Control device and control method for variable frequency speed regulation inverter power supply

Abstract

The invention provides a control device and a control method for a variable frequency speed regulation inverter power supply, and the device comprises an inverter full bridge and a detection control unit. The output end of the inverter full bridge is also connected with a multi-stage low-pass filter, the output end of the multi-stage low-pass filter is connected with the input end of the detection control unit, and the output end of the detection control unit is connected with the input end of the inverter full bridge; the inverter full bridge at least comprises a left bridge arm and a right bridge arm; the detection control unit is used for outputting a corresponding control signal to the inverter full bridge, the control signal at least comprises a corresponding fundamental frequency output to the left bridge arm and a corresponding carrier frequency output to the right bridge arm, and the control signal is used for controlling the inverter full bridge to perform single-pole work according to the control signal; the left bridge arm performs commutation according to the received fundamental wave frequency; and the right bridge arm works according to the received carrier frequency. The problem that the waveform of the inverter power supply is difficult to stabilize in rapid frequency conversion application is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic conversion and control, and particularly to a control device and a control method for a variable-frequency speed-regulating inverter power supply. Background Art

[0002] Low-frequency power supplies are widely used in industrial production, scientific research experiments and other fields. At present, most of the variable-frequency power supply devices on the market rely on mains power supply, and adjust the output frequency and voltage through power electronic conversion technologies such as rectification and inversion. There are problems such as single function, insufficient waveform coefficient, large volume, low efficiency, and lack of flexibility, making it difficult to meet the complex and changeable test requirements, especially the requirements of handheld test devices.

[0003] A typical application of traditional variable-frequency power supplies is frequency converters for AC motors, which usually use single-phase or three-phase mains power supply and output fixed voltage and frequency. After passing through links such as rectification, buffering, inversion, and filtering, high-voltage alternating current with power frequency output is obtained, and the adjustment range of the output voltage and frequency is limited.

[0004] Compared with handheld applications, traditional solutions have problems such as low switching frequency, large equipment volume, high cost, and low control accuracy, and have obvious deficiencies in aspects such as power management, energy efficiency optimization, low-voltage load carrying, and high starting voltage regulation, making it difficult to adapt to variable load characteristics. Summary of the Invention

[0005] The purpose of the present invention is to provide a control device and a control method for a variable-frequency speed-regulating inverter power supply to solve the technical problem that the waveform of the inverter power supply is difficult to stabilize in fast variable-frequency applications.

[0006] On the one hand, a control device for a variable-frequency speed-regulating inverter power supply is provided, including:

[0007] An inverter full bridge and a detection and control unit; the output end of the inverter full bridge is also connected to a multi-stage low-pass filter, the output end of the multi-stage low-pass filter is connected to the input end of the detection and control unit, and the output end of the detection and control unit is connected to the input end of the inverter full bridge; the inverter full bridge includes at least a left bridge arm and a right bridge arm;

[0008] The detection and control unit is used to output corresponding control signals to the inverter full bridge, and the control signals at least include outputting corresponding fundamental frequencies to the left bridge arm and outputting corresponding carrier frequencies to the right bridge arm. The control signals are used to control the inverter full bridge to operate monopolar according to the control signals; the left bridge arm commutes according to the received fundamental frequency; the right bridge arm operates according to the received carrier frequency.

[0009] Preferably, the detection and control unit is specifically configured to receive the current measurement output by the inverter and the voltage and current measurement output by the multi-stage low-pass filter, generate corresponding control signals according to the current measurement and the voltage and current measurement, and output the control signals to the full-bridge inverter.

[0010] On the other hand, a control method for a variable-frequency speed-regulating inverter power supply is also provided, which is implemented based on the above control device and includes:

[0011] Obtain the current measurement output by the inverter and the voltage and current measurement output by the multi-stage low-pass filter;

[0012] Compare the preset target output voltage and frequency with the current measurement and the voltage and current measurement to generate corresponding control signals; the control signals at least include the fundamental frequency output to the left bridge arm and the carrier frequency output to the right bridge arm;

[0013] Control the working state of the variable-frequency speed-regulating inverter power supply according to the control signals to achieve precise variable voltage and variable frequency output.

[0014] Preferably, it further includes determining a corresponding error control amount according to the output voltage of the inverter power supply and correcting the corresponding control signals.

[0015] Preferably, determining the corresponding error control amount according to the output voltage of the inverter power supply includes determining the difference between the received output voltage of the inverter power supply and the preset instantaneous value of the target voltage, and outputting the difference to the PI controller in the variable-frequency speed-regulating inverter power supply to obtain the corresponding current parameter. Determine the difference between the received output voltage of the inverter power supply and the preset instantaneous value of the target voltage, and output the difference to the PI controller in the variable-frequency speed-regulating inverter power supply to obtain the corresponding current parameter.

[0016] Preferably, determining the corresponding error control amount according to the output voltage of the inverter power supply further includes determining the difference between the obtained current parameter and the current measurement, and outputting the difference to the multi-stage low-pass filter. After filtering and limiting by the multi-stage low-pass filter, the final error control amount is obtained.

[0017] Preferably, correcting the corresponding control signals includes correcting the current parameter and related other parameters of the control signals according to the error control amount to obtain the final control signals.

[0018] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0019] The control device and control method for a variable-frequency speed-regulating inverter power supply provided by the present invention provide an excitation source for a current transformer test device, and can also provide solutions for other precision test equipment with low-frequency VVVF requirements, including various application scenarios such as the testing of electrical products, laboratory research, and on-site maintenance, and solve the problem that the waveform is difficult to stabilize in the rapid variable-frequency application of traditional inverter power supplies. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, obtaining other drawings based on these drawings still belongs to the scope of the present invention.

[0021] Figure 1 It is a schematic diagram of a control device for a variable-frequency speed-regulating inverter power supply in an embodiment of the present invention.

[0022] Figure 2 It is a main flow schematic diagram of a control method for a variable-frequency speed-regulating inverter power supply in an embodiment of the present invention.

[0023] Figure 3 It is a logic schematic diagram of a control method for a variable-frequency speed-regulating inverter power supply in an embodiment of the present invention.

[0024] Figure 4 It is a schematic diagram of a closed-loop control in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings.

[0026] As Figure 1 shown, it is a schematic diagram of an embodiment of a control device for a variable-frequency speed-regulating inverter power supply provided by the present invention. In this embodiment, it includes:

[0027] Inverting full bridge and detection control unit; the output end of the inverting full bridge is also connected to a multi-stage low-pass filter, the output end of the multi-stage low-pass filter is connected to the input end of the detection control unit, and the output end of the detection control unit is connected to the input end of the inverting full bridge; the inverting full bridge at least includes a left bridge arm and a right bridge arm; the detection control unit is configured to output corresponding control signals to the inverting full bridge, and the control signals at least include outputting corresponding fundamental frequencies to the left bridge arm and outputting corresponding carrier frequencies to the right bridge arm, and the control signals are used to control the inverting full bridge to operate in a single-pole manner according to the control signals; the left bridge arm commutates according to the received fundamental frequency; the right bridge arm operates according to the received carrier frequency. It can be understood that the driving allocation strategy as shown in Figure 2 is adopted. It should be noted that the full bridge operates in a single-polarity manner, the left bridge arm commutates according to the fundamental frequency, and the right bridge arm operates according to the carrier frequency. Dead zones are arranged only at the zero-crossing points of the AC fundamental wave to avoid the upper and lower bridge arms being directly connected. Whether it is the positive half-cycle or the negative half-cycle of the fundamental wave, a strategy similar to that of a Buck circuit is adopted. The advantage of this is that the dead zones only appear at the commutation points, the fidelity of SPWM is higher, the range that the control algorithm needs to adjust is smaller, and the selection of the switching frequency can be much higher than that of an inverter using a traditional algorithm. The Buck circuit is a conventional setting in this field and will not be elaborated here.

[0028] In one embodiment, the detection control unit is specifically configured to receive the current measurement output by the inverter and the voltage and current measurements output by the multi-stage low-pass filter, and generate and output corresponding control signals to the inverting full bridge according to the current measurement and the voltage and current measurements.

[0029] As shown in Figure 3 , it is a schematic diagram of an embodiment of a control method for a variable-frequency speed-regulation inverting power supply provided by the present invention. In this embodiment, the method includes the following steps:

[0030] Step S1, obtaining the current measurement output by the inverter and the voltage and current measurements output by the multi-stage low-pass filter; it can be understood that the subsequent data basis for control parameters is realized by the controller monitoring the output voltage and frequency in real time and comparing them with the target values.

[0031] Step S2, comparing the preset target output voltage and frequency with the current measurement and the voltage and current measurements to generate corresponding control signals; the control signals at least include outputting corresponding fundamental frequencies to the left bridge arm and outputting corresponding carrier frequencies to the right bridge arm; it can be understood that the target output voltage and frequency are set; the output voltage and frequency are monitored in real time and compared with the target values; according to the comparison results, the control parameters of the DC-DC converter and the inverter are dynamically adjusted.

[0032] It should be noted that the full bridge can be controlled to operate in a single - polarity manner through a control signal. The left bridge arm commutes at the fundamental frequency, and the right bridge arm operates at the carrier frequency. A dead zone is arranged only at the zero - crossing point of the AC fundamental wave to avoid the direct connection of the upper and lower bridge arms. Whether it is the positive or negative half - cycle of the fundamental wave, a strategy similar to the Buck circuit is adopted. The advantage of this is that the dead zone only appears at the commutation point, the fidelity of SPWM is higher, the range that the control algorithm needs to adjust is smaller, and the selection of the switching frequency can far exceed that of an inverter using a traditional algorithm.

[0033] In one embodiment, the corresponding error control quantity is determined according to the output voltage of the inverter source, and the corresponding control signal is corrected. Specifically, the difference between the received output voltage of the inverter source and the preset instantaneous value of the target voltage is determined, and this difference is output to the PI controller in the variable - frequency speed - regulating inverter power supply to obtain the corresponding current parameter. The difference between the obtained current parameter and the current measurement is determined, and this difference is output to the multi - stage low - pass filter. After filtering and limiting by the multi - stage low - pass filter, the final error control quantity is obtained. According to this error control quantity, the current parameter and other related parameters of the control signal are corrected to obtain the final control signal. It can be understood that a double - loop structure of a voltage outer loop and a current inner loop is adopted as Figure 4 shown, which is only used to illustrate the closed - loop control principle and drive generation logic. Vsin contains three elements of alternating current: amplitude, phase, and frequency. Vo is the output voltage of the inverter source, IF is the output current of the full bridge, VTRI is the carrier frequency, and the actual control code is consistent with this block Figure 1 : The difference between the instantaneous value of the target voltage and the instantaneous value of the voltage feedback is calculated. After passing through the PI controller, it is used as the given value of the inner - loop current. After further calculating the difference with the full - bridge current and passing through low - pass filtering and limiting, the final error control quantity is obtained. This is a lightweight closed - loop algorithm. Based on the premise of excellent open - loop waveform characteristics, the overall operation amount is less than that of a traditional inverter.

[0034] Step S3, control the working state of the variable - frequency speed - regulating inverter power supply according to the control signal to achieve precise variable - voltage and variable - frequency output.

[0035] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0036] The control device and control method for the variable - frequency speed - regulating inverter power supply provided by the present invention provide an excitation source for the current transformer test device, and can also provide solutions for other precision test equipment with low - frequency VVVF requirements, including various application scenarios such as the testing of electrical products, laboratory research, and on - site maintenance, solving the problem that the waveform is difficult to be stable in the rapid variable - frequency application of traditional inverter power supplies.

[0037] The above-disclosed is only the preferred embodiment of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A control device for a variable-frequency speed-regulating inverter power supply, characterized in that, Comprising: An inverter full bridge and a detection and control unit; the output end of the inverter full bridge is further connected to a multi-stage low-pass filter, the output end of the multi-stage low-pass filter is connected to the input end of the detection and control unit, and the output end of the detection and control unit is connected to the input end of the inverter full bridge; the inverter full bridge at least includes a left bridge arm and a right bridge arm; The detection and control unit is used to output corresponding control signals to the inverter full bridge, the control signals at least include outputting corresponding fundamental frequencies to the left bridge arm and outputting corresponding carrier frequencies to the right bridge arm, and the control signals are used to control the inverter full bridge to operate in a single-pole mode according to the control signals; the left bridge arm commutates according to the received fundamental frequency; the right bridge arm operates according to the received carrier frequency.

2. The control device according to claim 1, characterized in that, Specifically, the detection and control unit is used to receive the current measurement output by the inverter and the voltage and current measurement output by the multi-stage low-pass filter, and generate and output corresponding control signals to the inverter full bridge according to the current measurement and the voltage and current measurement.

3. A control method for a variable-frequency speed-regulating inverter power supply, which is implemented based on the control device described in claim 1 or 2, is characterized in that, Including, Obtaining the current measurement output by the inverter and the voltage and current measurement output by the multi-stage low-pass filter; Comparing a preset target output voltage and frequency with the current measurement and the voltage and current measurement to generate corresponding control signals; the control signals at least include outputting corresponding fundamental frequencies to the left bridge arm and outputting corresponding carrier frequencies to the right bridge arm; Controlling the working state of the variable-frequency speed-regulation inverter power supply according to the control signals to achieve precise variable voltage and variable frequency output.

4. The control method according to claim 3, wherein It further includes determining a corresponding error control amount according to the output voltage of the inverter source and correcting the corresponding control signals.

5. The control method according to claim 4, characterized in that, The determining the corresponding error control amount according to the output voltage of the inverter source includes determining the difference between the received output voltage of the inverter source and the preset instantaneous value of the target voltage, and outputting the difference to the PI controller in the variable-frequency speed-regulation inverter power supply to obtain corresponding current parameters. Determine the difference between the received output voltage of the inverter source and the preset instantaneous value of the target voltage, and output the difference to the PI controller in the variable-frequency speed-regulation inverter power supply to obtain corresponding current parameters.

6. The control method according to claim 5, wherein The determining the corresponding error control amount according to the output voltage of the inverter source further includes determining the difference between the obtained current parameters and the current measurement, and outputting the difference to the multi-stage low-pass filter. After filtering and limiting by the multi-stage low-pass filter, the final error control amount is obtained.

7. The control method according to claim 6, wherein The correcting the corresponding control signals includes correcting the current parameters and related other parameters of the control signals according to the error control amount to obtain the final control signals.

Images