The silicon carbide rod uses the customer's telephone to consult the heating principle of the silicon carbide rod controller, so today I will explain the heating principle of the silicon carbide rod controller.

   In engineering practice, the most widely used regulator control laws are proportional control, integral control and differential control, referred to as PID control, also known as PID regulation. Since the advent of the PID controller, it has been

It has a history of nearly 70 years. Because of its simple structure, good stability, reliable operation and convenient adjustment, it has become one of the main technologies of industrial control.

controller

When the structure and parameters of the controlled object cannot be fully grasped or an accurate mathematical model cannot be obtained, the structure and parameters of the system controller must be determined through experience and on-site debugging. At this time, PID control technology is the most convenient. That is to say, when we do not fully understand a system and the controlled object, or when the system parameters cannot be measured effectively, the PID control technology is most suitable. In practical applications, PID control also has PI and PD control. The PID controller is a controller that controls the system error through proportional, integral, and differential calculation of control quantities.

1. Proportional control (P):

Proportional control is one of the most commonly used control methods. For example, we keep the heater thermostat at 100 degrees. When heating starts, it is far from the target temperature. At this time, we usually increase the heating to make the temperature rise rapidly. When the temperature exceeds 100 degrees, we turn off the output. Usually we use this method. Function

E(t) = SP-y(t) -

U(t) = e(t) * P

SP - Settings

E(t) - Error value

Y(t) - Feedback value

U(t) - Output value

P-proportionality coefficient

The proportional control method can make the controlled object with small lag meet the control requirements, but many controlled objects have lag.

That is to say, if the temperature is set at 200 degrees, when using proportional control, if P is selected relatively large, when the temperature reaches 200 degrees, the output is 0, and the temperature will continue to climb upward, for example, 230 degrees, when the temperature exceeds 200 degrees Too much and it will start to fall back, even though the output starts to generate heat. But the temperature will still drop to a certain temperature, then stop falling, rise again, say, to 170 degrees, and finally the whole system will stabilize and oscillate within a certain range.

Proportional control can be used if the amplitude of oscillation is allowed, such as the control of household appliances.

2. Proportional integral control (PI):

The presence of integral is an improvement over the differential or oscillatory characteristics of proportional control. Proportional control is usually used, that is, PI control.

There are many kinds of formulas, but most of them are indistinguishable. The standard formula is as follows:

U(t) = Kp*e(t) +Ki_e(t) +u0

U(t) - output

Kp-Scale amplification factor

Ki-Integral amplification factor

E(t) - Error

U0 - reference value of control quantity (baseline deviation)

As you can see, the integral term is a cumulative value of historical errors. If we use proportional control alone, we know that either we cannot reach the setpoint or we can oscillate. Using the integral term can solve the problem that the static error cannot reach the set value. For example, when a PI control is used in a control, if there is a static error. The cumulative error value of the integral term increases as the cumulative value multiplied by Ki accounts for a larger proportion of the output. The larger the cumulative error value is, the larger the output u(t) is, and the purpose of eliminating static error is finally achieved.

The above is the relevant consultation about the controller organized by the editor. Through the sharing of this content, everyone has a certain understanding of the controller. If you want to know more about the market information of the controller, you can contact our company. salespersons, or go to the field to discuss and exchange.