CN101989833B - Control device of induction motor and application thereof - Google Patents

Abstract

The invention discloses a control device of an induction motor, comprising a tri-phase bridge rectifier, an insulated gate bipolar transistor (IGBT) or an intelligent power module (IPM), the induction motor, a dual-path current transformer, a pulse-width modulation (PWM) driver and a driving operation system, wherein the driving operation system comprises a microprocessor, and adopts a V/F (voltage/frequency) control mode to realize control on the induction motor; the driving operation system also comprises a filter circuit which is connected between a voltage/frequency operation unit and a current effective value operation unit and is used for filtering the effective value Ic of line current fed back by the current transformer, and the output filter value Icm of the feedback line current is input into the voltage/frequency operation unit; and the voltage/frequency operation unit adjusts the finally output voltage/frequency in real time based on the filter value Icm of the feedback line current. The invention also discloses an application of the control device of the induction motor. In the invention, on the premise of not weakening the heavy load driving capacity of an escalator and a moving walk, the effect of stable operation of the motor with minimum current under a medium/light load condition is realized, thus achieving energy conservation.

Description

The control device of induction motor and application thereof

Technical field

Technical field

The present invention relates to a kind of driving control system that is used for escalator and Travelator system; Particularly relate to a kind of ability and realize energy-conservation induction motor energy-saving control device.The invention still further relates to of the application of said arrangement for controlling induction motor at escalator and/or moving sidewalk.

Background technology

The operation of escalator and moving sidewalk possibly be in various states, like the Light Condition under the unmanned condition, or full load condition.When escalator was up simultaneously, motor overcame staircase frictional force and the acting of pedestrian's potential energy, is in motoring condition; And staircase is when descending, and pedestrian's potential energy drive motor operation makes motor be in reproduced state.Therefore be used for the induction motor drive system of escalator and moving sidewalk, the load that is added on the induction motor has very wide excursion.To need the problem of overriding concern be the load that can drive fully loaded pedestrian to the drive system of escalator and moving sidewalk generally speaking.Yet through statistics, escalator and the moving sidewalk most of the time in the whole service cycle is to be in the light running state, and the driving parameters that can drive fully loaded load this moment is added on the induction motor, and the efficient of induction motor is very low.Therefore consider escalator and the moving sidewalk energy-conservation significance under the underloading condition with reality.

As the VVVF frequency-conversion voltage-varying speed system of the induction motor of known technology, its common way is the exciting current I with induction motor _dFixing, then the torque current Iq of induction motor will be directly proportional with the output torque T of induction motor, so just can utilize linear control theory that induction motor realization decoupling zero has been controlled.This fixed excitation electric current I _dMethod because will take into account the driving force of fully loaded load, I _dChoose and be generally induction motor no-load current Io when moving (on induction motor, apply rated voltage Un induction motor electric current) with rated frequency Fn.Therefore, shortcomings such as escalator induction electric pusher side electric current under the underloading condition is bigger than normal, power factor low and induction motor still generates heat have been caused even to drive an extremely light load current still bigger for induction motor.If with exciting current I _dReduce, under the induction motor load becomes big situation suddenly, might cause stopping or fluctuation of service, this is unallowed in the running of escalator and moving sidewalk.

Chinese invention patent specification CN1032724C (patent No.: ZL92111351.X, Granted publication day: on September 4th, 1996) a kind of control of induction high efficiency operation controller and control method in the motor load weight range of a broad are provided.Through by the measured power factor of motor and relatively motor load control the supply voltage of motor for the comparative result between the best power factor, also can reach stable operation and minimum power consumption when making motor be operated in light-load state.But it at first need confirm the optimum power factor curve of motor; The loading condition of its less important definite motor operation could realize control.It does not relate to the ruuning situation when motor is in reproduced state in addition.Therefore existing control method does not solve the problem of escalator and moving sidewalk light-load energy saving well.

Summary of the invention

The technical problem that the present invention will solve provides a kind of control device of induction motor; Make escalator and moving sidewalk under the situation that does not weaken heavily loaded driving force; Induction motor all can be realized energy-conservation with minimum current stable operation under medium load or light-load conditions; For this reason, the present invention also will provide a kind of application of control device of said induction motor.

For solving the problems of the technologies described above, the control device of induction motor of the present invention comprises:

The three-phase commutation bridge heap is realized the conversion of AC-DC;

IGBT or IPM power model are connected with said three-phase commutation bridge heap, realize the DC-AC conversion, for induction motor provides driving power voltage;

Induction motor is connected with power model, is used to drive load;

Two-way current transformer, the U that measures said induction motor respectively mutually with V phase current mutually, and input to by the driving arithmetic system;

Pwm driver is connected between driving arithmetic system and the power model, under the control of the U that drives arithmetic system output, V, W three-phase voltage output valve, produces the supply voltage of frequency and voltage variable, the triggering of power controlling module;

Said driving arithmetic system is made up of microprocessor; Adopt the V/F control mode; Realization is to the control of said induction motor, wherein: this driving arithmetic system comprises a filter circuit, and the voltage-frequency that is connected said driving arithmetic system is than between arithmetic element and the current effective value arithmetic element; Effective value Ic to the line current of current transformer feedback carries out filtering, the feedback line current filtering value I of its output _CmInput to said voltage-frequency and compare arithmetic element;

Said voltage-frequency than arithmetic element according to feedback line current filtering value I _CmThe voltage-frequency of the final output of real-time regulated makes the total current of said induction motor minimum than V/F.

Arrangement for controlling induction motor recited above is used for drive controlling escalator or moving sidewalk.

Owing to adopt control device of the present invention, guaranteed induction motor in low loading condition total current minimum down, reach purpose of energy saving; While, the heat radiation power of corresponding inverter also can reduce, and has improved the condition of work of inverter owing to electric current reduces.

Control device control logic of the present invention is simple, only need know the no-load current I of induction motor ₀, and do not need complicated motor Mathematical Modeling, and just can be implemented under the situation that does not weaken heavily loaded driving force, when middle underloading, realize the control of motor minimum current.The present invention can make in the wide region of induction motor under electric model and power generation mode and move, and is particularly suitable for load capacity and changes escalator realization Energy Saving Control greatly.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is done further detailed explanation:

Fig. 1 is an example structure figure of the control device of induction motor;

Fig. 2 is an induction motor Current Decomposition polar plot.

Embodiment

Referring to shown in Figure 1, said arrangement for controlling induction motor comprises:

Three-phase commutation bridge heap 3 links to each other with the civil power three phase mains, realizes the conversion of AC (interchange)-DC (direct current).

IGBT (Insulated Gate Bipolar Transistor; Igbt) or IPM (Intelligent Power Module; SPM) power model 2; Be connected with three-phase commutation bridge heap 3 through dc bus 4, realize the DC-AC conversion, for induction motor 1 provides driving power voltage.

Induction motor 1 links to each other with power model 2, is used to drive escalator and/or moving sidewalk.

Two-way current transformer 7,8, the U that measures induction motor 1 respectively mutually with V phase current mutually, and input to the driving arithmetic system 6 that constitutes by microprocessor.

Pwm driver 5 is connected between driving arithmetic system 6 and the power model 2, under the control of the U that drives arithmetic system output, V, W three-phase voltage output valve, produces the supply voltage of frequency and voltage variable, the triggering of power controlling module.

Said driving arithmetic system 6 is cores of arrangement for controlling induction motor, adopts the V/F control mode, realizes the control to induction motor 1.

Said driving arithmetic system 6 comprises:

Current effective value arithmetic element 21 is connected with two-way current transformer 7,8, to the electric current I u of current transformer 7,8 feedback, Iv can calculate the feedback line electric current by following formula effective value Ic:

$I_c=\sqrt{(I_u^2+I_v^2+I_w^2)/3}=\sqrt{[I_u^2+I_v^2+{(-I_u-I_v)}^2]/3}$

In the formula, Iw is the phase current of W phase in the civil power three phase mains.

The filter circuit of being realized by software 22 is connected voltage-frequency than between arithmetic element 25 and the current effective value arithmetic element 21, eliminates the burr of the effective value Ic of feedback line electric current, and the output valve of filter circuit 22 is feedback line current filtering value I _Cm, input to voltage-frequency than arithmetic element 25.

Speed command arithmetic element 24 is used to produce the rate control instruction value of induction motor 1.

Electric machine frequency arithmetic element 23 is connected with speed command arithmetic element 24, is used to produce the control frequency F of induction motor 1.

Voltage-frequency is connected with filter circuit 22 and electric moter voltage arithmetic element 26 than arithmetic element 25, and the voltage-frequency that is used to calculate induction motor 1 compares V/F.

Electric moter voltage arithmetic system 26 is connected than arithmetic element 25 with electric machine frequency arithmetic element 23 and voltage-frequency, is used to produce U, V, the W three-phase voltage output valve of control of induction 1 and inputs to pwm driver 5.

For escalator system, its outer load by zero load to fully loaded or by fully loaded be not rapidly to unloaded period of change, general more than 10 second time of needs at least, so the suitable time constant filter of filter circuit 22 is between 200ms～1s.

Voltage-frequency is not that fixed value is adopted in the existing V/F control of picture than the voltage-frequency that arithmetic element 25 produces than V/F in the present invention; But according to the effective value I of the feedback current of current transformer 7,8 _cCome the voltage-frequency of the final output of real-time regulated to compare V/F.Induction motor control system with 380V/50Hz is example (being rated voltage Un=380V, rated frequency Fn=50Hz), and voltage-frequency is regulated induction motor 1 by following mode than arithmetic element 25 voltage-frequency is than V/F:

During 1, as , V/F=380V/50Hz;

During 2, as

, V/F=k * 380V/50Hz;

3, when $k\&times;\sqrt{2}{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100576867E00021.png"\; state="\{\{state\}\}">I</figure-callout>}}_0<I_{\mathrm{Cm}}<\sqrt{2}{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100576867E00021.png"\; state="\{\{state\}\}">I</figure-callout>}}_0$ The time, $V/F=[I_{\mathrm{Cm}}/\left(\sqrt{2}{I}_0\right)]\&times;380V/50\mathrm{Hz}.$

Wherein, I _CmBe filtered feedback line current filtering value; I ₀Be the no-load current of induction motor 1, the current value of the induction motor 1 when promptly on induction motor 1, applying rated voltage Un and moving with rated frequency Fn; K is the constant less than 1, and is not enough to prevent induction motor 1 driving moment.

For escalator system; When staircase is unloaded because the frictional force of mechanical systems such as handrail; Induction motor 1 needs the moment of output to be about 20% of rated moment; Be the minimum electronic load of escalator; According to the relation that output torque is directly proportional with current squaring, choose and be k=0.4～0.5th, suitable.

The 1st kind of regulative mode; Be used to limit the maximum of voltage-frequency, can limit the maximum of exciting current, prevent that the overexcitation phenomenon from appearring in induction motor 1 than V/F; Load increased outside (feedback current is excessive) meaned when induction motor 1 electric current is big simultaneously; Need exciting current be set in normal value, enough voltage output is arranged, guarantee the fan-out capability of induction motor 1.

The 2nd kind of regulative mode is used to limit the minimum value of voltage-frequency than V/F, can limit the minimum value of exciting current; Prevent that induction motor 1 from causing stall or speed unstable because of moment is not enough; Because electric current is less at this moment, mean that outer load is less simultaneously, can reduce the voltage of induction motor 1.

The 3rd kind of regulative mode, can make induction motor 1 under the low loading condition, the voltage-frequency of induction motor 1 makes the total current minimum of induction motor 1 than the state that reaches an optimum.According to Principle of Electric Engine; If do not consider the pressure drop of motor stator resistance; The voltage-frequency of motor is directly proportional with its exciting current than V/F, and the voltage-frequency of regulating motor is also promptly regulated the exciting current of motor than V/F, and therefore the physical meaning of above-mentioned the 3rd kind of regulative mode is equivalent to:

When $k\&times;\sqrt{2}{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100576867E00021.png"\; state="\{\{state\}\}">I</figure-callout>}}_0<I_{\mathrm{Cm}}<\sqrt{2}{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100576867E00021.png"\; state="\{\{state\}\}">I</figure-callout>}}_0$ The time, make the exciting current of motor $I_{\mathrm{Ds}}=I_{\mathrm{Cm}}/\sqrt{2}.$

Explain that below in conjunction with Fig. 2 the 3rd kind of regulative mode can make the total current of induction motor 1 finally can be stabilized on the minimum current.

With ABC curve under Fig. 2 certain loads condition is example.If the initialization point of induction motor 1 is the A point, this moment, induction motor 1 load was less, the excitation current component large percentage, and induction motor 1 power factor is low.The feedback current I that A is ordered _Cm=| OA|, excitation current component $I_d=\left|\mathrm{OI}\right|{>I}_{\mathrm{Cm}}/\sqrt{2},$ Therefore using the 3rd kind of regulative mode has reduced the excitation current component under this certain loads condition, and the real work point of induction motor 1 moves to the B point.If the initialization point of induction motor 1 is the C point, this moment, induction motor 1 excitation current component was very little, caused total current bigger equally, the feedback current I that C is ordered _Cm=| OC|, excitation current component $I_d=\left|\mathrm{OL}\right|<I_{\mathrm{Cm}}/\sqrt{2},$ Use the 3rd kind of regulative mode and increased the excitation current component under this certain loads condition this moment, and the real work point of induction motor 1 moves to the B point.Therefore the working point under this certain loads condition finally all can reach the B point through repeatedly repetitive operation, and this moment, the total current of induction motor 1 was minimum.

If induction motor 1 is in running, outer load changes, and is example with the load increase; Under this loading condition, the working curve of induction motor 1 moves to XYZ, if induction motor 1 originally was operated in the B point; The working point of induction motor 1 correspondingly moved to the M point after then load increased; Under this loading condition, to use the 3rd kind of regulative mode and still can make the working point of induction motor 1 move to the Y point, still be total current under this loading condition this moment | OY| is minimum.

Likewise the 3rd kind of regulative mode not only can be operated in motoring condition, also can be operated in generating state.When torque current Iq less than 0 the time, induction motor 1 promptly is operated in generating state, this moment, the working point of corresponding diagram 2 correspondingly was in the 2nd quadrant.If induction motor 1 is in generating state, to use the 3rd kind of regulative mode induction motor 1 is worked on the working point of ray OF ', this moment is the total current minimum of induction motor 1 correspondingly.

More than through embodiment the present invention has been carried out detailed explanation, but these are not to be construed as limiting the invention.Those skilled in the art also can make some distortion and improvement under the situation that does not break away from the principle of the invention, and these also should be regarded as belonging to protection scope of the present invention.

Claims (5)

1. the control device of an induction motor comprises:

The three-phase commutation bridge heap is realized the conversion of AC-DC;

IGBT or IPM power model are connected with said three-phase commutation bridge heap, realize the DC-AC conversion, for induction motor provides driving power voltage;

Induction motor is connected with power model, is used to drive load;

Two-way current transformer, the U that measures said induction motor respectively mutually with V phase current mutually, and input to by the driving arithmetic system;

Pwm driver is connected between driving arithmetic system and the power model, under the control of the U that drives arithmetic system output, V, W three-phase voltage output valve, produces the supply voltage of frequency and voltage variable, the triggering of power controlling module;

Said driving arithmetic system is made up of microprocessor; Adopt the V/F control mode; Realization is characterized in that the control of said induction motor: this driving arithmetic system comprises a filter circuit, and the voltage-frequency that is connected said driving arithmetic system is than between arithmetic element and the current effective value arithmetic element; Effective value Ic to the line current of current transformer feedback carries out filtering, the feedback line current filtering value I of its output _CmInput to said voltage-frequency and compare arithmetic element;

Said voltage-frequency than arithmetic element according to feedback line current filtering value I _CmThe voltage-frequency of the final output of real-time regulated makes the total current of said induction motor minimum than V/F.

2. control device as claimed in claim 1 is characterized in that: said voltage-frequency carries out real-time regulated to voltage-frequency than V/F by following mode than arithmetic element:

When

The time, V/F=U _n/ F _n

When

The time, V/F=k * U _n/ F _n

During as ,

I wherein ₀Be the no-load current of said induction motor, k is the constant less than 1, U _nAnd F _nBe respectively the rated voltage and the rated frequency of induction motor.

3. control device as claimed in claim 1 is characterized in that: the time constant filter of said filter circuit is chosen 200ms～1s.

4. control device as claimed in claim 2 is characterized in that: the value of k is 0.4～0.5.

5. like the control device of each said induction motor of claim 1-4, it is characterized in that: be used for drive controlling escalator or moving sidewalk.

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