JP2011114894A - Power generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a highly-efficient operation by reducing a peak current and by increasing a magnetic flux when a torque is changed. <P>SOLUTION: A power generation device includes an induction motor 30 and an inverter circuit 31 for supplying a current into the induction motor 30. The inverter circuit 31 is the power generator for making a slip frequency of the induction motor 30 almost zero before increasing an absolute value of a torque, and having a period to increase an input current. Then, the inverter circuit 31 preferentially and automatically obtains increase of a required magnetic flux, thereby preventing an overcurrent and enhancing efficiency even with a simple configuration. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to various power generation devices used for general households and business use, such as a power source of an electric washing machine.

  Conventionally, this type of induction motor control device is provided with a target torque change detection unit, a cut-off frequency setting unit, a target torque calculation unit, a vector control calculation unit, and a motor drive unit, minimizing the peak current when the torque rises, When the torque falls, the current is quickly reduced (see, for example, Patent Document 1).

  FIG. 9 shows a block diagram of a conventional induction motor control device described in Patent Document 1. In FIG. As shown in FIG. 9, in addition to a general vector control calculation unit including an excitation current calculation unit 13, a torque current calculation unit 15, a slip frequency calculation unit 16, and an integration calculation unit 17, a steady loss minimum magnetic flux calculation unit. 11, a target magnetic flux calculation unit 12, a target torque calculation unit 14, a target torque change detection unit 18, and a cut-off frequency setting unit 19, which has a control system configuration in which torque response and magnetic flux response can be varied independently, and target torque The cut-off frequency ωT of the transfer function and the cut-off frequency ωφ of the target magnetic flux transfer function are set to optimum values according to the direction of change of the target torque, and can be controlled to always minimize the loss at the transient time. The peak current is suppressed to the minimum value at the rising time, and the torque current and the excitation current are rapidly reduced at the falling time of the torque.

JP-A-8-149900

  However, in the conventional configuration, it is possible to reduce the peak current value at the time of the torque rise, but since the number of components is very large and the calculation within each block is very complicated, the apparatus is realized. Therefore, a very high capability of a processing device (processor) such as a microcomputer is required, and the cost is extremely high.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a power generation device that can reduce the peak current of torque change with a simpler and lower cost configuration while having a simpler configuration. And

  In order to solve the above-described conventional problem, the power generation device of the present invention is configured such that the inverter circuit that supplies current to the induction motor inputs the slip frequency of the induction motor as substantially zero before increasing the absolute value of the torque. It has a period for increasing the current.

  This makes it possible to preferentially and automatically obtain an increase in the magnetic flux required when the torque increases, while maintaining a very simple and low-cost configuration, while preventing excessive current and high torque periods. The efficiency can be kept high.

In the power generator of the present invention, the inverter circuit that supplies current to the induction motor has a period during which the input current is increased while keeping the slip frequency of the induction motor substantially constant when increasing the absolute value of the torque. It is what you have.

  This makes it possible to increase the magnetic flux corresponding to the increase in torque and to smoothly increase the generated torque, and to prevent the current peak value from jumping excessively, while having a relatively simple and low-cost configuration. Thus, it is possible to prepare for high-efficiency operation when shifting to high torque.

  In the power generator of the present invention, the inverter circuit for supplying current to the induction motor has a period for increasing the input current while decreasing the slip frequency of the induction motor when increasing the absolute value of the torque. It is.

  This makes it possible to preferentially increase the magnetic flux while suppressing transient torque pulsation while maintaining a relatively simple and low-cost configuration of adjusting the slip frequency and current value. While preventing the value from jumping excessively, it is possible to prepare for high-efficiency operation when shifting to high torque.

  The power generation device of the present invention can drive an induction motor that secures efficiency by suppressing current when torque is increased while having a simple configuration.

1 is a block diagram of a power generation device according to Embodiment 1 of the present invention. Circuit diagram of current detection means of the power generator (A) Waveform diagram of the line current of each of the three phases of the current detection means of the power generation device (b) Waveform diagram of the output voltage Vout of the current detection means of the power generation device (A) Waveform diagram of slip frequency of the power generation device (b) Waveform diagram of current of the power generation device (c) Waveform diagram of secondary magnetic flux of the power generation device (d) Waveform of torque of the power generation device Figure (A) Waveform diagram of slip frequency of power generation device according to embodiment 2 of the present invention (b) Waveform diagram of current of power generation device (c) Waveform diagram of secondary magnetic flux of power generation device (d) Waveform diagram of torque of power generator (A) Waveform diagram of slip frequency of power generator according to Embodiment 3 of the present invention (b) Waveform diagram of current of power generator (c) Waveform diagram of secondary magnetic flux of power generator (d) Waveform diagram of torque of power generator Block diagram of a power generation device according to Embodiment 4 of the present invention Block diagram of a conventional motor control device

  A first invention includes an induction motor and an inverter circuit that supplies current to the induction motor, and the inverter circuit sets the slip frequency of the induction motor to almost zero before increasing the absolute value of the torque. By using a power generation device having a period for increasing the power, it is possible to preferentially and automatically obtain an increase in magnetic flux required when the torque is increased while having a very simple and low-cost configuration. While preventing excessive current, the efficiency during the high torque period can be kept high.

A second invention includes an induction motor and an inverter circuit that supplies current to the induction motor, and the inverter circuit keeps the slip frequency of the induction motor substantially constant when increasing the absolute value of the torque. However, by using a power generation device having a period for increasing the input current, it is possible to obtain an increase in magnetic flux corresponding to the increase in torque and a smooth increase in generated torque, while having a relatively simple and low-cost configuration, and It is also possible to prevent the current peak value from jumping excessively, and to prepare for high-efficiency operation when shifting to high torque.

  A third invention has an induction motor and an inverter circuit for supplying current to the induction motor, and the inverter circuit is input while decreasing the slip frequency of the induction motor when increasing the absolute value of the torque. By adopting a power generation device with a period to increase current, it is a relatively simple and low-cost configuration that adjusts the slip frequency and current value, while giving priority to increasing magnetic flux while suppressing transient generated torque pulsation. Thus, it is possible to prepare for high-efficiency operation when shifting to high torque while preventing the peak value of current from jumping excessively.

  In the fourth invention, in particular, by using the inverter circuit of any one of the first to third inventions as a power generation device having a current detecting means for detecting the input current of the induction motor, the input current of the induction motor is reduced. It is possible to control to the set value with high accuracy, ensuring the stability of torque in the steady state, and reliably preventing the jumping of current when changing the torque, etc., high stability and high efficiency A power generation device can be realized.

  According to a fifth aspect of the invention, in particular, the inverter circuit of the fourth aspect of the invention performs pulse width modulation of a predetermined carrier period, the current detection means has a peak hold circuit of the input current of the induction motor, and the peak of the peak hold circuit The holding time constant is a power generator longer than the carrier cycle, so that the input current of the induction motor can be detected with a simple configuration, and the output signal includes a carrier frequency component even when PWM is performed. Therefore, an inexpensive AD converter (analog / digital converter) connected at a later stage can be used, for example, an AD converter having a low conversion speed can be used.

  In the sixth aspect of the invention, in particular, the inverter circuit of the fourth aspect of the invention is made transient by using a power generation device having current control means for controlling the output of the current detection means by dividing it into a magnetic flux component and a component orthogonal thereto. It is possible to realize a power generation device that can respond more quickly to responsiveness to various torque fluctuations.

  In the seventh aspect of the invention, in particular, the inverter circuit according to any one of the first to sixth aspects of the present invention is a power that outputs a current in the vicinity of the slip frequency at which the efficiency of the induction motor is maximized under steady torque and speed conditions. By making it a generator, it is possible to appropriately increase the magnetic flux at the time of torque increase, and also in the steady state, it is possible to keep high operating conditions with only a simple element definition of the slip frequency. The configuration is simple and high-efficiency steady operation is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a block diagram of a power generation device according to Embodiment 1 of the present invention.

  In FIG. 1, an induction motor 30 and an inverter circuit 31 for supplying current to the induction motor 30 are provided. The inverter circuit 31 includes a slip frequency setting means 32 and a current setting means 33, and the absolute value of the torque. Before increasing the output frequency, the frequency setting means 32 once outputs zero, and the current setting means 33 increases the output value, so that the frequency of the induction motor 30 is substantially zero, and the input current of the induction motor 30 is increased. It has a period to increase.

In the first embodiment, the inverter circuit 31 further includes a three-phase six-stone inverter module 35 that supplies a variable-frequency current to the three-phase induction motor 30, and a speed detection that detects the actual rotation speed of the induction motor. Means 36, adding means 37 for adding the outputs of speed detecting means 36 and slip frequency setting means 32 to calculate the primary frequency, integrating means 38 for time-integrating the output of the adding means 37 to obtain instantaneous phase θ, Rotation distribution means 40 that inputs θ and a voltage set value and distributes the three phases (U, V, W) to each phase, and outputs the triangular wave carrier (with a predetermined period (predetermined frequency) of 66 microseconds (15 kHz) ( PWM that outputs a signal of 6 stones by performing a pulse width modulation using a carrier wave and inserting a dead time period in which the upper and lower sides (P side and N side) of the same phase are simultaneously turned off. A step 41 is provided.

  Further, in the first embodiment, the inverter circuit 31 has current detection means 45 that detects the input current of the induction motor 30, and one resistor connected to the low potential side input of the inverter module 35. A peak hold circuit 47 that holds the peak value of the voltage generated in the resistor 46 and the resistor 46 is provided.

  The difference between the outputs of the current detection means 45 and the current setting means 33, that is, the current error is input to the current error amplifying means 50, where an amplification operation using PI (proportional and integral) is performed, and the result is a voltage setting. The value is output to the rotation distribution means 40.

  FIG. 2 shows a circuit diagram of the current detection means of the power generation device according to Embodiment 1 of the present invention.

  In FIG. 2, the inverter module 35 has three stones of switching elements 55, 56, and 57 on the high potential side (P side) and three stones of switching elements 58, 59, and 60 on the low potential side (N side). Each switching element is composed of an IGBT and a reverse conducting diode connected in parallel to the IGBT.

  In addition, although not shown in figure, about the inverter module 35, the gate drive circuit of each IGBT, a protection circuit, etc. are enclosed with one package.

  In the resistor 46, the emitter terminals of the low-potential side switching elements 58, 59, 60 are connected in common, and are inserted into a GND point (to be on the negative side of the input DC voltage VDC). A voltage generated in a resistor 46 generally called a one shunt is input to a peak hold circuit 47.

  In the first embodiment, the peak hold circuit 47 includes a low-pass filter circuit 63 for removing a very short noise component such as 1 microsecond or less of the voltage generated in the resistor 46. The resistor 64 and the capacitor 65 are configured to be connected to the positive input terminal of the operational amplifier 66 in a state where noise is removed.

  A diode 67 and a capacitor 68 are connected to the output of the operational amplifier 66, and a voltage obtained by dividing the voltage of the capacitor 68 by the resistor 69 and the resistor 70 is connected to the negative input terminal of the operational amplifier 66. In the first embodiment, the peak value of the output of the low-pass filter circuit 63 is 11 times the predetermined magnification (the value obtained by dividing the sum of the resistance values of the resistors 69 and 70 by the resistance value of the resistor 70). Voltage) is obtained as Vout, and peak hold is performed while amplifying.

Here, if the impedance of the circuit connected to Vout is sufficiently high as the discharge path of the capacitor 68, the sum of the resistors 69 and 70 (series circuit) is the main one. The peak holding time constant is {(capacitance [F] of capacitor 68) × (sum of resistors 69 and 70 [Ω])}. In the first embodiment, 1 ms
It's about something.

  On the other hand, since the inverter circuit performs pulse width modulation with the carrier period used in the PWM means 41 being 66 μs (frequency 15 kHz), the peak holding time constant of the peak hold circuit 47 is longer than the carrier period. ing.

  About the motive power generator comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  FIG. 3 (a) is a waveform diagram of the line current of each of the three phases of the current detection means of the power generation device according to Embodiment 1 of the present invention, and FIG. 3 (b) is the current detection means of the power generation device. The waveform diagram of the output voltage Vout is shown.

  In FIG. 3A, U-phase current Iu (thick line), V-phase Iv (thin line), and W-phase Iw (broken line) are currents supplied from the inverter circuit 31 to the induction motor 30, respectively. By using the current detection means 45 using 47, the waveform of the analog voltage output signal Vout as shown by the solid line in FIG. 3B can be obtained.

  This is a three-phase full-wave rectified waveform, that is, a value corresponding to the maximum value Ip of the absolute value of the three-phase current, in other words, in the form of removing the PWM component in the resistor 46. This is equivalent to the envelope of the waveform of the flowing current In.

  However, in the case where three-phase pulse width modulation is performed using a single triangular carrier wave that is generally used, if the absolute value of the phase (power factor angle) of the current with respect to the voltage exceeds 30 degrees, FIG. Although the Vout waveform is slightly different from that in (b), the equivalent peak value Vp can be obtained even if the peak value that occurs once every 60 degrees electrical angle period is performed in the subsequent AD conversion processing routine. It will be.

  In addition, when the absolute value of the power factor angle exceeds 60 degrees, the peak value Vp for every period of 60 electrical angles tends to decrease, so that the phase is shifted as the carrier wave of each phase. The peak value Vp of Vout corresponding to the actual peak current value (absolute value is Ip) can be obtained by devising such as.

  Since Vout is a value corresponding to the peak value Ip of the absolute value of the line current, it has a substantially proportional relationship with the current vector value Ia (corresponding to the root three times the effective value of the line current in the steady state). Therefore, the current Ia can be controlled to a predetermined value.

  There are various types of configurations of the peak hold circuit 47 other than the configuration using such an operational amplifier, and various types can be used by appropriately designing.

  4A is a waveform diagram of the slip frequency of the power generation device according to Embodiment 1 of the present invention, FIG. 4B is a waveform diagram of the current of the power generation device, and FIG. The waveform diagram of the secondary magnetic flux of the power generation device, FIG. 4D shows the waveform diagram of the torque of the power generation device.

  In FIG. 4, the period up to t1 is a first steady state with a small torque (0.36 Nm), and the period after t3 is a second steady state with a four times larger torque (1.46 Nm).

In the first embodiment, in the period from t1 to t2, the current is doubled from 3A to 6A as shown in FIG. 4 (b) while the sliding frequency is substantially zero as shown in FIG. 4 (a). This increases the torque value by a factor of four from the first steady state.
This shows a setting when the current magnification is 2 which is the square root of the torque multiplication factor 4 when moving to the steady state.

  The period from t1 to t2 is 300 ms. This is a secondary time constant of the induction motor 30 used in the first embodiment, which is about L2 / R2 = 100 ms (where L2 is 2 The secondary inductance... 0.1H, R2 is longer than the secondary resistance... 1.0 ohm), and is about 3 times, thereby preventing the rate of change of the secondary magnetic flux φ2 from becoming too rapid. Consideration is given so that transient losses such as an increase in loss due to the M-axis current on the secondary side can be suppressed to some extent.

  As a result, the secondary magnetic flux (magnetic flux) shown in FIG. 4C is increased, and the secondary magnetic flux is increased from the time t1 at the time t2.

  At t2, the current Ia value is set to a constant value, and the slip frequency is increased from zero to a value used in the second steady state, thereby preparing for a period of large torque after t3.

  In the first embodiment, the secondary magnetic flux value at t2 is a considerably high value of 0.54 Wb. Therefore, by generating the sliding frequency fs at 1.6 at 1.6 Hz, that is, by returning it to the same value as before t1, it is generated. A torque exceeding 1.46 Nm is obtained, and at the time t3 when about twice the secondary time constant has passed, the secondary M-axis current almost disappears and a large torque (second steady state) It will move to.

  The sliding frequency after t2 is equivalent to a small torque (first steady state) before t1 of 1.6 Hz, but the influence of magnetic saturation (non-linearity of L1 value) even when the induction motor 30 is on the large torque side. If this is not a problem, there is an effect that a substantially minimum value can be maintained as the current value with respect to the torque.

  On the other hand, when the influence of the magnetic saturation of the induction motor 30 comes out, as shown by a two-dot chain line, by setting the value higher than 1.6 Hz (for example, 2.2 Hz), It is possible to set the minimum condition of the supplied current.

  Regarding the efficiency of the induction motor 30, a high value can be obtained under the condition that the current value can be minimized, but there may be a slight difference from the condition that maximizes the efficiency, and the maximum induction motor according to each steady torque. If an efficiency of 30 is desired, a good effect can be obtained by using a method of determining the slip frequency according to the torque.

  In the first embodiment, by performing very simple control of simply setting the slip frequency to zero in the period from t1 to t2, all of the current supplied to the induction motor 30 is excited current (magnetization current, M Therefore, it is possible to increase the speed of increasing the secondary magnetic flux, and to effectively increase the secondary magnetic flux in a short time.

  Then, at t2, a large transient torque is generated due to the increase in magnetic flux generated during the period from t1 to t2, and the secondary time constant (L2 / R2... L2 is a secondary inductance, R2 of the induction motor 30. Is about 2 to 3 times as long as the time calculated by (secondary resistance), the transient phenomenon is almost finished, and it can be considered that t3 has been reached.

  Such a transient generation of large torque may have an adverse effect on noise and vibration, but it has the advantage that a large torque can be generated instantaneously, with the current jump suppressed. There are also applications that can be used.

  In the period from t1 to t2, the torque generated as shown in FIG. 4 (d) is almost zero. However, when the inertia of the load is relatively large, the speed decreases. There is no.

  In the first embodiment, the increase in the current Ia during the period from t1 to t2 is linear (linear function), so that the microcomputer can be controlled relatively easily. It is not always necessary to increase the current in a straight line, and the current may be increased with an appropriate curve.

  As described above, in the first embodiment, the inverter circuit 31 increases the input current by setting the slip frequency of the induction motor 30 to approximately zero before increasing the absolute value of the torque (period t1 to t2). ), The secondary magnetic flux can be effectively increased in a short time while preventing a sharp jump in the current value, and the subsequent operation with a large torque can be performed efficiently.

(Embodiment 2)
Also in the second embodiment, the block diagram, the configuration and the operation waveform of the current detection means 45 can be the same as those in FIGS. 1 to 3 described in the first embodiment, and the slip frequency setting means. Only 32 operations are slightly different.

  The operation and action of the power generation device according to the second embodiment will be described below.

  5A is a waveform diagram of the slip frequency of the power generation device according to Embodiment 2 of the present invention, FIG. 5B is a waveform diagram of the current of the power generation device, and FIG. The waveform diagram of the secondary magnetic flux of the power generating device, FIG. 5D, shows the waveform diagram of the torque of the power generating device.

  FIG. 5 is different from the first embodiment in that the sliding frequency during the period from t1 to t2 in FIG. 5A is kept at 1.6 Hz, but the sliding frequency fs is the same as in the first embodiment. The current Ia is changed, that is, when the absolute value of the torque is increased, the input current is increased while the slip frequency of the induction motor 30 is kept substantially constant.

  As for the secondary magnetic flux, the change from the first steady state to the second steady state is doubled as seen in FIG. 5 (c). Is a gentle change that is smaller and the maximum value does not exceed 0.38 Wb in the second steady state.

  Regarding the torque, there is no period of zero as in the first embodiment, and the absolute value increases four times by monotonically increasing from the first steady state to the second steady state.

  Therefore, the secondary magnetic flux and the torque that change gently during the period from t1 to t3 can be obtained.

  Further, as a response to the non-linear influence due to magnetic saturation of the induction motor 30, the sliding frequency after t2 may be raised to 2.2 Hz, which is the same as that described in the first embodiment.

As described above, in the second embodiment, the inverter circuit 31 has a period for increasing the input current while keeping the slip frequency of the induction motor 30 substantially constant when increasing the absolute value of the torque. Although it is a relatively simple and low-cost configuration, an increase in magnetic flux corresponding to an increase in torque and a smooth increase in generated torque can be obtained, and an excessive increase in current peak value can be prevented. It is possible to prepare for high-efficiency operation when shifting to torque.

(Embodiment 3)
Also in the third embodiment, the block diagram, the configuration and the operation waveform of the current detection means 45 can be the same as those in FIGS. 1 to 3 described in the first embodiment, and the slip frequency setting means. Only 32 operations are slightly different.

  The operation and action of the power generation device according to the third embodiment will be described below.

  6A is a waveform diagram of the slip frequency of the power generation device according to Embodiment 3 of the present invention, FIG. 6B is a waveform diagram of the current of the power generation device, and FIG. The waveform diagram of the secondary magnetic flux of the power generating device, FIG. 6D, shows the waveform diagram of the torque of the power generating device.

  6 is different from the first and second embodiments in that the sliding frequency in the period from t1 to t2 in FIG. 6A is linearly decreased from 1.6 Hz to 0.2 Hz. In other respects, the slip frequency fs and the current Ia are changed in the same manner. That is, when the absolute value of the torque is increased, the input current is increased while the slip frequency of the induction motor 30 is decreased. It has a structure having a period.

  As for the secondary magnetic flux, it becomes similar to the first embodiment in that the secondary magnetic flux once becomes larger than the second steady state at t2, and settles to 0.38 Wb in the second steady state at t3.

  Regarding the torque, the point that a substantially constant value is maintained is different from that of the first embodiment, and until the time t2 is reached, a value substantially equal to the first steady state can be maintained. For example, when the torque increase timing can be predicted in advance, or when the torque increase timing is determined by the operation sequence (schedule) of the apparatus, the operation is performed under a small torque condition until t2, and the time point t1 calculated backward from the t2 timing Thus, if the operation of FIG. 6 is performed, it is possible to drive the highly efficient induction motor 30 while suppressing the current in the second steady state, which is a large torque condition. The induction motor 30 can be operated in the vicinity of the slip frequency at which the efficiency of the induction motor 30 is maximized.

  Further, as a response to the non-linear influence due to magnetic saturation of the induction motor 30, the sliding frequency after t2 may be raised to 2.2 Hz, which is the same as that described in the first embodiment.

  As described above, in the third embodiment, the inverter circuit 31 has a period having a period in which the input current is increased while the sliding frequency of the induction motor 30 is decreased when the absolute value of the torque is increased. This makes it possible to preferentially increase the magnetic flux while suppressing transient torque pulsation while maintaining a relatively simple and low-cost configuration of adjusting the slip frequency and current value. It is possible to prepare for high-efficiency operation when shifting to high torque while preventing excessive jumping.

  In the third embodiment, since the sliding frequency fs in the period from t1 to t2 is linearly decreased and the current Ia is linearly increased, the microcomputer to be used is simple. Realization by program is also possible.

However, when the torque generated during the period from t1 to t2 is to be kept strictly constant, at least one of the slip frequency fs and the current Ia needs to be curved, for example, the inertia moment of the load is small. When a large speed fluctuation is caused by the torque fluctuation during the period from t1 to t2, if a non-linear, that is, a curve-changing element is used as needed, it is possible to suppress the torque fluctuation without any problem.

(Embodiment 4)
FIG. 7 shows a block diagram of a power generation device according to Embodiment 4 of the present invention.

  In FIG. 7, the induction motor 30 is the same as that in FIG. 1, and the configuration of the inverter circuit 80 for supplying current to the induction motor 30 is the inverter module 35, speed detection means 36, addition means 37, integration means 38, rotation distribution. The means 40 and the PWM means 41 are the same as those described in FIG.

  In the fourth embodiment, the current detection means 81 has three resistors 82, 83, 84 and a high-speed AD converter 85 provided for each low potential side switching element of the inverter module 35. The AD converter 85 converts the voltage generated in each of the resistors 82, 83, 84 to digital at the timing of the latch signal SL output in synchronization with the peak timing of the triangular carrier wave in the PWM means 41. Thus, a digital signal corresponding to the line current of each phase can be obtained.

  The rotation distributing means 86 outputs the phase θ signal and the line current of each phase from the AD converter 85 in the form of components orthogonal to each other such as the M axis and the T axis. In addition, an apparatus that performs error amplification independently for each component of the M-axis and the T-axis is provided.

  In the fourth embodiment, the current setting means 90 is also provided with two M-axis current setting means 91 and T-axis current setting means 91, and both set values are input to the current error amplifying means 87. It becomes.

  The sliding frequency setting means 94 adds the output value to the speed of the induction motor 30 detected by the speed detecting means 36 and the adding means 37 to calculate the primary frequency, and the integrating means 38 converts it to the phase θ. Is the same as in the first embodiment.

  The operation of the power generation device configured as described above will be described.

  Similar to the slip frequency setting means 32 described in the first to third embodiments, the slip frequency setting means 94 performs the period of t1 to t2 as described in FIGS. 4 to 6 when increasing the absolute value of the torque. Zero is set as the slip frequency at. Alternatively, a substantially constant value is maintained. Or decrease. It is possible to obtain the same effects as those described in the first to third embodiments.

  The fourth embodiment is different only in that the current is controlled by being divided into mutually orthogonal components of the M axis and the T axis.

  In the fourth embodiment, the current Ia supplied to the induction motor 30 is equal to the square root of the sum of the squares of the components Im1 * and It1 * of the M-axis current setting unit 91 and the T-axis current setting unit 92, respectively. Further, regarding the sharing of Im1 and It1, the value of the ratio It1 / Im1 is expressed by Equation 1 (where L1 is the primary inductance [H], R2) with respect to the output value fs [Hz] of the slip frequency setting means 94. Is the same direction as the secondary magnetic flux φ2, and Im1 and It1 are an excitation current (or magnetization current) component and a current component (also referred to as a torque current component) orthogonal thereto, respectively. Become.

  When the It1 is changed from the steady state, the generated torque can be immediately changed. For example, if the setting is such that the It1 increases rapidly, the torque will increase rapidly. Can be made.

  Here, regarding the absolute value of Ia (the vector sum of Im1 and It1), if Im1 is decreased during the increase period of It1, excessive jumping of the output current Ia of the inverter circuit 80 can be prevented. is there.

  Note that the change in the secondary magnetic flux φ2 when Im1 is changed is such that the rate of change is suppressed with the secondary time constant, so the response to the φ2 change in a microcomputer or the like is It is not so burdensome and can be used without problems even with an inexpensive and low-speed processor such as a microcomputer.

  Since the generated torque is controlled with good responsiveness, for example, when it is not necessary to obtain rapid acceleration for a portion where FIG. 4D and FIG. It is not necessary to jump up, but rather it is possible to quickly adjust the generated torque so that the torque becomes a constant value of 1.46 Nm, and effects such as reduction of stress on the mechanical system, reduction of noise and vibration, etc. Can also be obtained.

  As described above, in the fourth embodiment, the inverter circuit 80 has a particularly high responsiveness by adopting a configuration in which the output of the current detection unit 81 is controlled by being divided into the magnetic flux component Im1 and the component It1 orthogonal thereto. It is possible to control the torque, and it is possible to realize a power generation device that can respond more quickly to transient torque fluctuations while suppressing the current Ia.

  In the configuration described in the fourth embodiment, the setting values Im1 * and It1 * of the current setting unit 90 are determined from the output of the slip frequency setting unit 94. The slip frequency setting means 94 may calculate the slip frequency fs from each set value. If the output of the current detection means 81 can be divided and controlled into a magnetic flux component Im1 and a component It1 orthogonal thereto, various types are possible. Is possible.

  In addition, the configuration of the current detection means 81 is also referred to as a three-shunt using three resistors 82, 83, and 84 in the fourth embodiment, but is not particularly limited to this configuration. Also, one using DCCT, one using only one shunt resistor (also referred to as one shunt), AD converting a voltage value corresponding to the timing in the carrier of the PWM, and detecting a three-phase current can be used.

  As described above, the power generation device according to the present invention has a simple configuration, but can suppress the current when increasing torque and can drive an induction motor that ensures efficiency. The present invention can also be applied to various power generators used for general households and business use, such as a power source.

30 Induction motor 31, 80 Inverter circuit 45, 81 Current detection means 47 Peak hold circuit

Claims (7)

An induction motor and an inverter circuit for supplying current to the induction motor, and the inverter circuit has a period of increasing the input current with the slip frequency of the induction motor being substantially zero before increasing the absolute value of the torque. Power generator. An induction motor and an inverter circuit for supplying current to the induction motor, and the inverter circuit increases the input current while keeping the slip frequency of the induction motor substantially constant when increasing the absolute value of the torque. A power generation device having a period. An induction motor and an inverter circuit for supplying current to the induction motor, and the inverter circuit has a period for increasing the input current while decreasing the slip frequency of the induction motor when increasing the absolute value of the torque. Power generation device having. The power generation device according to any one of claims 1 to 3, wherein the inverter circuit includes current detection means for detecting an input current of the induction motor. 5. The inverter circuit performs pulse width modulation of a predetermined carrier cycle, the current detection means has a peak hold circuit for an input current of the induction motor, and a peak hold time constant of the peak hold circuit is longer than the carrier cycle. The power generator described. ,
The power generation device according to claim 4, wherein the inverter circuit controls the output of the current detection means by dividing it into a magnetic flux component and a component orthogonal thereto. The power generation device according to any one of claims 1 to 6, wherein the inverter circuit outputs a current in the vicinity of a slip frequency at which the efficiency of the induction motor under a torque and speed condition is maximized in a steady state.

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