JP5397760B2 - Power saving drive apparatus and method for apparatus having the same load pattern - Google Patents

Description

  The present invention relates to a power saving driving apparatus and method for apparatuses having the same load pattern.

The present invention is directed to an apparatus that is driven by a motor supplied with power from an inverter and that is repeatedly operated in the same load pattern. Hereinafter, such a device is referred to as a “same load pattern device”.
In addition, although the same load pattern apparatus mainly assumes industrial apparatuses, such as a servo press, the die cushion for a press, a conveying apparatus, and a physical distribution apparatus, it is not limited to them.

The amount of loss in the same load pattern device described above varies depending on parameters of the power conversion circuit, such as the carrier wave frequency and the voltage change rate dv / dt of the switching waveform.
Here, the “loss amount” means the difference between the received power of the inverter and the motor output, that is, the form of heat generation or electromagnetic radiation in the electric circuit (including the inverter and motor) from the inverter to the motor and the magnetic circuit inside the motor. Means the amount of work lost in
As means for reducing this loss amount, for example, Patent Document 1 has already been proposed. Moreover, the technique relevant to this invention is disclosed by patent document 2 and nonpatent literature 1,2.

  In Patent Document 1, when the operating condition of the apparatus changes, the power conversion parameter (the carrier frequency of the DC / DC converter) is changed to reduce the loss amount.

  Non-Patent Document 2 discloses that loss is reduced by switching the switching frequency during operation according to a low speed region, a medium speed region, and a high speed region.

JP 2003-116280 A, “DRIVE DEVICE AND POWER OUTPUT DEVICE” Japanese Patent Laid-Open No. 5-184182, “Inverter Control Device”

The Institute of Electrical Engineers of Japan, Semiconductor Power Conversion System Research Committee, “Power Electronics Circuit” Ohmsha 2000 Koichi Okubo, et al., “Development of low-loss inverters for EV motors”, Mitsubishi Heavy Industries Technical Report VOL. 45 NO. 3: 2008

In Patent Document 1, a carrier frequency (referred to as a carrier) for reducing the loss amount is used as (A) the loss characteristics of the energy storage means, the switching element, and each phase coil of the motor as the loss characteristics. Means to seek have been proposed.
However, if the means of Patent Document 1 is applied to various apparatuses, particularly industrial apparatuses such as servo presses, press die cushions, conveying apparatuses, and distribution apparatuses, there are the following problems.

As for (A), there is a problem that “loss characteristics of other components are not considered”.
For example, wiring between the inverter and the motor, electromagnetic noise removing elements (ferrite cores and filters), and loss in the rotor of the motor (loss due to current induced in the rotor, etc.) are not considered.
Further, in industrial devices, the wiring between the inverter and the motor is long, or the electromagnetic noise removing element and the motor are large, so the amount of loss from these components is often not negligible.

As for (B), there is a problem that “it is difficult to obtain in advance data (total loss characteristics) for determining a carrier frequency”.
This reason is based on the following reason, for example.
(A) Since the wiring work matches the actual product, the electrical characteristics of the wiring cannot be predicted in advance.
(B) An element for removing electromagnetic noise may be added after installation of the device.
(C) Although a motor may fail and be replaced, each motor has different characteristics.
(D) The temperature of the motor is low immediately after the start of the apparatus and rises when the apparatus is continuously operated, but the loss characteristic of the motor varies depending on the temperature.

Furthermore, the conventional method is sufficiently effective in reducing the amount of loss when one cycle of the load pattern includes a plurality of operations with significantly different operating conditions (typically, motor rotation speed and torque). May not be obtained.
For example, in servo presses and die cushions for pressing, during one cycle, the mold is in contact with the workpiece and press molding is performed, and the mold is separated from the workpiece for loading and unloading the workpiece. There is a section being moved. In the section where press molding is performed, a low torque is required but a large torque is required. In a section where the mold is moving, a low torque but a high speed is required. In such a case, it is possible to select a parameter that further reduces the amount of loss compared to the conventional method by changing the parameter of the inverter in each section.

  The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to obtain all the characteristics of the wiring characteristics, the presence / absence of an electromagnetic noise removing element, the loss characteristics and temperature changes of each motor, and the like, without acquiring the data of the loss characteristics by conducting experiments in advance. It is an object of the present invention to provide a power-saving drive device and method for a device having the same load pattern that can minimize the amount of loss in consideration of the loss characteristics of elements.

According to the present invention, a power-saving drive device for a device driven by a motor supplied with power from an inverter and having the same load pattern,
An electric energy calculator that calculates the received electric energy of the inverter for each of a plurality of sections in the same load pattern;
A parameter selection / commander for changing the parameter of the inverter to a plurality of values, comparing the received power amount in each parameter, selecting a parameter that minimizes the received power amount, and instructing the inverter; A power-saving drive device for a device having the same load pattern is provided.

  According to a preferred embodiment of the present invention, there is provided a command value generator for outputting a cycle start signal and a cycle end signal of the load pattern and a section number indicating each section in the load pattern.

  The parameter of the inverter is a carrier frequency and / or a voltage change rate of the switching waveform.

According to the present invention, there is also provided a power saving driving method for a device driven by a motor supplied with power from an inverter and having the same load pattern,
Change the inverter parameters to multiple values,
Calculate the amount of received power of the inverter for each of a plurality of sections in the same load pattern in each parameter,
There is provided a power saving driving method for a device having the same load pattern, wherein the received power amount in each parameter is compared, a parameter that minimizes the received power amount is selected, and an inverter is commanded .

  According to a preferred embodiment of the present invention, the plurality of sections are set such that the speed, the speed, or the torque of the motor in the load pattern is different.

  According to the apparatus and method of the present invention, an electric energy calculator and a parameter selector / commander are provided, the inverter parameters are changed to a plurality of values, and the inverter is set for each of a plurality of sections in the same load pattern in each parameter. Calculate and compare the received power amount, select the parameter that minimizes the received power amount, and instruct the inverter, so the electrical characteristics of the wiring, the presence or absence of electromagnetic noise removal elements, the loss characteristics for each motor In addition, it is possible to minimize the loss amount in consideration of the loss characteristics of all the constituent elements without acquiring the loss characteristic data by performing experiments on temperature change and the like in advance.

When industrial devices such as a servo press, a press die cushion, a transport device, and a physical distribution device are repeatedly operated with the same load pattern, the motor output is the same in each cycle.
Therefore, when the parameter of the inverter is, for example, the carrier frequency, the operation is performed at the carrier frequency f1 in one cycle and the carrier frequency f2 in another cycle, and the measured values of the received electric energy of the inverter in each cycle are E1 and E2. The amount of loss is the difference between the amount of power received by the inverter and the integrated value of the motor output. Therefore, if E1 <E2, the carrier frequency f1 is smaller, and if E1> E2, the carrier frequency f2 is greater. Loss is small.
Therefore, by changing the inverter parameters (for example, carrier wave frequency) and measuring and comparing the amount of power received by the inverter in the cycle, the parameter that minimizes the amount of loss can be found, and the device is operated with that parameter. As a result, the amount of loss can be minimized.

Further, the inverter has a function of switching parameters (carrier frequency, voltage change rate dv / dt of the switching waveform) even in the middle of one cycle.
In the present invention, one cycle is divided into a plurality of sections, and the energy calculator calculates the amount of power for each section, and for each section, between a plurality of cycles with different parameters. Since the amount of power is compared and the parameter that minimizes the amount of power is selected, the amount of loss can be further reduced.

Therefore, according to the apparatus and method of the present invention, the following effects can be obtained.
(1) It is possible to operate with a small loss by searching for a carrier frequency with a small loss, without the effort and time to obtain the loss characteristic data by experimenting in advance.
(2) The present invention can be applied to the case where the motor performs not only power running but also regeneration in the operation of the apparatus, and further to only regeneration.
(3) In response to changes in external conditions such as wiring changes, motor replacement, and temperature changes, the system automatically searches for a carrier frequency with low loss while maintaining the operation of the device, and operates with low loss. A configuration for performing the above is also possible.
(4) It is also possible to perform an operation with a small loss by automatically adjusting a parameter other than the carrier frequency affecting the loss, for example, the voltage change rate dv / dt of the switching waveform.
(5) Since the parameter that minimizes the electric energy is selected for each of a plurality of sections in one cycle, the loss amount can be further reduced.

It is a figure which shows 1st Embodiment of the power saving drive device by this invention. It is operation | movement explanatory drawing of the same load pattern apparatus which this invention makes object. It is a figure which shows the example of the method of producing | generating the signal shown in FIG. 2 with a command value generator. 3 is a schematic diagram of an internal configuration of an electric energy calculator 81. FIG. 6 is an operation explanatory diagram of a parameter selection / command device 83. FIG. It is a figure which shows 2nd Embodiment of the power saving drive device by this invention. It is explanatory drawing of the method of searching and determining a some parameter. It is a figure which shows 3rd Embodiment of the power saving drive device by this invention. It is a figure which shows 4th Embodiment of the power saving drive device by this invention. It is another block diagram of a voltage measuring device and a current measuring device. It is a figure which shows the example of a division | segmentation of an area.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram showing a first embodiment of a power-saving drive device according to the present invention.

In this figure, 11 is an external power source, which is a power source supplied from an electric power company or a private power generator. The external power supply 11 is assumed to supply a three-phase alternating current in this embodiment, but may be another form of power supply such as a single-phase alternating current.
Reference numeral 13 denotes a converter that converts electric power supplied from the external power supply 11 into direct current and supplies the direct current to the direct current bus 15. The converter 13 is assumed to be a diode bridge in this embodiment, but may be a thyristor bridge whose voltage is variable by phase control, or a regenerative bridge using a power control element such as a power MOSFET or IGBT.
Reference numeral 15 denotes a DC bus, which electrically connects the converter 13 and the inverter 19. In the drawing, the upper side shows the plus side (+) of the DC bus 15, and the lower side shows the minus side (−) of the DC bus 15.
A capacitor 17 smoothes the voltage of the DC bus 15. As the capacitor 17, an aluminum electrolytic capacitor is often used, but other types of capacitors and electric double layer capacitors may be used.

Reference numeral 19 denotes an inverter which controls the current / voltage flowing from the DC bus 15 to the motor 21 so that the motor 21 generates a desired torque. The inverter 19 is assumed to be a voltage type inverter in this embodiment, but may be a current type inverter. In the case of a current type inverter, a reactor is used instead of the capacitor 17.
Further, in this embodiment, the inverter 19 is assumed to be a four-quadrant drive inverter capable of forward / reverse rotation, power running / regeneration of the motor 21, but depending on the characteristics and operation of the mechanical load 23 (same load pattern device), The inverter may be capable of rotating only in one direction or powering only.

  Further, in the present application, the inverter 19 has a function of switching parameters (carrier frequency, voltage change rate dv / dt of the switching waveform) even in the middle of one cycle.

Reference numeral 21 denotes a motor. The combination of the inverter 19 and the motor 21 causes the motor 21 to generate torque following the torque command value input from the controller 27.
In this embodiment, the motor 21 is assumed to be a three-phase induction motor or a three-phase permanent magnet synchronous motor. However, other types of motors may be used as long as the torque and rotational speed are variable in combination with an inverter.

Reference numeral 23 denotes a mechanical load, that is, the same load pattern device, which is driven by the motor 21.
Reference numeral 25 denotes a motor encoder, which measures the rotational position (angle) of the motor 21. As the motor encoder 25, an optical or magnetic rotary encoder or resolver is used. When the controller 27 performs speed control, the rotational speed (angular speed) of the motor 21 may be measured. In this case, the rotational position measured with a rotary encoder or resolver may be time-differentiated, or the rotational speed may be directly measured like a tachometer.

Reference numeral 27 denotes a controller, and the inverter 19, the motor 21, the motor encoder 25, and the controller 27 constitute a feedback loop, and the motor 21 is controlled to follow the command value from the command value generator 29.
The controller 27 assumes position control in this embodiment, but may be speed control. As a calculation method inside the controller, PID control, I-PD control, and the like are often used, but other control methods may be used. A feedforward calculation for improving controllability may be combined. The controller 27 can be realized by a programmable device using DSP or a microcomputer, an analog circuit, or a combination thereof.

  A command value generator 29 outputs a motor rotation angle command value Ac to be followed by the motor 21 to the controller 27 at each time. For transmission of the motor rotation angle command value Ac, transmission by a two-phase pulse train whose phase is shifted by 90 degrees or transmission by various communication networks is used. Since the rotation angle of the motor 21 and the mechanical load 23 are mechanically linked, instructing the rotation angle of the motor 21 has the same meaning as instructing the position of the mechanical load 23.

FIG. 2 is an operation explanatory view of the same load pattern device targeted by the present invention.
Since the present invention is intended for a device that is repeatedly operated with the same load pattern (same load pattern device), in this embodiment, as shown in FIG. 2, the motor rotation angle command value Ac is a cycle (same repeated pattern). The command value generator 29 outputs a cycle start signal Cs and a cycle end signal Ce at the start time and end time of the cycle, respectively. In FIG. 2, C indicates one cycle.

In the present application, the command value generator 29 generates a section number K indicating which section in one cycle is at a certain time, and outputs the section number K to the electric energy calculator 81 and the parameter selector / commander 83. In this example, the section numbers 1, 2, and 3 correspond to the low speed range, the medium speed range, and the high speed range, respectively. It is preferable to set the motor speed, speed, or torque so that they differ greatly.
The output of the command value generator 29 between cycles is not related to the operation of the present invention. However, in view of the fact that there are many cases where the apparatus is stopped or manually operated at low speed between cycles, Therefore, in the following description, it is assumed that a section number (section 1 in the embodiment) corresponding to the lowest speed is output as a section number between cycles.

In FIG. 2, the cycle start signal Cs and the cycle end signal Ce are pulse signals. However, other signal waveforms such as a cycle start being indicated by a rising edge of the signal and a cycle end being indicated by a falling edge of the signal. Good.
When the controller 27 performs speed control, the command value generator 29 may output the motor rotation speed command value.

  The command value generator 29 can be realized by a programmable device using a DSP or a microcomputer having a storage device such as a semiconductor memory.

FIG. 3 is a diagram illustrating an example of a method for generating a motor rotation angle command value and a section number by a command value generator.
As one method of generating the motor rotation angle command value and the section number by the command value generator 29, as shown in FIG. 3A, the relationship between the time and the motor rotation angle command value / section number is stored in a table system. The motor rotation angle command value is linearly interpolated between the points specified in the table as shown in FIG. 3 (B), and the section number is the time specified in the table as shown in FIG. 3 (C). In the meantime, the section number specified in the table can be output.

The inverter 19 is composed of the following elements, and PWM modulation is performed using a carrier wave Cw having a frequency according to the carrier frequency command value F output from the parameter selector / commander 83.
Details of the configuration and operation example of the inverter are shown in Non-Patent Document 1, for example. An example of a method for performing PWM modulation with a variable carrier frequency is disclosed in Patent Document 2. In Patent Document 2, the carrier wave is called a carrier.

  Reference numeral 41 denotes a power control unit which controls the voltage / current from the DC bus 15 to the motor 21 by a power control element whose conduction state is changed by a gate signal. In this embodiment, it is assumed that the power control unit 41 uses a power control element that can be extinguished by turning off a gate signal such as a power MOSFET or IGBT. However, power control of other types of power control elements such as GTO is performed. You may use it combining with the appropriate gate drive circuit according to an element.

  A motor current measuring device 43 measures the current of each UVW phase from the power control unit 41 to the motor 21. The motor current measuring device 43 is a non-contact type device that measures a magnetic field generated around an electric wire with current, a device that inserts a resistor into a circuit and measures a potential difference generated at both ends of the resistor with current. It is. The method for realizing the current measuring device 63 is the same.

  A command calculator 45 outputs a modulated wave Mw for each phase of UVW to the PWM modulator 47 so that the motor 21 generates torque following the torque command value Tc from the controller 27. The command calculator 45 can be a device that compares the current command to each phase calculated by vector calculation with the measured value of the motor current measuring device 43 to obtain the modulated wave of each phase, but other devices may be used. The command calculator 45 can be realized by a programmable device using a DSP or a microcomputer, an electronic circuit, or a combination thereof. In addition, the structure which reduces the number of required motor current measuring devices 43 using methods, such as state estimation, is also possible.

  A PWM modulator 47 modulates the modulated wave Mw with the carrier wave Cw, and outputs a notch wave Nw that determines conduction / non-conduction of the power control element. The PWM modulator 47 uses a triangular carrier wave in this embodiment, and assumes a means for determining on / off of the notch wave Nw by comparing the magnitude of the modulated wave Mw and the carrier wave Cw. The PWM modulator 47 can be realized by an analog electronic circuit (comparator) or a program of a DSP or a microcomputer.

49 is a carrier wave oscillator, which oscillates a carrier wave Cw for PWM modulation. The carrier wave oscillator 49 is configured such that the oscillation frequency is variable according to the carrier wave frequency command value F.
The carrier oscillator 49 oscillates a triangular carrier wave by configuring an up / down counter that repeats counting up and down between two values M1 and M2 by an electronic circuit, a DSP, or a program of a microcomputer, and according to the carrier frequency command value F Although it is possible to change the oscillation frequency by appropriately changing the values of M1 and M2, it may be configured by other methods such as an oscillation circuit using an analog electronic circuit.

  A gate driving circuit 51 insulates, level-converts or amplifies the notch wave Nw and outputs a gate signal for driving the gate of the power control element. The gate drive circuit 51 can be realized by an electronic circuit using an insulating power source, a photocoupler, or the like.

61 is a voltage measuring device, and 63 is a current measuring device. The voltage measuring device 61 and the current measuring device 63 measure the voltage and current to calculate the amount of power flowing into the inverter 19 from the DC bus 15 (including the capacitor 17), respectively, and measure the voltage measurement value V (t) and current. The measured value I (t) is output to the electric energy calculator 81. The voltage measurement value V (t) and the current measurement value I (t) can be transmitted digitally by means of analog transmission as voltage amplitude or current amplitude, or by using various communication networks.
The voltage on the plus side with respect to the minus side of the DC bus 15 at time t measured by the voltage measuring device 61 is denoted as V (t). Further, the current flowing from the left to the right on the positive side of the DC bus at time t measured by the current measuring device 63 is denoted as I (t). A negative current measurement value indicates that current flows from right to left in the figure.

  81 is an electric energy calculator, and calculates electric energy for each of a plurality of sections in one cycle. That is, a value obtained by multiplying the voltage measurement value V (t) and the current measurement value I (t) is obtained from the time when the cycle start signal Cs is input to the time when the cycle end signal Ce is input for each of a plurality of intervals. Integrate each time separately and output.

  That is, in this embodiment, the power calculator calculates the power amounts W1, W2, and W3 for the sections 1, 2, and 3 in one cycle in each cycle. In this embodiment, the number of sections is 3, but when the number of sections is N, the power amounts W1,..., WN for the sections 1,.

For transmission of the electric energy W1, W2, and W3 for the section 1, section 2, and section 3 in one cycle, it is possible to perform digital transmission using means for analog transmission as voltage amplitude and current amplitude, and various communication networks. is there.
The electric energy calculator 81 can be realized by a programmable device using a DSP or a microcomputer, an analog electronic circuit, or a combination thereof.
The electric energy calculator 81 performs the following calculation.
The power P (t) at time t is the product of voltage and current, and is expressed by equation (1). Here, when P (t) is a positive value, power flows from left to right in the figure, and when P (t) is a negative value, power flows from right to left in the figure.
P (t) = V (t) × I (t) (1)

Since the power amount is a time integral of the power, the power amount W1 for the section 1 in one cycle, the power amount W2 for the section 2 in one cycle, and the power amount W3 for the section 3 in one cycle are expressed by the formula (2 ), Formula (3), and formula (4). However, T1 and T2 are the time of the cycle start signal and the time of the cycle end signal for the cycle, respectively. A1 (t), A2 (t), and A3 (t) are the following signals, respectively.
A1 (t): 1 in section 1, 0 otherwise
A2 (t): 1 in section 2, 0 otherwise
A3 (t): 1 in section 3, 0 otherwise
For example, when the section number changes as shown in the top graph of FIG. 4B, A1 (t), A2 (t), and A3 (t) are the second from the top of FIG. 4B, respectively. The signal changes as shown in the third and fourth graphs.
In the embodiment, the number of sections is 3, but when the number of sections is N, the power amounts for the sections are W1,..., WN, and the signals are A1 (t),.

FIG. 4 is a schematic diagram of the internal configuration of the power amount calculator 81.
In this figure, 82a indicates interval discrimination, 82b indicates multiplication, and 82c indicates integration. 82c starts the integration when the cycle start signal Cs is input, and ends the integration when the cycle end signal Ce is input.
By configuring the inside of the electric energy calculator 81 as shown in FIG. 4, for example, W1, W2, and W3 can be calculated.

If the calculation by the electric energy calculator 81 is performed in a period of time ΔT, the equations (2) to (4) are differentiated and V (t) × I independently for each of a plurality of sections from time T1 to time T2. If (t) × ΔT is integrated, the power amounts W1, W2, and W3 for a plurality of sections in one cycle are obtained. That is, at the end of a cycle, the amount of power for each of a plurality of sections in the cycle can be output.
As described above, the present invention is applicable even when power running and regeneration are mixed in one cycle by allowing negative values for the current measurement value and power. That is, positive and negative power corresponds to power running and regeneration, respectively.

  Reference numeral 83 denotes a parameter selection / command device that commands parameter values that affect the loss amount, and also selects appropriate parameter values based on the amount of power in each of a plurality of sections in each cycle. In this embodiment, the parameter is the frequency of the carrier wave Cw, and the parameter selector / commander 83 outputs the carrier frequency command value F to the carrier wave transmitter 49. The parameter selector / commander 83 can be realized by a programmable device using a DSP or a microcomputer.

FIG. 5 is an operation explanatory diagram of the parameter selection / commander 83.
The procedure for searching and determining a parameter for reducing the loss by the parameter selector / commander 83 is as follows.
The parameter selector / commander 83 outputs a different carrier frequency command value F for each cycle. At the end of the cycle, the power amount calculator 81 outputs the power amount for each of a plurality of sections in each cycle, and is stored in the parameter selector / commander 83. The parameter selector / commander 83 compares the power amounts of different cycles for the same section with respect to the stored power amount for each section in one cycle, and determines the carrier frequency command value F with the smallest power amount as The subsequent carrier frequency command value F for the section is output.

As an example, as shown in FIG. 5, the carrier frequency command value F is changed to F1, F2, F3, and F4 for each of four cycles (C1, C2, C3, and C4 in the figure). It is assumed that the amount of power for each of a plurality of sections in one cycle is W1-1, 2, 3, W2-1, 2, 3, W3-1, 2, 3, and W4-1, 2, 3. W1-1,2,3, W2-1,2,3, W3-1,2,3, W4-1,2,3 are stored, and when cycle 4 (C4 in the figure) ends. As shown in FIG. 5, the electric energy is compared between the different cycles in section 1, section 2, and section 3.
(1) Compare the electric energy of section 1 in cycle 1 (C1), section 1 in cycle 2 (C2), section 1 in cycle 3 (C3),.
(2) Compare the electric energy of section 2 in cycle 1 (C1), section 2 in cycle 2 (C2), section 2 in cycle 3 (C3),.
(3) Compare the electric energy of section 3 in cycle 1 (C1), section 3 in cycle 2 (C2), section 3 in cycle 3 (C3),.

That is, the amount of electric power is compared as follows and a parameter is selected.
(1) For section 1, W1-1, W2-1, W3-1, and W4-1 are compared. Assuming that W1-1 is the smallest, it can be seen that for interval 1, the carrier frequency command value F1 corresponding to W1-1 is the carrier frequency command value that minimizes the loss. Therefore, the parameter selector / commander 83 continues to output F1 as the carrier frequency command value in section 1 thereafter.
(2) For section 2, W1-2, W2-2, W3-2, and W4-2 are compared. If W3-2 is the smallest, it can be seen that for interval 2, the carrier frequency command value F3 corresponding to W3-2 is the carrier frequency command value that minimizes the loss. Therefore, the parameter selector / commander 83 continues to output F3 as the carrier frequency command value in the interval 2 thereafter.
(3) For section 3, W1-3, W2-3, W3-3, and W4-3 are compared. If W4-3 is the smallest, it can be seen that for interval 3, the carrier frequency command value F4 corresponding to W4-3 is the carrier frequency command value that minimizes the loss. Therefore, the parameter selector / commander 83 continues to output F4 as the carrier frequency command value in the section 3 thereafter.

  In the example shown in FIG. 5, the carrier frequency command value F is changed in four ways, F1 to F4, and four cycles C1 to C4 are required for searching and determining the parameter (carrier frequency command value). The number for changing the carrier wave frequency command value F is not limited to 4, and may be a number Q of 2 or more. In this case, Q cycles are required for searching and determining the parameter (carrier frequency command value).

For example, the following (1) to (3) are conceivable as timings for searching and determining parameters.
(1) Search and determine parameters immediately after a hardware change that affects loss, such as adding a noise filter to the wiring from the inverter to the motor, replacing the motor, or modifying the mechanical load. . For example, a push button (not shown) is connected to the parameter selection / commander 83, and when a hardware change is made, a human pushes the push button. The parameter selection / commander searches and determines the parameters (carrier frequency command value in this example) in the first cycle (in this example, the first 4 cycles) after the push button is pressed. Continue to output the carrier frequency command value determined for the section.

  (2) When a certain number of cycles or a certain period of time has elapsed after the device is operated, the parameter search / determination is performed again. For example, a counter that counts the number of occurrences of the cycle start signal or cycle end signal or a timer that measures the elapsed time is provided in the parameter selection / commander, and when the counter value or timer value reaches a certain value, the parameter search / Redo the decision. At the same time, reset the counter or timer to restart the cycle count or elapsed time measurement.

  If the device continues to operate, the temperature of electrical components (motors, inverters, wiring, filters, etc.) and mechanical components (bearings, etc.) may rise, and the relationship between parameters and losses may change. In such a case, it is always possible to operate with a parameter that minimizes the loss.

  (3) When the present invention is applied to an apparatus having a plurality of operation patterns (for example, a servo press to which a plurality of molds can be attached and each of the molds moves differently), the operation patterns are switched. Immediately after that, search and determine parameters. For example, a controller (not shown) instructing switching of the operation pattern is configured to notify the parameter selection / commander of the switching of the operation pattern, and when the switching of the operation pattern is notified, the parameter is searched and determined. .

  Note that the timing for searching and determining parameters may be determined by a combination of the above timings. Moreover, the above is an example, and the timing of parameter search / determination is not limited to these.

FIG. 6 is a diagram showing a second embodiment of the power-saving drive device according to the present invention.
The second embodiment is an example in which the voltage change rate dv / dt of the switching waveform is used as a parameter in addition to the carrier frequency.
Only the differences from the first embodiment of FIG. 1 will be described below.

  Reference numeral 51a denotes a gate drive circuit, which controls the gate voltage and the gate current in accordance with the voltage change rate command value G in addition to the gate drive circuit 51 of the first embodiment, and sets the voltage change rate dv / dt of the switching waveform as a voltage. It has a soft gate drive function that suppresses the change rate to the command value G. An example of the soft gate driving method is shown in Non-Patent Document 1.

Reference numeral 83a denotes a parameter selection / command device, which has a function of outputting a voltage change rate command value G to the gate drive circuit 51a in addition to the parameter selection / command device 83 of the first embodiment.
Similarly to the first embodiment, the carrier frequency command value F output from the parameter selector / commander 83a and the command value G of the voltage change rate are changed to store the electric energy for each of a plurality of sections in one cycle. Comparing the electric energy for the section between different cycles, the carrier frequency command value F and the voltage change rate command value G for which the power amount is the smallest, and the subsequent carrier frequency command value F and the voltage change rate command value for the section Output as G.
In this embodiment, the loss can be further reduced as compared with the first embodiment by changing the command value G of the voltage change rate.

FIG. 7 is an explanatory diagram of a method for searching and determining a plurality of parameters.
As a method for searching and determining a plurality of parameters (carrier frequency command value F and voltage change rate command value G) for reducing the loss, for example, there are the following methods.

  For all combinations of the carrier wave frequency command value F and the voltage change rate command value G, the electric energy for each of a plurality of sections in one cycle is stored and compared. For example, when there are four carrier frequency command values F1, F2, F3, and F4, and three voltage change rate command values G1, G2, and G3, 4 × 3 = 12 cycles as shown in FIG. For one cycle (in the figure, C1 to C12), one cycle of electric energy (in the figure, W1-1, W1-2, W1-3, ..., W12-1, W12-2, W12-3) is stored. Then, the amount of power is compared between different cycles in section 1, section 2, and section 3, and the carrier frequency command value F and the voltage change rate command value G are selected.

In the example of FIG.
(1) For section 1: Compare W1-1 to W12-1, and select the carrier frequency command value F2 and voltage change rate G1 corresponding to W4-1 having the smallest value.
(2) For section 2: W1-2 to W12-2 are compared, and carrier frequency command value F3 and voltage change rate G2 corresponding to W8-2 having the smallest value are selected.
(3) For section 3, W1-3 to W12-3 are compared, and the carrier frequency command value F4 and voltage change rate G2 corresponding to W11-3 having the smallest value are selected.
Thereafter, the parameter selector / commander 83a selects the selected carrier frequency command value and the selected voltage change for each of the sections 1, 2, and 3 after the end of the cycle 12 (that is, after the cycle C13 in the figure). Continue to output rate. That is, in section 1, F2 is output as the carrier wave frequency command value and G1 is output as the voltage change rate. In section 2, F3 is output as the carrier wave frequency command value and G2 is output as the voltage change rate. In section 3, F4 is output as the carrier wave frequency command value and G2 is output as the voltage change rate.

  In the example shown in FIG. 7, the carrier frequency command value F is changed in four ways F1 to F4, and the voltage change rate command value G is changed in three ways G1 to G3, and parameters (carrier frequency command value and voltage change rate are changed). 4 × 3 = 12 cycles (C1 to C12 in the figure) are required for the search / determination of the command value). The numbers are not limited to 4 and 3, respectively, and may be 2 or more. In this case, Q × R cycles are required for searching and determining parameters (carrier frequency command value and voltage change rate command value).

  In the above method, if the number of parameter value combinations (12 in the above example) becomes too large and the number of cycles required for parameter search / determination becomes too large, random numbers or genetics are selected from the parameter combinations. Only combinations selected by an algorithm may be used. Other methods based on the experimental design may be used.

FIG. 8 is a diagram illustrating a third embodiment of the power-saving drive device according to the present invention.
In this example, there are a plurality of inverters and motors, each of which moves independently. For example, the transport apparatus has an x-axis, a y-axis, and a z-axis, and each of them is moved along an independent locus and moved to an arbitrary position in the three-dimensional space.
An example in which a plurality of inverters and motors are provided in the second embodiment is shown, but if the command value G for the voltage change rate is omitted, this corresponds to a case in which a plurality of inverters and motors are provided in the first embodiment. Although the figure shows the case where there are three inverters and motors, the same applies to the case where there are two or four or more motors. In the figure, since the internal configuration of the inverters 19A, 19B, and 19C is the same as that of the second embodiment, the internal configuration of the inverter is not shown.

Since the following components are provided for each inverter and motor, they are identified by adding A, B, and C at the end. The configuration of each element is the same as in the second embodiment.
19A, 19B, 19C Inverters 21A, 21B, 21C Motors 23A, 23B, 23C Mechanical loads 25A, 25B, 25C Motor encoders 27A, 27B, 27C Controllers 29A, 29B, 29C Command value generators 61A, 61B, 61C Voltage measuring instruments 63A, 63B, 63C Current measuring devices 81A, 81B, 81C Energy calculators 83aA, 83aB, 83aC Parameter selection / commander

  Since the three sets with A, B, and C at the end operate completely independently, each set performs the same operation as in the second embodiment, so that the parameters (carrier frequency command value F and voltage for each set) are set. The change rate command value G) is searched and determined, and the loss of each set can be reduced.

FIG. 9 is a diagram showing a fourth embodiment of the power saving drive device according to the present invention.
In this example, there are a plurality of inverters and motors, all of which move in the same manner. For example, since the size of the motor is limited, the integrated mechanical load is driven by a plurality of motors.
An example in which a plurality of inverters and motors are provided in the second embodiment is shown, but if the command value G for the voltage change rate is omitted, this corresponds to a case in which a plurality of inverters and motors are provided in the first embodiment. Although the figure shows the case where there are three inverters and motors, the same applies to the case where there are two or four or more motors. In the figure, since the internal configuration of the inverter is the same as that of the second embodiment, the internal configuration of the inverter is not shown.

Since the following components are provided for each inverter and motor, they are identified by adding A, B, and C at the end. The configuration of each element is the same as in the second embodiment.
19A, 19B, 19C Inverters 21A, 21B, 21C Motors 23A, 23B, 23C Mechanical loads 25A, 25B, 25C Motor encoders 27A, 27B, 27C Controllers

  Since the three sets with A, B, and C at the end operate in exactly the same way, there is only one parameter selector / commander, and the parameters (carrier frequency command value F and voltage change rate) for each set The command value G) is always the same. Since the voltage / current measuring device is connected so as to measure the power consumption of the three sets of totals, the same amount of power calculation, parameter search / determination operation as in the second embodiment is performed, so that the loss of the three sets of totals is lost. The parameters (the carrier wave frequency command value and the voltage change rate command value G) are searched and determined so as to reduce.

  The above-described cycle of the present invention only needs to be a section in which the apparatus moves in the same manner, and does not have to exactly coincide with the operation cycle of the apparatus to which the present invention is applied. For example, only a section in which the apparatus moves strongly and a large current flows through the motor may be treated as a cycle in the present invention.

  The voltage measuring device 61 and the current measuring device 63 may be interchanged to bring the current measuring device to the left side in the figure.

  The configuration shown in each embodiment described above is divided by function, and the physical configuration may be different. For example, a programmable device using a DSP (digital signal processor) or microcomputer inside the inverter may be used to realize not only a command calculator but also an electric energy calculator and a parameter selector / commander. One or both of the voltage measuring device and the current measuring device (however, only the first, second, and third embodiments) may be configured inside the inverter.

FIG. 10 is another configuration diagram of the voltage measuring device and the current measuring device.
In the first, second and fourth embodiments described above, instead of measuring the voltage and current of the DC bus with the voltage measuring device and the current measuring device, as shown in FIG. Measure the voltage (relative to the neutral point) and current of each phase of AC and use it as an input to the energy calculator, add the product of the voltage and current of each phase over three phases, find the power, and integrate the time It is good also as electric energy of 1 cycle. That is, if the measured voltage values for each phase are V1 (t), V2 (t), V3 (t) and the measured current values are I1 (t), I2 (t), I3 (t), then P (t ) Is expressed by equation (5) instead of equation (1).

P (t) = V1 (t) × I1 (t) + V2 (t) × I2 (t) + V3 (t) × I3 (t) (5)
What is necessary is just to calculate the formula which substituted this Formula (5) for each of Formula (2), Formula (3), and Formula (4) with an electric energy calculator.

  In order to reduce the measurement error, instead of changing the parameter value every cycle in parameter search / determination, the parameter value is changed every N cycles (N is 2 or more). Alternatively, one cycle of measured energy may be averaged over N cycles.

(How to divide the section)
FIG. 11 is a diagram illustrating an example of segment division.
In the present application, as means for dividing one cycle into a plurality of sections having greatly different operating conditions, for example, there are the following means.
A. When a load pattern (motor rotation angle command value or motor rotation speed command value) is given, a person makes a judgment and divides one cycle into sections to determine section numbers in the sections. In particular, when the load pattern itself is determined by a person, it is reasonable to determine the load pattern and the section division at the same time.
B. When a load pattern (motor rotation angle command value or motor rotation speed command value) is given, it is automatically divided into sections based on speed and acceleration values.

  For example, when a load pattern (motor rotation angle command value in this example) as shown in FIG. 11A is given, the speed is obtained as shown in FIG. 11B by calculating the time derivative of the load pattern. . The speed is classified into a predetermined low speed area, medium speed area, and high speed area, as shown in FIG. 11C, the low speed area is section 1, the medium speed area is section 2, and the high speed area is By setting it as the section 3, the inside of one cycle is divided into sections and the section number in each section is determined. As a method for predetermining the low speed range, the medium speed range, and the high speed range, for example, assuming that the rated maximum speed of the motor is Vmax, the lower speed range is less than 30% of Vmax, and the intermediate speed is 30% or more and less than 60% of Vmax. It is possible to decide that the high speed range is to be set in the range and beyond.

  Although the voltage type inverter is used in the above-described embodiment, the present invention can be applied to any system that controls the voltage or current supplied to the motor by switching the power control element. For example, the present invention can be applied to a current type inverter, a voltage type or current type multilevel inverter, a matrix converter in which a converter and an inverter are integrated, a multilevel matrix converter, and the like. When a matrix converter is used, since there is no DC bus, voltage / current measurement may be performed for three-phase AC immediately after the external power supply 11 as shown in FIG.

The motor 21 may be a linear motor instead of the rotary motor.
Instead of the motor encoder, a rotary encoder or linear encoder that directly detects the position / speed of the mechanical load may be used.
Instead of a combination of an external power source and a converter, power may be directly supplied to the DC bus from a DC power source (DC generator, fuel cell, battery, etc.).
Although an example of sensorless vector control using a three-phase induction or synchronous motor has been shown, vector control using a rotation speed detection sensor with a three-phase induction motor or vector control using a rotation angle detection sensor with a three-phase synchronous motor may be used.
The external power supply may be a non-contact power supply device. The non-contact power feeding device may include a converter.

  In the above-described embodiment, the method of determining on / off of the notch wave by comparing the magnitude of the modulated wave and the carrier wave in the PWM modulator is assumed. However, the modulation method using the concept of the instantaneous space vector exemplified in Non-Patent Document 1 is used. When employed, for example, the carrier wave is a square wave, and at the timing of the rising edge of the carrier wave, the DSP or microcomputer constituting the PWM modulator is interrupted to perform one vector operation per cycle of the carrier wave. What is necessary is just to comprise.

  According to the apparatus and method of the present invention described above, the electric energy calculator 81 and the parameter selector / commander 83 are provided, the parameter of the inverter 19 is changed to a plurality of values, and a plurality of parameters within the same load pattern in each parameter are included. Calculate and compare the received power amount of the inverter for each section, select the parameter that minimizes the received power amount, and instruct the inverter, so the electrical characteristics of the wiring, the presence or absence of electromagnetic noise removal element, motor The loss amount can be minimized in consideration of the loss characteristics of all the constituent elements without obtaining the loss characteristic data by experimenting in advance with the loss characteristics and temperature changes of each component.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

11 external power supply, 13 converter, 15 DC bus,
17 capacitor, 19, 19A, 19B, 19C inverter,
21, 21A, 21B, 21C motor,
23, 23A, 23B, 23C Mechanical load (same load pattern device),
25, 25A, 25B, 25C motor encoder,
27, 27A, 27B, 27C controller,
29, 29A, 29B, 29C command value generator,
41 power control unit, 43 motor current measuring device,
45 command calculator, 47 PWM modulator, 49 carrier oscillator,
51, 51a Gate drive circuit,
61, 61A, 61B, 61C Voltage measuring device,
63, 63A, 63B, 63C Current measuring instrument,
81, 81A, 81B, 81C electric energy calculator,
83, 83a, 83aA, 83aB, 83aC Parameter selection / commander

Claims (5)

A power-saving drive device driven by a motor supplied with power from an inverter and having the same load pattern,
An electric energy calculator that calculates the received electric energy of the inverter for each of a plurality of sections in the same load pattern;
A parameter selection / commander for changing the parameter of the inverter to a plurality of values, comparing the received power amount in each parameter, selecting a parameter that minimizes the received power amount, and instructing the inverter; A power-saving drive device for a device having the same load pattern.   2. The power saving drive device according to claim 1, further comprising a command value generator that outputs a cycle start signal and a cycle end signal of the load pattern, and a section number indicating each section in the load pattern.   The power-saving drive device according to claim 1, wherein the parameter of the inverter is a carrier frequency and / or a voltage change rate of a switching waveform. A power-saving driving method for a device driven by a motor supplied with power from an inverter and having the same load pattern,
Change the inverter parameters to multiple values,
Calculate the amount of received power of the inverter for each of a plurality of sections in the same load pattern in each parameter,
A power-saving drive method for a device having the same load pattern, wherein the received power amount in each parameter is compared, a parameter that minimizes the received power amount is selected, and an inverter is commanded. The power saving drive method according to claim 4, wherein the plurality of sections are set such that the speed, the speed, or the torque of the motor in the load pattern is different.

Images