Full digitalized vector control type high-voltage large-power frequency converter based on DSP chip

Abstract

The invention discloses a DSP chip-based all-digital vector control high-voltage high-power inverter, differing from traditional high-voltage high-power inverters in aspects: its control part master control board adopts DSP chip as CPU; adopts vector control mode to calculate all the parameters controlling the machine, to obtain output frequency of the inverter, and turn-on frequency and time of the control power module unit. It solves the difficult problem of implementing high-performance control; implements more accurate and faster control, real constant torque and fast dynamic response, restarting for accident and power-off, automatic load limitation, etc.

Description

technical field [0001] The present invention relates to a high-voltage high-power frequency converter, especially a kind of fully digital control based on DSP chip, without harmonic pollution, with automatic detection of output current and limiting, capable of flying car start and power-off restart function High voltage and high power inverter. Background technique [0002] With the development of power electronics technology, as a product of the development of power electronics technology, frequency converters have been widely used in various fields of the national economy such as metallurgy, petrochemicals, tap water, electric power and other industries, and are playing an increasingly important role. Yes, the application of high-voltage and high-power inverters is becoming more and more extensive. [0003] Such as figure 1 As shown, at present, the general-purpose high-voltage high-power inverter is mainly composed of a multi-secondary winding transformer 1', several po...

AI Technical Summary

Problems solved by technology

[0005] 1. Real constant torque control cannot be realized, dynamic response speed is slow, and high-performance motor control cannot be realized

[0006] Since this general-purpose high-voltage and high-power inverter adopts a variable voltage variable frequency (VVVF) open-loop control method, which is relatively simple, it cannot realize complex control

Although this common variable voltage variable frequency (VVVF) open-loop control method is theoretically constant torque, the drive command to drive the power device on and off has to go through a period of time from the inverter controller to the final drive power device. The series of actuators, the accumulation of errors in each link, makes the actual output torque of the inverter and the design output target torque have some errors, so that the real constant torque cannot be realized, and the dynamic response is relatively slow. Enabling High-Performance Motor Control

[0007] 2. Industrial rotation restart cannot be realized

[0008] Since the general-purpose high-voltage and high-power inverter adopts the variable voltage and variable frequency (VVVF) open-loop control method, its controller part cannot recognize the speed of the motor, and cannot track the actual speed again at a certain time after the power device drive signal is blocked and continue to issue drive commands, that is, Industrial rotary restart cannot be realized

If the motor is rotating before starting, it cannot be started immediately. It must wait for the motor to be completely static before starting again, otherwise it is easy to cause an overcurrent fault of the inverter

Similarly, because it cannot identify the actual speed of the motor, it cannot track the actual speed of the motor after the power grid voltage of the frequency converter disappears suddenly for a period of time and continue to realize correct control and drive of the power device, that is, it cannot realize the power-down restart function

[0009] 3. The overvoltage and overcurrent protection functions are weak, and the power module unit is easy to burn out

[0010] Since the general-purpose high-voltage and high-power inverter adopts the variable voltage and variable frequency (VVVF) open-loop control method, its control part cannot identify and judge the energy fed back from the motor to the inverter after slowing down the output of the inverter, which results in reducing the output of the inverter. If the set deceleration time is too short, due to the strong inertia of the unit, the feedback energy of the motor is too much and the energy storage capacitor of the power part of the frequency converter cannot absorb it in time, resulting in a DC bus overvoltage fault, resulting in the failure of the frequency conversion device to continue to operate normally

[0011] In addition, because the control part of the general-purpose high-voltage high-power inverter is designed based on the single-chip microcomputer and its peripheral circuits, its operation and response speed are relatively slow, and the current output from the inverter to the motor winding cannot be detected and monitored in time. Automatically limit the output of the inverter when the load changes

The usual situation is that when the motor load suddenly increases, the output current of the inverter suddenly increases, resulting in an overcurrent fault, and the power unit is burned.

[0012] 4. It is impossible to realize soft start of multiple motors driven by one frequency converter

[0013] Since this general-purpose high-voltage and high-power inverter adopts a variable voltage and variable frequency (VVVF) open-loop control method, it lacks the detection of the grid voltage amplitude and phase, so that the inverter puts the motor from being controlled by the inverter to being driven. When the power supply network is directly driven, due to the large difference in amplitude and phase between the motor terminal voltage and the power grid, an overcurrent fault occurs, and the motor cannot be freely switched between being controlled by the frequency converter and being directly connected to the power grid. As a result, the role of the frequency converter in controlling the motor cannot be fully utilized, and the function of one frequency converter driving multiple motors to soft start cannot be realized.

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