JPH08140388A - Common power supply inverter controller - Google Patents

Abstract

PURPOSE: To enhance the operational efficiency by operating an acceleration/ deceleration rate based on an output from a power control circuit, a machine side limit value of load, an inertial moment of the load, and a torque limit value of the system while taking account of priority. CONSTITUTION: A plurality of inverters 10 are connected through a smoothing capacitor 13 with a common wire 8 in order to drive individual motors 1. Speeds ω1 , ωn of individual motors 1 are detected through a speed detector 2 and fed to a load torque operating circuit 3 and a motor output capacity operating circuit 6. Capacities PM1 , PMn to be outputted from the motors 1 are then operated at a motor output capacity operating circuit 6 and the total sum ΣPM is determined at a total output capacity operating circuit 7. When the total output capacity ΣPM of the motors 1 exceeds the allowable output value of a common power supply 8, a power limit circuit 9 delivers a power limit command PL to an acceleration/deceleration rate operating circuit 11. Since a quick acceleration/deceleration can be realized in low speed region and selective acceleration/deceleration can be realized in high speed region, the operational efficiency is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common power supply inverter control device having a plurality of common power supply type inverter devices.

[0002]

2. Description of the Related Art In a common power supply type inverter device, when operating a motor load with a plurality of inverter devices, the capacity of the common power supply is such that the load of the connected inverter is accelerated to the maximum speed in the minimum time or from the maximum speed. It was selected based on the peak value required for deceleration, but during normal operation only a smaller output than the rated capacity was required.

[0003]

As described above, the capacity of the common power source is uneconomical because it is selected at the peak value required during acceleration / deceleration. Also, in order to reduce the capacity of the common power source, the acceleration / deceleration rate must be lengthened, and in equipment with a large load of moment of inertia, the acceleration / deceleration time becomes longer and operating efficiency declines. When the capacity of the common power supply is reduced, the common power supply may overload and break down during sudden acceleration / deceleration, causing a full load stop.

The present invention relates to a common power supply type inverter device in which a plurality of inverter devices operate a motor load,
A speed detector that detects the speed of each motor, a load torque calculation circuit that calculates the torque of the load corresponding to that speed from the speed detected by the speed detector, a preset moment of inertia of the load, and an acceleration / deceleration rate. Acceleration / deceleration torque calculation circuit for calculating the torque required during acceleration / deceleration, a motor torque calculation circuit for calculating the torque to be output by each electric motor from the load torque and the acceleration / deceleration torque, the speed of the electric motor and the output of the electric motor. A motor output capacity calculation circuit that calculates the capacity to be output of each motor from the power torque,
The total output capacity calculation circuit that calculates the output capacity of all the motors by summing the output capacity of each motor and the output capacity of all the motors and the allowable output capacity of the common power supply are compared. A power limiting circuit for limiting the output, the output of the power limiting circuit, the preset torque limit value of the machine for each load, the load inertia moment, and the torque limit value of each inverter. It is an object of the present invention to provide a common power supply inverter control device that includes an acceleration / deceleration rate calculation circuit that calculates the acceleration / deceleration rate of 1 above, solves the above-mentioned problems, and improves operating efficiency.

[0005]

A common power supply inverter control device of the present invention detects a plurality of inverter devices connected to a common power supply to drive a motor load, and rotation speeds of the motors driven by the inverter device. Necessary for acceleration / deceleration of the motor based on the speed detector and the load torque calculation circuit that calculates the load torque corresponding to the rotation speed from the rotation speed detected by the speed detector, and the preset moment of inertia of the load and acceleration / deceleration rate. Acceleration / deceleration torque calculation circuit that calculates various acceleration / deceleration torques, motor torque calculation circuit that calculates the output torque of the motor from the load torque and acceleration / deceleration torque, and the output capacity of the motor from the rotation speed of the motor and the output torque of the motor And a total output capacity calculation circuit for calculating the total output capacity of all the motors by summing up the respective output capacities, A power limiting circuit that limits the output of the common power source by comparing the output capacity with the allowable output capacity of the common power source, the output of the power limiting circuit, the preset machine side limit value of each load, the load inertia moment, and the inverter. An acceleration / deceleration rate calculation circuit for calculating the acceleration / deceleration rate of each inverter device in consideration of the priority order from the torque limit value of the device.

[0006]

In the common power supply inverter control device of the present invention, a plurality of inverter devices are connected to a common power source to drive the electric motor load, and the rotation speed of the electric motor operated by the inverter device is detected by the speed detector. The load torque corresponding to the rotation speed is calculated from the rotation speed detected by the speed detector, and the acceleration / deceleration torque required during acceleration / deceleration of the motor is calculated from the preset moment of inertia of the load and the acceleration / deceleration rate to obtain the load torque. The output torque of the electric motor is calculated from the acceleration and deceleration torque and the output capacity of the electric motor is calculated from the rotation speed of the electric motor and the output torque of the electric motor. The output of the common power supply is limited by comparing the output capacity with the allowable output capacity of the common power supply, and the output of the power limiting circuit and the preset machine-side limit value of each load are compared. Characterized in that in consideration of the priority from the torque limit value of the load inertia and the inverter device calculates a deceleration rate of each of the inverter device.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the common power supply inverter control device of the present invention will be described. In FIG. 1, the inverter device 1
0 is connected to the common power source 8 to drive the electric motor 1. The speed detector 2 is attached to the electric motor 1, and the inverter device 1
The rotation speed of the electric motor 1 driven at 0 is detected. The load torque calculation circuit 3 is connected to the speed detector 2 and obtains a load torque corresponding to the rotation speed from the rotation speed detected by the speed detector 2. The acceleration / deceleration torque calculation circuit 4 calculates the acceleration / deceleration torque required during acceleration / deceleration of the electric motor 1 based on the inertia moment of the load preset in the inertia moment setting circuit 15 and the acceleration / deceleration rate output from the acceleration / deceleration rate circuit 12. The motor torque calculation circuit 5 is connected to the acceleration / deceleration torque calculation circuit 4, and the motor output capacity calculation circuit 6 for calculating the output torque of the motor 1 from the load torque and the acceleration / deceleration torque is the motor torque calculation circuit 5 and the speed detector 2.
The output capacity of the electric motor is calculated from the rotational speed of the electric motor and the output torque of the electric motor. The total output capacity calculation circuit 7 is connected to the electric motor output capacity calculation circuit 6 and sums the output capacities of the electric motor output capacity calculation circuits 6 to calculate the total output capacity of all electric motors. The power limiting circuit 9 is connected to the total output capacity calculating circuit 7 and compares the total output capacity from the total output capacity calculating circuit 7 with the allowable output capacity of the common power supply to limit the output of the common power supply. The acceleration / deceleration rate calculation circuit 11 is connected to the power limiting circuit 9, the machine side torque limiting circuit 16, the inverter side torque limiting circuit 17 and the moment of inertia setting circuit 15, and is output in advance by the output of the power limiting circuit 9 and the machine side torque limiting circuit 16. Each inverter is set in consideration of the priority from the set machine side control limit value of each load, the inverter device torque limit value from the inverter side torque limit circuit 17, and the load inertia moment obtained by the inertia moment setting circuit 15. The acceleration / deceleration rate of the device 10 is calculated.

The speed of the electric motor 1 is detected by the speed detector 2 attached to the electric motor 1. The load torque is obtained by the load torque calculation circuit from the relationship between the detected speed, the preset speed, and the load torque.

The acceleration / deceleration torque required for acceleration / deceleration is calculated by the acceleration / deceleration torque calculation circuit as follows based on the inertia moment of the load and the acceleration / deceleration rate set in advance.

J · dω / dt = T _a Here, J is the moment of inertia of the load, dω / dt is the rate of change in angular velocity (acceleration / deceleration rate), and T _a is the acceleration / deceleration torque.

From the load torque and the acceleration / deceleration torque, the torque to be output by the electric motor is obtained from the electric motor torque calculation circuit.

T _M = T _L + T _a where T _M is the torque to be output from the electric motor, T _L is the load torque, and T _a is the acceleration / deceleration torque.

Next, the capacity to be output by the electric motor is obtained from the torque to be output by the electric motor and the speed of the electric motor by the electric motor output capacity calculation circuit as follows.

T _M · ω = P _M where P _M is the capacity of the electric motor to be output, T _M is the torque to be output of the electric motor, and ω is the angular velocity.

Further, the capacity to be output by the common power source is obtained by summing up the capacities to be output by the respective electric motors.

[0016]

[Equation 1] Here, P _C is the capacity that the common power source should output, P _Mi is the capacity that each electric motor should output, and n is the number of electric motors.

In the power limiting circuit, the capacity to be output by the common power source is compared with the allowable output value of the common power source, and if the capacity to be output by the common power source exceeds the allowable output value, the power limiting command is the acceleration / deceleration rate. It is output to the arithmetic circuit 11.

When the acceleration / deceleration rate calculation circuit 11 does not output a power limit command, the acceleration / deceleration time is determined from the preset machine side torque limit value of each load, the torque limit value of the inverter device 10 and the inertia moment of the load. The acceleration / deceleration rate is calculated so that

[0019] T _LL <when the _{T LI dω / dt = J /} (T LL -T L) T LL> when the _{T LI dω / dt = J /} (T LL -T L) However T _LL load of machinery Side torque limit value, T _LL is the torque limit value of the inverter device, J is the moment of inertia of the load, T
_L is a load torque, and dω / dt is an angular velocity change rate (acceleration / deceleration rate).

When the power limit command is output, the acceleration / deceleration rate is determined in order from the load having the largest inertia moment. First, the acceleration / deceleration rate of the load having the maximum moment of inertia is determined so as not to exceed the allowable output value of the common power source and minimize the acceleration / deceleration time. Also at this time, the machine side torque limit value of the load and the inverter device torque limit value are also taken into consideration.

Next, the acceleration / deceleration rate is similarly determined for the load having the second largest moment of inertia, but the allowable output value of the common power source is calculated as a value obtained by subtracting the output capacity required for the first load. The acceleration / deceleration rate is sequentially obtained in the same manner. Each calculated acceleration / deceleration rate is output from the acceleration / deceleration rate calculation circuit and input to each acceleration / deceleration rate command circuit, and each inverter device is controlled according to the value.

When all loads need to be accelerated / decelerated in conjunction with each other, a common acceleration / deceleration rate that does not exceed the allowable output value of the common power source is calculated.

After understanding the above operation, it will be explained again with reference to FIG.

In a common power supply type inverter device 10 in which a plurality of inverter devices operate a motor load, a speed detector 2 for detecting the speed of each electric motor 1 and a speed ω ₁ , detected by the speed detector 2, A load torque calculation circuit 3 for _obtaining load torques T _L1 and T _Ln corresponding to the speed ω from ω _n, and a torque T required during acceleration / deceleration from a preset load inertia moment J and acceleration / deceleration rate dω / dt.
_an acceleration / deceleration torque calculation circuit 4 for calculating _a1 and T _an, and a motor torque calculation circuit 5 for calculating torques T _M1 and T _Mn to be output by each electric motor 1 from the load torque T _L and the acceleration / deceleration torque T _a , A motor output capacity calculation circuit 6 for calculating the capacities P _M1 and P _Mn to be output from each motor 1 from the speeds ω ₁ and ω _n of the motor 1 and the torques T _M1 and T _Mn to be output from the motor 1.
When the electric machine and the total output capacity calculation circuit 7 which outputs the total capacity P _M should computing the capacity .SIGMA.P _M to be output of all the motor 1 of 1, the common power source and an output to be capacity .SIGMA.P _M of all motor 1 8 Of the power limiting circuit 9 for limiting the output of the common power source 8 by comparing the allowable output capacities of the power limiting circuit 9 and the output P _L of the power limiting circuit 9, the preset torque limit value T _LL on the machine side of each load, and the moment of inertia of the load. Each inverter 1 in consideration of the priority from J and the torque limit value T _{LI of} each inverter 10
1 shows a controller for a common power supply inverter having a plurality of inverters 10 each having an acceleration / deceleration rate calculation circuit 11 for calculating an acceleration / deceleration rate dω / dt of 0.

A plurality of inverter devices 10 are connected to a common power source 8 via a smoothing capacitor 13, and each motor 1
Are driving. The speeds ω ₁ and ω _n of the respective electric motors 1 are detected by the speed detector 2. Detected speed ω ₁ ,
ω _n is input to the load torque calculation circuit 3 and the motor output capacity calculation circuit 6. Load torque computing circuit the load torque TL ₁ to the preset 3, T _Ln and speed ω _1, ω _n is the load torque T _L is calculated from the relationship. Preset load inertia moments J ₁ and J _n and acceleration / deceleration rate dω ₁ / d
Acceleration / deceleration torque T required for acceleration / deceleration based on t and dω _n / dt
_a1 and T _an are calculated by the acceleration / deceleration torque calculation circuit 4. Based on the load torque T _L and the acceleration / deceleration torque T _a1 and T _an , the torque T _M1 and T _Mn to be output from the electric motor 1 is the electric motor torque calculation circuit 5
Is calculated in. Torques T _M1 and T to be output from the electric motor 1
_{From the Mn} and the speeds ω ₁ and ω _n , the capacities P _M1 and P _Mn to be output from the electric motor 1 are calculated by the electric motor output capacity calculation circuit 6. The sum ΣP _{M of the} capacities P _M1 and P _Mn to be output from each electric motor 1 is obtained by the total output capacity computing circuit 7.

[0026] Compared the power limiting circuit 9 the sum .SIGMA.P _M capacity P _M to be output of the electric motor 1 and the allowable output value of the common power supply 8, a power limiting command P _L is deceleration rate calculation exceed the allowable output value It is output to the circuit 11.

When the power limit command P _L is not input, the acceleration / deceleration rate calculation circuit 11 sets the preset machine side torque limit value T _{LL of} each load, the torque limit value T _{LI of the} inverter 10 and the load. Acceleration / deceleration rate dω / dt so that the acceleration / deceleration time is minimized from the inertia moments J ₁ and J _{n of}
Is calculated. When the power limit command P _L is input, the acceleration / deceleration rates dω ₁ / dt and dω _n / dt are calculated in descending order of the load inertia moments J ₁ and J _n . The calculated acceleration / deceleration rates dω ₁ / dt and dω _n / dt are output to the acceleration / deceleration rate command circuit 12, and the inverter 10 is controlled by the values.

[0028]

According to the present invention, rapid acceleration / deceleration is possible in the low speed range where the required power is small, and acceleration / deceleration can be selectively performed in the high speed range where the required power is large. It is possible to realize an economical common power supply without doing so, and it is possible to prevent problems such as full load stop due to overload of the common power supply.

Further, the common power source can be efficiently used in the entire speed range.

[Brief description of drawings]

FIG. 1 is a control block configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Motor 2 Speed Detector 3 Load Torque Calculation Circuit 4 Acceleration / Deceleration Torque Calculation Circuit 5 Electric Motor Torque Calculation Circuit 6 Motor Output Capacity Calculation Circuit 7 Total Output Capacity Calculation Circuit 8 Common Power Supply 9 Power Limiting Circuit 10 Inverter Device 11 Acceleration / Deceleration Rate Calculation Circuit

Claims (1)

[Claims] 1. A plurality of inverter devices connected to a common power source to drive a motor load, and a speed detector for detecting a rotation speed of a motor operated by the inverter device.
A load torque calculation circuit for obtaining a load torque corresponding to the rotation speed from the rotation speed detected by the speed detector, and an acceleration / deceleration required for acceleration / deceleration of the electric motor from a preset load inertia moment and acceleration / deceleration rate. An acceleration / deceleration torque calculation circuit for calculating a deceleration torque, a motor torque calculation circuit for calculating an output torque of the electric motor from the load torque and the acceleration / deceleration torque, and the electric motor based on a rotation speed of the electric motor and an output torque of the electric motor. The motor output capacity calculation circuit for calculating the output capacity of the motor, the total output capacity calculation circuit for calculating the total output capacity of all the motors by summing up the output capacities of each, and the total output capacity and the allowable output capacity of the common power supply. A power limiting circuit that limits the output of the common power supply by comparison, and the output of this power limiting circuit and the preset machine side limit value of each load Moment of inertia and the inverter from the torque limit value of the device in consideration of priorities and deceleration rate computing circuit for computing the deceleration rate of each of the inverter apparatus, comprises a common power inverter control device.