ECM Motor Torque Correction for PSC Substitution
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Solution Overview
Problem
Permanent-split capacitor (PSC) motors in HVAC systems have low efficiency at low rotational speeds and limited torque adjustment capabilities, making them unsuitable for varying environmental conditions, especially when substituting with electronically-commutated motors (ECM) without complex reconfiguration.
Innovation Solution
A method for automatically correcting torque in ECM motors by presetting rotational speeds and torque data for both high and low gear sets, allowing the microprocessor to select the appropriate set based on the PSC motor's rated speed and environmental conditions, ensuring accurate torque control and wide application range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ECM motor is used to substitute PSC motor without changing original wire arrangement, then device complexity is reduced and ease of operation is improved, but torque control accuracy deteriorates due to factory default torque data not being suitable for all environmental conditions
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing multiple sets of torque data corresponding to different power points and rotational speeds before the motor operates in actual environmental conditions. This allows the microprocessor to select appropriate torque data based on detected conditions, eliminating the need for complex real-time torque calculation while maintaining high control accuracy.
2Ease of manufacture
If factory default torque data is used for ECM motor, then ease of manufacture is improved, but adaptability to different environmental conditions deteriorates
Solution Approach 1:
The patent applies parameter changes by storing multiple sets of torque data with different parameters (torque values at different power points and rotational speeds) in the microprocessor. The system detects actual environmental conditions and selects the appropriate parameter set, enabling the motor to adapt to varying environmental conditions while maintaining simple factory default configuration.
3Productivity
If PSC motor operates at low rotational speed, then productivity is maintained for HVAC systems, but use of energy deteriorates with efficiency dropping below 20%
Solution Approach 1:
The patent applies dynamics by enabling the ECM motor to dynamically adjust its operational parameters based on detected environmental conditions. The microprocessor selects appropriate torque data sets and adjusts motor output accordingly, allowing the motor to operate efficiently across a wide range of rotational speeds while maintaining required productivity for HVAC systems.
Data Source
AI summary
A method for correcting torque including: presetting rotational speed of each gear by corresponding gear input lines of a microprocessor; providing a mechanism to select one rotational speed set; electing N power points within a range of the rated power, acquiring a set of torque data corresponding to each set of the rotational speed at each power point, and storing a total 2×N sets of torque data; allowing the motor to enter the torque correction mode; recording a steady torque Tadj when the motor operates in a steady state; and comparing the steady torque Tadj with a maximum gear torque Tmax, and selecting the set of torque data to which T[M]max belongs when the steady torque Tadj satisfies the relationship: 110%×T[M−1]max<Tadj≦110%×T[M]max, M=1, 2, . . . , N; when M=1, T0max=0.