PM motor direct power control constant-air-volume control method and HVAC system using same

Abstract

The invention discloses a PM motor direct power control constant-air-volume control method and an HVAC system using same. The control method comprises the steps of step A, receiving the target air volume IN-CFM through a starting motor; step B, obtaining a corresponding function P=f (n) according to the target air volume IN-CFM; step C, entering a direct power control constant-air-volume control mode: controlling the motor to reach a stable work point (pt, nt) along the function P=f (n) control track; step D, calculating motor real-time input power Pi according to motor operation parameters, wherein delta P=/Pt-Pi/; step E, maintaining the prior work point if delta P is smaller than the set value Pset; step F, calculating whether the speed ring operation time is reached if delta P is larger than or equal to the set value Pset, and maintaining the prior work point if the operation time is not reached; step G, entering the speed control circuit adjusting speed, that is, making pt=Pi and nt=ni, if the time is reached to achieve a novel work point (Pi, ni) on the track, and returning to the step C. The control method and the HVAC system have the advantages that the method is particularly applicable to air volume control in the steady state, the algorithm is concise, the requirement for CPU operation is not high, the cost is low, and the control accuracy is high.

Description

Technical field: [0001] The invention relates to a constant air volume control method for a variable speed motor, in particular to a constant air volume control method for direct power control of a PM motor and the HVAC system and other variable speed motor systems to which it is applied. Background technique: [0002] PM motor, the abbreviation of brushless DC permanent magnet synchronous motor, can also be called ECM motor. Because the PM motor is used in different environments, its control modes are also different. Generally, there are: constant speed control, constant torque control and constant air volume control. Air volume control is a more commonly used mode in HVAC (heating ventilation system). [0003] In the indoor ventilation ducts of domestic air conditioners, the static pressure often changes over time, for example due to dust accumulation in the ducts or clogged filters. The static pressure is also often higher than the standard static pressure of the manufac...

AI Technical Summary

Problems solved by technology

[0007] 1) Torque is a mechanical variable, it is difficult to measure and calculate it, and it will affect the control accuracy;

[0008] 2) Torque control is mostly used for dynamic control applications, but the constant air volume control is a typical steady-state control, so it is not very applicable;

[0009] 3) Torque control is more complicated in motor control. The best example is vector control to achieve a good torque control, but the accuracy of torque control in this system is limited by the cost of system hardware and software;

[0010] 4) Moment is not a characteristic parameter for consumers and government management to understand the operation of the system

[0011] In other words: torque is a mechanical variable, which is not easy to measure directly. Using torque as a variable control to achieve constant air volume control results in complex calculations and high costs, and it is difficult to connect torque with the energy-saving and environmental protection management and standards advocated by the government, which is not intuitive.

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