uc1, S1 = 1 and T1 conducts; otherwise, S1 = 0 and T1 turns off. When Uv_REF < uc2, S2 = 1 and T2 conducts; otherwise, S2 = 0 and T2 turns off.

5. The low-loss, high-power, high-harmonic AC power supply control method according to claim 3, characterized in that: It includes four modes: the positive half-cycle T1 transistor on mode, the positive half-cycle T1 transistor off mode, the negative half-cycle T2 transistor on mode, and the negative half-cycle T2 transistor off mode. In the positive half-cycle, the signal controls the linear transistor Q1 to conduct linearly, and the voltage Uo across the load resistor RL works in the positive half-wave. In the negative half-cycle, the signal controls the linear transistor Q2 to conduct linearly, and Uo works in the negative half-wave.

6. The low-loss, high-power, high-harmonic AC power supply control method according to claim 5, characterized in that: The positive half-cycle T1 transistor on mode is as follows: T1 conducts, and the current flows from the bus power supply V1 through T1, through the filter inductor L. The voltage across the inductor V1 - VC1 charges the inductor, then flows through diode D3, capacitor C1, and then back to the negative pole of the bus power supply V1. At this time, the linear transistor Q1 conducts linearly correspondingly, flows through the load, and then back to the lower end of C1. VC1 is the voltage across capacitor C1, and Uo works in the positive half-wave; The positive half-cycle T1 transistor off mode is as follows: T1 is turned off, the bus power supply V1 stops outputting energy, the filter inductor L discharges continuously, flows through the diode D3 and the capacitor C1, and then flows into the positive electrode of the bus power supply V2, and flows back to the other end of the inductor L through the body diode of the switch tube T2. At this time, the linear tube Q1 is linearly turned on, and flows back to the lower end of C1 after passing through the load, and Uo works in the positive half wave; The turn-on mode of T2 tube in the negative half cycle is: T2 is turned on, and the current flows from the bus power supply V2 through the capacitor C2, through the D4 filter inductor L, and then flows back to the negative electrode of the bus power supply V2 through T2. At this time, the linear tube Q2 is correspondingly linearly turned on, and the current flows from the upper end of the capacitor C2 through the negative electrode of the load to the positive electrode of the load, and then flows back to the lower end of C2 through Q2. VC2 is the voltage between the upper end and the lower end of the capacitor C2, and Uo works in the negative half wave; The turn-off mode of T2 tube in the negative half cycle is: T2 is turned off, the bus power supply V2 stops outputting energy, and the filter inductor L continues to discharge, flows through the body diode of the switch tube T1, the bus power supply V1, and then flows into the upper end of the capacitor C2, and flows back to the other end of the inductor L through the diode D4. At this time, the linear tube Q2 is linearly turned on, and the voltage VC2 flows from the upper end of the capacitor C2, through the negative electrode of the load to the positive electrode, and then flows back to the lower end of C2 through Q2, and Uo operates in the negative half-wave.

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