Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Single chip microcomputer STM32L151CCU6

GW MB10F 0.8A 1000V rectifier bridge

1 inverter control method

It is determined by the torque characteristics of the load. The mechanical load torque characteristics of the motor are determined by the following equation: P=Tn/9550 where: P: motor power KW.T: motor torque N*Mn: motor speed rpm . The relationship between the torque T and the rotational speed n can be divided into three types: 1 constant torque: a load with a constant torque when the rotational speed changes. Such as conveyor belts, cranes, etc.; 2 constant power: speed and torque are inversely proportional, but the product of the two is constant. Such as machine tool spindle; 3 variable torque: the load varies with the change of the speed according to a certain functional relationship. Such as fans, pumps and so on. When the parameter inverter control mode P1300=0, the inverter works in linear U/F mode, which can adapt to most constant torque loads. If the load is a fan, the pump class is P1300=1. In the case of variable frequency speed regulation, the system may resonate, resulting in abnormal system operation or even mechanical damage. For this reason, the inverter provides the function of jumping frequency. P1091~P1094 are used to set the jump frequency point P1101 for setting jump. Frequency bandwidth to avoid resonance. When P1300=3, the inverter works in programmable U/F control mode P1320.P1322.P1324 provides programmable frequency coordinates, P1321.P1323.P1325 provides programmable voltage coordinates, which can be specific The motor is supplied with a specific torque at a frequency to accommodate changes in the load. The vector control is based on the control idea of ​​the DC motor to control the asynchronous motor. First, the stator three-phase current is converted into the excitation current component and the armature current component by coordinates and the two quantities are respectively controlled. Therefore, the mechanical characteristics of the motor are very hard and have a high dynamic response capability. If necessary, P1300=20/21 no/with feedback vector control or P1300=22/23 no/with feedback vector torque control to meet the control accuracy of the load.

2 acceleration / deceleration time

The acceleration time is defined as the time required for the output frequency to rise from 0 to the maximum frequency, which is defined as the time it takes for the output frequency to fall from maximum to zero. The reasonable setting of the acceleration/deceleration time has a great influence on the starting and stopping of the motor and the response of the speed regulation system to the speed change. The setting of the acceleration time should limit the stator current of the motor to the rated current of the inverter without causing the overcurrent protection device to operate. The motor is in the regenerative braking state during deceleration, and the returned energy is sent back to the electrolytic capacitor of the DC bus through the freewheeling diode on the inverter, so that the voltage at both ends rises. Therefore, the deceleration time is set so that the voltage of the DC bus does not exceed the overvoltage alarm value. Calculation formula of acceleration time: ta=(Jm+Jl)*n/(9.56*(Tma-Tl)) Calculation formula of deceleration time: tb=(Jm+Jl)*n/(9.56*(Tmb-Tl)) Where: Jm: Motor inertia Jl: Load inertia. n: Motor speed Tma: Motor drive torque Tmb: Motor brake torque Tl: Load torque. It can be calculated using the formula acceleration/deceleration time, but also You can use the empirical method to calculate: First, make the drag system run at full speed (operating frequency is 50Hz), then cut off the power supply to make the drag system in free braking state, and use the stopwatch to measure the time required for its speed to drop to 0rpm. That is, the magnitude of its moment of inertia can be known. Usually the time constant can be selected as 1/5~1/3 of the free braking time. Finally, repeat the above process to observe whether the inverter has an overcurrent or overvoltage alarm, adjust the set value of the acceleration/deceleration time, and determine the optimal time constant based on the principle of no alarm.

3 setting of moment of inertia

The setting of the moment of inertia of the motor and the loaded load is often neglected. It is considered that the system can work normally as long as the acceleration/deceleration time is set correctly. In fact, if it is set improperly, the system will oscillate or the inverter will alarm. Moment of inertia formula: J=T/(dω/dt) where T: motor torque. ω: motor angular velocity. t: time. Motor and load moment of inertia acquisition method: First, let the inverter work at the appropriate frequency, such as: 5Hz~10Hz, let the motor run at no load and load, read the rated torque of the motor r0333 and the starting time of the r0345 motor. Then set the moment of inertia of the motor of parameter P0341 and the ratio of the total inertia of the P0342 drive to the motor inertia. Such a variable frequency speed control system can achieve satisfactory results.

4 quick commissioning

Quick commissioning must be performed before using the drive to drive the motor. Parameter P0010=1 (start quick commissioning); be sure to input the nameplate parameters of the motor correctly to the inverter during the commissioning process. When the rated power of the inverter is greater than the rated power of the motor it is driving, parameter P0640 (overload factor of the motor) should be set reasonably to prevent the motor from being damaged due to overload. In the vector control mode with/without sensor feedback, the automatic data detection of the motor (P1910) must be performed in a cold state (normal temperature). If the ambient temperature of the motor is different from the default value (20 °C), P0625 (the ambient temperature of the motor operation) must be set to the actual temperature value. P3900=3 (End of quick commissioning, motor calculation without I/O reset) Turn on the motor for automatic parameter detection. When the detection is completed, alarm A0541 will disappear automatically and the inverter will enter the “Ready to run” state.

5 dynamic buffer function

This function is used to define the inverter to automatically perform undervoltage compensation when the voltage drops or the instantaneous undervoltage. The motor is operated in a generator mode with appropriate frequency reduction, fed back by load energy and supplied to the frequency converter with this energy to maintain non-tripping operation. First, enable the dynamic buffer function by parameter P2800=1 and then set the value of the dynamic buffer on level P1245 according to the formula P1245[V]=P1245[%]*1.414*P0210 (supply voltage). If the setting is too large, the transmission will be disturbed. The normal operation of the device. Finally, according to the corresponding measures selected by P1256, the holding speed of the dynamic buffer is determined to be the output frequency P1257 of the inverter. Configuration of DC voltage controller P1240=2 [Maximum DC voltage controller (dynamic buffer enable)].

6 load brake

When the production machinery requires rapid deceleration or parking, the problem of the consumption of the motor regenerative braking energy is generated. The kinetic energy of the load can be reversed back to the DC bus through the freewheeling diode on the inverter after the motor is converted into electricity. Since the DC power cannot be returned to the AC grid through the AC-DC uncontrolled rectifier circuit and is only absorbed by the electrolytic capacitor on the DC bus, a "pump voltage" is formed on the electrolytic capacitor to increase the voltage of the DC bus and is too high. The DC voltage will cause the inverter to generate an overvoltage alarm. Therefore, the MM440 frequency converter provides the resistance energy braking function. The internal braking unit and the external braking resistor are used to consume the feedback energy generated during braking in the form of heat energy to ensure reliable braking of the variable frequency speed control system. . China's power grid voltage fluctuates greatly, so the brake unit cannot be malfunctioned due to the increase of the grid voltage. The brake limit voltage should be high enough. However, the inverter should be operated as close as possible to the rated voltage, which is beneficial to its safe operation. Therefore, parameter P2172 (the threshold voltage of the DC circuit) must be properly set according to the actual situation on site, and then P1240=1 (configuration of DC voltage controller: The maximum DC voltage controller enables dynamic braking). The stop period P1237 can be selected according to the load condition 1~5 (work stop period: 5%, 10%, 20%, 50%, 100%). The choice of braking resistor resistance and capacity should not be less than the value given in the selection manual, otherwise it will cause damage to the inverter and braking resistor.

7 torque boost

This function, also called torque compensation, is a method of compensating for the torque drop of the motor at low speeds due to the resistance of the stator windings of the motor, and increasing the U/F of the low frequency range. The parameter P1310 is continuously upgraded, P1311 is accelerated and the P1312 starting and lifting should be determined according to the mechanical characteristics of the load. The lifting value is the result of the combination of the lifting values ​​when P1310, P1311 and P1312 are used together, but these parameters are The priority is: P1310>P1311>P1312. P1316 (Frequency of the end point of the lift): The percentage of the end frequency of the lift relative to the rated frequency of the motor. In the parameter setting, the principle of small to large must be followed. Otherwise, the U/F which is over-raised under the light load will make the magnetic circuit of the motor be supersaturated, and the waveform of the excitation current will be distorted. Overcurrent tripping of the frequency converter caused by a sharp peak wave.

Only the correct and reasonable setting of the parameters of the frequency converter can fully exert its performance, so that the various control indicators of the variable frequency speed control system reach a satisfactory level.