Closed-loop variable period control algorithm of power control power supply

Abstract

The invention provides a closed-loop variable-period control algorithm of a power control power supply, and relates to the technical field of control power supply power regulation, and the closed-loop variable-period control algorithm of the power control power supply comprises the following steps: converting a collected zero-crossing signal of an alternating current into a PWM wave signal, collecting a power regulation signal, calculating a power regulation ratio, and combining with the rated power of the control power supply according to the power regulation ratio. Calculating the output expected power of the power supply to be controlled, calculating the single-cycle power according to the real-time output current value and voltage value of the control power supply, and calculating the number of cycles needing to be started for adjusting the expected power in the cycle time according to the output expected power and the single-cycle power; according to the PWM wave signal, the time length of a small cycle and the number of cycles in the small cycle are adjusted in the cycle time, the cycles are evenly distributed in the cycle time, according to the cycle distribution condition and a rising edge signal of the PWM wave signal, the controller module controls output of the cycles by controlling opening and closing of the thyristor, and therefore output of power of the power source is adjusted and controlled.

Description

Technical Field

[0001] The invention relates to the technical field of power regulation of a control power supply, and in particular to a closed-loop variable-period control algorithm for a power control power supply. Background Art

[0002] Power control power supplies are widely used in heating applications in industrial furnaces, mechanical equipment, glass industry, automobile industry, chemical industry and other industries. Power needs to be strictly distributed to each position of the load without large temperature differences. This requires that the output power can quickly reach the expected level under different power adjustment ratios and the frequency is evenly distributed, so that different output power ranges can be determined according to different adjustment signals.

[0003] In the prior art, publication number CN101662153A discloses a thyristor power control triggering method, which controls the number of on-state cycles and off-state cycles within a control period T during load power regulation, and controls an angle a on the on-state cycles within the period T.

[0004] However, although this method is adjusted through frequency and frequency angle, it does not output the frequency at zero point. The output is a non-shaped wave, which may produce large instantaneous voltage and current spikes, causing the circuit to have overshoot and oscillation. At the same time, there is a lack of feedback signal. The system is prone to become unstable or oscillate when there is external interference or load changes. Therefore, there is an urgent need for a closed-loop variable-cycle control algorithm for a power control power supply with closed-loop regulation and periodic power control to make the power output more balanced and without oscillation.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0006] The object of the present invention is to provide a closed-loop variable-cycle control algorithm for a power control power supply to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A closed-loop variable-cycle control algorithm for a power control power supply, the specific steps comprising:

[0009] Step 1: Connect the power supply to be controlled to the voltage stabilizer and the filter in sequence to obtain a stable power supply to be controlled, collect the zero-crossing signal of each phase of the three-phase AC power of the power supply to be controlled, and convert the positive half-wave of the AC sine wave into a high-level pulse signal, and the negative half-wave into a PWM wave signal of a low-level pulse signal, and send it to the controller module;

[0010] Step 2: By inputting a power regulation signal at the acquisition end of the power regulation sampling circuit, a power regulation ratio between the power regulation signal and the range of the sampling signal of the sampling circuit is calculated, and the output expected power of the power supply to be controlled is calculated according to the power regulation ratio and the rated power of the control power supply;

[0011] Step 3: By collecting the real-time current and voltage signals of the output end of the control power supply and preprocessing the collected real-time current and voltage signals, the effective value of the phase voltage and the effective value of the phase current of each phase are calculated, and the single-cycle power of the output power supply is calculated by the effective values ​​of the voltage and current;

[0012] Step 4: Set the adjustment accuracy value for the expected output power, calculate the number of cycles that the expected output power needs to be turned on within the cycle time according to the expected output power and the single-cycle power, and calculate the length of the small adjustment cycle within the cycle time and the number of cycles in the small cycle according to the variable cycle algorithm based on the number of cycles;

[0013] Step 5: Based on the small cycle and the number of cycles in the small cycle, the cycles are evenly distributed within the cycle time through calculation. Based on the frequency distribution and the rising edge signal of the PWM wave signal, the controller module controls the output of the control cycle by controlling the opening and closing of the thyristor to adjust the power supply power.

[0014] In this embodiment, the calculation formula of the power adjustment ratio is:

[0015]

[0016] Among them, R is the power regulation ratio, and Y is the power regulation signal input by the acquisition end;

[0017] The calculation formula of the expected power of the power supply to be controlled is:

[0018] P exp =P*R

[0019] Among them, P exp is the expected power, P is the rated power, and R is the power regulation ratio.

[0020] In this embodiment, the specific steps of preprocessing the collected real-time current and voltage signals and calculating the effective value of the phase voltage and the effective value of the phase current of each phase are:

[0021] Data is collected every 0.001ms. After collecting data 200 times, the effective value collected is calculated. The specific calculation formula is:

[0022]

[0023] Among them, a rmsis the effective value of voltage and current signal, a n is the data collected for the nth time, where n is a positive integer, n=1,2…200;

[0024] The calculation formula of the output power of the power supply to be controlled is:

[0025]

[0026] Among them, P sin is the output power, C A , C B , C C are the current values ​​in the three-phase AC phase A, phase B, and phase C circuits, respectively, and U AB , U BC They are the line voltage between phase A and phase B, and the line voltage between phase B and phase C in the three-phase AC phase A, phase B, and phase C circuits respectively.

[0027] In this embodiment, the calculation formulas for the line voltage between phase A and phase B and the line voltage between phase B and phase C are:

[0028]

[0029]

[0030] Among them, U AB U is the line voltage between phase A and phase B in the three-phase AC line, BC U is the line voltage between phase B and phase C in the three-phase AC line, A is the line voltage of phase A, U B is the line voltage of phase B, U C is the line voltage of phase C.

[0031] In this embodiment, the calculation formula for calculating the time length of the small adjustment cycle within the cycle time and the number of cycles in the small cycle according to the variable cycle algorithm is:

[0032]

[0033] Among them, X is the frequency that needs to be turned on, T is the adjustment period, P sin is the output power, P exp is the expected power, t is a single cycle period;

[0034] The calculation formula for calculating the time length of the small cycle within the cycle time and the number of cycles in the small cycle is:

[0035]

[0036]

[0037] Among them, M is the time length of the small period, q is the adjustment precision value, and N is the number of cycles within the small period.

[0038] In this embodiment, the specific logic for evenly distributing the cycles within the period time is as follows:

[0039]

[0040] When N > X - N, first alternately cycle M + 1 and M small periods for X - N times, and then cycle M + 1 small periods for X - 2N times;

[0041] When N < X - N, first alternately cycle M + 1 and M small periods for N times, and then cycle M small periods for X - 2N times.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows: By collecting the zero-crossing signal of the alternating current, converting it into a PWM wave signal, collecting the power adjustment signal, calculating the power adjustment ratio, and combining with the rated power of the control power supply according to the power adjustment ratio, calculating the expected output power of the power supply to be controlled, calculating the single-cycle power according to the real-time output current value and voltage value of the control power supply, calculating the number of cycles that need to be turned on within the period time for adjusting the expected power according to the expected output power and the single-cycle power, as well as the time length of the adjustment small period within the period time and the number of cycles within the small period, making the cycles evenly distributed within the period time. According to the cycle distribution situation and the rising edge signal of the PWM wave signal, the controller module controls the output of the cycles by controlling the opening and closing of the thyristor, thereby adjusting the output of the control power supply power.

[0043] The present invention performs feedback based on the signals of the output voltage and current to form a closed-loop control. At the same time, a variable-period algorithm is adopted to distribute the cycles to be output as evenly as possible within the period time, making the power output more balanced. At the same time, each cycle is adjusted and output at the zero point, so that there is no overshoot and no oscillation phenomenon in the voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the overall method flow of the present invention;

[0045] Figure 2 It is a schematic diagram of the zero-crossing detection circuit principle of the present invention;

[0046] Figure 3 It is a waveform diagram of the input and output of the zero-crossing detection circuit of the present invention;

[0047] Figure 4 It is a sampling circuit diagram of the power adjustment signal of the present invention;

[0048] Figure 5It is a power output waveform diagram of the variable period algorithm of the present invention;

[0049] Figure 6 It is a flow chart of the variable period algorithm of the present invention. DETAILED DESCRIPTION

[0050] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0051] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0052] Example:

[0053] See also Figure 1-6 , the present invention provides a technical solution:

[0054] A closed-loop variable-cycle control algorithm for a power control power supply, the specific steps comprising:

[0055] Step 1: Connect the power supply to be controlled to the voltage stabilizer and the filter in sequence to obtain a stable power supply to be controlled, collect the zero-crossing signal of each phase of the three-phase AC power of the power supply to be controlled, and convert the positive half-wave of the AC sine wave into a high-level pulse signal, and the negative half-wave into a PWM wave signal of a low-level pulse signal, and send it to the controller module;

[0056] The voltage stabilizer helps maintain the amplitude and waveform of the output voltage, ensuring that it is as close to the ideal sine wave as possible. This is very important for control power supplies, because the performance optimization of control power supplies is very dependent on the quality of the voltage waveform. At the same time, the voltage stabilizer helps to filter or suppress harmonic interference in the power grid, improve the overall quality of the power supply, and thus protect downstream equipment from the impact of non-ideal power quality. Harmonics are frequency components higher than the fundamental frequency that exist in the power supply. They can be generated by nonlinear loads in the power grid, such as switching power supplies, LED lights, and electronic devices. Harmonics will cause the waveform quality of the AC power to deteriorate, affecting the operating efficiency and life of the control power supply. The filter can effectively remove these high-frequency harmonics, thereby maintaining the sine waveform on the power line, ensuring the stable operation of the power system, and reducing electromagnetic interference. The zero-crossing detection circuit is an electronic circuit used to detect the moment when the voltage of the alternating current (AC) signal passes through the zero point. When the voltage of the AC changes from positive to negative or from negative to positive, it is considered that the voltage has passed the zero point, which is very important for the power regulation of the control power supply. Through the zero-crossing signal, the positive half-wave of the AC sine wave is converted into a high-level pulse signal, and the negative half-wave is converted into a PWM wave signal of a low-level pulse signal, and sent to the controller module. The continuous and periodic high and low levels form a PWM wave with a duty cycle of 50% and a frequency of 50Hz.

[0057] The zero-crossing signal of each phase of the three-phase alternating current of the controlled power supply is collected by a zero-crossing detection circuit, which is composed of a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, an optical coupler 1, an optical coupler 2, an optical coupler 3, a VCC power supply terminal and a GND ground terminal. The resistor R1 is connected in series with the resistor R2, the resistor R4 is connected in series with the resistor R5, and the resistor R7 is connected in series with the resistor R8. connected in series with the resistor R8, one end of the resistor R2 is electrically connected to one end of the resistor R5, one end of the resistor R8, one end of the capacitor C1, one end of the capacitor C2, one end of the capacitor C3, the second input end of the optocoupler 1, the second input end of the optocoupler 2 and the second input end of the optocoupler 3, the other end of the resistor R2 is electrically connected to one end of the resistor R3 and the other end of the capacitor C1, the other end of the resistor R3 is electrically connected to the first input end of the optocoupler 1, the other end of the resistor R5 is electrically connected to one end of the resistor R6 and the other end of the capacitor C2, and the other end of the resistor R6 is electrically connected to the first input end of the optocoupler 2,

[0058] The other end of resistor R8 is electrically connected to one end of resistor R9 and the other end of capacitor C3, the other end of resistor R9 is electrically connected to the first input end of optocoupler 1, the VCC power supply end is electrically connected to one end of resistor R10, the other end of resistor R10 is electrically connected to the third input end of optocoupler 1, the third input end of optocoupler 2, the third input end of optocoupler 3, one end of resistor R11, one end of resistor R12, one end of resistor R13, one end of capacitor C4, one end of capacitor C5, and one end of capacitor C6, the fourth input end of optocoupler 1 is electrically connected to the fourth input end of optocoupler 2, the fourth input end of optocoupler 3, the other end of capacitor C4, the other end of capacitor C5, the other end of capacitor C6 and the GND grounding end, resistor R1, resistor R2, and resistor R3 are respectively connected to three-phase AC phase A, phase B and phase C, resistor R11, resistor R12 and resistor R13 are connected to the input pin of the controller module, with phase A as the input pin. Taking the circuit as an example, after the voltage signal is divided by resistors R1 and R2, it is connected to the first input terminal of the optocoupler 1. Resistors R2, R5 and R8 form a star connection. The voltage at the connection point is a neutral voltage. The connection point is connected to the second input terminal of the optocoupler 1. When the voltage in the A-phase circuit passes through zero in the positive direction, the optocoupler 1 changes from the original on state to the off state. The VCC power supply end passes through resistors R10 and R11 to output the value controller module. When the voltage in the A-phase circuit passes through zero in the reverse direction, the optocoupler 1 changes from the original off state to the on state. The VCC power supply end passes through resistor R10 and optocoupler 1 and flows into the GND grounding terminal. Resistor R11 does not output a signal, so the phase difference of the three-phase output signal is the same as the city grid voltage, with a duty cycle of 50%, a frequency of 50Hz, and a phase difference of one-third of the cycle. Capacitors C1, C2 and C3 are voltage stabilizing capacitors, and capacitors C4, C5 and C6 are filter capacitors.

[0059] The controller module adopts the main control chip of model TMS320F28035, which is used for sampling, calculating, and generating driving signals, and can accurately perform closed-loop variable period algorithm and accurately control the pulse width of output PWM.

[0060] Step 2: By inputting a power regulation signal at the collection end of the power regulation sampling circuit, the power regulation ratio between the power regulation signal and the range of the sampling signal of the sampling circuit is calculated, and the expected output power of the power supply to be controlled is calculated based on the power regulation ratio and the rated power of the control power supply.

[0061] Furthermore, the calculation formula of the power adjustment ratio is:

[0062]

[0063] Among them, R is the power regulation ratio, and Y is the power regulation signal input by the acquisition end;

[0064] The calculation formula of the expected power of the power supply to be controlled is:

[0065] P exp =P*R

[0066] Among them, P exp is the expected power, P is the rated power, and R is the power regulation ratio.

[0067] The power regulation ratio is used to adjust the output power of the control power supply. It is input through the collection end of the sampling circuit. The collection end of the sampling circuit inputs a 4-20mA analog signal. The larger the input current, the larger the power regulation ratio and the larger the output power of the control power supply. That is, the power regulation ratio is linearly positively correlated with the output power of the control power supply.

[0068] The power regulation sampling circuit is mainly composed of an operational amplifier U1, a diode D1, a diode D2, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2. The resistor R2 is connected in series with the resistor R1, the capacitor C1 is connected in parallel to the resistor R1, one end of the resistor R1 is electrically connected to the anode of the diode D1, the 4-20mA analog signal is converted into a voltage signal after passing through the resistors R1 and R2, and the R1 and R2 are connected to the positive input terminal of the operational amplifier after voltage division. The two diodes D1 and the diode D2 are connected in series, wherein the anode of the diode D1 is connected to GND, the connecting part of the diode D1 and the diode D2 is connected to the positive input terminal of the operational amplifier U1, and the cathode of the diode D2 is connected to VCC; the upper operational amplifier U1 is electrically connected to the VCC power supply terminal, the inverting input terminal, the negative input terminal and the output terminal, and the output is connected to the ADC1 pin of the DSP main control chip.

[0069] The external input signal is converted into a 1-5V voltage signal after being divided by resistors R1 and R2, and is transmitted to the positive electrode of the comparator U1. After the negative electrode of the comparator is short-circuited with the output side, a voltage follower is formed, which can adjust the input and output impedance of the circuit and realize the unit gain circuit as an electrical buffer to isolate circuits or devices from each other and prevent adverse interactions.

[0070] Step 3: Install a current and voltage signal acquisition module at the output end of the control power supply to collect the real-time output current and voltage values ​​of each phase of electricity, and collect the real-time current and voltage signals for preprocessing. According to the sampling ratio of the acquisition circuit, calculate the effective value of the voltage and current of each phase of electricity, and calculate the single-cycle power through the effective values ​​of the voltage and current.

[0071] Furthermore, the specific steps of collecting real-time current and voltage signals for preprocessing are: collecting data every 0.001ms, and calculating the effective value of the collected data after collecting 200 times. The specific calculation formula is:

[0072]

[0073] Among them, a rms is the effective value of voltage and current signal, a n is the data collected for the nth time, where n is a positive integer, n=1,2…200;

[0074] The calculation formula of the output power of the power supply to be controlled is:

[0075]

[0076] Among them, P sin is the output power, X A , C B , C C are the current values ​​in the three-phase AC phase A, phase B, and phase C circuits, respectively, and U AB , U BC They are the line voltage between phase A and phase B, and the line voltage between phase B and phase C in the three-phase AC phase A, phase B, and phase C circuits respectively;

[0077]

[0078]

[0079] Among them, U AB U is the line voltage between phase A and phase B in the three-phase AC line, BC U is the line voltage between phase B and phase C in the three-phase AC line, A is the line voltage of phase A, U B is the line voltage of phase B, U C is the line voltage of phase C.

[0080] Step 4: Based on the expected output power and the single-cycle power, calculate the number of cycles that need to be turned on within the cycle time to adjust the expected power. By setting the adjustment accuracy value, calculate the length of the small adjustment cycle within the cycle time and the number of cycles in the small cycle.

[0081] Frequency refers to the time required for AC to complete a complete change. One cycle of a sine wave is the frequency of AC. It is used to describe the number of repetitions of a periodic phenomenon or the number of cycles per unit time. The unit of frequency is Hertz (Hz), which indicates the number of changes per second.

[0082] Regulation accuracy refers to the smallest change that a power control system can distinguish or adjust. High resolution allows for more detailed adjustment of output voltage or current, and is suitable for applications that require very fine control.

[0083] Furthermore, the calculation formula for calculating the frequency number that needs to be turned on within the cycle time for adjusting the expected power is:

[0084]

[0085] Among them, X is the frequency to be turned on, T is the adjustment period, and P sin is the output power, and P exp is the desired power, and t is the period of a single cycle;

[0086] The calculation formula for the time length of the adjustment sub-cycle within the cycle time and the number of cycles within the sub-cycle is;

[0087]

[0088]

[0089] Among them, M is the time length of the sub-cycle, q is the adjustment precision value, and N is the number of cycles within the sub-cycle;

[0090] The sub-cycle refers to the smallest periodic cycle in which the cycles are evenly distributed within the cycle time, and the number of cycles within the sub-cycle refers to the number of cycles output by the smallest cycle.

[0091] Step 5: According to the sub-cycle and the number of cycles within the sub-cycle, make the cycles evenly distributed within the cycle time through calculation. According to the cycle distribution situation and the rising edge signal of the PWM wave signal, the controller module controls the output of the cycles by controlling the opening and closing of the thyristor, thereby adjusting and controlling the output of the power supply.

[0092] Further, the specific logic for making the cycles evenly distributed within the cycle time is;

[0093]

[0094] When N > X - N, first alternately cycle M + 1 and M sub-cycles for X - N times, and then cycle M + 1 sub-cycles for X - 2N times;

[0095] When N < X - N, first alternately cycle M + 1 and M sub-cycles for N times, and then cycle M sub-cycles for X - 2N times.

[0096] The variable cycle algorithm aims to evenly distribute the cycles to be turned on as much as possible. After calculating multiple sub-cycles and the number of sub-cycles, each turned-on cycle needs to be distributed as evenly as possible. When N > X - N, first alternately cycle M + 1 and M sub-cycles for X - N times, and then cycle M + 1 sub-cycles for X - 2N times. When N < X - N, first alternately cycle M + 1 and M sub-cycles for N times, and then cycle M sub-cycles for X - 2N times.

[0097] For example, it is calculated that 17 waves need to be turned on within 100 cycles. At this time, it is calculated that M=5, N=15, that is, 6(M+1) and 5(M) are the widths of the small cycles after division, 15(N) and 2(XN) are the number of executions of the two small cycles, and at this time N>XN, so the cycle lengths of 6 and 5 are alternately cycled twice, that is, the thyristor is turned on once every 6 sine waves, and then turned on once every 5 sine waves. After completing this stage, 13 cycles of 6 are cycled again, and the 17 conducted sine waves are evenly distributed.

[0098] The present invention converts the collected zero-crossing signal of the alternating current into a PWM wave signal, collects the power regulation signal, calculates the power regulation ratio, calculates the output expected power of the power supply to be controlled according to the power regulation ratio and in combination with the rated power of the control power supply, calculates the single-cycle power according to the real-time output current value and voltage value of the control power supply, calculates the number of cycles that need to be turned on within the cycle time to adjust the expected power according to the output expected power and the single-cycle power, and calculates the time length of the small cycle adjusted within the cycle time and the number of cycles within the small cycle, so that the cycles are evenly distributed within the cycle time. According to the cycle distribution and the rising edge signal of the PWM wave signal, the controller module controls the output of the cycle by controlling the opening and closing of the thyristor, thereby adjusting the output of the control power supply power. The present invention performs feedback according to the output voltage and current signals to form a closed-loop control, and adopts a variable cycle algorithm to distribute the cycles that need to be output as evenly as possible within the cycle time, so that the power output is more balanced, and each cycle is adjusted and output at zero point, so that the voltage has no overshoot and no oscillation.

[0099] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0100] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. Those skilled in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0101] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0102] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A closed-loop variable-cycle control algorithm for a power control power supply, characterized in that: The specific steps are as follows: Step 1: Connect the power supply to be controlled to a voltage stabilizer and a filter in sequence to obtain a stable power supply to be controlled. Collect the zero-crossing signals of each phase of the three-phase alternating current of the power supply to be controlled, and convert the positive half-wave of the sine wave of the alternating current into a high-level pulse signal and the negative half-wave into a PWM wave signal of a low-level pulse signal, and send it to the controller module; Step 2: By inputting a power adjustment signal at the acquisition end of the power adjustment sampling circuit, calculate the power adjustment ratio between the power adjustment signal and the sampling signal range of the sampling circuit, and calculate the expected output power of the power supply to be controlled according to the power adjustment ratio and in combination with the rated power of the control power supply; Step 3: Collect the real-time current and voltage signals at the output end of the control power supply, preprocess the collected real-time current and voltage signals, calculate the effective value of the phase voltage and the effective value of the phase current of each phase, and calculate the single-cycle power of the output power supply through the effective values of voltage and current; Step 4: Set an adjustment accuracy value for the expected output power. According to the expected output power and the single-cycle power, calculate the number of cycles that the expected output power needs to be turned on within the cycle time, and according to the number of cycles, calculate the time length of the adjustment small cycle within the cycle time and the number of cycles within the small cycle according to the variable-cycle algorithm; Step 5: According to the small cycle and the number of cycles within the small cycle, make the cycles evenly distributed within the cycle time through calculation. According to the cycle distribution situation and the rising edge signal of the PWM wave signal, the controller module controls the output of the cycles by controlling the opening and closing of the thyristor to adjust the power of the control power supply.

2. The closed-loop variable-cycle control algorithm of a power control power supply according to claim 1, characterized in that: The calculation formula for the power adjustment ratio is; where R is the power adjustment ratio and Y is the power adjustment signal input at the acquisition end; The calculation formula for the expected power of the power supply to be controlled is; P exp =P*R Among them, P exp is the expected power, P is the rated power, and R is the power regulation ratio.

3. The closed-loop variable-cycle control algorithm of a power control power supply according to claim 1, characterized in that: The specific steps for preprocessing the collected real-time current and voltage signals and calculating the effective value of the phase voltage and the effective value of the phase current of each phase are; Collect data once every 0.001 ms. After collecting 200 times of data, calculate the collected effective value. The specific calculation formula is; Among them, a rms is the effective value of voltage and current signal, a n is the data collected for the nth time, n is a positive integer, n=1,2…200; The calculation formula for the output power of the power supply to be controlled is; Among them, P sin is the output power, C A , C B , C C are the current values ​​in the three-phase AC phase A, phase B, and phase C circuits, respectively, and U AB , U BC They are the line voltage between phase A and phase B, and the line voltage between phase B and phase C in the three-phase AC phase A, phase B, and phase C circuits respectively.

4. The closed-loop variable-cycle control algorithm of a power control power supply according to claim 3, characterized in that: The calculation formulas for the line voltage between phase A and phase B and the line voltage between phase B and phase C are; Among them, U AB U is the line voltage between phase A and phase B in the three-phase AC line, BC U is the line voltage between phase B and phase C in the three-phase AC line, A is the line voltage of phase A, U B is the line voltage of phase B, U C is the line voltage of phase C.

5. The closed-loop variable-cycle control algorithm of a power control power supply according to claim 1, characterized in that: The calculation formulas for calculating the time length of the adjustment small cycle within the cycle time and the number of cycles within the small cycle according to the variable-cycle algorithm are; Among them, X is the frequency that needs to be turned on, T is the adjustment period, P sin is the output power, P exp is the expected power, t is a single cycle period; The calculation formulas for calculating the time length of the adjustment small cycle within the cycle time and the number of cycles within the small cycle are; where M is the time length of the small cycle, q is the adjustment accuracy value, and N is the number of cycles within the small cycle.

6. The closed-loop variable-cycle control algorithm of a power control power supply according to claim 1, characterized in that: The specific logic for making the cycles evenly distributed within the cycle time is; When N>X−N, first alternately cycle M + 1 and M small cycles for X−N times, and then cycle M + 1 small cycles for X−2N times; when N<X−N, first alternately cycle M + 1 and M small cycles for N times, and then cycle M small cycles for X−2N times.

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