JP4485903B2 - Inverter device, compressor drive device and refrigeration / air-conditioning device - Google Patents

Description

  The present invention relates to an inverter device for driving a motor. Further, the present invention relates to a compressor driving device driven by the inverter device, a refrigeration device equipped with the inverter device, and an air conditioner (collectively referred to as refrigeration Air conditioner).

  Permanent magnet synchronous motors are widely used because they have excellent maintainability, controllability, and environmental resistance, and can be operated with high efficiency and high output. Synchronous reluctance motors that do not use permanent magnets are also actively studied as inexpensive and easy-to-recycle motors.

  In order to perform high-performance control of a synchronous motor such as a permanent magnet synchronous motor or a synchronous reluctance motor, it is important to flow a sine wave current according to the position of the rotor. Therefore, in general, a position sensor that detects the position of a rotor such as a Hall element, an encoder, or a resolver is used in the motor control device. Further, in place of the position sensor, Patent Literature 1 and Patent Literature 2 disclose a method for indirectly obtaining the rotor position by calculation based on information on the voltage and current of the motor.

  However, in the case of a position sensor, not only is it a major factor that hinders downsizing of the equipment, but it also requires multiple wires and receiving circuits to transmit the position sensor signal, so reliability, workability, cost, etc. There was a problem. In addition, in the method of indirectly calculating the position of the rotor based on information on the voltage and current of the motor, there is a problem that the control device becomes expensive because complicated and high-speed calculation processing is required.

  In view of the above problems, a control is disclosed that is controlled by the phase difference between the voltage and current of the synchronous motor. Here, the synchronous motor drive device controlled by the phase difference between the voltage and current of the synchronous motor will be described. FIG. 6 is a control block diagram of a conventional synchronous motor driving apparatus.

  As shown in FIG. 6, the synchronous motor driving device includes an AC power supply 4 for supplying electric power, AC power and DC power to drive a synchronous motor 1 having a three-phase coil in a stator and a permanent magnet in a rotor. An inverter circuit 2 and a converter circuit 3 that convert the motor current, a current sensor 5 that detects a motor current, a motor current detection amplifier unit 6 that amplifies the detected motor current and adds an offset, and a microcomputer 7 that controls them It is composed of

  According to the above configuration, the power supplied from the AC power source 4 is converted into AC power via the inverter circuit 2 and the converter circuit 3, and the converted AC power is supplied to the synchronous motor 1 to drive the motor.

  The current sensor 5 detects a motor current flowing in a specific phase (hereinafter referred to as a U phase) among the phases of the coil terminals U, V, and W of the synchronous motor 1. The motor current detected by the current sensor 5 is given to the motor current detection amplifier unit 6, and a predetermined amount of amplification and offset are added, and a motor current signal is given to the control unit 7.

  The microcomputer 7 includes a phase difference detection unit 8, a target phase difference information storage unit 9, an adder 10, a PI calculation unit 11, a rotation speed setting unit 12, a sine wave data table 13, and sine wave data creation. Unit 14 and PWM creation unit 15, and each process is performed according to each program.

  The phase difference detection unit 8 takes in a motor current signal supplied from the motor current detection amplifier unit 6 by A / D conversion at a predetermined timing, and samples each current obtained by sampling the drive voltage phases of two motors for each period. The motor current signal area is calculated by integrating sampling data. The calculated area ratio between the two motor current signal areas is output as phase difference information.

  The target phase difference information storage unit 9 stores target phase difference information. Error data between the target phase difference information and the phase difference information is calculated by the adder 10. The PI calculation unit 11 calculates proportional error data and integral error data with respect to the calculated error data, and outputs a duty reference value. The addition unit 10 and the PI calculation unit 11 constitute a phase difference control unit 27.

  The rotation speed setting unit 12 sets a rotation speed command for the synchronous motor 1. The sine wave data table 13 stores sine wave data corresponding to a predetermined rotational speed of the synchronous motor 1. The sine wave data creation unit 14 reads out sine wave data corresponding to each phase of the coil terminals U, V, and W of the synchronous motor from the sine wave data table 13 according to the rotational speed command of the synchronous motor 1 and the passage of time. U-phase motor drive voltage phase information is output based on the U-phase sine wave data. The PWM creation unit 15 creates a PWM waveform based on the sine wave data and the duty reference value, and outputs the created PWM waveform to the drive elements of the synchronous motor terminals U, V, and W of the inverter circuit 2.

Patent Document 3 discloses a method for realizing sine wave driving by controlling the phase difference between a motor voltage and a motor current, such as the above-described synchronous motor driving device. Further, Patent Document 4 discloses a method for improving the stability of synchronous motor drive by preventing torque and current vibrations and step-out during sudden load changes in a synchronous motor drive device using V / f constant control.
Japanese Unexamined Patent Publication No. 07-177799 (paragraphs 0005 to 0007, FIG. 1) Japanese Patent Application Laid-Open No. 07-245981 (paragraphs 0005 to 0013, FIG. 1) JP 2001-112287 A (paragraphs 0021 to 0042, FIG. 1) JP 2000-236694 A (paragraphs 0007 to 0013, FIG. 1)

  In Patent Document 3, the control device can be made inexpensive because the control of the synchronous motor is simple. However, when a large fluctuation occurs in the load, turbulence occurs. When the amplitude of this turbulence is large, there is a problem in stability such that recovery is impossible and operation is impossible due to step-out.

  Patent Document 4 is more stable than Patent Document 3, but requires a current sensor that detects a two-phase current, and there are problems in cost reduction and miniaturization. In addition, calculation processing such as coordinate conversion from the three-phase coordinate system to the two-phase coordinate system is required, so that the calculation amount of the microcomputer increases and the calculation takes too much time. For example, as the synchronous motor is driven at a higher speed, the time required for the calculation becomes longer, and there is a problem that the calculation is not completed within a predetermined time corresponding to the number of rotations and the driving becomes impossible.

  Therefore, an object of the present invention is to provide an inexpensive and high-performance inverter device that enables stable synchronous motor operation with a simple configuration and control.

In order to achieve the object, the present invention includes an inverter circuit that converts DC power into AC power, and a control device that controls the inverter circuit by a phase difference control method, and the control device flows through the inverter circuit. Current detection means for detecting current, phase difference detection means for detecting a phase difference between an AC voltage and an AC current based on the detected current, and an error between the detected phase difference and a target phase difference An adjustment unit that adjusts a duty reference value according to the current, a current vibration detection unit that detects a vibration component of the alternating current, a frequency correction amount calculation unit that calculates a frequency correction amount based on the vibration component of the alternating current, and a calculation Frequency correction means for correcting a frequency command value based on the corrected frequency correction amount, output waveform data corresponding to the corrected frequency command value, and the adjusted duty And a PWM signal generating means for calculating a PWM signal based on the tee reference value, the inverter circuit is output AC voltage of a plurality of phases, one of said plurality of phase one of the AC voltage of a particular phase When the phase of the current is approximately 90 degrees and / or approximately 270 degrees, the current detection means detects the current of the specific phase, and the control device outputs the PWM signal to the inverter circuit. And

  The current detection means is provided with a current detection resistor in a DC circuit connecting the inverter circuit and the converter circuit, and detects a DC current flowing through the inverter circuit based on a voltage generated at both ends of the current detection resistor. The phase difference detection means detects the phase difference between the AC voltage and the AC current based on the detected DC current, and uses this as AC voltage / current phase difference information. The adjustment unit compares the detected AC voltage / current phase difference information with the target phase difference information, and calculates a duty reference value corresponding to the error.

The current vibration detection means detects the vibration component of the alternating current from the direct current detected by the direct current detection means, and corrects the frequency command value based on the detected vibration component .

  Further, the frequency correction amount calculating means adjusts the magnitude of the frequency correction amount according to the magnitude of the alternating current vibration component. For example, when the vibration component detected by the current vibration detection means is large, the frequency correction amount is increased. Further, when the vibration component is small, the frequency correction amount is decreased. The adjustment of the frequency correction amount is not only detected from the alternating current oscillation component, but may be performed according to the magnitude of the alternating voltage frequency or the duty reference value, for example.

Moreover, it is good also as a motor drive inverter apparatus by providing a synchronous motor in the output side of an inverter circuit. In this case, since the rotational speed of the motor and the frequency are in a proportional relationship, the control device includes a direct current detecting means for detecting a direct current flowing through the inverter circuit, and an alternating voltage and an alternating current based on the detected direct current. A phase difference detecting means for detecting a phase difference between the phase difference and a target phase difference, an adjustment means for adjusting a duty reference value in accordance with an error between the detected phase difference and a target phase difference, and detecting a vibration component of the alternating current Current vibration detection means, rotation speed correction amount calculation means for calculating the rotation speed correction amount of the motor based on the vibration component of the alternating current, and motor rotation speed command value based on the calculated rotation speed correction amount A PWM signal for calculating a PWM signal based on the motor rotational speed correcting means for correcting, the output waveform data corresponding to the corrected motor rotational speed command value, and the adjusted duty reference value. And a creation unit, the inverter circuit is output AC voltage of a plurality of phases, phase approximately 90 degrees in any one of the AC voltage of a particular phase of the plurality of phase or / and approximately 270 degrees At this time, the current detection means detects the current of the specific phase, and the control device outputs the PWM signal to the inverter circuit.

  According to the present invention, 180-degree energization driving including sinusoidal driving can be performed without providing a rotor position sensor or motor current sensor, and motor efficiency can be improved, and noise and vibration can be realized. Further, the amount of calculation of the microcomputer is reduced, and the processing speed of the A / D converter, the microcomputer, etc. can be lowered. Therefore, it is possible to obtain a highly reliable inverter device that can control motor torque and current vibration with a simple configuration and control, prevent step-out and perform stable control, and is small and highly reliable. A compressor driving device and a refrigeration / air conditioning device can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a block diagram showing a schematic configuration of an inverter device according to the present invention, FIG. 2 is a waveform diagram of U-phase voltage / current of an inverter circuit, and FIG. 3 is a schematic configuration of a current vibration detection unit and a rotational speed correction amount calculation unit. FIG. 4 is a block diagram showing a schematic configuration of the rotation speed correction amount calculation unit, and FIG. 5 is a block diagram showing a schematic configuration of the rotation speed correction amount calculation unit.

  In the inverter apparatus for driving a motor according to the present invention, as shown in FIG. 1, a motor 1 which is a three-phase synchronous motor is connected to the output side of an inverter circuit 2, and is driven by inverter control. The inverter circuit 2 is supplied with the AC voltage from the AC power source 4 converted into a DC voltage by the converter circuit 3.

  A current detection resistor 21 is provided on the negative side of the DC circuit connecting the converter circuit 3 and the inverter circuit 2. Based on the voltage generated at both ends of the current detection resistor 21, the DC current detection amplifier unit 22 detects the DC current flowing through the inverter circuit 2. The direct current detection amplifier unit 22 is connected to the microcomputer 7 as a control device, amplifies the detected direct current, and outputs it to the microcomputer 7 as a direct current signal. The DC current detection amplifier unit 6 serves as DC current detection means for detecting a DC current flowing through the inverter circuit 2.

  The microcomputer 7 includes a phase difference detection unit 8, a target phase difference information storage unit 9, an adder 10, a PI calculation unit 11, a rotation speed setting unit 12, a sine wave data table 13, a sine wave data creation unit 14, and a PWM creation unit. 15, a motor current estimation unit 16, a current vibration detection unit 17, a rotation speed correction amount calculation unit 18, and a rotation speed correction unit 19, and each process is performed in software according to a program.

  The motor current estimation unit 16 obtains a change in the DC current from the input DC current signal by the current change calculation means, and estimates and calculates the motor current signal by the distribution calculation means for the change in the DC current signal. Here, the current change calculation means and the distribution calculation means are described in Japanese Patent Application Laid-Open No. 8-19263.

  The phase difference detection unit 8 detects motor voltage / current phase difference information using the motor current signal estimated and calculated by the motor current estimation unit 16.

  The target phase difference information storage unit 9 stores target phase difference information, and the adder 10 calculates error data between the target phase difference information and the phase difference information output from the phase difference detection unit 8, The calculation result is output to the PI calculation unit 11. The PI calculation unit 11 calculates proportional error data (P) and integration error data (I) with respect to the calculated error data, and outputs a duty reference value to the PWM generation unit 15.

  The current vibration detection unit 17 detects a vibration component of the motor current signal based on the motor current signal estimated and calculated by the motor current estimation unit 16. The rotation speed correction amount calculation unit 18 calculates the rotation speed correction amount based on the vibration component detected by the current vibration detection unit 17. The rotation speed setting unit 12 stores a target rotation speed command value, and the rotation speed correction unit 19 stores error data between the rotation speed command value and the rotation speed correction amount output from the rotation speed correction amount calculation unit 18. And the calculation result is output to the sine wave data creation unit 14.

  The sine wave data table 13 stores in advance sine wave data composed of a predetermined number of data, and outputs the sine wave data to the sine wave data creation unit 14. The sine wave data creation unit 14 reads out sine wave data corresponding to each phase of the motor winding terminals U, V, and W from the error data that is the calculation result of the rotation speed correction unit 19 and the sine wave data table 13. , And outputs the U-phase motor drive voltage phase information to the phase difference detector 8 from the U-phase sine wave data.

  The PWM generator 15 outputs a PWM waveform signal, which is a motor drive voltage, to each drive element of the inverter circuit 2 for each phase from the sine wave data and the duty reference value. Note that the sine wave data may be created by calculation instead of being created based on the sine wave data table 13.

  The adder 10 obtains an error amount between the motor voltage / current phase difference information detected by the phase difference detection unit 8 and the target phase difference information, and the PI calculation unit 11 performs a predetermined amplification on the error amount by P control. To calculate the proportional error amount, integrate the error amount by I control, amplify the value to calculate the integral error amount, and add both to calculate the duty reference value. The PWM generator 15 calculates the output duty each time based on this duty reference value and sine wave data separately obtained from the rotational speed command value, and applies it to the motor winding via the inverter 2 to allow the motor 1 to Driven.

  That is, the magnitude of the drive voltage (duty width of the PWM duty) is determined by the phase difference control feedback loop for controlling the motor winding current phase difference with respect to the motor drive voltage (output duty) to be constant. Further, in order to rotate the motor 1 at a desired rotational speed, the rotational speed is determined by sine wave data output at a desired frequency. As a result, the motor 1 can be driven and controlled with a desired phase difference and a desired rotational speed.

  Next, setting of the rotation speed and PWM output will be described. The phase difference control method according to the present invention is different from the method in which a speed control is performed by detecting a counter electromotive voltage pulse or the like. That is, the rotation speed of the motor 1 is so-called forced excitation drive that is determined by the frequency of a sine wave voltage composed of a PWM wave that is energized to the motor winding.

  As shown in FIG. 2A, in the current vibration detection unit 17, since the motor current is an alternating current, it is difficult to understand the vibration amount as it is. Therefore, the current vibration detection unit 17 detects the current of the specific phase when the phase of the AC voltage of any one of the plurality of phases is approximately 90 degrees.

  For example, when the specific phase is a U-phase voltage, the U-phase voltage of the motor current signal output from the motor current estimation unit 16 by the U-phase current data detection unit 23 of the current vibration detection unit 17 illustrated in FIG. The U-phase current at the time when the phase is 90 degrees (see FIG. 2B) is detected. This is designated as U-phase current data A. By passing the detected U-phase current data A through the high-pass filter 24, the DC component is removed, and a U-phase current oscillation component (see FIG. 2C) that is a pure fluctuation amount is calculated. The rotation speed correction amount is calculated by passing the calculated vibration component through a proportional amplifier 25 provided in the rotation speed correction amount calculation unit 18. Note that the direct current component is, for example, a value to be subtracted in order to capture the value of the alternating current when the phase of the alternating voltage is 90 degrees as a pure fluctuation amount.

  Thereby, the magnitude of the rotational speed correction amount can be adjusted according to the magnitude of the vibration component. That is, when the vibration component detected by the current vibration detector 17 is large, the rotational speed correction amount is increased. When the vibration component is small, the rotational speed correction amount is reduced.

  Further, as shown in FIG. 4, the rotation speed correction amount calculation unit 18 passes the vibration component detected by the current vibration detection unit 17 through the proportional amplifier 25 and then multiplies the motor rotation speed command value by the multiplier 26. And the rotational speed correction amount may be calculated. Thereby, the magnitude of the rotational speed correction amount can be adjusted according to the magnitude of the vibration component and the rotational speed.

  Further, as shown in FIG. 5, after passing the vibration component through the proportional amplifier 25, the multiplier 26 multiplies the duty reference value calculated by the PI calculation unit 11 to calculate the rotational speed correction amount. Good. Thereby, the magnitude of the rotational speed correction amount can be adjusted according to the magnitude of the vibration component and the magnitude of the duty reference value. These methods shown in FIGS. 4 and 5 can cope with changes in the motor speed and load conditions.

  The rotation speed correction amount calculation unit 18 performs correction to increase or decrease the rotation speed command value based on the rotation speed correction amount. The corrected rotational speed command value is input to the sine wave data creation unit 14, and sine wave data corresponding to the corrected rotational speed command value is read from the sine wave data table 13.

  Here, the sine wave data table 13 stores a data string in which a sine wave waveform is output when analog values are continuously output. The reference address of this data string is updated by a predetermined number every PWM carrier cycle. If this predetermined number is large, the rotation speed is high. In other words, the motor rotation speed is determined by the update interval between the PWM carrier frequency and the reference data in the sine wave data table 13 except for the structural one of the motor 1. For example, if the number of winding phases is 3, the data of each phase may be referred to sine wave data shifted by 120 degrees in electrical angle. In each case, sine wave data may be generated by performing sine wave calculation.

  In the PWM creation unit 15 such as a PWM waveform generator, the obtained sine wave data of each phase is multiplied by the duty reference value calculated by the phase difference control, the duty width of the PWM duty is determined, and the PWM waveform signal is obtained. It is output to each drive element of the inverter circuit 2. For example, the PWM waveform generator generates a triangular wave at a PWM carrier cycle, compares the peak value of the triangular wave with the multiplied value, and outputs a High / Low signal based on the comparison result.

  Here, in a compressor used in a refrigeration / air conditioner or the like, the inside is in a high temperature state, and it is difficult to provide a position sensor for detecting the rotor position such as a Hall IC, so the motor 1 is driven without a position sensor. There is a need to. Therefore, the above inverter device is used to drive the motor of the compressor driving device. As a result, a current sensor configured to detect an alternating current such as a current sensor constituted by a coil and a Hall element and a current transformer is not required, and a position sensor is also unnecessary. And the compressor drive device provided with this inverter apparatus is mounted in a refrigerating / air-conditioning apparatus. This makes it possible to operate a refrigeration / air conditioning apparatus such as a refrigerator, a freezer, or an air conditioner.

  In addition, this invention is not limited to the said embodiment, Of course, many corrections and changes can be added to the said embodiment within the scope of the present invention.

  In the present embodiment, the U-phase current data A detects the value of the specific phase current at the time when the phase of the specific phase voltage is 90 degrees, but this is not particularly limited. For example, since the phase difference between the U-phase voltage and the U-phase current when driving the synchronous motor 1 is approximately 0 degrees, if the U-phase current is detected when the phase of the U-phase voltage is 90 degrees, the U-phase current is detected. Detection is performed near the peak value on the positive side of the current, and the U-phase current data A is naturally a large value.

  Further, if the value of the U-phase current is detected when the phase of the U-phase voltage is 270 degrees, the detection is performed near the negative peak value of the U-phase current. Therefore, the U-phase current data may be obtained by inverting the sign of the U-phase current value when the phase of the U-phase voltage is 270 degrees. Furthermore, both 90 degree and 270 degree values may be used.

  Further, in the present embodiment, the inverter device of the present invention is used for driving a motor of a compressor used in a refrigeration / air conditioning device or the like, but is not particularly limited to this. For example, you may use for electric appliances, such as a fluorescent lamp and an induction heating cooking appliance, or electric products, such as a train, an electric vehicle, and an elevator. Thereby, stable driving can be performed.

The block diagram which shows schematic structure of the inverter apparatus which concerns on this invention Waveform diagram of U-phase voltage / current of inverter circuit A block diagram showing a schematic configuration of a current vibration detection unit and a rotation speed correction amount calculation unit Block diagram showing schematic configuration of rotation speed correction amount calculation unit Block diagram showing schematic configuration of rotation speed correction amount calculation unit Block diagram showing schematic configuration of conventional inverter device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Synchronous motor 2 Inverter circuit 3 Converter circuit 4 AC power supply 5 Current sensor 6 Motor current detection amplifier part 7 Microcomputer 8 Phase difference detection part 9 Target phase difference information storage part 10 Adder 11 PI calculation part 12 Rotation speed setting part 13 Sine Wave data table 14 Sine wave data creation unit 15 PWM creation unit 16 Motor current estimation unit 17 Current vibration detection unit 18 Speed correction amount calculation unit 19 Speed correction unit 21 Current detection resistor 22 DC current detection amplifier unit 23 U-phase current data Detector 24 High-pass filter 25 Proportional amplifier 26 Multiplier A U-phase current data

Claims (5)

Includes an inverter circuit for converting DC power to AC power, and a control unit for controlling the inverter circuit by the phase difference control method, the control device includes a current detecting means for detecting a current flowing through the inverter circuit is detected A phase difference detecting means for detecting a phase difference between the AC voltage and the AC current based on the measured current, and an adjusting means for adjusting the duty reference value in accordance with an error between the detected phase difference and a target phase difference; A current vibration detecting means for detecting a vibration component of the alternating current, a frequency correction amount calculating means for calculating a frequency correction amount based on the vibration component of the alternating current, and a frequency command based on the calculated frequency correction amount. PWM signal based on the frequency correction means for correcting the value, the output waveform data corresponding to the corrected frequency command value, and the adjusted duty reference value. And a PWM signal generating means for calculating the inverter circuit is output AC voltage of a plurality of phases, the phase of one of the AC voltage of a particular phase of the plurality of phases substantially 90 degrees, or / In addition, at approximately 270 degrees, the current detecting means detects the current of the specific phase, and the control device outputs the PWM signal to the inverter circuit. The frequency correction amount calculation means increases the frequency correction amount when the vibration component detected by the current vibration detection means is large, and decreases the frequency correction amount when the vibration component is small. The inverter device according to Item 1. A synchronous motor driving inverter circuit for converting direct current power to alternating current power; and a control device for controlling the inverter circuit by a phase difference control method, wherein the control device detects direct current flowing through the inverter circuit. A detection unit; a phase difference detection unit that detects a phase difference between an AC voltage and an AC current based on the detected DC current; and a duty depending on an error between the detected phase difference and a target phase difference. Adjusting means for adjusting a reference value; current vibration detecting means for detecting a vibration component of the alternating current; and a rotational speed correction amount calculating means for calculating a rotational speed correction amount of the motor based on the vibration component of the alternating current; Motor rotational speed correction means for correcting the motor rotational speed command value based on the calculated rotational speed correction amount, and an output corresponding to the corrected motor rotational speed command value And a PWM signal generating means for calculating a PWM signal on the basis of said duty reference value adjusted with the shape data, the inverter circuit is output AC voltage of a plurality of phases, one of said plurality of phase When the phase of the AC voltage of one specific phase is approximately 90 degrees and / or approximately 270 degrees, the current detection means detects the current of the specific phase, and the control device converts the PWM signal into the inverter An inverter device that outputs to a circuit. A compressor driving device comprising the inverter device according to claim 1. A refrigeration / air-conditioning apparatus comprising the compressor driving apparatus according to claim 4.