Mine frequency converter is the application of frequency conversion technology and microelectronics technology, by changing the motor power supply frequency to control the AC motor power control equipment. The frequency converter is mainly composed of rectification, filtering, inverter, brake unit, drive unit, and detection unit micro-processing unit. By changing the frequency of the power supply to achieve the purpose of changing the power supply voltage, according to the actual needs of the motor to provide the required power supply voltage, and thus achieve the purpose of energy saving, speed control.
China is rich in mineral resources, with particularly many minerals such as iron ore, coal mines, phosphate rock, and rare earths. With the improvement of mining mechanization, safe operation is a top priority. Mine frequency converters are an important equipment for mining electrical systems. The role is also crucial. Mine energy-saving inverters are mainly used in the application of wind turbines, transmissions, mine vehicles, hoists, mining and other equipment. In order to ensure the reliability of production, all kinds of production machinery are left with a certain margin when designing and using power drives. When the motor cannot be operated at full load, the excess torque increases the consumption of active power in addition to the power drive requirements, resulting in a waste of electrical energy.
2, the principle of Hall current sensor
The Hall current sensor is based on the magnetic balance Hall principle, that is, the closed loop principle. When the magnetic flux generated by the primary current IP is concentrated in the magnetic circuit through the high quality magnetic core, the Hall element is fixed in the air gap to detect the magnetic flux, The multi-turn coil on the magnetic core outputs a reverse compensation current for canceling the magnetic flux generated by the primary IP so that the magnetic flux in the magnetic circuit always remains zero. After special circuit processing, the output of the sensor can output current changes that accurately reflect the primary current.
3, the basic requirements of Hall current sensor
There are many domestic Hall current sensor manufacturers, in principle, there is no difference, but there are differences in the selection of components, production processes, product production process control, etc., we use the current in the mining inverter industry The JCE508-TS6 sensor is taken as an example. After being tested by the China Aerospace 513 Institute and certified by the Aerospace Institute, the basic technical parameters are as follows:
Model: JCE508-TS6
Rated measuring current IPN: 500A
Measuring range IP: 0~±800 A
Rated measurement output IM: 100mA
Supply voltage (±5%): ±15V~±18V
Conversion ratio KN: 1:5000
Current consumption IC: ≤20 (@±15V) + IS mA (output measurement current)
Accuracy X: - Accuracy XG (@ VPN, TA=+25°C): ±0.6%
- Nonlinearity εL (@ VPN, TA=+25°C): <0.1%
— Zero offset current IO: ≤±0.15mA (@+25°C)
— Zero temperature offset IOT: ≤±0.49mA (@-10°C~+70°C)
- Response time tr (@90% of VP max): ≤1us
— Operating frequency f: DC-100KHz
Withstand voltage Vd: Withstand voltage between primary circuit and secondary circuit: 6kV/50/60Hz/1min
Working temperature TA: -25?C~+80?C
Secondary side internal resistance RS: 60Ω (TA=70°C)
After testing its response time and output signal, draw its correlation curve, as follows
4, when selecting the current sensor need to pay attention to the problem
1) When selecting the sensor, pay attention to the ambient temperature of the product, industrial grade can not meet the basic requirements, must be -40 °C - 85 °C;
2) For altitude above 3,500 meters;
3) When selecting the sensor, the measuring range can be slightly larger, leaving some room for product overload. Note that the closed-loop current sensor cannot measure overload for a long time.
4) For the selection of the terminal, the special seismic type terminal for railway should be used as far as possible so as to avoid falling off by the strong earthquake when the inverter is in transit or under operation conditions;
5) Do not use the sensor under humid conditions to prevent the product from working due to condensation or moisture.
6) As the shell of the mine inverter itself belongs to the explosion-proof level, the current sensor is required to be shock-resistant, and the explosion-proof is not required to be excessive.