JP3680494B2 - Inverter device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter device having a function of monitoring output power of an inverter and output power of a motor driven by the output power.
[0002]
[Prior art]
In the inverter device, various variables used for control can be monitored on the panel surface or the like. FIG. 3 shows a configuration example of a voltage source inverter device that performs a current control and has a function of monitoring the power of the inverter and the motor.
[0003]
In the figure, 1 is a forward conversion unit that obtains direct current from a commercial power source, 2 is a smoothing capacitor, 3 is a direct conversion unit that converts direct current to alternating current, and drives an induction motor 5, and 4 is an inverter that controls the reverse conversion unit 3. It is a vector control calculation part which calculates an output current command.
[0004]
The vector control calculation unit 4 takes in the set rotation speed, excitation current setting, motor rotation speed from the speed detection circuit 11, inverter output current from the output current detection circuit 12, and DC voltage detection from the DC voltage detection circuit 14, and The output current command is calculated.
[0005]
34 is a power calculation circuit for calculating the inverter output power and the motor output power from the DC current and DC voltage from the DC current detection circuit 13 and DC voltage detection circuit 14, and the inverter loss is calculated from the input power multiplied by the DC current and DC voltage. Is used as the inverter output power, and the motor output power is obtained by subtracting the motor loss. Reference numeral 35 denotes a panel display circuit for displaying the output power of the inverter, the output power of the motor, and other monitor item data on the panel 37 surface.
[0006]
[Problems to be solved by the invention]
The conventional inverter device requires a current detector CT1 and a voltage detector PD for detecting a direct current and a direct voltage in order to display electric power. Further, in order to obtain the output power of the motor, it is necessary to take a step of obtaining the inverter output power and then subtracting the loss of the motor, and the calculation is complicated.
[0007]
The present invention has been made in view of such conventional problems, and its object is to calculate the output power of a motor or inverter without a special detector such as a DC current detector. It is to provide an inverter device that can display.
[0008]
[Means for Solving the Problems]
The present invention relates to a speed detection circuit that detects the number of revolutions of a motor driven by an inverter, an output current detection circuit that detects an output current of the inverter, and a torque current corresponding to a rating by a three-phase to two-phase conversion calculation. In an inverter device including a three-phase to two-phase conversion circuit that obtains components,
A motor output power calculation function that calculates motor output power from the torque current detection component, detected motor speed, motor rated capacity, circuit constants, and excitation current is provided, and the calculated power value is displayed as an absolute value or comparison value. It is characterized in that the monitor can be displayed on a surface or the like.
[0009]
Alternatively, the motor output power includes the motor secondary power loss from the torque current detection component, the inverter output speed obtained by adding the motor slip to the motor speed, and the motor rated capacity, circuit constant, and excitation current. And an inverter output power calculation function for calculating the inverter output power by adding the primary copper loss, mechanical loss, iron loss, and stray load loss to the motor, and calculating the output power value as an absolute value or The monitor display can be performed on the panel surface or the like with the ratio value.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
FIG. 1 shows a vector control block diagram of the inverter device according to the first embodiment. In the figure, 16 is a speed amplifier for PI calculation of the deviation between the set rotational speed and the motor rotational speed from the speed detection circuit 11, and 17 is the slip rotational speed of the motor 5 based on the torque current command from the speed amplifier 16 and the excitation current setting. , 20 is a vector control current control loop.
[0011]
The current control loop 20 adds a slip to the motor rotation speed and outputs the output rotation speed of the inverter, a frequency-phase conversion circuit 22 that converts the output rotation speed of the inverter into a phase (angular velocity), and this phase. The three-phase to two-phase conversion circuit 23 that converts the output current from the output current detector CT2 into the excitation current component and the torque current component by the rotation coordinates that rotate at, and the excitation current detected and the excitation current detected by the phase conversion A current control amplifier 25 for PI calculation of the deviation, a current control amplifier 27 for PI calculation of a deviation between the torque current command from the speed amplifier 16 and the torque current detected by phase conversion, and excitation currents from the amplifiers 25 and 27, It is composed of a two-phase to three-phase conversion circuit that converts torque current into a three-phase current command.
[0012]
Reference numeral 31 denotes known motor data such as the rated capacity, circuit constant, and excitation current of the motor 5. Reference numeral 32 denotes this known motor data, torque current detected by the three-phase to two-phase conversion circuit 23, and motor rotation from the speed detection circuit 11. A motor power calculation circuit for calculating the motor power from the number, etc., 35 is a display conversion circuit for converting the motor power calculated by the power calculation circuit 32 and the data of each monitor item input via the power calculation circuit into a panel displayable, A panel 37 displays these monitor items, and a D / A output circuit 38 outputs the motor power from the display conversion circuit 35 to the outside.
[0013]
In general, the output power Pout of the motor is obtained by the following equation.
Pout = 1.027 × torque (kg · m) × rotational speed (rpm)
On the other hand, the torque current component obtained by the three-phase to two-phase conversion of vector control is a value proportional to the actual torque generated by the motor.
[0014]
The power calculation circuit 32 calculates the output power Pout of the motor by the following equation.
Pout = coefficient × torque current detection × motor rotation speed This coefficient is calculated in advance from the known motor data 31.
[0015]
The calculated motor output power Pout is displayed on the surface of the panel 37 via the display conversion circuit 35 together with other monitor items as one type of monitor item. Further, the motor output power from the display conversion circuit 35 is analog output to the outside via the D / A output circuit 38 and monitored.
[0016]
Embodiment 2
FIG. 2 shows a vector control block diagram of the inverter device according to the first embodiment. 1 is different from that shown in FIG. 1 in that the power calculation circuit 32 in FIG. 1 calculates the output power of the motor 5, whereas the power calculation circuit 33 in FIG. This is the point where Therefore, the same components as those in FIG. 1 are denoted by the same reference numerals, and redundant description thereof is omitted.
[0017]
The inverter output power calculation circuit 33 will be described below. The power calculator 33 multiplies the inverter output rotational speed (motor rotational speed + slip) from the adder 21 and the torque current detection value from the three-phase to two-phase conversion circuit by a coefficient to obtain electric power, The inverter output power is calculated by adding the primary copper loss, iron loss, mechanical loss, and stray load loss.
[0018]
In general, the output power Pin (motor input power) of the inverter is obtained by the following equation.
Pin = Pout (motor output power) + secondary copper loss + 1 secondary copper loss + mechanical loss + stray load loss Pout = 1.027 × torque (kg · m) × (motor rotational speed + slip (rpm)) (Motor rotation speed + slip (rpm)) is always calculated by vector control.
[0019]
On the other hand, the torque current component (torque current detection) obtained by the three-phase / two-phase conversion circuit 23 of vector control is a value proportional to the actual torque generated by the motor IM.
[0020]
The power calculation circuit 33 calculates the inverter output Pin by the following equation.
Pin = coefficient × torque current detection × (motor rotation speed + slip (rpm)) + 1 copper loss + iron loss + mechanical loss + stray load loss This coefficient is calculated in advance from the known motor data 31. The primary copper loss is calculated from the primary current and the motor circuit constant, and the iron loss and mechanical loss are calculated using (motor rotation speed + slip (rpm)) as a parameter. Further, stray load loss is calculated using (motor rotation speed + slip (rpm)) and torque current component as parameters.
[0021]
The calculated inverter output power Pin is displayed on the surface of the panel 37 via the display conversion circuit 35 together with other monitor items as one type of monitor item. The motor output power from the display conversion circuit 35 is output to the outside via the D / A output circuit 38 and monitored.
[0022]
【The invention's effect】
Since this invention is comprised as mentioned above, there exists an effect described below.
[0023]
(1) It is possible to perform power calculation only with a detection system circuit necessary for performing vector control without attaching a special detector such as a direct current detector for power calculation.
[0024]
(2) Since the power can be monitored by the inverter, the user can manage the power.
[Brief description of the drawings]
FIG. 1 is a vector control block diagram of an inverter device according to a first embodiment;
FIG. 2 is a vector control block diagram of the inverter device according to the second embodiment;
FIG. 3 is a block diagram showing a configuration of an inverter device according to a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Forward conversion part 3 ... Reverse conversion part 4 ... Vector control calculating part 5 ... Induction motor 11 ... Speed detection circuit 12 ... Output current detection circuit 13 ... DC current detection circuit 14 ... DC voltage detection circuit 16 ... Speed amplifier 17 ... Slip Arithmetic circuit 20 ... current control loop 22 ... frequency-phase conversion circuit 23 ... three-phase to two-phase conversion circuit 25, 26 ... current control amplifier 28 ... two-phase to three-phase conversion circuit 31 ... known motor data such as motor capacity and constants 32, 33, 34 ... power calculation circuit 35 ... display conversion circuit 37 ... display panel 38 ... D / A output circuit PD ... DC voltage detector CT1 ... DC current detector CT2 ... output current detector PP ... encoder R1 ... charge limit Current resistance S1 ... Resistance short-circuit switch MC ... Electromagnetic switch.

Claims (3)

A speed detection circuit that detects the number of revolutions of the motor driven by the inverter, an output current detection circuit that detects the output current of the inverter, and a torque current component with respect to the rating is obtained by performing a three-phase to two-phase conversion operation on the detected output current. In the inverter device provided with the phase-2 phase conversion circuit,
A motor output power calculation function is provided to calculate the motor output power from the torque current detection component and the detected motor speed, motor rated capacity, circuit constant, and excitation current,
An inverter device characterized in that the calculated power value can be displayed on the panel surface as an absolute value or a comparison value. A speed detection circuit that detects the number of revolutions of the motor driven by the inverter, an output current detection circuit that detects the output current of the inverter, and a three-phase circuit that obtains a torque current component with respect to the rating by performing a three-phase to two-phase operation on the detected output current -In an inverter device provided with a 2-phase conversion circuit,
From the torque current detection component, the inverter output speed obtained by adding the motor slip to the motor speed, the motor rated capacity, circuit constants, and excitation current, the motor output power including the secondary copper loss is calculated. And add an inverter output power calculation function to calculate the inverter output power by adding the primary copper loss, mechanical loss, iron loss, stray load loss of the motor to them,
An inverter device characterized in that the calculated output power value can be displayed on the panel surface as an absolute value or a ratio value. In claim 1 or 2,
An inverter device having a D / A conversion function of outputting the calculated absolute value or ratio value of electric power as an analog quantity to the outside.

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