Motor Control System Using Four-Pin Speed Input for Seventeen Settings
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Solution Overview
Problem
Current motor control systems for HVAC blower motors are limited to eight speed settings due to the constraints of the industry standard five pin speed connector, which only allows three pins for speed inputs.
Innovation Solution
A motor control system that utilizes industry standard control signals and a five pin speed connector to achieve at least seventeen discrete motor speed settings by reconfiguring the pins to include four speed setting input pins and one speed monitoring output pin.
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 industry standards, but the maximum number of speed settings is limited to eight
Solution Approach 1:
The patent changes the electrical parameters of the connector pins by eliminating the transmit circuitry on the fourth pin to make it an open collector, and eliminating the DC bias network on the fifth pin. This allows both pins to be used as speed setting inputs, changing the functional parameters from 3 input pins to 4 input pins, thereby enabling 17 speed settings instead of 8.
Solution Approach 2:
The patent makes the fifth pin multi-functional by removing its dedicated DC bias network function, allowing it to serve as a fourth speed setting input pin. This multi-functionality approach enables the connector to provide more speed settings without requiring additional pins or a different connector type.
2Adaptability or versatility
If the transmit circuitry on the fourth pin is eliminated to make it an open collector, then the fourth pin becomes available as a speed setting input, but the circuit complexity increases
Solution Approach 1:
The patent extracts and removes the transmit circuitry from the fourth pin, converting it from a bidirectional communication pin to a simple open collector input pin. This extraction simplifies the circuit function of that pin while enabling it to be used for speed setting, ultimately reducing overall system complexity despite the initial modification.
3Adaptability or versatility
If the DC bias network on the fifth pin is eliminated, then the fifth pin becomes available as a speed setting input, but the power supply stability may be affected
Solution Approach 1:
The patent introduces an isolated flyback power supply as an intermediary component to replace the traditional DC bias network. This isolated power supply provides the necessary voltage reference and power stability while allowing the fifth pin to be repurposed as a speed setting input, thus maintaining power supply reliability while increasing adaptability.
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.