Page 7 - EE Times Europe Magazine – June 2024

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Unlocking Efficiency: Exploring the Advantages of Heat Pumps

to water, which can be used for heating spaces through radiators and as the ratio of the heat energy transferred by the heat pump to the
underfloor heating or even for hot water supply. energy input required to achieve that transfer, typically in the form of
Heat pumps operate on the simple principle of moving the heat electrical energy. Figure 2 shows a heat pump that uses only 1 kW of
from one location to another. In winter, a heat pump extracts heat electricity to achieve a CoP of 4 kW. The heat pump is very efficient, as
from the outside air and transfers it indoors to heat the desired space. 3 kW of energy has been sourced from the air.
For cooling purposes in summer, the process reverses; the heat pump Heat pumps have a high CoP. At a high level, you get more heat
removes heat from the inside and releases it outside. energy out of the system than the electrical energy you put into it. The
higher the CoP, the more energy-efficient the device is. Another way
Inverters based on wide-bandgap devices like to look at it, the higher the CoP, the more money you can save on your
heating or air conditioning bill.
silicon carbide or gallium nitride offer higher DRIVING A HEAT-PUMP INVERTER
efficiency due to lower switching losses and Heat pumps use a motor drive that operates a compressor to con-

can operate at higher frequencies. vert electricity into heat in the vapor-compression cycle. Driving a
heat-pump compressor efficiently involves a combination of proper
compressor selection, efficient motor control, advanced inverter tech-
nology and optimized system design. The goal is to achieve high energy
This transfer of heat is made possible through the refrigeration efficiency, reliability and performance that contributes to the overall
cycle. A heat pump uses a refrigerant to absorb heat at a low tem- CoP of the heat pump.
perature and release it at a higher temperature. The system consists Whether the heat-pump system is a monoblock or split between
of an indoor unit, an outdoor unit and a network of pipes that carry outdoor and indoor units, the objective is to drive the compressor, fan
the refrigerant between the two. The compressor, part of the outdoor and circulation pump efficiently. Selecting the right topology, such as
unit, plays a key role in pressurizing the refrigerant to facilitate totem-pole and Vienna rectifier for the power-factor-correction and
heat transfer. All components—circulation pump, fan and compres- inverter stages, especially for three-phase systems, results in a high-
sor—are operated by a motor drive to increase energy efficiency and efficiency inverter design.
reduce losses.
WIDE-BANDGAP DEVICES IN HEAT PUMPS
COEFFICIENT OF PERFORMANCE Inverters based on wide-bandgap devices like silicon carbide (SiC) or
The attractiveness of the heat pump is that it creates more heating gallium nitride (GaN) offer higher efficiency due to lower switching
energy than it takes. The coefficient of performance (CoP) for a heat losses and can operate at higher frequencies. This leads to smaller and
pump is a measure of its efficiency in transferring heat. It is defined more efficient inverters.

Figure 2: Heat pump that uses only 1 kW of electricity to achieve a CoP of 4 kW

www.eetimes.eu | JUNE 2024