Heat Pump Water Heater Control for Off-Peak Auxiliary Heating

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Solution Overview

Problem

Existing heat pump water heater control methods fail to accurately determine when to activate the electric auxiliary heater, leading to increased energy consumption or delayed temperature achievement due to changes in heating capacity and ambient temperature over time.

Innovation Solution

A control method that calculates the time period required for the water temperature to rise by a set temperature when both the heat pump host and electric auxiliary heater are turned on, and adjusts the operation of the electric auxiliary heater based on real-time calculations, ensuring the water temperature is reached within the available off-peak electricity time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the electric auxiliary heater is controlled to be turned on when the water temperature reaches the set temperature, then the control method is simple, but the heating capacity changes and environment temperature changes cause large deviations, resulting in the electric auxiliary heater being turned on in advance (increasing energy consumption) or delayed opening (so that water temperature cannot reach set temperature)

Engineering Contradiction:
Improvecontrol method simplicityVSAvoidtemperature control accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by making the control parameters adaptive rather than fixed. The system dynamically adjusts the water temperature threshold for activating the electric auxiliary heater based on ambient temperature and heat pump operating status. This allows the control strategy to adapt to changing environmental conditions and heating capacity variations, resolving the contradiction between simple control and accurate temperature management.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameter from a fixed set temperature to a dynamic threshold temperature that varies with ambient temperature and heat pump operation state. By modifying the parameter based on real-time conditions, the system achieves accurate temperature control without complex control logic, resolving the contradiction between simplicity and precision.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the electric auxiliary heater is turned on in advance to ensure water temperature reaches set temperature, then the temperature requirement is satisfied, but energy consumption increases

Engineering Contradiction:
Improvetemperature requirement satisfactionVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements feedback control by continuously monitoring water temperature, ambient temperature, and heat pump operation status. The electric auxiliary heater activation decision is based on real-time feedback from these parameters, ensuring the heater is activated only when necessary to meet temperature requirements, thereby avoiding unnecessary energy consumption while guaranteeing temperature satisfaction.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by pre-calculating the optimal activation threshold for the electric auxiliary heater based on ambient temperature and heat pump status before the heating process begins. This allows the system to prepare the optimal control strategy in advance, ensuring energy-efficient operation while meeting temperature requirements without trial-and-error adjustments.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If a simple calculation method is used to control the electric auxiliary heater, then the control logic is straightforward, but large deviations occur due to heating capacity changes and environment temperature changes

Engineering Contradiction:
Improvecontrol logic complexityVSAvoidtemperature control precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent resolves the contradiction by implementing dynamic control logic that adapts to changing conditions. The control system adjusts the electric auxiliary heater activation threshold based on ambient temperature and heat pump operation status, maintaining high temperature control precision without requiring complex control algorithms. The dynamics principle allows the system to respond to variations in heating capacity and environmental conditions while keeping the control logic relatively simple.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameter from a fixed value to a variable that depends on ambient temperature and heat pump status. This parameter change approach allows the system to maintain accurate temperature control across different operating conditions without significantly increasing control logic complexity, as the parameter adjustments follow clear conditional rules.

Inventive Principle:
Principle #35Parameter changes

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

This approach effectively saves energy while ensuring the water temperature meets user requirements by optimizing the operation of both the heat pump host and electric auxiliary heater.

Implementation Method 1

a heat pump host, an electric auxiliary heater and a water tank

Methodology Applied
Scientific EffectHeat pump: Heat Exchanger

Implementation Method 2

an electric auxiliary heater... when the first time period is less than the second pre-set time period, the electric auxiliary heater is controlled to be in the turned-on state

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3537059B1Heat pump water heater unit and control method and device thereof
Publication Date: 2020.05.27 GD MIDEA HEATING & VENTILATING EQUIP CO LTD
  • EP3537059B1 patent drawingFigure 1~2
  • EP3537059B1 patent drawingFigure 3~4
  • EP3537059B1 patent drawingFigure 5

AI summary

Disclosed are a heat pump water heater unit and a control method and device thereof. The method comprises the following steps: after receiving an off-peak electricity signal, obtaining the water temperature of a water tank (30); if the water temperature is lower than a set temperature, controlling a heat pump main machine (10) to be in a turned-on state; calculating the time needed for the water temperature of the water tank (30) to rise by a first pre-set temperature every time when the heat pump main machine (10) and an electric auxiliary heater (20) are turned on at the same time as every other first pre-set time, and recording the time as a first time; and if the first time is less than a second pre-set time, controlling the electric auxiliary heater (20) to be in a turned-on state. In the method, turning on of the electric auxiliary heater (20) is controlled according to a time that is calculated in real time and needed for the temperature of the water tank (30) to rise by a pre-set temperature every time when the heat pump main machine (10) and the electric auxiliary heater (20) are turned on at the same time, thus not only the purpose of saving energy can be achieved, but also the requirement of a user for the water temperature can be satisfied.