Three-phase numerical control any-phase alternating current voltage generating device and generating method

Abstract

The invention provides a three-phase numerical control any-phase alternating current voltage generating device which is characterized by comprising a power supply isolation subsystem, a numerical control alternating current voltage dividing unit, an output subsystem and a control subsystem serving as a control source. The power supply isolation subsystem is connected to the AC power supply input unit, and utilizes closed-loop control to convert a power grid AC voltage into an internal DC voltage and then convert the internal DC voltage into an internal AC voltage isolated from the internal DC voltage. The numerical control alternating current voltage dividing unit obtains internal alternating current voltage from one path of alternating current phase end, generates internal alternating current divided voltage and then outputs the internal alternating current divided voltage to the output subsystem. And the output subsystem outputs three paths of internal alternating-current voltages and multiple paths of internal alternating-current partial voltages through an output test terminal group, prompts an output voltage value by using a measurement display unit, and feeds back the output voltage value to the control subsystem. The invention also comprises a method. According to the invention, alternating-current voltage and arbitrary partial voltage of the same phase are output in an isolated manner, a safety protection function is provided, safe on-site education demonstration is provided, and different display outputs can be selected according to different requirements of teaching and examination.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrical teaching and electrical measurement, and particularly to a three-phase numerical control arbitrary phase AC voltage generating device and method. BACKGROUND

[0002] The use and simulation of electrical teaching and electrical measurement instruments require real AC voltage electrical quantities, and have certain requirements in terms of parameter setting, grading, convenient demonstration for teachers and simulation for students, personal safety and equipment protection, etc. The existing simple voltage electrical quantity generating devices composed of discrete components have different performances and do not have the function of dynamic parameter setting for teaching management and assessment, which is inconvenient for teaching demonstration and lacks sufficient safety protection measures for student simulation operation. At present, electrical teaching and electrical measurement instrument courses are directly demonstrated using electrical quantities provided by power systems, which has limitations in terms of parameter adjustment and grading setting, and has great safety hazards in terms of personal safety and equipment short circuit. The existing voltage electrical quantity devices for electrical measurement instruments do not have the function of rapid setting and adjustment of parameter grading groups, which is inconvenient for student measurement simulation operation assessment, the test process is complicated, the test efficiency is low, the intelligent degree is low, the assessment efficiency is low, and the assessment management process is not scientific. SUMMARY

[0003] The present application aims to provide a three-phase numerical control arbitrary phase AC voltage generating device and method, which mainly solves the problems existing in the prior art and provides arbitrary phase and adjustable amplitude grading AC voltage electrical quantities for on-site teaching demonstration and simulation of electrical measurement instruments.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present application is to provide a three-phase numerical control arbitrary phase AC voltage generating device, characterized in that it comprises a power isolation subsystem, a numerical control AC voltage dividing unit, an output subsystem and a control subsystem.

[0005] The control subsystem reads the working parameters, controls the power isolation subsystem, the numerical control AC voltage dividing unit and the output subsystem; the power isolation subsystem is connected to the AC power input unit, and uses closed-loop control to convert the grid AC voltage into internal DC voltage and then into internal AC voltage which is isolated from the grid AC voltage; the power isolation subsystem contains three AC phase terminals and a neutral terminal; the internal AC voltage is output to the numerical control AC voltage dividing unit and the output subsystem with the AC phase terminals as live wires and the neutral terminal as a zero line; the numerical control AC voltage dividing unit obtains the internal AC voltage from one of the AC phase terminals, generates internal AC voltage dividing and outputs to the output subsystem; the output subsystem contains output test terminal groups and a measurement display unit, and outputs three internal AC voltages and multiple internal AC voltage divisions through the output test terminal groups, and uses the measurement display unit to prompt the output voltage value and feeds back to the control subsystem.

[0006] Further, the power isolation subsystem contains a numerical control analog-digital conversion unit, a three-phase inverter unit and an output protection unit.

[0007] The numerical control analog-digital conversion unit converts the grid AC voltage into internal DC voltage under the control of the control subsystem; one of the internal DC voltages provides power for the control subsystem, and the other enters the three-phase inverter unit; the three-phase inverter unit converts the internal DC voltage into internal AC voltage under the control of the control subsystem and outputs at the AC phase terminals and the neutral terminal; the AC phase terminals enter the output subsystem through the output protection unit, and the neutral terminal is directly connected to the input subsystem; the output protection unit samples the internal AC voltage and internal AC circuit and feeds back to the control subsystem, thereby realizing closed-loop control and safety protection.

[0008] Further, the numerical control analog-digital conversion unit is an isolated flyback switching power supply circuit, containing an input rectifier bridge, an input capacitor, a switch tube, a flyback transformer, an output rectifier tube and an output capacitor.

[0009] The grid AC voltage enters the rectifier bridge, is rectified, and then the high-frequency noise is filtered out by the input capacitor, and then enters the primary coil of the flyback transformer under the control of the switch tube, thereby exciting a secondary current in the secondary coil of the flyback transformer; the secondary current is rectified by the output rectifier tube and then filtered by the output capacitor to obtain the internal DC voltage; the control subsystem controls the size of the internal DC voltage by controlling the duty cycle of the opening and conduction of the switch tube.

[0010] Further, the three-phase inverter unit contains a switch bridge arm, a filter circuit and a first output drive module.

[0011] The switch bridge arm comprises four groups of output channels corresponding to three AC phase ends and the neutral end respectively; the switch bridge arm converts the internal DC voltage into AC voltage; the filter circuit is connected between the AC phase end and the neutral end, further converts the AC voltage into a sine wave form, and finally outputs the internal AC voltage at the AC phase end through the first output driving module.

[0012] Further, the numerical control AC voltage dividing unit is used to realize the same-phase voltage reduction of the AC voltage, and comprises a pull-up switch, a pull-down switch, a filter module, and a second output driving module.

[0013] The pull-up switch is connected to one of the AC phase ends, and the pull-down switch is connected to the neutral end; the output from the pull-up switch or the pull-down switch is shaped into a sine wave through the filter module and the second output driving module, and becomes the internal AC voltage; the control subsystem adjusts the size of the internal AC voltage by controlling the duty cycle of the opening and closing of the pull-up switch and the pull-down switch.

[0014] Further, the control subsystem comprises a communication interface unit and an intelligent control unit; the intelligent control unit comprises an execution module, an inverter logic control module, and a voltage dividing logic control module.

[0015] The execution module obtains the working parameters from the communication interface unit, generates the voltage control signal of the power isolation subsystem using the inverter logic control module, generates the voltage dividing control signal of the numerical control AC voltage dividing unit using the voltage dividing logic control module, and controls the output subsystem to act.

[0016] Further, the inverter logic control module comprises a sine wave generator, a triangular wave generator, a first comparator, a first inverter, a first upper edge driver, and a first lower edge driver.

[0017] The sine wave generator and the triangular wave generator independently generate a sine wave and a triangular wave as two inputs of the first comparator, so that the output of the first comparator is a sine pulse width modulation signal; the sine pulse width modulation signal is divided into two paths, one of which directly passes through the first upper edge driver to form the voltage control signal, and the other of which passes through the first inverter and then passes through the first lower edge driver to also form the voltage control signal.

[0018] Further, in the inverter logic control module, the sine wave generator uses different control signals for the AC phase end and the neutral end.

[0019] The control signal of the sine wave generator corresponding to the AC phase end is generated by a module comprising an adder, a divider, a first proportional-integral controller and a step signal generator; the amplitude set value from the AC phase end of the working parameter is multiplied and then summed with the sampling value of the internal AC voltage by the adder, and then input into the divider as the divisor; the sampling value of the internal DC voltage is input into the divider as the dividend; the output of the divider is input into the first proportional-integral controller and the step signal generator, and then combined with the phase set value in the working parameter to become the control signal of the sine wave generator corresponding to the AC phase end;

[0020] The control signal of the sine wave generator corresponding to the neutral end is from the output of a three-input adder; the inputs of the three-input adder are three control signals of the sine wave generator corresponding to the AC phase end.

[0021] Further, the voltage division logic control module comprises an effective value calculation submodule, a second comparator, a second proportional-integral controller, a pulse width modulation generator, a second inverter, a second rising edge driver and a second falling edge driver;

[0022] The internal AC voltage division becomes a digital signal after passing through the effective value calculation submodule, and is input into the second comparator as one input; the voltage division set value from the working parameter is input into the second comparator as the other input; the output of the second comparator is input into the second proportional-integral controller to control the pulse width modulation generator; the output of the pulse width modulation generator is divided into two paths, one of which directly passes through the second rising edge driver to form the voltage division control signal, and the other of which passes through the second inverter and then passes through the second falling edge driver to also form the voltage division control signal.

[0023] The application also provides a voltage generation method using the three-phase numerical control arbitrary phase AC voltage generation device, which comprises the following steps:

[0024] In step S100, the working parameters are set by the control subsystem;

[0025] In step S200, the control subsystem controls the power isolation subsystem to generate the internal DC voltage from the AC voltage of the power grid, and then converts the internal DC voltage to generate the internal AC voltage; the size of the internal DC voltage is specified by the working parameters;

[0026] Step S300, the power isolation subsystem feeds back the internal AC voltage to the control subsystem, and stabilizes the internal AC voltage by closed-loop control; when the control subsystem detects abnormal internal AC current, the control subsystem controls the power isolation subsystem to reduce or cut off the internal AC voltage;

[0027] Step S400, the control subsystem controls the digital-controlled AC voltage dividing unit to output the internal AC voltage division;

[0028] Step S500, three-way internal AC voltage and multiple-way internal AC voltage division are obtained in the output subsystem; the output subsystem also feeds back the internal AC voltage and multiple-way internal AC voltage division to the control subsystem; the control subsystem controls the content displayed by the output subsystem according to the working parameters.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] 1. The three-phase digital-controlled arbitrary-phase AC voltage generating device of the present application isolates the output AC voltage from the AC power grid, has safety protection function, and can provide safe on-site education demonstration.

[0031] 2. The three-phase digital-controlled arbitrary-phase AC voltage generating device of the present application can output AC voltage of the same phase and arbitrary voltage division according to the requirement, and is convenient for on-site education demonstration.

[0032] 3. The generating method of the three-phase digital-controlled arbitrary-phase AC voltage generating device of the present application can select different display outputs according to different teaching and examination needs. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a system block diagram of a preferred embodiment of the three-phase digital-controlled arbitrary-phase AC voltage generating device of the present application;

[0034] Figure 2 is a circuit schematic diagram of a digital-controlled A / D conversion unit in a preferred embodiment of the three-phase digital-controlled arbitrary-phase AC voltage generating device of the present application;

[0035] Figure 3 is a circuit schematic diagram of a three-phase inverter unit in a preferred embodiment of the three-phase digital-controlled arbitrary-phase AC voltage generating device of the present application;

[0036] Figure 4 is a circuit schematic diagram of a digital-controlled AC voltage dividing unit in a preferred embodiment of the three-phase digital-controlled arbitrary-phase AC voltage generating device of the present application;

[0037] Figure 5is a first type of circuit schematic diagram of the pull-up switch and the pull-down switch in the numerical control AC voltage dividing unit in a preferred embodiment of the three-phase numerical control arbitrary phase AC voltage generating device of the present application;

[0038] Figure 6 is a second type of circuit schematic diagram of the pull-up switch and the pull-down switch in the numerical control AC voltage dividing unit in a preferred embodiment of the three-phase numerical control arbitrary phase AC voltage generating device of the present application;

[0039] Figure 7 is a third type of circuit schematic diagram of the pull-up switch and the pull-down switch in the numerical control AC voltage dividing unit in a preferred embodiment of the three-phase numerical control arbitrary phase AC voltage generating device of the present application;

[0040] Figure 8 is a system block diagram of the control subsystem in a preferred embodiment of the three-phase numerical control arbitrary phase AC voltage generating device of the present application;

[0041] Figure 9 is a system block diagram of the inverter logic control module in the control subsystem in a preferred embodiment of the three-phase numerical control arbitrary phase AC voltage generating device of the present application;

[0042] Figure 10 is a system block diagram of the sine wave generator control logic for the AC phase end in the control subsystem in a preferred embodiment of the three-phase numerical control arbitrary phase AC voltage generating device of the present application;

[0043] Figure 11 is a system block diagram of the sine wave generator control logic for the neutral end in the control subsystem in a preferred embodiment of the three-phase numerical control arbitrary phase AC voltage generating device of the present application;

[0044] Figure 12 is a system block diagram of the voltage dividing logic control module in the control subsystem in a preferred embodiment of the three-phase numerical control arbitrary phase AC voltage generating device of the present application;

[0045] Figure 13 is a method flow chart of a preferred embodiment of the generating method using the three-phase numerical control arbitrary phase AC voltage generating device of the present application.

[0046] In the figure: 100 - power supply isolation subsystem, 200 - numerical control AC voltage dividing unit, 300 - output subsystem, 400 - control subsystem, 500 - AC power supply input unit;

[0047] 110 - numerical control A / D conversion unit, 120 - three-phase inverter unit, 130 - output protection unit;

[0048] 111-input rectifier bridge, 112-input capacitor, 113-switching tube, 114-flyback transformer, 115-output rectifier tube, 116-output capacitor, 121-switching bridge arm, 122-filter circuit, 123-first output drive module;

[0049] 210-pull-up switch, 220-pull-down switch, 230-filter module, 240-second output drive module, 250-diode, 260-field effect tube, 270-triode;

[0050] 310-test terminal group, 320-measurement display unit;

[0051] 410-communication interface unit, 420-intelligent control unit, 430-execution module, 440-inversion logic control module, 450-voltage division logic control module;

[0052] 441-sine wave generator, 442-triangle wave generator, 443-first comparator, 444-first inverter, 445-first rising edge driver, 446-first falling edge driver; 4411-adder, 4412-divider, 4413-first proportional-integral controller, 4414-step signal generator, 4415-three-input adder; 451-effective value calculation sub-module, 452-second comparator, 453-second proportional-integral controller, 454-pulse width modulation generator, 455-second inverter, 456-second rising edge driver, 457-second falling edge driver. DETAILED DESCRIPTION

[0053] The application will be further described below in connection with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that after reading the content of the application, those skilled in the art can make various modifications or changes to the application, and these equivalent forms also fall within the scope of the appended claims.

[0054] Please refer to Figures 1 to 12 The application discloses a three-phase numerical control arbitrary phase AC voltage generating device. As shown in the figure, a preferred embodiment thereof comprises a power isolation subsystem 100, a numerical control AC voltage division unit 200, an output subsystem 300 and a control subsystem 400.

[0055] The control subsystem 400 provides a man-machine interface, receives working parameters provided by an operator in an upper computer, also sends real-time data of the device to the upper computer, and simultaneously manages and coordinates the working of the power isolation subsystem 100, the numerical control AC voltage division unit 200 and the output subsystem 300.

[0056] The power isolation subsystem 100 receives power input from the external AC power input unit 500, and converts the grid AC voltage from the AC power input unit 500 into internal DC voltage and then into internal AC voltage that is isolated from the grid AC voltage, so that the internal AC voltage is parametrically related to but physically isolated from the grid AC voltage. During the AC-DC-AC conversion, the power isolation subsystem 100 samples the output internal AC voltage information and feeds it back to the control subsystem 400, which continues to adjust the internal AC voltage until the specified value in the operating parameters is met, achieving closed-loop control.

[0057] Specifically, the power isolation subsystem 100 includes a digital-to-analog conversion unit 110, a three-phase inverter unit 120, and an output protection unit 130. The digital-to-analog conversion unit 110 obtains control signals from the control subsystem 400 and converts the grid AC voltage into internal DC voltage. The converted internal DC voltage is used to provide power to the control subsystem 400 and is further converted into internal AC voltage by the three-phase inverter unit 120. In the absence of control signals from the control subsystem 400, the digital-to-analog conversion unit 110 outputs internal DC voltage using default parameters, ensuring that operating voltage is provided before the control subsystem 400 is first powered on and initialized. The three-phase inverter unit 120 is also controlled by the control subsystem 400, which converts the internal DC voltage into internal AC voltage under the control signals provided by the control subsystem 400. The three-phase inverter unit 120 outputs three-phase AC power with three AC phase terminals and a neutral terminal. The three AC phase terminals are connected to the output protection unit 130 as live wires. The output protection unit 130 collects internal AC voltage information from the AC phase terminals and real-time internal AC current size and feeds it back to the control subsystem 400. The control subsystem 400 adjusts the control signals of the digital-to-analog conversion unit 110 and the three-phase inverter unit 120 based on the feedback information, forming a closed-loop control and adjusting the internal AC voltage to the specified value in the operating parameters. The internal AC voltage on the AC phase terminals passes through the output protection unit 130 and enters the output subsystem 300, appearing on different terminals of the test terminal group 310 of the input subsystem 300. The neutral terminal is connected to the zero line terminal of the test terminal group 310 of the input subsystem 300 as a zero line.

[0058] The specific implementation of the digital-to-analog conversion unit 110 is an isolated flyback switching power supply circuit, which is composed of an input rectifier bridge 111, an input capacitor 112, a switch tube 113, a flyback transformer 114, an output rectifier tube 115, and an output capacitor 116. The grid AC voltage from the AC power input unit 500 first passes through the rectifier bridge 111 and becomes a DC voltage containing high-frequency components after rectification. The input capacitor 112 located after the rectifier bridge 111 filters out the high-frequency noise in the high-frequency DC voltage, and then enters the primary coil of the flyback transformer 114 through the switch tube 113. The switch tube 113 is determined by the control signal of the control subsystem 400 whether to conduct or not. When the switch tube 113 is conducting, the change of the DC voltage causes the change of the magnetic field in the secondary coil of the flyback transformer 114, so that the changing secondary current is induced in the secondary coil of the flyback transformer 114. The changing secondary current is rectified by the output rectifier tube 115 and then filtered by the output capacitor 116, thereby obtaining the internal DC voltage from the grid AC voltage. The duty cycle of the turn-on and turn-off of the switch tube 113 determines the amount of energy passing through the flyback transformer 114, thereby determining the size of the internal DC voltage obtained. In the present application, the size of the internal DC voltage depends on the operating parameters, and in different scenarios, the control subsystem 400 provides different voltage control signals, usually making the internal DC voltage equal to 1.5 times the effective value of the internal AC voltage. Among them, the internal AC voltage takes the maximum value of the three-phase AC.

[0059] The three-phase inverter unit 120 is composed of a switch bridge arm 121, a filter circuit 122, and a first output drive module 123. The switch bridge arm 121 contains four groups of output channels, corresponding to three AC phase ends and a neutral end respectively. The switch bridge arm 121 is controlled by the control signal of the control subsystem 400 to conduct different channels in the four groups of output channels at different times, thereby converting the internal DC voltage into AC voltage again. In the switch bridge arm 121, the MOS transistor or IGBT transistor or other equivalent electronic switching device controls the on-off of the output channel. The filter circuit 122 is used to shape the converted AC voltage into a sinusoidal wave form, so it is connected across each AC phase end and the neutral end. The sinusoidal AC voltage becomes the output internal AC voltage on the AC phase end after passing through the first output drive module 123. The neutral end is directly output as the zero line. The frequency of the internal AC voltage tracks the grid frequency, and the amplitude is determined by the operating parameters.

[0060] The numerical control AC voltage dividing unit 200 realizes the same phase voltage reduction based on the output of one AC phase terminal of the power isolation subsystem 100 under the control of the control subsystem 400, and thus simultaneously gives different internal AC voltages on the test terminal group 310 of the input subsystem 300 for the teaching demonstration simulation. The numerical control AC voltage dividing unit 200 comprises an upper pull switch 210, a lower pull switch 220, a filter module 230 and a second output driving module 240. The upper pull switch 210 is connected to one AC phase terminal of the power isolation subsystem 100, while the lower pull switch 220 is connected to the neutral terminal. The upper pull switch 210 and the lower pull switch 220 are controlled by the control subsystem 400. When the upper pull switch 210 and the lower pull switch 220 are both turned on, a loop is formed between the internal AC voltage and the neutral terminal, and the current enters the filter module 230 to form a sine wave, which is then amplified and driven by the second output driving module 240 to output as the internal AC voltage. The control subsystem 400 controls the energy passing through the upper pull switch 210 and the lower pull switch 220 by controlling the duty cycle of the opening and closing of the upper pull switch 210 and the lower pull switch 220, thereby adjusting the size of the internal AC voltage. The size of the internal AC voltage output by the numerical control AC voltage dividing unit 200 is equal to the internal AC voltage multiplied by the duty cycle. According to the requirements, multiple numerical control AC voltage dividing units 200 can be configured in the same device to simultaneously output different internal AC voltages.

[0061] In Figure 5 , Figure 6 and Figure 7 , the upper pull switch 210 and the lower pull switch 220 are bidirectional electronic switches composed of bidirectional MOS transistors or bidirectional IGBT transistors or other equivalent electronic switch elements, containing two opposite unidirectional channels. It has multiple implementation methods. In the first implementation method, one diode 250 and one field effect transistor 260 constitute a controlled first unidirectional channel. The remaining one diode 250 and one field effect transistor 260 constitute a controlled second unidirectional channel. Replacing the field effect transistor 260 with a triode 270 can also constitute a unidirectional channel. That is, one diode 250 and one triode 270 constitute a controlled first unidirectional channel. The remaining one diode 250 and one triode 270 constitute a controlled second unidirectional channel. Different combinations of diodes 250 and triodes 270 constitute different implementation methods, such as the second and third implementation methods. In the above three implementations, the first unidirectional channel and the second unidirectional channel are symmetrically and oppositely arranged to constitute a bidirectional electronic switch.

[0062] The output subsystem 300 includes an output terminal group 310 and a measurement display unit 320. The output terminal group 310 is connected to three AC phase terminals and one neutral terminal for outputting three-phase AC power from the power isolation subsystem 100, and is also connected to the digital controlled AC voltage dividing unit 200 for outputting multiple internal AC voltage divisions. The measurement display unit 310 reads the output voltage values at the output terminal group 310, reduces the voltage drop error caused by the output lead, and then feeds back to the control subsystem 400. The control subsystem 400 uses the feedback output voltage values to form a closed loop control to ensure the stability of the output voltage, and also selects some or all of the output voltage values according to the working parameters and displays them on the measurement display unit 310. For example, in teaching demonstration, the host computer sets the voltage parameters to the desired values through the communication interface unit 410 and allows the actual output results to be displayed in real time on the measurement display unit 320, which facilitates the students to practice. In teaching examination, the host computer sets the voltage parameters to the desired values through the communication interface unit 410 and selectively disables the output display function of the measurement display unit 320 to achieve the purpose of examination.

[0063] The control subsystem 400 includes a communication interface unit 410 and an intelligent control unit 420. The intelligent control unit 420 further includes an execution module 430, an inverter logic control module 440, and a voltage dividing logic control module 450. The communication interface unit 410 is a human-computer interaction interface, and the working parameters that guide the system operation are entered into the execution module 430 through the communication interface unit 410. The execution module 430 generates the voltage control signal of the power isolation subsystem 100 using the inverter logic control module 440 and generates the voltage dividing control signal of the digital controlled AC voltage dividing unit 200 using the voltage dividing logic control module 450 according to the working parameters, and also controls the display content of the output subsystem 300.

[0064] The four inverter logic control modules 440 correspond to the four groups of output channels in the switching bridge arms 121 in the three-phase inverter unit 120, i.e., one inverter logic control module 440 for each of the three AC phase terminals and the neutral terminal. The inverter logic control module 440 includes a sine wave generator 441, a triangle wave generator 442, a first comparator 443, a first inverter 444, a first rising edge driver 445, and a first falling edge driver 446. The low-voltage sine wave generated by the sine wave generator 441 has the same phase as the high-voltage internal AC voltage generated by the three-phase inverter unit 120. The triangle wave generator 442 independently generates a low-voltage triangle wave that is an isosceles triangle with the same period and equal positive and negative amplitudes as the low-voltage sine wave. The low-voltage sine wave and the low-voltage triangle wave are input to the two input terminals of the first comparator 443, so that a sine pulse width modulation signal is obtained at the output terminal of the first comparator 443. The sine pulse width modulation signal is the control signal for the switching bridge arms 121 in the three-phase inverter unit 120, which controls the opening or closing of one of the four groups of output channels in the switching bridge arms 121. Specifically, the sine pulse width modulation signal is divided into two paths, one of which directly passes through the first rising edge driver 445 to drive the first switch in the switching bridge arm 121, and the other of which passes through the first inverter 444 and then through the first falling edge driver 446 to drive the second switch in the switching bridge arm 121. The two opposite sine pulse width modulation signals together constitute the voltage control signal.

[0065] In this embodiment, the four inverter logic control modules 440 share one triangle wave generator 442. Typically, the triangle wave frequency is in the range of several kilohertz to several hundred kilohertz, and the modulation coefficient is defined as the ratio of the sine wave amplitude to the triangle wave amplitude. By algorithmically controlling the maximum modulation coefficients of the three AC phase terminals and the neutral terminal, the maximum modulation coefficient is not more than 0.9 to 0.95. At the same time, although the overall design of the inverter logic control module 440 is the same, different low-voltage sine waves are used for the inverter logic control modules for the AC phase terminals and the neutral terminal, so the control signals used by the corresponding sine wave generators 441 in the intelligent control unit 420 are different.

[0066] The control signal of the sine wave generator 441 corresponding to the neutral terminal is a combination of the control signals of the three sine wave generators 441 corresponding to the three phase terminals. Specifically, after obtaining the control signals of the three sine wave generators 441 corresponding to the three phase terminals in the three-phase alternating current, the three sets of control signals are input into a three-input adder 4415. The output of the three-input adder 4415 is the control signal of the sine wave generator 441 corresponding to the neutral terminal.

[0067] The control signal of the sine wave generator 441 corresponding to the neutral terminal is a combination of the control signals of the three sine wave generators 441 corresponding to the three phase terminals. Specifically, after obtaining the control signals of the three sine wave generators 441 corresponding to the three phase terminals in the three-phase alternating current, the three sets of control signals are input into a three-input adder 4415. The output of the three-input adder 4415 is the control signal of the sine wave generator 441 corresponding to the neutral terminal.

[0068] The voltage division control signal generated by the voltage division logic control module 450 is used to control the conduction and turn-off of the paired pull-up switch 210 and pull-down switch 220 in the digital controlled alternating current voltage division unit 200. The voltage division logic control module 450 includes a root mean square calculation submodule 451, a second comparator 452, a second proportional integral controller 453, a pulse width modulation generator 454, a second inverter 455, a second rising edge driver 456, and a second falling edge driver 457. The internal alternating current voltage division output by the digital controlled alternating current voltage division unit 200 is fed back to the execution module 430, converted into a digital signal by the root mean square calculation submodule, and used as one input of the subsequent second comparator 452. At the same time, the intelligent control unit 420 reads the voltage division set value in the working parameters as the other input of the second comparator 452. The output of the second comparator 452 represents the difference between the current internal alternating current voltage division and the voltage division set value. This difference is used to control the pulse width modulation generator 454 to generate a pulse width modulation signal after passing through the second proportional integral controller 453. The pulse width modulation signal is divided into two paths, one of which directly passes through the second rising edge driver 456 to drive the pull-up switch 210, and the other of which passes through the second inverter 455 and then through the second falling edge driver 457 to drive the pull-down switch 220. The two opposite pulse width modulation signals together constitute the voltage division control signal.

[0069] Please refer to Figure 13The application also discloses a voltage generating method using the three-phase numerical control arbitrary phase AC voltage generating device, which comprises the following steps:

[0070] Step S1, configuring working parameters.

[0071] After accessing the AC grid voltage, the power isolation subsystem generates internal DC voltage by using default parameters to supply power for the control subsystem. Before each test, the working parameters set by the operator are received through the communication interface unit and transmitted to the intelligent control unit to complete the configuration of the control subsystem. The working parameters include the internal AC voltage size and amplitude, the internal AC voltage divider size, and whether the measurement display unit displays the voltage on each output test terminal group.

[0072] Step S2, generating internal AC voltage.

[0073] The control subsystem generates voltage control signals by using the inverter logic control module according to the working parameters to control the numerical control digital-to-analog conversion unit and the three-phase inverter unit in the power isolation subsystem, complete AC-DC-AC conversion, and obtain three internal AC voltages.

[0074] In the process of converting the grid AC voltage into internal DC voltage for the first time, the size of the internal DC voltage is specified by the working parameters. In the conversion process from internal DC voltage to internal AC voltage, there is no voltage change.

[0075] Step S3, closed-loop regulation of internal AC voltage.

[0076] The output protection unit in the power isolation subsystem reads the internal AC voltage output by the three-phase inverter unit and feeds back to the control subsystem. The inverter logic control module in the control subsystem adjusts the voltage control signal according to the feedback until the internal AC voltage is stable.

[0077] At the same time, the output protection unit also samples the size of the internal AC current and feeds back to the control subsystem. When the control subsystem detects abnormal internal AC current feedback, the inverter logic control module sends voltage control signals to reduce or cut off the internal AC voltage, ensuring the safety of the user and the safe operation of the device itself.

[0078] Step S4, generating internal AC voltage divider.

[0079] The control subsystem generates voltage control signals by using the voltage divider logic control module according to the working parameters to control the numerical control AC voltage divider unit to output internal AC voltage divider.

[0080] Step S5, the output subsystem outputs each voltage.

[0081] The output three-way internal AC voltage and the multiple internal AC voltage dividers are outputted on the output test terminal group of the output subsystem. Meanwhile, the output subsystem also feeds back the internal AC voltage and the multiple internal AC voltage dividers to the control subsystem. The control subsystem reads the working parameters and controls the display content on the display unit in the output subsystem.

[0082] The above merely describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, which is made according to the content of the present application specification and drawings, is also included in the patent protection scope of the present application.

Claims

1. A three-phase digital controlled arbitrary phase AC voltage generator, characterized in that: It includes power isolation subsystem, digital control AC voltage divider unit, output subsystem and control subsystem; The control subsystem reads the working parameters, controls the power isolation subsystem, the digital control AC voltage divider unit and the output subsystem; the power isolation subsystem is connected to the AC power input unit, and uses closed-loop control to convert the grid AC voltage into an internal DC voltage and then into an internal AC voltage isolated from it; the power isolation subsystem includes three AC phase terminals and one neutral terminal; the internal AC voltage is output to the digital control AC voltage divider unit and the output subsystem with the AC phase terminal as the live wire and the neutral terminal as the zero wire; the digital control AC voltage divider unit obtains the internal AC voltage from one AC phase terminal, generates an internal AC divided voltage and also outputs it to the output subsystem; the output subsystem includes an output test terminal group and a measurement display unit, and outputs the three internal AC voltages and multiple internal AC divided voltages to the outside through the output test terminal group, and also uses the measurement display unit to prompt the output voltage value and feed it back to the control subsystem.

2. The three-phase digital controlled arbitrary phase AC voltage generator according to claim 1, characterized in that: The power isolation subsystem includes a digital control analog-to-digital conversion unit, a three-phase inverter unit and an output protection unit; The digital control analog-to-digital conversion unit, under the control of the control subsystem, isolates and converts the grid AC voltage into an internal DC voltage; one path of the internal DC voltage provides power to the control subsystem, and the other path enters the three-phase inverter unit; the three-phase inverter unit, under the control of the control subsystem, converts the internal DC voltage into an internal AC voltage, and outputs it at the AC phase terminal and the neutral terminal; The AC phase terminal enters the output subsystem through the output protection unit, while the neutral terminal is directly connected to the input subsystem; the output protection unit samples the internal AC voltage and internal AC circuit and feeds back to the control subsystem, thereby achieving closed-loop control and safety protection.

3. The three-phase digital controlled arbitrary phase AC voltage generator according to claim 2, characterized in that: The digital control analog-to-digital conversion unit is an isolated flyback switching power supply circuit, comprising an input rectifier bridge, an input capacitor, a switch tube, a flyback transformer, an output rectifier tube and an output capacitor; The AC voltage from the power grid enters the rectifier bridge, is rectified, and high-frequency noise is filtered out by the input capacitor. Then, under the control of the switching tube, it enters the primary coil of the flyback transformer, thereby stimulating a secondary current in the secondary coil of the flyback transformer. The secondary current is rectified by the output rectifier tube and then filtered by the output capacitor to obtain the internal DC voltage. The control subsystem controls the magnitude of the DC internal voltage by controlling the duty cycle of the switching tube.

4. The three-phase digital controlled arbitrary phase AC voltage generator according to claim 2, characterized in that: The three-phase inverter unit includes a switch bridge arm, a filter circuit and a first output drive module; The switch bridge arm includes four groups of output channels, corresponding to the three AC phase terminals and the neutral terminal respectively; the switch bridge arm converts the internal DC voltage into an AC voltage; the filter circuit is connected across the AC phase terminal and the neutral terminal, further converts the AC voltage into a sinusoidal wave form, and finally outputs the internal AC voltage at the AC phase terminal through the first output drive module.

5. The three-phase digital controlled arbitrary phase AC voltage generator according to claim 1, characterized in that: The digitally controlled AC voltage divider unit is used to achieve in-phase voltage reduction of the AC voltage, and includes a pull-up switch, a pull-down switch, a filter module, and a second output drive module; The pull-up switch is connected to one of the AC phase terminals, and the pull-down switch is connected to the neutral terminal; the output from the pull-up switch or the pull-down switch is shaped into a sine wave by the filtering module and the second output driving module, and the output is the internal AC divided voltage; The control subsystem adjusts the magnitude of the internal AC voltage division by controlling the duty ratio of the pull-up switch and the pull-down switch being turned on and off.

6. The three-phase digital controlled arbitrary phase AC voltage generator according to claim 1, characterized in that: The control subsystem includes a communication interface unit and an intelligent control unit; the intelligent control unit includes an execution module, an inverter logic control module and a voltage division logic control module; The execution module obtains the working parameters from the communication interface unit, uses the inverter logic control module to generate the voltage control signal of the power isolation subsystem, uses the voltage divider logic control module to generate the voltage divider control signal of the digital control AC voltage divider unit, and also controls the action of the output subsystem.

7. The three-phase digital controlled arbitrary phase AC voltage generator according to claim 6, characterized in that: The inverter logic control module includes a sine wave generator, a triangle wave generator, a first comparator, a first inverter, a first rising edge driver and a first falling edge driver; The sine wave generator and the triangular wave generator independently generate a sine wave and a triangular wave, which serve as two inputs of the first comparator, so that the first comparator outputs a sinusoidal pulse width modulated signal; the sinusoidal pulse width modulated signal is divided into two paths, one path directly passes through the first rising edge driver to form the voltage control signal; the other path passes through the first inverter and then passes through the first falling edge driver to also form the voltage control signal.

8. The three-phase digital controlled arbitrary phase AC voltage generator according to claim 7, characterized in that: In the inverter logic control module, the sine wave generator uses different control signals for the AC phase terminal and the neutral terminal; The control signal generation module of the sine wave generator corresponding to the AC phase end includes an adder, a divider, a first proportional-integral controller, and a step signal generator; the amplitude setting value of the AC phase end from the operating parameter is multiplied by the adder and the sampled value of the internal AC voltage, and then enters the divider as the divisor input; the sampled value of the internal DC voltage serves as the dividend input of the divider; the output of the divider, after passing through the first proportional-integral controller and the step signal generator, together with the phase setting value in the operating parameter, becomes the control signal of the sine wave generator at the AC phase end; The control signal of the sine wave generator corresponding to the neutral end comes from the output of a three-input adder; the input of the three-input adder is the control signal of the sine wave generator of the three AC phase ends.

9. The three-phase digital controlled arbitrary phase AC voltage generator according to claim 6, characterized in that: The voltage division logic control module includes an effective value calculation submodule, a second comparator, a second proportional integral controller, a pulse width modulation generator, a second inverter, a second rising edge driver and a second falling edge driver; The internal AC voltage divider becomes a digital signal after passing through the effective value calculation submodule, which serves as an input of the second comparator; the voltage divider setting value from the operating parameter serves as another input of the second comparator; the output of the second comparator passes through the second proportional-integral controller to control the pulse width modulation generator; the output of the pulse width modulation generator is divided into two paths, one path directly passes through the second rising edge driver to form the voltage divider control signal; the other path passes through the second inverter and then passes through the second falling edge driver to also form the voltage divider control signal.

10. A voltage generating method using the three-phase digitally controlled arbitrary phase AC voltage generating device according to claim 1, characterized in that: Contains steps: Step S100, setting the operating parameters through the control subsystem; In step S200, the control subsystem controls the power isolation subsystem to generate the internal DC voltage from the grid AC voltage, and then convert the internal DC voltage to generate the internal AC voltage; the magnitude of the internal DC voltage is specified by the operating parameter; Step S300: The power isolation subsystem feeds back the internal AC voltage to the control subsystem, and stabilizes the internal AC voltage through closed-loop control; when the control subsystem detects an abnormal internal AC current, the control subsystem controls the power isolation subsystem to reduce or cut off the internal AC voltage; Step S400, the control subsystem controls the digital control AC voltage divider unit to output the internal AC voltage divider; Step S500: obtaining outputs of the three internal AC voltages and the multiple internal AC divided voltages in the output subsystem; the output subsystem also feeds back the internal AC voltages and the multiple internal AC divided voltages to the control subsystem; The control subsystem controls the content displayed by the output subsystem according to the working parameters.

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