Blower Motor Speed Control Using a Five-Pin Connector
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Solution Overview
Problem
The industry standard five pin speed connector limits the number of discrete speed settings for blower motors in HVAC systems to eight, as only three pins are available for speed inputs, restricting the ability to provide enhanced comfort and control for end-users and increasing product diversity for manufacturers.
Innovation Solution
A motor control system that utilizes industry standard control signals and the five pin speed connector to achieve at least seventeen discrete speed settings by repurposing pins, including using one speed monitoring output pin and four speed setting input pins, with at least one input pin decoding two binary and two frequency states, and implementing modifications such as eliminating certain circuitry and optocouplers to liberate additional pins for speed settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the industry standard five pin speed connector is used with three pins for speed inputs, then the system maintains compatibility with standard connectors, but the number of discrete speed settings is limited to eight
Solution Approach 1:
The patent applies multi-functionality by making the fifth pin serve dual purposes: it can be used as a speed setting input pin (pin 5) or as an additional binary state input (pin 6) depending on the configuration. This allows the same physical pin to expand the speed settings capability from 8 to 17 discrete speeds without requiring a different connector type, thereby resolving the contradiction between versatility and device complexity
Solution Approach 2:
The patent changes the electrical parameter configuration of the connector pins by eliminating the DC bias network on the fifth pin and repurposing it as a speed input. This parameter change allows the system to decode 17 speed settings using the same five-pin physical connector, achieving higher versatility without increasing physical complexity
2Adaptability or versatility
If additional speed settings are implemented beyond eight, then user comfort and airflow control are improved, but the number of input pins required increases beyond three
Solution Approach 1:
The patent makes the speed monitoring output pin (pin 1) multi-functional by allowing it to serve both as a speed monitoring output and as an additional speed setting input (pin 6). This resolves the contradiction by providing 17 speed settings without requiring additional dedicated input pins, maintaining ease of operation with the standard five-pin connector
3Reliability
If the fifth pin is used for DC bias network, then the transmission circuit has proper voltage reference, but the pin cannot be used for additional speed settings
Solution Approach 1:
The patent extracts the DC bias network functionality from the fifth pin by eliminating the bias network circuitry. This extraction frees up the fifth pin to be used as a speed setting input, resolving the contradiction between transmission circuit stability and speed settings versatility. The system maintains reliability through alternative voltage reference arrangements while gaining the ability to provide 17 discrete speed settings
Data Source
AI summary
A motor control system providing at least seventeen speed settings using industry standard control signals and an industry standard five pin speed connector. One speed monitoring pin transmits an output signal for monitoring the speed of the motor, and four speed setting pins receive input signals for setting the speed. One of the speed setting pins receives and decodes two binary states and two frequency states, thereby providing a total of thirty-two speed settings. A non-regulated isolated winding is added to an internal transformer to provide an internal isolated flyback power supply for the motor, thereby liberating a pin on the industry standard five pin speed connector to provide the fourth speed setting input pin. Transmission circuitry is associated with the speed monitoring pin, and the non-regulated isolated winding is used to provide a direct current bias to the transmission circuitry.