HVAC Actuator with Capacitive Voltage Divider for Line Voltage Input

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Solution Overview

Problem

HVAC actuators require a specific input voltage of 24 VAC for proper operation, but typical building automation systems provide standard power supply line voltages of 120 VAC or 230 VAC, necessitating the use of transformers or switching power supplies, which are complex and expensive to implement.

Innovation Solution

An actuator with a housing, mechanical transducer, and a voltage divider circuit that includes capacitors and transistors to adjust capacitance, allowing it to receive a standard power supply line voltage and reduce it to a suitable voltage for the mechanical transducer, eliminating the need for external transformers or switching power supplies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a transformer or switching power supply is used to convert line voltage to 24 VAC, then the actuator can receive the required voltage, but the device complexity and cost increase

Engineering Contradiction:

Improvevoltage conversion reliabilityVSAvoidvoltage conversion equipment complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the voltage conversion function from external equipment (transformers or switching power supplies) and implements it directly within the actuator using a voltage divider circuit with capacitors and resistors. This eliminates the need for separate voltage conversion devices, reducing overall system complexity while maintaining the required 24 VAC output for the motor.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The actuator is designed to perform multiple functions: it directly accepts line voltage input, performs voltage conversion internally through the voltage divider circuit, and drives the motor. This multi-functional design eliminates the need for separate dedicated voltage conversion equipment, simplifying the overall system architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a transformer or switching power supply is used to convert line voltage to 24 VAC, then the actuator can receive the required voltage, but the implementation cost increases

Engineering Contradiction:

Improvevoltage conversion reliabilityVSAvoidimplementation cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, complex voltage conversion equipment (transformers or switching power supplies) with a simple, inexpensive voltage divider circuit composed of basic electronic components (capacitors and resistors). This significantly reduces the cost of implementation while providing the necessary voltage conversion functionality.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If the actuator accepts line voltage directly, then the installation is simplified, but the actuator components must withstand higher voltage stress

Engineering Contradiction:

Improveinstallation simplicityVSAvoidvoltage stress on components

Core Design Contradiction:

Ease of operationVSStress or pressure

Solution Approach 1:

The voltage divider circuit performs preliminary voltage reduction before the electricity reaches the motor and other sensitive components. By converting line voltage to 24 VAC in advance within the actuator, the circuit protects downstream components from high voltage stress while maintaining installation simplicity with direct line voltage connection.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the actuator to operate efficiently with standard power supply line voltages without the need for additional voltage conversion equipment, simplifying installation and reducing costs.

Implementation Method 1

The voltage divider circuit includes a first capacitor disposed in series between the input connection and the motor, a second capacitor arranged in parallel with the first capacitor between the input connection and the motor

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11609589B2HVAC actuator with automatic line voltage input selection

Publication Date: 2023.03.21 TYCO FIRE & SECURITY GMBH

AI summary

An actuator in a HVAC system includes a mechanical transducer, an input connection configured to receive a power supply line voltage, and a voltage divider circuit. The voltage divider circuit includes a first capacitor in series between the input connection and the mechanical transducer, a second capacitor in parallel with the first capacitor between the input connection and the mechanical transducer, and a first transistor operable to connect and disconnect the first capacitor and/or the second capacitor from the voltage divider circuit based on the power supply line voltage, thereby adjusting a capacitance between the input connection and the mechanical transducer. The voltage divider circuit is configured to receive the power supply line voltage from the input connection, use at least one of the first capacitor or the second capacitor to reduce the power supply line voltage to a reduced voltage, and provide the reduced voltage to the mechanical transducer.