CN2679921Y

CN2679921Y - Three-phase current smooth controller of a.c. dynamo

Info

Publication number: CN2679921Y
Application number: CNU2004200327142U
Authority: CN
Inventors: 吕虹
Original assignee: GUILIN STARS POWER ELECTRORNICS CO Ltd
Current assignee: GUILIN STARS POWER ELECTRORNICS CO Ltd
Priority date: 2004-01-18
Filing date: 2004-01-18
Publication date: 2005-02-16
Anticipated expiration: 2014-01-18

Abstract

The three-phase current smooth controller of AC dynamo of the utility model comprises a vector generator, a current closed loop controller and a three-phase winding which are mutually connected as a loop, and besides comprises a circuit network of abstracting central points. In a typical circuit network port voltage of a three-phase motor is led out and is respectively connected with impedance of an equivalent value and connected together at a point Q in radial connection, and the electric potential of the central point Q is introduced into a controller to carry out slide control of three-phase current. When the disbalance of the three-phase current causes the electric potential of a central point O of a winding to deviate from a zero value, the electric potential of the point Q directly models the electric potential of the central point O of the winding, and engages in controlling to correct the given magnitude or the back-feed magnitude of three-phase sinusoidal current in real time for avoiding saturation of a three-phase control loop and waveform aberration of the three-phase current. The utility model is of simple circuit, overcomes a complex process of zero sequence component analysis and control, and lowers a precision requirement for the three-phase current controlling the closed loop; besides, the utility model realizes the zero sequence control of three-phase current control of a motor, and ensures that the controller outputs the three-phase sinusoidal current of smooth output waveform, same amplitude value and 120 degrees phase difference.

Description

Alternating-Current Dynamo Three-Phase Current Smooth Controlling Device

(1) technical field

The utility model relates to a kind of control device of alternating current machine three-phase current, is specially a kind of level and smooth control device of alternating current machine three-phase current.

(2) technical background

The control of three phase alternating current motor, desirable method is to give by frequency converter or AC servo driver to feed in three phase windings of motor that changeable frequency, amplitude are identical, the symmetrical three phase sine electric current of phase place mutual deviation 120 degree, thereby produce an excitation magnetic potential that intensity, direction of rotation and rotary speed are controlled, be circular excitation magnetic potential, therefore produce rotational stator magnetic field.

According to " the Alternating Current Governor System " (author that in May, 2003, China Machine Press published, old when uncle, Chen Minxun) described, generally be to adopt sinusoidal wave pulse width to regulate method-SPWM method to provide three phase sine voltage at present, perhaps adopt current tracking control method to provide the three phase sine electric current to motor to motor.The direct controlling object of SPWM method is an electric moter voltage, and the actual current of motor is subjected to that armature reaction, magnetic field are saturated etc. to be influenced, and often the existence owing to high order harmonic component departs from sine, thereby can not get the Optimal Control characteristic.Current tracking control method adopts the three-phase current closed loop circuit to solve the problem of high order harmonic component preferably, but three-phase current is respectively the given signal of three phase sine that is produced by driver, three current closed-loop controllers are output current independently of one another, and three characteristics of the middle term electric current is the loop each other, so three-phase current flashy summation in office is zero, this yet " summation is zero " is " pressure ", because there is not non-vanishing return passage.Because the effect of checking and balance of three-phase current control, then no matter given, the feedback and control how accurate, always have one tunnel electric current in the three-phase control loop and be not by self closed-loop control but obtain by other biphase current addition, therefore exist the difference that to eliminate in a period of time between this phase actual current and the set point, the integration amount in the proportion integration differentiation of this phase (PID) loop can't reach feedback equalization in the certain hour of loop, so will reach capacity.Particularly during the motor low-speed running, this phenomenon is fairly obvious, and the three-phase loop controller enters the integration saturation condition in turn.Though, it is little to the current waveform influence to enter saturation condition, but because integration moves back and saturatedly needs the regular hour, so will on output current wave, superposed waveform distort, saltus step can take place in this direction that is equivalent to stator flux vector, and this disturbance to torque and motor speed control is self-evident.And because the high fdrequency component that should distort is bigger, motor will generate heat because of having increased high-frequency loss.

At the problems referred to above, the control device of research is the design sample circuit usually, gets the current value on three phase windings, it is carried out zero-sequence component resolves, by after the calculating of complexity with input control circuit as a result, through being a row control procedure, finally realize the Balance Control of electric current.But this control device is the claimed apparatus complexity not only, current sample precision height, and also the calculation control process is numerous and diverse, is difficult to actual use.

(3) utility model content

The purpose of this utility model is to design a kind of level and smooth control device of simple alternating current machine three-phase current, introduce the amount relevant and send driver back to three-phase current unbalance, make three-phase current simultaneously controlled, level and smooth output, and reduction is to the requirement of three-phase circuit controls precision.

The level and smooth control device of the alternating current machine three-phase current of the utility model design comprises the vector generator that produces the given signal of three phase sine, contains the three-phase current closed loop controller of PID circuit, pwm circuit, loop of power circuit.The three-phase sine-wave signal of vector generator output is sent into three current closed-loop controllers respectively as given signal, and controller is sent the three phase sine electric current into three phase windings by the loop of power circuit of inside, and three phase windings are the loop each other.Comprise also in this device that central point extracts circuit network, the three phase electric machine port voltage is drawn, insert the circuit network that extracts three phase winding central point Q point current potentials, Q point current potential introducing controller is carried out three-phase current smoothly control.

Because being exactly the current potential of three phase winding central point O, asymmetric, the unbalanced direct result of three-phase current departs from null value.Center Q point current potential direct modeling three phase alternating current motor winding central point O point current potential with the circuit network of drawing, Q point current potential is sent into controller and is participated in control, can revise the given value or the feedback value of three phase sine electric current in real time, make the three-phase control loop all avoid entering saturated, avoid the three-phase current waveform to distort.

This device circuit is simple, can directly obtain reflection three-phase current unbalance status detection amount---three-phase neutral potential, overcome the complex process that zero-sequence component is resolved and controlled, make the level and smooth control of follow-up electric current become simple, reduced required precision simultaneously three-phase current control closed loop.This device has been realized the zero sequence control in the control of alternating current machine three-phase current, and guaranteeing that the controller output waveform is level and smooth, amplitude is identical, differing is 120 ° three phase sine electric current.

(4) description of drawings

Fig. 1 is the realization theory diagram that obtains and revise of virtual midpoint potential;

Fig. 2 is for adopting this device front and back alternating current machine three-phase current comparison of wave shape figure.

(5) embodiment

The circuit of the level and smooth control device of the utility model alternating current machine three-phase current comprises the vector generator, the three-phase current closed loop controller that produce the given signal of three phase sine as shown in Figure 1.The three-phase sine-wave signal of vector generator output is sent into three current closed-loop controllers respectively as given signal, and controller is sent the three phase sine electric current into three phase windings by the loop of power circuit of inside, and three phase windings are the loop each other.Comprise also in this device that central point extracts circuit network, the three phase electric machine port voltage is drawn, each inserts an equivalent impedance, connect altogether at the Q point by wye connection, constitute to extract the circuit network of three phase winding central point Q point current potentials, get current potential introducing controller that this star-like circuit mid point Q orders and carry out three-phase current and smoothly control.

Shown in Fig. 2 a, adopt the preceding alternating current machine three-phase current waveform of this device, because the effect of checking and balance of three-phase current control, then no matter given, the feedback and control how accurate, always have in the three-phase control loop one tunnel electric current be not by self closed-loop control but obtain by other biphase current addition, therefore exist the difference that to eliminate in a period of time between this phase actual current and the set point, the integration amount of this phase pid loop can't reach feedback equalization in the certain hour of loop, so will reach capacity.Particularly during the motor low-speed running, the three-phase loop controller enters the integration saturation condition in turn.Though it is little to current waveform influence to enter saturation condition because integration moves back and saturatedly needs the regular hour, on output current wave superposition a wave distortion.

Adopt this device back alternating current machine three-phase current waveform shown in Fig. 2 b, owing to avoided the control loop of three-phase current to enter the saturated distortion that causes output current wave, current waveform is level and smooth.

With the center Q point current potential simulated machine three phase winding central point voltages of circuit network, this voltage is sent into the three-phase current closed loop controller again by amending unit.Amending unit monitoring in real time and the real-time feedback signal of revising the given signal of three-phase current or revising three-phase current, avoid the control loop of three-phase current to enter the saturated distortion that causes output current wave, so that the three-phase loop remains operating in unsaturated zone in dynamic adjustment process.

Amending unit is analog circuit or digital circuit or the mixing of the two.Amending unit is by changing numerical value given or feedback, a perhaps additional given or feedback biasing, thus guarantee that the controller output waveform is level and smooth, amplitude is identical, differ to be 120 ° three phase sine electric current.

Insert computer in the amending unit, the realization of relevant makeover process has computer to participate in, and is more accurately quick.

Claims

The level and smooth control device of 1 one kinds of alternating current machine three-phase currents comprises the vector generator, the three-phase current closed loop controller that produce the given signal of three phase sine; Vector generator is connected with three current closed-loop controllers, and the three-phase current closed loop controller is sent electric current into motor three phase windings, and three phase windings are the loop each other; It is characterized by:

Comprise that also central point extracts circuit network, the three phase electric machine port voltage drawn, insert neutral potential and extract circuit network that get the current potential of the three-phase central point Q of this circuit network, Q point current potential is introduced the three-phase current closed loop controller.
The level and smooth control device of 2 alternating current machine three-phase currents according to claim 1 is characterized by:

Described circuit network is that the three phase electric machine port respectively inserts an equivalent impedance, connects altogether at the Q point by star connection, and the forming circuit network is got the current potential of this star circuit mid point Q and introduced the three-phase current closed loop controller.
The level and smooth control device of 3 alternating current machine three-phase currents according to claim 1 and 2 is characterized by:

The center Q point current potential of motor three phase winding central point voltage subtraction circuit networks is sent into the three-phase current closed loop controller again by amending unit.
The level and smooth control device of 4 alternating current machine three-phase currents according to claim 3 is characterized by:

Amending unit is analog circuit or digital circuit or the mixing of the two, and makeover process can have the participation of computer.
The level and smooth control device of 5 alternating current machine three-phase currents according to claim 4 is characterized by:

The signal of amending unit output is directly directly sent into the three-phase current closed-loop system in the mode of specified rate correction value or feedback quantity correction value.