CN101257279B - Motor drive device - Google Patents

Abstract

The invention provides an electric motor driving mechanism. In an AC/AC direct conversion device, the fluctuation caused by the rapid variation of the motor current is not produced, during driving or braking, the motor current can be reduced, and the conversion device can have a safe and continuous operation. A motor drive using AC/AC direct conversion devices such as a matrix converter to drive the motor, includes a current testing unit 106 for testing motor current; a comparison unit 107 for detecting whether the motor current testing value exceeds the limitation level; a induction voltage calculating unit 2 for calculating the induction voltage of the motor; when the comparison unit 107 detects that the motor current testing value exceeds the limitation level, the induction voltage calculated by the induction voltage calculating unit is taken as an output voltage instruction value which is provided to a switch unit 109 and a PWM generating unit 101 of a matrix converter 1.

Description

Motor drive

Technical field

The present invention relates to utilize for example AC-AC Direct Transform device such as matrix converter, polyphase ac voltage is transformed into the polyphase ac voltage of any size and frequency, thereby the motor drive of drive motor, be particularly related to amplitude, thereby can in overheated, the damage that prevents motor or power-converting device, make its continuously motor drive of operation by the restrictions motor electric current.

Background technology

Utilizing with converter (inverter) and matrix converter (matrix converter) is that the power-converting device of representative makes under the situation that motor moves; in order to prevent overheated, the damage of motor or power-converting device; be provided with protective device; the amplitude of this protective device monitoring motor electric current; and when motor current oversteps the extreme limit level (limit level), all thyristors that constitute power-converting device are disconnected with out of service.

But, in case power-converting device is out of service suddenly, then can cause the voltage that applies to motor sharply to change, therefore, might damage motor or connected driving arrangement.In addition, this is not suitable for wishing the power-converting device purposes of operation continuously.

Therefore, in patent documentation 1 described later following prior art being disclosed: the limit levels lower than above-mentioned Limiting Level is set, surpasses under the situation of this limit levels at motor current, further increase Yi Bian suppress motor current, Yi Bian continue operation.

Fig. 5 is the block diagram of the major part of disclosed prior art in the expression patent documentation 1.

In Fig. 5, the 102nd, power supply, the 103rd, power-converting device, the 104th, motor.

Output voltage command calculations unit 100 calculates the output voltage command value of power-converting device 103, PWM generating unit 101 is according to above-mentioned output voltage command value, calculates the PWM pattern (PWMpattern) of the thyristor on/off that is used to make power-converting device 103.

On the other hand, by supply voltage detecting unit 105 detected supply voltages with by motor current detecting unit 106 detected motor currents, be used to produce PWM pattern with the rightabout output voltage vector of current phasor that calculates by the motor current detected value to current limiting unit 108 input by its calculating and output.

In addition, the 107th, be set with the comparing unit of the limit levels lower than the Limiting Level of motor current, motor current detected value and above-mentioned limit levels are compared.

Suppose under the situation of motor current greater than limit levels, then utilize the output of comparing unit 107, switch unit 109 is switched to current limiting unit 108 sides, thus, be used to produce the PWM pattern with the rightabout output voltage vector of current phasor, be provided for power-converting device 103 by switch unit 109.

Thus, motor current reduces, and can therefore, on one side power-converting device 103 is turned round continuously, flow through motor 104 Yi Bian prevent overcurrent with its amplitude suppressing below above-mentioned Limiting Level.

On the other hand, prior art with respect to above-mentioned patent documentation 1, thereby the spy in first to file is willing to disclose in 2005-238593 number in order to reduce calculated load reduction output current fluctuation, utilizes the invention (should be also not open when the application proposes in first to file) of power-converting device output no-voltage.

Fig. 6 is this block diagram in the major part of the invention of first to file of expression, adopts identical symbol with the part that has identical function among Fig. 5.

With the difference of Fig. 5 is to be provided with no-voltage generating unit 110 to replace current limiting unit 108, and no-voltage generating unit 110 is according to supply voltage, PWM patterns and the output of selecting the output phase voltage all to equate.

In said structure,,, will offer power-converting device 103 from the PWM pattern of no-voltage generating unit 110 by switch unit 109 when motor current during greater than limit levels.Power-converting device 103 is for example to the maximal phase voltage of all output phase out-put supplies 102.

If the voltage of all output phases equates that then voltage between lines is zero, therefore, motor current reduces, and its amplitude can not reach capacity more than the level.

Patent documentation 1: the spy opens 2004-180390 communique ([0015]～[0018], Fig. 1 etc.)

In the prior art of patent documentation shown in Figure 51, because output and the rightabout voltage vector of electric electromechanics flow vector, so reduce the effect height of electric current, but because the output voltage of power-converting device 103 is sharply changed, so the fluctuation that occurs in the output current (ripple) becomes greatly.

Under the situations of AC-AC Direct Transform device as power-converting device 103 such as use matrix converter, power supply 102 directly is connected by two-way semiconductor switch with motor 104, therefore, if there is fluctuation in the output current, then input current also can be out of shape (distort).The fluctuation of output current can cause the torque pulsation or the noise of motor 104, and therefore not preferred, in addition, the fluctuation of input current can cause the misoperation of the miscellaneous equipment that is connected with power supply 102 etc., and is therefore not preferred equally.

On the other hand, according to the invention in first to file shown in Figure 6, as when braking, make energy from motor 104 under the operation condition of power-converting device 103 sides regeneration, motor current might not reduce on the contrary and increase.

Below, the reason that motor current increases during to the 103 output no-voltages of power-converting device in the regeneration action describes.

Fig. 7 is that the power-converting device 103 that is illustrated among Fig. 6 is that matrix converter, motor 104 are under the situation of synchronous motor, the circuit diagram of an output phase of matrix converter.

If the output voltage of matrix converter is v _o, the induced voltage that produces of motor is e _m, motor primary coil resistance be R ₁, elementary synchronous inductance is L _σ, elementary angular frequency is ω, the motor current when then driving is by formula 1 expression.

[formula 1]

$i_o=\frac{1}{R_1+{\mathrm{j\ωL}}_{\mathrm{\σ}}}(v_o-e_m)$

On the other hand, the motor current in the regenerative braking action is by formula 2 expressions.

[formula 2]

$i_o=\frac{1}{R_1+{\mathrm{j\ωL}}_{\mathrm{\σ}}}(e_m-v_o)$

Formula 1 and formula 2 are compared, as can be seen, output voltage v _oWith induced voltage e _mOpposite in sign.In the structure of Fig. 6, the output voltage that makes matrix converter (power-converting device 103) is rapidly zero, is to make v when the driving of formula 1 expression _o=0, thus, i _oReduce.But, when the regenerative braking of formula 2 expressions, if make v _o=0, You Bian (e then _m-v _o) than making v _oBecame big before=0, therefore, motor current i _oIncrease on the contrary.Circuit diagram with Fig. 7 is explained, by making v _o=0, in matrix converter, make induced voltage e _mShort circuit, so current i _oIncrease.

In addition, electric current ways to restrain as voltage source converter with energy buffer (energy buffer), known have a mode of putting down in writing in the spy opens flat 3-74175 number (No. the 2745691st, patent) communique, the document discloses: when the size of current phasor surpasses limits value, the nearest voltage vector of rightabout vector of chosen position and above-mentioned current phasor, and make voltage source converter export this voltage vector.

But in Direct Transform devices such as matrix converter, the production method of pwm pulse is different with converter, therefore, is difficult to the prior art is directly applied to the Direct Transform device.

Summary of the invention

Therefore, the problem that the present invention will solve provides a kind of motor drive, this motor drive is when utilizing AC-AC Direct Transform device drive motors such as matrix converter, can not produce the fluctuation that the rapid variation because of motor current causes, driving and braking under arbitrary situation of (regenerative braking), motor current is reduced, and can make the operation continuously safely of Direct Transform device.

In order to solve above-mentioned problem, a first aspect of the present invention provides a kind of motor drive, utilization connects the many phase alternating current straightening AC-AC Direct Transform device drive motor of the polyphase ac voltage that is transformed into any size and frequency, at motor current is that limit levels (restrictionlevel) is when following, provide the first output voltage command value to above-mentioned converting means, make above-mentioned converting means operation, it is characterized in that above-mentioned motor drive comprises:

Detect the current detecting unit of motor current;

Detect the comparing unit whether the motor current detected value surpasses limit levels;

Calculate the induced voltage computing unit of the induced voltage of above-mentioned motor; With

When above-mentioned comparing unit detects the motor current detected value above limit levels, replace the above-mentioned first output voltage command value, the induced voltage that above-mentioned induced voltage computing unit is calculated offers the unit of above-mentioned converting means as the second output voltage command value.

The invention of second aspect is characterised in that in first aspect, above-mentioned induced voltage computing unit uses the above-mentioned first output voltage command value, motor current detected value and electric electromechanics constant, calculates induced voltage.

The invention of the third aspect is characterised in that in first aspect, above-mentioned induced voltage computing unit uses output voltage detected value, motor current detected value and the electric electromechanics constant of above-mentioned converting means, calculates induced voltage.

In the present invention, amplitude for the restrictions motor electric current, calculate the induced voltage of motor, and this induced voltage replaced the first output voltage command value when common as the second output voltage command value and offer power-converting device, the output voltage of power-converting device is equated with above-mentioned induced voltage.

Thus, the running status of motor is irrelevant when driving, during braking etc., motor current can be suppressed at below the limit levels, thereby the rapid variation that can not produce the output voltage of power-converting device makes its operation continuously safely.

Description of drawings

Fig. 1 is the block diagram of expression first execution mode of the present invention.

Fig. 2 is the block diagram of the structure of the induced voltage computing unit in the presentation graphs 1.

Fig. 3 is the block diagram of expression second execution mode of the present invention.

Fig. 4 is the block diagram of the structure of the induced voltage computing unit in the presentation graphs 3.

Fig. 5 is the block diagram of the major part of expression prior art.

Fig. 6 is the block diagram of major part that is illustrated in the invention of first to file.

Fig. 7 is in the invention in first to file, drives under the situation of synchronous motor the circuit diagram of an output phase with matrix converter.

Symbol description

1 matrix converter

2,2A induced voltage computing unit

3 output voltage detecting units

21,21A, 24 coordinate transformation unit

22 driving judging units

23 computing blocks (induced voltage calculating formula)

25 matrix converter voltage instruction computing units

100 output voltage command calculations unit

101 PWM generating units

102 power supplys

104 motor

105 supply voltage detecting units

106 motor current detecting units

107 comparing units

109 switch units

Embodiment

Below, with reference to accompanying drawing, embodiments of the present invention are described.

At first, Fig. 1 is the block diagram of first execution mode of the present invention of expression first aspect and second aspect, adopts identical numbering with the structural element that has identical function among Fig. 5 and Fig. 6, omits its explanation, below, be that the center describes with the part different with it.

In Fig. 1, the 1st, as the matrix converter of AC-AC Direct Transform device, by power supply 102 and motor 104 direct-connected a plurality of bidirectional switchs are constituted.For example, at power supply 102 is that three-phase alternating-current supply, motor 104 are under the situation of three-phase synchronous motor, between the input and output terminal of each three-phase, add up to be connected with 9 bidirectional switchs, these bidirectional switchs for example constitute by thyristor inverse parallels such as the IGBT connection that has reverse withstand voltage properties with 2.

The 2nd, the induced voltage computing unit of the induced voltage that calculating motor 104 produces, to its input from the motor current detected value of motor current detecting unit 106, from the supply voltage detected value of supply voltage detecting unit 105 with from the first output voltage command value of output voltage command calculations unit 100 (motor current for below horizontal common of restriction time output voltage command value).Then, the induced voltage that calculates by induced voltage computing unit 2, (motor current surpasses limit levels as the second output voltage command value to matrix converter 1, output voltage command value when needing the restriction electric current), be input to a switched terminal of switch unit 109, be input to another switched terminal from the first output voltage command value of above-mentioned output voltage command calculations unit 100.

Switch unit 109 similarly switches switched terminal according to the output of comparing unit 107 with Fig. 5 and Fig. 6.Surpass under the situation of limit levels at the amplitude that detects motor current by comparing unit 107, switch unit 109 is connected with induced voltage computing unit 2 sides, the induced voltage that is calculated by this unit 2 is provided for PWM generating unit 101 as the output voltage command value by switch unit 109.

Below, the restriction principle of the motor current of present embodiment is described.

From above-mentioned formula 1, formula 2 as can be known, if make v _o=e _m, then with drive, braking is irrelevant, reduces to zero by the voltage that the primary coil of motor produces, and therefore, motor current reduced.That is, make the output voltage of matrix converter 1 equate with the induced voltage of motor 104 as long as be controlled to.

At this,, the structure and the effect of induced voltage computing unit 2 described with reference to Fig. 2.In addition, establish motor 104 and be synchronous motor.

If offering the output voltage command value of the three-phase of matrix converter 1 from the output voltage command calculations unit 100 of Fig. 1 is v _u ^*, v _v ^*, v _w ^*, the coordinate transformation unit 21 of Fig. 2 utilizes formula 3 with above-mentioned output voltage command value v _u ^*, v _v ^*, v _w ^*Be transformed into two composition v of vertical interchange _α ^*, v _β ^*

[formula 3]

$\left[\begin{array}{c}{v_{\mathrm{\α}}}^{*}\\ {v_{\mathrm{\β}}}^{*}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{v_u}^{*}\\ {v_v}^{*}\\ {v_w}^{*}\end{array}\right]$

Coordinate transformation unit 21 is similarly utilized the motor current detected value i of formula 4 with three-phase _u, i _v, i _wBe transformed into two component i of vertical interchange _α, i _β

[formula 4]

$\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_u\\ i_v\\ i_w\end{array}\right]$

Further, coordinate transformation unit 21 is with above-mentioned v _α ^*, v _β ^*, i _α, i _βBe converted on the coordinate (d-q coordinate) with elementary angular frequency rotation, obtain formula 5 and formula 6.

Wherein, θ=∫ ω dt, θ can obtain according to the speed detected value that is obtained by velocity transducer, speed value or speed guess value.

[formula 5]

$\left[\begin{array}{c}{v_d}^{*}\\ {v_q}^{*}\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{v_{\mathrm{\α}}}^{*}\\ {v_{\mathrm{\β}}}^{*}\end{array}\right]$

[formula 6]

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]$

Driving judging unit 22 utilizes formula 7 to calculate instantaneous effective power p from formula 5, formula 6.

[formula 7]

p＝v _d ^*i _d+v _q ^*i _q

The situation of driving judging unit 22 in p 〉=0 judges to driving, and it is braking (regenerative braking) that the situation in p＜0 judges, and signal is judged in output driving judgement signal and braking respectively.In synchronous motor, the position of stator and rotor is equal, therefore, and the d axle ingredient e of induced voltage _dBe zero.On the other hand, the q axle ingredient e of induced voltage _qVoltage equation according to motor calculates as formula 8.

At this, the motor parameter in the formula 8 (electric electromechanics constant) R ₁, L _σMeasured value can be used, also guess value can be used.

[formula 8]

$e_q={v_q}^{*}-\mathrm{\ω}{L}_{\mathrm{\σ}}{i}_d-R_1{i}_q-{\mathrm{\ωL}}_{\mathrm{\σ}}\frac{{\mathrm{di}}_q}{\mathrm{dt}}$ ∵p≥0

$e_q={v_q}^{*}-\mathrm{\ω}{L}_{\mathrm{\σ}}{i}_d-R_1{i}_q-{\mathrm{\ωL}}_{\mathrm{\σ}}\frac{{\mathrm{di}}_q}{\mathrm{dt}}$ ∵p＜0

The d axle ingredient e of the induced voltage that will obtain by the computing block 23 that is equivalent to formula 8 _d(=0) and q axle ingredient e _qAs command value, coordinate transformation unit 24 is transformed into the three-phase alternating voltage ingredient e with above-mentioned command value _u ^*, e _v ^*, e _w ^*

Different with converter, matrix converter obtains voltage by directly supply voltage being carried out PWM control, therefore, in order to export the induced voltage of expectation, needs the amplitude information of supply voltage.Therefore, matrix converter voltage instruction computing unit 25, as formula 9, with the size of supply voltage | V _i| remove e _u ^*, e _v ^*, e _w ^*, calculate revised output voltage command value λ _u ^*, λ _v ^*, λ _w ^*, and with them as the second output voltage command value, export switch unit 109 sides to.

Wherein,

v _{I α}And v _{I β}Be two compositions of interchange of supply voltage.

[formula 9]

$\left[\begin{array}{c}{{\mathrm{\λ}}_u}^{*}\\ {{\mathrm{\λ}}_v}^{*}\\ {{\mathrm{\λ}}_w}^{*}\end{array}\right]=\left[\begin{array}{c}{e_u}^{*}\\ {e_v}^{*}\\ {e_w}^{*}\end{array}\right]\frac{1}{\left|V_i\right|}$

After this method during the on/off of the thyristor of compute matrix converter 1 have multiple, but owing to be not major part of the present invention, so omit its explanation.

When motor current surpassed limit levels, the switch unit 109 among Fig. 1 according to the output of comparing unit 107, was selected the second output voltage command value based on formula 9, to 101 outputs of PWM generating unit.When motor current reduces, when being lower than limit levels, selecting the first output voltage command value (common output voltage command value) from output voltage command calculations unit 100 once more and offer PWM generating unit 101, normally move thus.

Like this, in the present embodiment, when motor current surpasses limit levels, not directly to switch the PWM pattern, but the output voltage command value is switched to the value that equates with the induced voltage of motor, carry out the electric current restriction thus, therefore, can prevent that the fluctuation that sharply changes the output current that causes because of impulse waveform (pulsepattern) from increasing, and then can reduce the fluctuation of input current.

In addition, in the above-described first embodiment the computational methods of Shuo Ming induced voltage, be that the structure of Fig. 2 is an example, also can not carry out coordinate transform and, also can answer voltage observer (induction voltage observer) to infer induced voltage by usability according to motor model (motor model) directly with alternating component calculating.In addition, present embodiment is not limited to synchronous motor as the motor 104 of object, if change formula 8 according to the voltage equation of motor, then also can be applied to induction motor.

Next, Fig. 3 is the block diagram of second execution mode of the present invention of the expression first aspect and the third aspect.This execution mode is with the different of first execution mode, uses the output voltage detected value of matrix converter 1 in the calculating of induced voltage.

That is, append output voltage detecting unit 3 in Fig. 1, the voltage detecting value input induced voltage computing unit 2A with it is used to calculate induced voltage.

In the first embodiment, if there is the error of calculation in induced voltage, the output voltage instruction when then limiting electric current is not equal to genuine induced voltage, the v in formula 1 or the formula 2 _o=e _mBe false, the restriction effect of motor current reduces.In addition, the error of calculation of induced voltage comprises the various errors such as error that the sum of errors computing relay of motor parameter causes, the commutation error of thyristor (commutation error) is (in matrix converter, in order to prevent power supply short circuit and load side open circuit simultaneously, (halt period) during the termination is set and the voltage error that produces in switching mode) and the output voltage error that causes because of the connection voltage drop of thyristor account for very big ratio.

Be conceived to this point, in second execution mode, detection to the motor 104 actual output voltages that apply, uses this voltage detecting value to calculate induced voltage by matrix converter 1, thus, reduces the error of calculation, the v in formula 1 or the formula 2 _o=e _mAlways set up, thereby improve restriction electric current effect.

Fig. 4 is the block diagram of the induced voltage computing unit 2A among Fig. 3.

That is, in Fig. 4, will be by the output voltage detecting unit 3 detected voltage detecting value input coordinate converter unit 21A of Fig. 3, same with first execution mode, utilize coordinate transform, obtain two composition v on the rotational coordinates _d, v _qThat is, with voltage detected value v _u, v _v, v _wReplace the v in the formula 3 _u ^*, v _v ^*, v _w ^*, obtain two composition v _α, v _β, use v _α, v _βReplace the v in the formula 5 _α ^*, v _β ^*, obtain v _d, v _q

After this, use v _qThe v that replaces formula 8 _q ^*, calculate the q axle ingredient e of induced voltage with computing block 23 _q, with this e _qAnd e _dAs command value e _q ^*And e _d ^*(=0) utilizes coordinate transformation unit 24 once more it to be transformed into the three-phase alternating voltage ingredient e _u ^*, e _v ^*, e _w ^*Later on identical with Fig. 2, so omit explanation.

According to this execution mode, with the induced voltage that the actual output voltage that uses matrix converter 1 calculates, the output voltage command value output during as the restriction electric current, therefore, the error of calculation of induced voltage reduces, and can make the v in formula 1 or the formula 2 _o=e _mAlways set up.As a result, the restrictions motor electric current can make power-converting device move continuously reliably.

In addition, in the respective embodiments described above, switch unit 109 is arranged between induced voltage computing unit 2 or 2A and the PWM generating unit 101, but also can: generate the PWM pattern in advance and it be stored in the memory cell according to the induced voltage that calculates, and between PWM generating unit 101 and matrix converter 1, switch unit is set, with switch unit to from the common operation of PWM generating unit 101 time the PWM pattern and the PWM pattern when being stored in restriction electric current in the said memory cells switch, and provide it to matrix converter 1.

Claims (3)

1. motor drive, utilization connects the many phase alternating current straightening AC-AC Direct Transform device drive motor of the polyphase ac voltage that is transformed into any size and frequency, when motor current is below horizontal for limiting, provide the first output voltage command value to described converting means, make described converting means operation, it is characterized in that described motor drive comprises:

Detect the current detecting unit of motor current;

Detect the comparing unit whether the motor current detected value surpasses limit levels;

Calculate the induced voltage computing unit of the induced voltage of described motor; With

When described comparing unit detects the motor current detected value above limit levels, replace the described first output voltage command value, the induced voltage that described induced voltage computing unit is calculated offers the unit of described converting means as the second output voltage command value.

2. motor drive as claimed in claim 1 is characterized in that:

Described induced voltage computing unit uses the described first output voltage command value, motor current detected value and electric electromechanics constant, calculates induced voltage.

3. motor drive as claimed in claim 1 is characterized in that:

Described induced voltage computing unit uses output voltage detected value, motor current detected value and the electric electromechanics constant of described converting means, calculates induced voltage.

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