JP3475727B2 - Inverter device and inverter control system device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a general-purpose unitized inverter device for driving an electric motor at an arbitrary frequency, its protection, and an efficient operation control function.

[0002]

2. Description of the Related Art Conventionally, in an inverter device for driving an electric motor such as a compressor of an air conditioner at an arbitrary frequency, for example, as disclosed in JP-A-60-219996,
The inverter device is configured by separately installing a main circuit, a power transistor, and the like, and connecting them with a cable. Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 8-9653, a forward conversion section, an inverse conversion section, and a terminal block of a main circuit are integrally molded by resin molding to form a main circuit terminal block integrated module. It was downsized and reduced wiring.

As a device for protecting the switching element from heating, for example, as disclosed in Japanese Patent Laid-Open No. 7-67389, the element is detected by stopping the driving of the motor by detecting the temperature of the inverter section. Protects. Further, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-19494, a plurality of temperature sensors are provided in the vicinity of a switching element (IGBT) used in an inverter, and the temperature of the maximum value thereof is a predetermined value. When it is larger than the value, the inverter device is protected from heating by limiting the torque command to the motor.

A device for avoiding troubles due to torque shortage or overcurrent abnormality due to fluctuations in the inverter output voltage due to fluctuations in the input voltage to the inverter device is disclosed, for example, in Japanese Patent Application Laid-Open No. 61-98163. As shown, the output voltage is inversely proportional to the input DC voltage in the arithmetic circuit that compensates the voltage signal corresponding to the inverter DC input voltage to compensate the input DC voltage fluctuation. In addition, for example, JP-A-6-31178
As disclosed in Japanese Patent Publication No. 7, etc., the correction circuit corrects the frequency control signal in order to obtain an output frequency with a rated V / F ratio according to the detection output of the power supply voltage detection circuit.
The output voltage is set to a voltage determined by the rated V / F ratio.

Further, as a dead time compensating device for preventing the output voltage waveform of the inverter from being distorted by the dead time for preventing the short circuit of the switching element, for example, as disclosed in JP-A-7-7967. In addition, there has been proposed a method of performing dead time compensation by providing polarity determining means for detecting an inverter output current and determining its polarity, and applying voltage correction based on the current polarity.

In any of the methods, it is possible to realize an inverter device which is miniaturized, has high reliability, and can perform stable inverter operation in response to fluctuations in input power source voltage to the inverter device, dead time, and the like. Has an aim.

[0007]

However, in such an inverter device, only a switching element such as a power transistor and its peripheral circuit are modularized, and a control including a microcomputer for generating a PWM signal to the switching element is performed. Since the device has a separate configuration, a space for installing the control device separately is required, and a large number of connection wirings between the control device and the module are required, resulting in an increase in assembly man-hours and a decrease in reliability. It was

Further, in the proposed protection device for the switching element of the inverter device, since the inverter output frequency is limited only according to the current value of the temperature of the element detected by the thermistor, for example, the temperature of the element is decreasing. In this case, even if it is possible to cancel the frequency limitation, it is impossible to effectively use the maximum capacity of the inverter because the frequency limitation is continued.

Further, in the proposed compensator for the fluctuation of the input voltage to the inverter device, when the load of the electric motor increases, even if the output voltage compensation amount by the detected input power supply voltage is added, the load is increased. There was a phenomenon that the inverter output voltage dropped due to the voltage drop, causing insufficient torque and abnormal overcurrent.

In the proposed inverter dead time compensator, the inverter output current is detected, and the compensation amount and the compensation timing are determined according to the polarity of the current which can be seen from the inverter output current. Therefore, a highly accurate current detector is provided. There was a need. Further, since the detected current value is used, there is a problem in the control reliability when the waveform is disturbed or noise is generated.

The present invention solves the above-mentioned problems of the prior art, provides an inverter device that contributes to cost reduction and general versatility by downsizing and wire saving, and protects elements due to a rise in temperature of the inverter. It is possible to realize stable driving even with power supply voltage fluctuations and load fluctuations by shaping the output voltage waveform with a simpler configuration to achieve higher efficiency and stable operation. To aim.

[0012]

In order to achieve this object, an inverter device of the present invention includes a plurality of switching elements, a gate drive circuit, a control microcomputer, and a control power supply circuit including their connecting wirings. Integrated into a module.

[0013]

In order to solve the above-mentioned problems, the present invention integrates a plurality of switching elements, a gate drive circuit, an inverter controller, and a control power supply circuit, which constitute an apparatus, as a module. As a result, there is no need for a space to install these components individually and no wiring between them, so system miniaturization and assembly man-hours are reduced, which further improves system device reliability and costs. It can contribute to the reduction.

Further, the inverter output frequency is adjusted according to the temperature detected by the element temperature detecting means installed inside the module, and further according to the rise and fall of the element temperature, the element is heated while the continuous operation is realized. It is intended to prevent destruction.

Further, by correcting the inverter output voltage in accordance with the minimum value of the DC power supply input voltage detected by the voltage detecting means, the fluctuation of the power supply voltage and the fluctuation of the output voltage of the inverter device due to the fluctuation of the output load of the inverter device. It is possible to suppress the occurrence of torque shortage and overcurrent abnormality.

In addition, by correcting the AC output voltage waveform of the inverter according to a predetermined correction voltage and the phase to which the correction voltage is applied, stable dead time correction can be performed with a simple structure without detecting the polarity of the output current. Can be performed, and the efficiency of the inverter device can be increased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the inverter device according to the present invention will be described below with reference to the drawings.

FIG. 1 is an external view of an embodiment of an inverter device according to the present invention. The constituent elements of the inverter device 4 including the control function are an integral module integrally molded of a synthetic resin material, and a power input terminal 7, an AC output terminal 8 and a control communication terminal 9 are provided on the upper part, Inputs and outputs with external devices.

FIG. 2 is a system configuration diagram of an embodiment of the inverter device according to the present invention. After the AC power supply 1 is rectified by the rectification unit 2, it is smoothed by the smoothing capacitor 3 to obtain a DC power supply. The inverter device 4 inputs this DC power supply through the power supply input terminal 7, receives a frequency command from the system control device 5, and outputs an alternating current of the commanded frequency through the alternating current output terminal 8. The induction motor 6 is driven by the output alternating current.

The inverter device 4 includes switching elements IGBTs (insulated gate bipolar transistors) 40a to 40f necessary for converting direct current into alternating current, and flywheel diodes 41a to 41a connected in antiparallel thereto.
It is composed of 6 arms of 41f, and is composed of a three-phase inverter circuit formed by connecting these arms in a bridge between the positive electrode side and the negative electrode side of the DC bus. Phase alternating current is output.

The communication means 44 in the inverter device 4 is connected to the control communication terminal 9 from the system controller 5 installed outside.
The information of the frequency command transmitted by the serial communication via is decoded, and the information is output to the inverter controller 43. The inverter controller 43 includes the switching elements 40a to 40f necessary for outputting the alternating current of the frequency.
The ON-OFF switching signal of is output to the gate drive circuit 42. ON-OFF switching of the switching element,
General PWM (Pulse Width Modul)
However, detailed description is omitted here. The gate drive circuit 42 turns ON / OFF each switching element 1GBT according to the switching signal. As a result, the alternating current output terminal 8 outputs an alternating current that matches the commanded command frequency. Further, the power supply circuit 46 includes an inverter controller 43, a gate drive circuit 42, and a communication means 44.
The power supply for control is supplied to the.

FIG. 3 is a block diagram of an embodiment of an inverter controller in the inverter device according to the present invention. Based on the command frequency information obtained from the communication unit 44, the output voltage calculation unit 434 calculates the output voltage command according to a predetermined frequency-voltage relational expression (normally called V / F characteristic). FIG. 4 shows a typical V / F characteristic diagram.
The PWM calculation means 430 is based on the calculated command voltage and command frequency, and the switching element 40 of the PWM system.
The drive signals a to 40f are calculated and output to the gate drive circuit 42.

In FIG. 2, the element temperature detecting means 44 provided near the switching element is the switching element 40.
The temperatures of a to 40f are detected and the information is output to the inverter controller 43. The heating determination means 435 in the inverter controller 43, when the detected temperature of the element becomes a predetermined temperature set in advance, for example, 120 ° C. or higher,
The output to the gate drive circuit 42 is fixed and a signal is output to the PWM calculation means 430 so as to stop the AC output.
This prevents the switching elements 40a-40f from being destroyed by heating. At the same time, the abnormality information is output to the external system control device 5 by the communication means 44. The system control device 5 receives the abnormality information and performs abnormality processing such as entering a standby state.

Next, the operating principle of the temperature control means 436 in the inverter controller 43 according to the present invention will be described. The temperature control means 436 obtains the detected element temperature and the variation value of the temperature, and controls the AC output frequency based on the estimated time set in advance, for example, the temperature after one minute. FIG. 5 is a diagram showing a method of limiting the frequency of the AC output. When the predicted element temperature exceeds a certain temperature T0, for example, 100 ° C., the output frequency is decreased. Further, when the temperature exceeds the temperature T1, it is completely stopped.

FIG. 6 shows a temperature transition diagram showing the temperature prediction principle of the temperature control means 436. For example, the temperature one minute ago is T1
1. If the current measurement is T12, the temperature after 1 minute is estimated to be T13 by linear approximation. Based on this T13, the temperature control means 436 limits the output frequency of the AC output. When the temperature one minute before is measured as T21 and the current temperature is measured as T22, the temperature after one minute is estimated to be T23 by linear approximation. Based on T23, the temperature control means 436 limits the output frequency of the AC output, that is, stops the output. By controlling the AC output based on the temperature after a certain period of time predicted in this way, it becomes possible to quickly respond to changes in temperature and stop compared to the case where the limit is only applied from the conventional temperature value. The number of times is reduced, and the capacity of the inverter device can be utilized to the maximum.

Next, the operating principle of power supply voltage compensation in the inverter controller 43 according to the present invention will be described. The detected voltage output of the voltage detection means 45 for detecting the voltage of the DC power supply input to the inverter device 4 via the power supply input terminal 7 is input to the inverter controller 43. The minimum voltage value detecting means 432 in the inverter controller 43 detects the minimum voltage value of the voltage of the DC power supply. Voltage deviation calculation means 4
In 33, the minimum voltage value is compared with a predetermined reference voltage, and the deviation is output voltage calculation means 43.
Output to 4. The output voltage calculation means 434 sends a signal to the gate drive circuit 42 so that the AC output voltage output from the switching elements 40a to 40f becomes constant even when the voltage of the DC power supply has a deviation from the reference voltage. Adjust the output of. FIG. 7: is a figure which shows the relationship between the output voltage of this inverter apparatus 4, and an output frequency. When the induction motor 6 serving as the load of the inverter device 4 is driven, generally, in order to avoid magnetic saturation of the induction motor 6, the ratio of the output voltage to the output frequency (V / F ratio) is set to a predetermined constant value. . This is because the voltage of the DC power supply has a certain value (hereinafter,
It is a ratio designed to maximize efficiency, assuming that it is a reference voltage Vref). However, when the input of the DC power supply fluctuates, for example, when the voltage reaches Vmax,
In an ordinary inverter device, the induction motor 6 is accordingly
The output voltage to the output fluctuates, resulting in reduced efficiency and increased current. On the other hand, in the present invention, as shown in FIG. 3, for example, in the case of the frequency f1, the voltage V2 that is originally desired to be output is
Then, the correction is added by (V2-V1) so that the output is added to the gate drive circuit 42. By the way, when the load of the inverter device 4, here the load of the induction motor 6, increases, a voltage drop of the output voltage occurs accordingly. Further, at the same time, the ripple of the voltage of the DC power source rectified by the rectifying unit 2 and the smoothing capacitor 3 generally increases due to the load. FIG. 8 shows a waveform diagram of the voltage fluctuation. When correction is applied by the average voltage calculated from this voltage fluctuation, the output voltage is
The voltage is lower than the predetermined V / F straight line. In contrast,
The inverter controller 43 in the inverter device 4 according to the present invention determines the minimum value of the fluctuations in the detected voltage detected by the voltage detecting means 45 as the minimum voltage value detecting means 432.
Then, the output voltage is corrected using the minimum voltage value, and the gate drive circuit 42 is driven. As a result, the voltage is output in a form of compensating for the voltage drop due to the load, so that it is possible to drive the inverter with high efficiency while always maintaining the output voltage against the power supply voltage fluctuation and the load fluctuation.

Next, the operation principle of dead time compensation in the inverter controller 43 according to the present invention will be described.
In such a PWM inverter, an alternating current is generated by the ON-OFF operation of the upper and lower arm elements composed of the switching elements 40a to 40f, but in order to avoid a short circuit due to the simultaneous ON state of the upper and lower arm elements, respectively. A period (dead time) in which both the upper and lower arm elements are in the OFF state when the ON-OFF state is reversed is set. During this common OFF period, the follow current of the inductive load of the induction motor 6 circulates in the closed circuit composed of the inductive load and the flywheel diodes 41a to 41f, so the polarity of the output voltage is determined by the direction in which the current flows. As a result, a negative error voltage is generated when the current I <0, and a positive error voltage is generated when I> 0. These relationships are shown in FIG. This causes distortion in the inverter output voltage waveform, which reduces efficiency,
It was a cause of increased vibration.

On the other hand, the inverter device 4 of this embodiment
Then, the current detecting resistor 47 is provided on the DC bus, and the current detecting means 48 for detecting the current value consumed in the inverter device 4 from the voltage across the DC bus is provided. The compensation voltage phase calculating means 431 of the inverter controller 43 is A correction value to be added to the output voltage waveform is determined according to the detected current value, and P
The WM calculation means 430 corrects the waveform. Figure 5
FIG. 3 is a diagram showing the principle of voltage deviation generation due to dead time in waveform generation of the inverter device according to the present invention. The error voltage is a negative error voltage when the output current is positive, and a positive error voltage when the output current is negative. Since the error voltage is generated according to the current phase, the output voltage of FIG. To correct. That is, the influence of the error voltage is eliminated by adding or subtracting a predetermined correction amount at the timing of the correction phase difference corresponding to the phase difference between the voltage and the current. Here, the correction phase difference varies depending on the inverter load. Therefore, with respect to the detected current value, FIG.
The replacement correction phase difference is determined by a linear relational expression as shown in. As a result, a good voltage waveform can be obtained even if the load changes. In this method, it is not necessary to directly measure the phase of the current, and therefore C which is necessary for measuring the phase
Since the voltage waveform can be generated without using an expensive sensor such as T, it is advantageous in terms of cost and stability.

Further, the inverter controller 43 and the communication means 44 of the present invention may be realized by a dedicated hardware circuit or software using a microcomputer.

[0030]

As described above, the inverter device according to the present invention comprises the switching element, the gate drive circuit, the communication means, the inverter controller and the control power supply circuit, and the circuit board and the terminal block on which these are mounted are combined. Since it is configured as an integrated module integrally molded with resin material, there is no need for a space to install these components individually, and wiring between them is also unnecessary, which reduces the system size and the number of assembly steps. Reduction can be achieved, which in turn can contribute to increased reliability and reduced cost of system equipment.

Further, by providing the element temperature detecting means for detecting the temperature of the switching element, and having the function of limiting the AC output based on the temperature detection value and the variation value thereof, the switching device etc. can be constituted by the inverter device alone. The components are protected from heating.

Further, since the AC output voltage is corrected according to the minimum value of the detected voltage by providing the voltage detecting means for detecting the DC power source input voltage, the output voltage is always maintained even if the power source voltage fluctuates or the voltage drops due to the load. Since it is constant, efficient operation is performed and overcurrent protection is prevented from occurring.

Further, the AC output voltage waveform of the inverter is corrected according to a predetermined correction voltage and a phase for applying the correction voltage to the inverter input current, so that the polarity of the output current is not detected and the configuration is simple. The stable dead time can be corrected by
The efficiency of the inverter device can be increased.

[Brief description of drawings]

FIG. 1 is an external view of an embodiment of an inverter device according to the present invention.

FIG. 2 is a system configuration diagram of an embodiment of an inverter device according to the present invention.

FIG. 3 is a block diagram of an inverter controller of an inverter device according to the present invention.

FIG. 4 is a characteristic diagram showing a frequency / voltage relationship of an inverter device according to the present invention.

FIG. 5 is a characteristic diagram showing the relationship between the output frequency and the element temperature of the inverter device according to the present invention.

FIG. 6 is a characteristic diagram showing a prediction principle of element temperature in the inverter device according to the present invention.

FIG. 7 is a frequency / voltage characteristic diagram showing the principle of power supply voltage correction of the inverter device according to the present invention.

FIG. 8 is a characteristic diagram showing an example of fluctuations in DC input power supply voltage in the inverter device according to the present invention.

FIG. 9 is a waveform diagram showing the principle of voltage deviation due to dead time in waveform generation of the inverter device according to the present invention.

FIG. 10 is a waveform diagram showing a dead time correction method for an inverter device according to the present invention.

FIG. 11 is a characteristic diagram showing an example of the relationship between the correction phase amount calculated by the correction phase difference calculation means of the inverter device according to the present invention and the current.

[Explanation of symbols]

1 AC power supply 2 Rectifier 3 smoothing capacitors 4 Inverter device 5 System controller 6 induction motor 7 Power input terminal 8 AC output terminals 9 Control communication terminal 40a-40f switching element 41a-41f flywheel diode 42 gate drive circuit 43 Inverter controller 44 Communication means 430 PWM calculation means 431 Correction voltage phase calculation means 432 Minimum voltage value detection means 433 Voltage deviation calculation means 434 Output voltage calculation means 435 Heating determination means 436 Temperature control means

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-8-9653 (JP, A) JP-A-7-67389 (JP, A) JP-A-7-19494 (JP, A) JP-A-6- 311787 (JP, A) JP 7-7967 (JP, A) JP 9-139461 (JP, A) JP 60-219968 (JP, A) JP 61-98163 (JP, A) JP-A-63-186559 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02M 7/48 H02M 7/5387 H02P 7/63

Claims (5)

(57) [Claims] 1. A plurality of switching elements, a gate drive circuit for driving the switching elements, a communication means having a function of inputting and outputting a signal such as a command frequency to the outside, and an alternating current of a command frequency obtained by the communication means. An inverter controller that outputs a signal to the gate drive circuit for outputting a control power supply circuit that supplies a signal power supply used for at least the inverter controller, and a command frequency given with a DC power supply as an input. In the inverter device that outputs alternating current, the switching element, the gate drive circuit, the communication unit, the inverter controller, the circuit board on which the control power supply circuit is mounted, and the terminal block are integrally molded of a synthetic resin material. And an inverter controller obtained by the communication means.
Output voltage that calculates the output voltage corresponding to the command frequency
Calculates the output signal to the calculation means and the gate drive circuit
The inverter controller controls the temperature of the switching element.
Temperature value detected by the element temperature detection means that detects
And predict the temperature ahead of a predetermined time from the time fluctuation,
Based on the prediction, the frequency of the AC output to the PWM calculation means
Temperature control hand with a function to output a command to limit the wave number
Inverter apparatus comprising the stage. 2. A plurality of switching elements, the switch
Gate drive circuit for driving the ching element, external and command frequency
A communication means having a function of inputting and outputting a signal such as a number,
It outputs the alternating current of the command frequency obtained by the communication means.
For outputting a signal to the gate drive circuit for
Controller, at least the signal used for the inverter controller
Control power supply circuit that supplies the
In that outputs the alternating current of the command frequency given as input
In the burner device, the switching element and the gate
Drive circuit, the communication means, the inverter controller, front
Circuit board and terminal block on which the power supply circuit for control is mounted
However, using an integrated module integrally molded with synthetic resin material
And the inverter controller is obtained by the communication means.
Output voltage that calculates the output voltage corresponding to the command frequency
Calculates the output signal to the calculation means and the gate drive circuit
And a voltage detection means for detecting a DC power supply input voltage.
The inverter controller has a minimum value of the detected voltage.
Minimum voltage value detecting means for calculating
Calculate the deviation from the predetermined reference voltage value
A voltage deviation calculating means, wherein the output voltage calculating means is
Output voltage determined by the command frequency using the voltage deviation value
An inverter device having a function of correcting the input voltage . 3. A plurality of switching elements, the switch
Gate drive circuit for driving the ching element, external and command frequency
A communication means having a function of inputting and outputting a signal such as a number,
It outputs the alternating current of the command frequency obtained by the communication means.
For outputting a signal to the gate drive circuit for
Controller, at least the signal used for the inverter controller
Control power supply circuit that supplies the
In that outputs the alternating current of the command frequency given as input
In the burner device, the switching element and the gate
Drive circuit, the communication means, the inverter controller, front
Circuit board and terminal block on which the power supply circuit for control is mounted
However, using an integrated module integrally molded with synthetic resin material
And the inverter controller is obtained by the communication means.
Output voltage that calculates the output voltage corresponding to the command frequency
Calculates the output signal to the calculation means and the gate drive circuit
The PWM calculation means in the inverter controller is provided .
Apply a predetermined correction voltage and its correction voltage.
To correct the AC output voltage waveform according to the phase value
Inverter device characterized by having function . 4. A plurality of switching elements, the switch
Gate drive circuit for driving the ching element, external and command frequency
A communication means having a function of inputting and outputting a signal such as a number,
It outputs the alternating current of the command frequency obtained by the communication means.
For outputting a signal to the gate drive circuit for
Controller, at least the signal used for the inverter controller
No. power and a supply system patronage power circuit, the inverter device outputs an AC command given frequency as the input DC power, the switching element, the gate drive circuit, said communication means, said inverter controller, The circuit board on which the control power supply circuit is mounted and the terminal block are configured by using an integral module integrally molded with a synthetic resin material, and the inverter controller is obtained by the communication means.
Output voltage that calculates the output voltage corresponding to the command frequency
Calculates the output signal to the calculation means and the gate drive circuit
And a current detecting means for detecting a DC power supply input current.
The inverter controller, according to the detected current value
Compensation voltage phase calculation means for determining compensation voltage and phase
And the PWM calculation means has the determined correction voltage and phase
An inverter device characterized by adding a correction to an AC output voltage waveform based on the above . 5. The inverter device according to claim 1,
An inverter control system device, comprising: a system control device having a function of setting at least an inverter command frequency to the inverter device.