CN103701383A - Method for restraining overvoltage of busbar in vector control system - Google Patents

Abstract

The invention discloses a method for restraining an overvoltage of a busbar in a vector control system. The method comprises the following steps: step 1, detecting the voltage of the busbar; step 2, comparing the detected voltage with a set voltage and performing voltage PI regulation so as to obtain an output voltage; step 3, performing amplitude limiting on a torque current according to the output voltage, wherein the lower limit amplitude is 0 and the upper limit amplitude is a set torque current value; step 4, if performing positive rotation, multiplying the upper and lower limit amplitude values by minus 1. By virtue of controlling the torque current size under an electricity generation state and controlling the transmit power of a motor to a driver, namely the speed of transmitting mechanical kinetic energy to the driver, restraint on the overvoltage of the busbar can be realized; the torque current set under the electricity generation state of the vector control system is automatically regulated, so that the speed reducing process is optimal.

Description

A kind of vector control system median generatrix over-voltage suppression method

Technical field

The present invention relates to a kind of vector control system median generatrix over-voltage suppression method, for asynchronous machine or synchronous machine Vector Speed-Control System.

Background technology

Vector control technology is applied more and more extensive in practice, and the high-power dragging system from the low pressure small-power servo-control system of several hectowatts to tens megawatts, has application case.For asynchronous machine, owing to adopting rotor flux-orientation vector control system, easily realize torque and magnetic field decoupling, the control performance having obtained.For permagnetic synchronous motor, owing to adopting rotor orientation (actual is to be also rotor field-oriented), easily realize torque and magnetic field decoupling, even do not need to calculate magnetic linkage, use very simple.No matter adopt which kind of vector control scheme, be all three-phase motor stator alternating current flow valuve, by coordinate transform, transform on two-phase synchronous rotating frame, become two DC quantity, torque component of an excitation component, controls respectively.

Principle of vector control: as shown in Figure 1, user's given speed and the comparison of motor actual speed, through speed pi regulator, obtain given torque current; Given torque current and actual torque current ratio, through torque current pi regulator, obtain needing the torque voltage of output; In control rate and torque while, for the dynamic property obtaining, need to control the exciting current of motor simultaneously, general given stator excitation electric current (below rated speed as required, the given no-load current that is generally of asynchronous machine rotor field orientation exciting current, permagnetic synchronous motor exciting current is given is generally equal to 0) and actual exciting current comparison, through exciting current pi regulator, obtain exporting exciting voltage.

In the vector control of standard, there is no busbar voltage controlling unit, when motor drags large inertia load; in quick shutdown process; epitrochanterian kinetic energy charges to DC bus by the fly-wheel diode of frequency converter, if do not controlled, is easy to cause bus overvoltage.Under normal circumstances, in the time can not increasing DC bus discharge cell, for fear of DC bus overvoltage, artificially increase deceleration time.

Summary of the invention

The object of the invention is the deficiency existing for prior art, a kind of vector control system median generatrix over-voltage suppression method is provided.

The object of the invention is to realize by following technological means:

Step 1, detects busbar voltage;

Step 2, detects voltage and setting voltage comparison, carries out voltage PI adjusting, obtains output voltage;

Step 3, carries out amplitude limit according to output voltage to torque current, and lower amplitude limit is 0, the torque current value of upper amplitude limit for setting;

Step 4, if forward is multiplied by-1 to torque current upper and lower limit amplitude.

Compared with prior art the present invention has following obvious advantage: the superpotential immediate cause of drive system DC bus is the anti-driver DC side of delivering to of motor kinetic energy, by controlling the size of torque current under generating state, control motor to driver through-put power, be that mechanical kinetic energy is transmitted speed to driver, realizing bus overvoltage suppresses, automatically the torque current of adjusting under vector control system generating state is given, makes moderating process optimum.

Embodiment

Below in conjunction with accompanying drawing explanation and embodiment, the present invention is described in further detail:

As shown in Figure 2 and Figure 3, a kind of vector control system median generatrix over-voltage suppression method, specific implementation step is as follows:

Step 1, detects busbar voltage;

Step 2, detects voltage and setting voltage comparison, carries out voltage PI adjusting, obtains output voltage;

Step 3, carries out amplitude limit according to output voltage to torque current, and lower amplitude limit is 0, the torque current value of upper amplitude limit for setting;

Step 4, if forward is multiplied by-1 to torque current upper and lower limit amplitude.

Claims (1)

1. a vector control system median generatrix over-voltage suppression method, is characterized in that, process following steps:

Step 1, detects busbar voltage;

Step 2, detects voltage and setting voltage comparison, carries out voltage PI adjusting, obtains output voltage;

Step 3, carries out amplitude limit according to output voltage to torque current, and lower amplitude limit is 0, the torque current value of upper amplitude limit for setting;

Step 4, if forward is multiplied by-1 to torque current upper and lower limit amplitude.

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