User Manual of EM760 High-Performance Inverter The PID output is limited. The output range of the PID module in the whole process is (F09.17, F09.16). That is, if the actual adjustment result is beyond this range, the output will be based on the boundaries. When the deviation between the PID setting and feedback is less than or equal to the deviation limit (F09.18), the PID will stop the adjustment. When the deviation between the setting and feedback is smaller, the output frequency will remain stable. This is valid for some closed-loop control applications. Ifthe input terminal function “41: process PID pause” is valid, the PID will also stop the adjustment.
Users need to use these two modes together. The differential (D) component ofthe PID regulator must not be greater than the PID differential limit (F09.19), in order to avoid the excessive deviation and output at a certain moment to cause system oscillations. If this value is set correctly, the impact of sudden interference on the system can be well suppressed. For better PID regulation, only PD or P adjustment is needed sometimes, while integral adjustment is not needed. For this reason, the EM760 series inverter has a special integral separation function.
When the deviation between the PID setting and feedback is greater than the PID integral separation threshold (F09.20), the integral separation will be valid. That is, the integral (I) adjustment of the PID regulator will be suspended. To facilitate remote control, the input terminal function “42: process PID integration pause” can be used. But if the function code setting is invalid (F09.20=100.00), the input terminal function will not work, as detailed below.
Table 6-6 Description of Integral Separation Function 93 Function code Function codename Parameter description Unit Default setting Attribute F09.16 Upper limit of PID output F09.17~+100.0 % 100.0 ● F09.17 Lower limit of PID output –100.0~F09.16 % 0.0 ● Function code Function codename Parameter description Unit Default setting Attribute F09.18 PID deviation limit 0.00-100.00 (0.00:
invalid) % 0.00 ● Function code Function codename Parameter description Unit Default setting Attribute F09.19 PID differential limit 0.00~100.00 % 5.00 ● Function code Function codename Parameter description Unit Default setting Attribute F09.20 PID integral separation threshold 0.00-100.00 (100.00% = invalid integral separation) % 100.00 ● Method Description F09.20 DI(42) F09.20: PID integral separation threshold; DI (42): Process PID integral pause 100.00% -- The integral (I) is always valid. 0.00% ~ 99.99% Depending on the relationship between |e(k)| and F09.20 as well as the status ofthe DI function Invalid If |e(k)|>F09.20, the integral separation is valid.
Valid The integral separation is valid.