WO2018094552A1

WO2018094552A1 - A thermostat apparatus and a temperature regulation system

Info

Publication number: WO2018094552A1
Application number: PCT/CN2016/106746
Authority: WO
Inventors: Chun Tak Jacky LAI; Yau Chung John Chan; Shun Cheung Ryan YEUNG; Chung Fai Norman Tse; Shu Hung Henry Chung
Original assignee: City University Of Hong Kong; Jacky Instruments Limited
Priority date: 2016-11-22
Filing date: 2016-11-22
Publication date: 2018-05-31
Also published as: CN110431358A; CN110431358B

Abstract

A thermostat apparatus (200) for use with or as part of a temperature regulation system (100), the temperature regulation system (100) includes at least a multi speed motor (152) coupled to a fan (154), wherein the thermostat apparatus (200) comprises: a motor driver (220) electrically coupled to a power supply (210) and configured to receive a power supply signal from the power supply (210); a switch assembly (280) disposed between the motor driver (220) and the multi speed motor (152), the switch assembly (280) is electrically coupled to the motor driver (220) and electrically coupled to a potential divider (153), wherein the potential divider (153) is electrically coupled to the multi speed motor (152); and a speed controller (230) in electronic communication with the motor driver (220); wherein the speed controller (230) is configured to provide a reference signal to the motor driver (220), the reference signal is based on a difference between a reference speed and a measured speed of the multi speed motor (152), the reference speed is based on a difference between a measured temperature and a reference temperature, the reference temperature is set by a user, the motor driver (220) is configured to generate a drive signal based on the received reference signal, the motor driver (220) is further configured to transmit the drive signal to the multi speed motor (152) via the switch assembly (280), the speed controller (230) is further configured to generate and transmit a switch control signal to the switch assembly (280), and the switch assembly (280) is configured to connect one of a plurality of connections of the potential divider (153).

Description

A THERMOSTAT APPARATUS AND A TEMPERATURE REGULATION SYSTEM

TECHNICAL FIELD

The present disclosure relates to a thermostat apparatus and a temperature regulation system including a thermostat apparatus, and in particular the present disclosure relates to a thermostat apparatus with an improved output control arrangement.

BACKGROUND

Temperature regulation systems are used commonly for regulating the temperature of a space such as for example a room, an office, a house and so on. Heating, ventilation and cooling (HVAC) systems are commonly used systems as temperature regulating systems. A thermostat apparatus is used to sense the thermal conditions of a space and provide a necessary signal to an air conditioning unit that is part of the HVAC system. Thermostats are in communication with one or more components of a HVAC system or a temperature regulation system.

Thermostats are generally are connected to and control the operation of fans or heating elements or heaters or valves within a temperature regulation system, such as for example an HVAC system. Typically, a thermostat senses the temperature of a space, and controls one or more components of an HVAC system to maintain the temperature of the space as close to a reference temperature as possible. The reference temperature is a temperature set point that is received from a user or remote operator. Thermostats include various sensors and typically include bimetallic strips or thermistors. Typical thermostats are binary type controllers that are configured to control various components, such as fans or heating elements, to switch between an ON and OFF position. Such thermostats provide a limited operating range for the control of components in a temperature regulation system.

Line voltages are another example of thermostats that are used commonly in temperature regulation systems. In line voltage thermostats the system power is directly switched by the thermostat. Line voltage thermostats can be used to control motors that drive fans in a temperature regulation system. The fan, in a temperature regulation system, is selectively turned on or off by the thermostat depending on the temperature of the space in relation to a reference temperature. The speed of the fan is controlled using a switch.

In prior art systems, an inductive potential divider or a capacitive potential divider arrangement is used to control the fan speed.

An inductive potential divider is widely used to change the fan speed, especially for a multi speed motor that drives the fan. The voltage and current applied to the driving winding are varied by changing the connections with the thermostat. A thermostat including an inductive potential divider includes multiple input taps and a switch that can connect to one of multiple input taps. Each tap connects to an inductor. For example in a thermostat with three taps, one tap connects the supply to two inductors and the motor, a second tap connects the supply to one inductor and the motor and the third tap connects the supply directly to the motor. The fan speed is controlled by connecting to one of the taps. The inductors reduce the voltage received by the motor by acting as an impedance to the AC voltage received from the power supply.

Using only an inductive potential divider has a number of disadvantages. An inductive potential divider arrangement can only adjust the fan speed in a discrete manner and limits the choices of speeds to discrete speeds relating to the number of taps. In the three tap example the fan speed can only be low, medium or high. The size of the motor used with an inductive divider is large and bulky because of the inductive divider arrangement being integrated into the motor housing. Further the inductive divider arrangement introduces parasitic elements resulting in power quality degradation. The parasitic elements can cause motor temperature rise, introduce conduction and magnetic core losses thus shorten the lifespan of the motor. Finally such an arrangement introduces additional losses and can increase the cost of the motor design.

A capacitive potential divider may be used in prior art thermostats to control the fan speed for a multi speed motor that drives the fan. The fan speed is varied by connecting the power source between a series of capacitors of predetermined value, which effectively limits the electrical power supplied to the motor. The capacitors are placed inside the motor housing or may be placed in the thermostat. The thermostat including a capacitive potential divider includes multiple input taps and includes a switch that can connect to one of the plurality of input taps. Each tap connects to a capacitor or across a capacitor. For example in a thermostat with three taps, one tap connects the supply to two capacitors, a second tap connects the supply to one capacitor and the third tap connects the supply directly to the motor. The fan speed is controlled by connecting to one of the taps. The capacitors reduce the voltage received by the motor by functioning as an impedance to the AC voltage received from the power supply.

Using only a capacitive potential divider also presents a number of drawbacks. One drawback is that the capacitance values have to be carefully matched with the impedance of the motor to allow for efficient operation and control of the motor. Practically this is challenging to do as the manufacturer of a fan or motor rarely provides impedance information thus making capacitance matching difficult and often unfeasible. Further the capacitors can introduce parasitic elements that can result in losses. Capacitive potential dividers also only for discrete speed adjustment of the fan based on the configuration of taps that are selected.

It is an object of the present disclosure to provide a thermostat apparatus and/or a temperature regulation system, which will substantially ameliorate at least some of the deficiencies

It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms a part of the common general knowledge in the art.

SUMMARY OF THE INVENTION

In accordance with a first aspect, the present disclosure provides a thermostat apparatus for use with or as part of a temperature regulation system, the temperature regulation system including at least a multi speed motor coupled to a fan, wherein the thermostat apparatus comprises；

a motor driver being electrically coupled to a power supply and configured to receive a power supply signal from the power supply,

a switch assembly disposed between the motor driver and the multi speed motor, the switch assembly being electrically coupled to the motor driver and electrically coupled to a potential divider, wherein the potential divider being electrically coupled to the multi speed motor,

a speed controller in electronic communication with the motor driver, the speed controller configured to provide a reference signal to the motor driver, the reference signal being based on a difference between a reference speed and a measured speed of the multi speed motor,

the reference speed being based on the difference between a measured temperature and a reference temperature, and the reference temperature being set by a user,

the motor driver being configured to generate the drive signal based on the received reference signal, the motor driver further configured to transmit the drive signal to the multi speed motor via the switch assembly,

wherein the speed controller further configured to generate and transmit a switch control signal to the switch assembly, and；

the switch assembly configured to connect one of a plurality of connections of the potential divider.

In an embodiment the drive signal that is provided to the multi speed motor comprises a drive voltage and a drive frequency, the reference signal comprises a reference voltage and a reference frequency, and wherein the drive voltage being adjusted based on the reference voltage.

In an embodiment the speed of the multi speed motor being based on the drive voltage and the connection between the switch assembly and the one of the plurality of connections of the potential divider.

In an embodiment the speed controller comprises a comparator configured to determine a speed error, wherein the speed error being the difference between reference speed and the measured speed, and the speed controller configured to generate the reference signal based on the speed error.

In an embodiment the speed controller comprises a reference signal generator, the reference signal generator being configured to generate a reference signal based on the speed error, the reference signal generator generating a reference voltage and the reference frequency being a nominal frequency.

In an embodiment the speed controller comprises a switch controller that is configured to generate the switch control signal, the switch control signal being based on the difference between the reference speed and the measured speed and/or the reference signal.

In an embodiment the potential divider comprises one or more impedances and the plurality of connections, each connection corresponding to one of the impedances.

In an embodiment the potential divider comprises three impedances and three connections, each connection corresponding to each impedance, and wherein the impedances are inductors or resistors or windings of the multi speed motor.

In an embodiment one of the connections relates to a high supply voltage, one connection relates to a medium supply voltage and one connection relates to a low supply voltage, the switch assembly comprising an electrically actuable moveable member, the moveable member connectable to one of the high, medium or low supply voltage connections based on the switch control signal.

In an embodiment the potential divider affects the drive voltage based on the position of the moveable member of the switch,

wherein in a high supply voltage connection the switch assembly coupling the motor driver to the multi speed motor through one impedance,

wherein in a medium voltage connection the switch assembly coupling the motor driver being to the multi speed motor through more impedances than the high voltage connection, but less impedances than the low voltage connection, and；

wherein in a low voltage connection the switch assembly coupling the motor driver to the multi speed motor through more impedances than the medium voltage connection and the high voltage connection.

In an embodiment the switch assembly comprises a plurality of double throw relays, the number of relays in the switch assembly being equal to one less than the number of impedances in the potential divider or one less than the number of windings of the multi speed motor.

In an embodiment the switch assembly comprises a relay controller that is configured to generate and transmit a relay control signal to each of the plurality of double throw relays to actuate the relay between a first position and a second position, the relay control signal being generated based on switch control signal.

In an embodiment the thermostat apparatus comprises a speed sensor in electronic communication with the speed controller, the speed sensor configured to determine and transmit a measured speed to the speed controller, and wherein the measured speed corresponds to a motor speed and wherein the speed sensor is a tachometer that is configured to measure instantaneous motor speed.

In an embodiment the thermostat apparatus comprises a temperature controller, the temperature being configured to generate the reference speed and transmit the reference speed to the speed controller, wherein the reference speed is generated based on a difference between a reference temperature and a measured temperature,

wherein the temperature controller is adapted to receive a reference temperature from a user interface, the temperature controller is further adapted to receive a measured temperature from a temperature sensor, the measured temperature relates to the temperature of a space,

wherein the temperature controller is configured to increase the magnitude of the reference speed if the measured temperature is greater than the reference temperature； and；

wherein the temperature controller is configured to decrease the magnitude of the reference speed if the measured temperature is less than the reference temperature.

In accordance with a second aspect, the present disclosure provides a temperature regulation system for regulating the temperature of a space, the temperature regulation system comprising: a fan assembly including a fan and a multi speed motor, the multi speed motor being connected to the fan and configured to drive the fan at a speed,

a thermostat apparatus in electrical communication with the multi speed motor and configured to control the multi speed motor,

the thermostat apparatus further comprising；

In an embodiment the temperature regulation system further comprises

a reservoir adapted to hold a thermal exchange material,

a heat exchanger in fluid communication with the reservoir, wherein the heat exchanger is adapted to receive the thermal exchange material from the reservoir,

a valve located between the heat exchanger and the reservoir, the valve being selectively moveable between an open position and a closed position, wherein in an open position the valve allows passage of the thermal exchange material from the reservoir to the heat exchanger and in a closed position the valve preventing the passage of the thermal exchange material from the reservoir to the heat exchanger,

a temperature sensor located within the space and configured to measure the temperature of the space to generate a measured temperature, the temperature sensor being in electrical communication with the thermostat apparatus to transmit the measured temperature to the thermostat apparatus,

a user interface adapted to communicate with a user and wherein the user interface is further adapted to receive a reference temperature from the user.

In an embodiment, the user interface may be arranged to be operated by any user, including a room user, a remote user or in the cases of large buildings, a building manager or operator. The user interface may also be autonomously controlled by a computing system to regular temperature of a room or building.

In an embodiment the drive signal that is provided to the multi speed motor comprises a drive voltage and a drive frequency, the reference signal comprises a reference voltage and a reference frequency, and wherein the drive voltage being adjusted based on the reference voltage and wherein the speed of the multi speed motor being based on the drive voltage and the connection between the switch assembly and the one of the plurality of connections of the potential divider.

In an embodiment the speed controller comprises a comparator configured to determine a speed error, wherein the speed error being the difference between reference speed and the measured speed, and the speed controller configured to generate the reference signal based on the speed error,

the speed controller further comprises a reference signal generator, the reference signal generator being configured to generate a reference signal based on the speed error, the reference signal generator generating a reference voltage and the reference frequency being a nominal frequency.

In accordance with a third aspect, the present disclosure provides a method for regulating a temperature of a space using a temperature regulation system, wherein the temperature regulation system comprises a thermostat apparatus in electronic communication with a multi speed motor, wherein the method for regulating a temperature comprises the steps of:

receiving a measured temperature from a temperature sensor,

receiving a reference temperature

determining a difference between the reference temperature and the measured temperature,

determining a reference speed based on the difference between the reference temperature and the measured temperature,

determining a measured speed of the multi speed motor from a speed sensor,

determining a difference between the reference speed and the measured speed,

generating a reference signal based on the difference between the reference speed and the measured speed,

generating a drive signal based on the reference signal,

generate and transmit a switch control signal to a switch assembly, the switch control signal causing the switch assembly to connect to one of a plurality of connections of a potential divider, transmit the drive signal to the multi speed motor via the switch assembly.

The term speed as used herein relates to rotational speed. The following specification will use the terms speed and rotational speed interchangeably. Rotational speed as defined herein relates to the rotational speed of the rotor that is part of the motor. The term motor speed is used to denote rotor speed i.e. rotational speed of the rotor and drive shaft of the motor. This may be equal to the rotational speed of the fan. The terms motor speed and rotor speed are interchangeably used in the following specification and mean the same.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:

Figure 1 illustrates a temperature regulation system including a thermostat apparatus.

Figure 2a illustrates an electrical schematic of the thermostat apparatus that can be used with or as part of the temperature regulation system.

Figure 2b is a logic block diagram showing an example of the internal logic to control an embodiment of the cooling and heating valves of the temperature regulation system of Figure 1.

Figure 3 illustrates an electrical schematic of the motor driver that forms part of the thermostat apparatus.

Figure 4 illustrates an electrical schematic of the speed controller when the speed controller is functioning in a variable voltage constant frequency mode.

Figure 5 illustrates an electrical schematic of the temperature controller that forms part of the thermostat apparatus.

Figure 6 shows an example hysteresis band and a plot of the measured temperature within a hysteresis band.

Figure 7a illustrates an electrical schematic of the switch assembly in a HIGH position.

Figure 7b illustrates an electrical schematic of a switch assembly in a MED position.

Figure 7c illustrates an electrical schematic of a switch assembly in a LOW position.

Figure 8 shows an embodiment of a method of operation of a switch controller that is part of the speed controller.

Figure 9 illustrates an embodiment of the switch assembly that is part of the thermostat apparatus. Figure 10 shows a truth table that is implemented in a relay controller that forms part of the switch assembly.

Figure 11 illustrates an embodiment of method of calibrating the speed sensor.

Figure 12 shows an embodiment of a method of regulating the temperature of a space using a temperature regulation system that also includes a thermostat apparatus.

Figure 13 shows another embodiment of a method of regulating the temperature of a space using a temperature regulation system that also includes a thermostat apparatus.

Figure 14 illustrates a graph of back EMF generated by a motor and square pulses generated at each zero crossing of the back EMF signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present disclosure relates to a thermostat apparatus that is used as part of a temperature regulation system, such as for example a heating, ventilation and air conditioning system (aHVAC system) . The thermostat apparatus is used as part of the HVAC system and is configured to control one or more components of the HVAC system to regulate temperature in a space. For example the thermostat apparatus is used as part of a HVAC system to regulate the temperature of a room, a house, a factory, a manufacturing space, a laboratory, a medical clinic, a hospital ward, an office, a building floor, a shop or any other such space.

The present disclosure relates to a thermostat apparatus with an improved output control arrangement. In particular the thermostat apparatus of the present disclosure is configured to provide a wider range of speed selection for controlling a multi speed motor as part of a temperature regulation system. The thermostat apparatus of the present disclosure is configured for use with or as part of a temperature regulation system that is configured to control the temperature of a space, the temperature regulation system comprising a multi speed motor, a heat exchanger and a thermostat apparatus. The thermostat apparatus controls at least the multi speed motor to control the temperature of the space. The thermostat apparatus provides an expanded speed control range for the multi speed motor.

Referring to Figure 1 there is illustrated a temperature regulation system 100 that is used to regulate the temperature of a space 102. The system 100 includes an inlet duct 110 and an outlet duct 112 that in fluid communication with each other. Return air 114 is sucked in through the inlet duct 110 and supply air 116 is delivered via the outlet duct. Air within the space 102 can be circulated through the temperature regulation system 100 to maintain the temperature of the space 102 at a selected or predetermined reference temperature.

The temperature regulation system 100 further comprises a passage 120 that is positioned between the inlet duct 110 and the outlet duct 112. The passage 120 includes an inlet opening 122 in fluid communication with the inlet duct 110 and an outlet opening 124 in fluid communication with the outlet duct 112. The passage 120 may include an inlet manifold (not illustrated) that is positioned at the inlet opening that can connect to multiple inlet ducts. The passage 120 may further include an outlet manifold (not illustrated) that is positioned at the outlet opening 124 that can connect to multiple outlet ducts.

Referring again to Figure 1, the temperature regulation system 100 further includes a heat exchanger 130, a reservoir 140 that is configured to hold a thermal exchange material and a fan assembly 150. As shown in Figure 1 the heat exchanger 130 and the fan assembly 150 are positioned within the passage 120 such that air from the inlet opening 122 passes over and across the heat exchanger 130 and into the fan assembly 150. The heat exchanger 130 is configured to facilitate thermal energy exchange between the air and the heat exchanger 130. In the illustrated embodiment of Figure 1, the heat exchanger 130 is configured to cool the air pass across the heat exchanger 130. The fan assembly 150 is configured to impart a driving pressure onto the air received into the fan assembly 150. The fan assembly 150 is configured to push cooled air out of the outlet duct 112 as supply air 116.

As shown in Figure 1, the temperature regulation system 100 comprises a filter 160 that is disposed downstream of the inlet duct 110 and downstream of the inlet opening 122. The filter 160 is located upstream of the heat exchanger130 and the fan assembly 150. The filter 160 is a dust filter such as for example a HEPA filter. The filter 160 is configured to filter out particulate matter such as dust, air borne particles, hair and other particulate matter from the air passing through the passage 120. The filter 160 prevents or reduces the amount of particulate matter such that the fan assembly 150 does not get blocked or cease up during operation.

The heat exchanger 130 will be described in more detail now. The heat exchanger130, as shown in Figure 1, is a shell and tube type heat exchanger. The heat exchanger 130 comprises a hollow shell 132 that houses a coiled tube 134. The coiled tube 134 is a single tube that includes a plurality of U bends, as seen in Figure 1. In the illustrated embodiment the tube 134 comprises seven U bends but alternatively may include any suitable number of U bends depending on the size of heat exchanger required and the amount of heat exchange required. The coiled tube 134, and in particular the section of the coiled tube 134 that includes the U bends defines a heat transfer area 139. In cooling mode, the air passing through the passage 120 is cooled as is passes through the heat transfer area 139 i.e. as the air passes across the U bends in the coiled tube 134. In heating mode, if the heat exchange is warmer than the air, then the air passing through the passage 120 is heated.

The heat exchanger 130 further comprises an inlet tube section 136 and an outlet tube section 138. The inlet tube section 136 is connected to and in fluid communication with the coiled tube 134 at one end and enters the shell 132 from one side. The outlet tube section 138 is connected to and in fluid communication with the coiled tube 134 at an opposing end to the inlet tube section 136. The outlet tube section 138 exits the shell 132 from an opposing side to the inlet of the inlet tube section 136. As shown in Figure 1, the inlet tube section 136 and outlet tube section 138 may be integrally formed with the coiled tube section 134. Alternatively the inlet tube section 136 and the outlet tube section 138 may be separate tubes that are connectable to the coiled tube 134.

The heat exchanger 130 is in fluid communication with the reservoir 140. The inlet tube section 136 and the outlet tube section 138 connect to the reservoir. A fluid pathway is formed between the reservoir 140 to the coiled tube 134 via the inlet tube section 136 and the outlet tube section 138. The reservoir is adapted to receive and hold a thermal exchange material. In the illustrated embodiment of Figure 1, the thermal exchange material is chilled water. The chilled water is transferred into the thermal exchanger 130 and cools the air passing across the thermal exchanger 130. The chilled water is introduced into the coiled tube 134 via the inlet tube section 136 and returned to the reservoir 140 via the outlet tube section 138. The chilled water flows through the inlet tube section 136, the coiled tube 134, the outlet tube section 138 and back to the reservoir 140.

The system 100 includes a at least one valve 170 that is located on the inlet tube section 136. For the purposes of describing the preferred embodiments of this invention, the term valve 170, unless otherwise specifically referred to as the cooling valve 170c or heating valve 170h will include either the cooling valve 170c or heating valve 170h or both valves 170c, 170h as some systems 100 will be implemented to provide cooling, heating or both. Essentially, the valves 170 which may include both the cooling or heating valves 170c, 170h operate in a similar manner so as to provide different functionalities of heating or cooling as desired by the user via the controller.

In this example embodiment as shown in Figure 1, this system has two valves, with a cooling valve, 170c and a heating valve 172h being located between the heat exchanger 130 and the reservoir 140. Generally, the two valves 170 are each selectively moveable between an open position and a closed position. When the valve 170 is in an open position the valve 170 allows passage of the thermal exchange material from the reservoir 140 to the heat exchanger 130. In a closed position the valve 170 prevents the passage of the thermal exchange material from the reservoir 140 to the thermal exchanger 130. In the illustrated example the valve 170 is an electronically controlled valve such as a solenoid valve. The valve 170 receives an actuation signal that includes state information including an ON state and an OFF state, the ON state causes the valve to move to an open position and the OFF state causes the valve to move to a closed position. In an open position the solenoid valve allows chilled water to flow from the reservoir 140 to the heat exchanger 130 and in a closed position the valve 170 prevents flow of the chilled water from the reservoir 140 to the heat exchanger 130. In turn, the reservoir 140, or also referred to as a plant which may deliver thermal exchange material, when the reservoir 140 is delivering heat exchange materials to the coil. The heat exchange materials may effectively operate as cooling agent or heating agent. As outlined in this example system 100, the two control valves 170 exist in the system to control which kind of heat exchange material passing through the coil, namely cooling valve 170c and heating valve 170h. The net result is that if it is the cooling valve 170c that is opened, then heat exchange material flows through the coil, and thus air passing through the heat exchanger is cooled. If the heating valve 170h is opened, the air passing through the heat exchanger is heated.

In one example, where the system 100 includes more than one valve 170, such as the system 100 as shown in Figure 1, where there are two valves 170, made up by the presence of a cooling valve 170c and a heating valve 170h, the two valves 170 may be controlled in accordance with the logic diagram as shown in Figure 2b where the Switch (S_value) and Cooling/Heating selection can be set by a user or program, with these signals being processed by the logic arrangement so as to control the valves 170 to provide the desired heating or cooling.

The fan assembly 150 will be described in more detail with respect to Figure 1. The fan assembly 150 comprises a motor 152 and a fan 154. The motor 152 is electrically connected to the fan 154 and mechanically coupled to the fan 154 by a drive shaft. The drive shaft is coupled to a rotor that is in the motor 152. The motor 152 is configured to drive the fan 154 at a speed. The motor 152 is a multi-speed motor and the motor 152 is configured to rotate the fan at a selected rotational speed. The multi speed motor 154 is a rotational motor that generates a rotational or rotary movement. Speed as defined within this specification refers to rotational speed. The fan 154 includes a plurality of fins. The fan 154 may include any suitable number of fins to create a driving pressure to push the air out of the outlet duct 112. The operation of the motor 152 is controlled by the thermostat apparatus 200.

The motor 152 may comprise a potential divider 153 (i.e. a voltage divider) . Alternatively the thermostat apparatus 200 may comprise the potential divider. The potential divider 153 includes a plurality of components arranged in series with multiple connections between the components. The components are impedances. In the illustrated embodiment the potential divider comprises a plurality of inductors. The potential divider 153 further comprises a plurality of connections arranged between the impedances (i.e. inductors) to allow the thermostat apparatus to vary the numbers of impedances in the divider circuit. The potential divider circuit 153 allows discrete speed variation of the multi speed motor 152.

The multi speed motor 152 further comprises a plurality of windings. The windings comprise electrical coils that are wound to form an inductor. The windings of the multi speed motor 152 are arranged to form the potential divider 153, as shown in Figure 2a. Each winding of the multi speed motor 152 acts as an impedance of the potential divider. Figure 2a shows an embodiment of the motor with three

windings

153a, 153b, 153c. The motor 152 is a three speed motor therefore it comprises three windings. The windings are arranged as a potential divider to selectively control the amount of voltage and/or power received at the motor. Further details of the motor and its functions will be described later.

The temperature regulation system 100 comprises a thermostat apparatus 200 that is in electrical communication with the multi speed motor 152 and is configured to control the multi speed motor 152. The thermostat apparatus 200 is in electrical communication with the multi speed motor 152 and the valve 170. The thermostat apparatus 200 is configured to control the operation of multi speed motor 152 and the valve 170 to try and maintain a reference temperature in the space 102.

Referring to Figure 1, the thermostat apparatus 200 includes a user interface 202. The user interface 202 is located within the space 102 and accessible by a user or person. In one example thermostat apparatus 200 may be disposed on a wall in the space or on any other suitable structure such that a user can access the thermostat apparatus 200. The user interface 202 allows a user to set a reference temperature for the space 102. The reference temperature is the temperature that is desired in the space 102. The user interface 202 is configured to be in electrical communication with one or more components of the thermostat apparatus 200.

Referring to Figures 2a to 13 the thermostat apparatus 200 will be described in more detail. Figure 2a shows an electrical schematic of the thermostat apparatus 200. The thermostat apparatus 200 is configured for use with or as part of the temperature regulation system 100. The thermostat apparatus 200 is electrically coupled to a power supply 210 is an AC power supply. In the illustrated embodiment the power supply 210 is a mains power supply that generates an alternating current and an alternating voltage. The voltage is generated at a specified frequency. The power supply provides a power signal that comprises at least a voltage and a frequency.

The thermostat apparatus 200 is a line voltage thermostat. The thermostat apparatus 200 is connected directly to the mains power. The thermostat apparatus 200 is configured to generate a drive signal by modulating the power supply signal received from the power supply 210. The thermostat apparatus is configured to generate a drive signal at a varying voltage with a constant frequency. The thermostat apparatus 200 provides an improved output to allow for an increased speed range for the multi speed motor 152.

Referring to Figure 2a, the thermostat apparatus 200 further comprises a motor driver 220. The motor driver 220 generates and provides a drive signal to the multi speed motor 152. The thermostat apparatus 200 further comprises a speed controller 230 in electronic communication with the motor driver 220. The speed controller 230 provides a reference signal to the motor driver 220. The reference signal is based on a difference between a reference speed and a measured speed of the multi speed motor 152. The drive signal is generated, by the motor driver, based on the reference signal from the speed controller 230.

The thermostat apparatus further comprises a speed sensor 240 in electronic communication with the speed controller. The speed sensor 240 determines the speed of the motor and provides feedback of the motor speed (labelled ω) to the speed controller 230. A temperature controller 250 is electronic communication with the speed controller 230. The temperature controller 250 provides a reference speed (labelled ω_ref) to the speed controller 230. The temperature controller 250 provides an actuation signal (labelled S_valve) to operate the valve 170, and in systems with both heating and cooling, then depending on the desired temperature, the temperature controller may also provide a heating or cooling signal in addition to the actuation signal so as to operate the cooling valve 170c or heating valve 170h. The drive signal is used to vary the speed (i.e. rotational speed) of the multi speed motor 152. The components of the thermostat apparatus 200 described are disposed in a casing 260. The casing 260 may be a metal or plastic casing. The details of the thermostat apparatus 200 are described in more detail below.

As stated above the motor driver 220 generates a drive signal based on the reference signal from the speed controller 230. The drive signal comprises a driving voltage and a driving frequency. The reference signal generated by the speed controller 230 comprises a reference voltage (labelled V_ref) and a reference frequency (labelled f_ref) . The driving voltage or the driving frequency or both are adjusted based on the reference signal. In particular the driving voltage is adjusted based on the received reference voltage V_ref and the driving frequency is adjusted based on the reference frequency f_ref. Specifically the motor driver is configured to provide a drive signal in a varying voltage with a constant frequency (VVCF mode) .

The motor driver 220 is electrically coupled to the power supply 210 and configured to receive a power signal from the power supply 210. The motor driver 220 is directly connected to the multi speed motor such that all the voltage of the drive signal is delivered to the multi speed motor 152. The motor driver 220 may include an inverter, cycloconverter, or a power flow controller. The motor driver 220 includes components depending on the cost of hardware implementation, power rating, heat dissipation, magnitude or noise and size constraints. Details of the motor driver 220 will be described later with respect to Figure 3.

The thermostat apparatus 200 further comprises a variable output arrangement that is configured to vary the drive voltage supplied to the multi speed motor by selectively connecting to various connections in the potential divider. In the illustrated embodiment the variable output arrangement is a switch assembly 280 that can connect to one of a plurality of connections of the potential divider 153. The switch assembly 280 connects the motor driver output to the potential divider 153 and motor 152. The voltage supplied to the motor is increased or reduced depending on connection between the switch assembly 280 and the potential divider 153.

Referring to Figure 2a, the switch assembly 280 comprises a moveable switch member 282. The moveable member is an electrically actuable member that is configured to move in response to a received electrical signal. As shown in Figure 2a, the switch assembly 280 is in electrical communication with the speed controller 230. The speed controller 230 is configured to control the operation of switch assembly 280 and in particular control the position of the moveable switch member 282. The speed controller 230 is configured to transmit a control signal i.e. an electrical signal that comprises position information causing the moveable switch member 282 to move to an appropriate position such that the member connects to one of the connections of the potential divider 153.

As shown in Figure 2a, the potential divider 153 comprises three impedances. Each impedance is formed by a winding of the multi speed motor. The multi speed motor 152 comprises three

windings

153a, 153b, 153c. The switch member 282 is connectable to any one of the three

windings

153a, 153b, 153c. The control signal from the speed controller 230 moves the switch assembly 280, to cause movement of the switch member 282 to connect to any one of the

windings

153a, 153b, 153c. The switch member 282 is a physical switch that is electrically actuable. The switch assembly can any suitable switch assembly such as an electromagnetic switch or a toggle switch etc. Alternatively the switch assembly 282 may be a digital electronics based switch assembly, such as for example comprising logic gates or other suitable digital circuitry.

The speed of the multi speed motor 152 is based on the voltage received at the multi speed motor 152 from the potential divider 153. The potential divider 153 receives a drive voltage from the motor driver 220. The drive voltage is reduced by the potential divider 153 depending on the position of the switch 282 in relation to the

windings

153a, 153b, 153c. The switch 282 is moveable between a HIGH, MID or LOW position. The HIGH position corresponds to a high speed of the motor 152, a MID position corresponds to a medium or mid speed of the motor 152 and a LOW position corresponds to a low speed of the motor 152. In a HIGH position the switch 282 connects to a single winding 153a. In the MID position the switch connects to two

windings

153a, 153b. In the LOW position the switch 282 connects to three

windings

153a, 153b and 153c. In the HIGH position the driving voltage from the motor driver 220, is delivered directly to the motor winding 153a. In the MID position the driving voltage is passed across two

windings

153a, 153b. Finally in the LOW position the driving voltage is passed across three

windings

153a, 153b and 153c. Further details of the switch assembly will be described later.

Referring to Figure 3 there is illustrated an embodiment of the motor driver 220. Figure 3 shows a schematic diagram of the motor driver 220. The motor driver 220 includes a switching network 221 that includes power electronics such as Triacs, Diodes, Power MOSFETS etc. These components are organized together to form an electrical switching network 221. The switching network effectively acts as an actuator to shape the motor voltage and its corresponding frequency. The switching network 221 is operated based on a gate signal that is generated by a driver feedback controller 224. The gate signals define the switching pattern of the switching network 221, such that the switching network outputs the appropriate driving signal including a driving voltage and a driving frequency. The motor driver 220 functions only in a variable voltage constant frequency (VVCF) mode. The motor driver 220 generates a drive signal that includes a driving voltage, which is variable, and a constant driving frequency.

The motor driver 220 further includes a passive network comprising passive elements such as capacitors and/or inductors. The passive network is connected to the switching network. The passive network acts as a low pass filter to smooth out pulsating voltage and current as well as improving the EMI performance. The passive network also reduces voltage spikes that may induced due to the coils in the motor 152.

The motor driver 220 comprises a command signal generator 222. The command signal generator 222 comprises appropriate circuitry to generate a command signal (labelled V_cmd (t)) that is provided to a voltage comparator 223. The command signal is generated based on a received reference signal, and specifically based on a received reference voltage V_ref and a reference frequency f_ref. The reference signal is generated by the speed controller 230 and provided to the command signal generator 222. In the illustrated embodiment the motor driver 220 is equipped with or implemented with a power factor corrector. The command signal is generated based on:

f_N is the nominal frequency of the motor in Hz

V_N is the nominal RMS voltage of the motor in VoltIn VVCF mode, the motor control engine only varies the motor voltage

V_Motor, while the frequency of the motor f_Motor is kept as the same as thenominal frequency of the motor f_N.

The power factor corrector may be implemented as a hardware module comprising a plurality of electronic circuit components. The electronic circuit components may be analog or digital electronic components. Alternatively the power factor corrector may be implemented as a software module within the motor driver 220. The power factor corrector is used to correct for power factors due to the supply being an alternating power (i.e. alternating current and voltage) , which alternates at a particular frequency.

As shown in Figure 3, the motor driver 220 further comprises a motor driver comparator 223. The motor driver comparator 223 generates an error signal ε_v that is provided to a driver feedback controller 224. The error signal is the difference between the command voltage signal V_cmd (t) and a sampled motor voltage V_motor. The driver feedback controller 224 comprises appropriate circuitry and the driver feedback controller 224 is configured to suppress the error signal to zero. The driver feedback controller 224 outputs an appropriate switching pattern i.e. gate signals that are delivered to the switching network 221. The driver feedback controller 224 may be a PID controller or any other suitable controller. The feedback controller 224 can be implemented using suitable analog or digital components.

The thermostat apparatus 200 further comprises a speed controller 230 in electronic communication with the motor driver 220, as illustrated in Figure 2a. The speed controller 230 is configured to provide a reference signal to the motor driver 220. The reference signal is based on the difference between a reference speed and a measured speed of the multi speed motor 152. The reference speed is based on the difference between a measured temperature and a reference temperature, wherein the reference temperature is set by a user via the user interface 202. The speed controller 230 is further configured

The speed controller 230 is configured to map the reference speed (i.e. a reference motor speed) to the reference signal. In particular the speed controller 230 is configured to map the reference speed ω_ref to the reference voltage V_ref and reference frequency f_ref. The motor driver 220 performs in a VVCF mode therefore the speed controller 230 is configured to generate a reference voltage that varies based on the difference between the measured speed and a reference speed, while maintaining a constant reference frequency. The speed controller 230 is also configured to generate a control signal that is provided to the switch assembly 280 to cause movement of the switch member 282. The switch member 282 can be moved based on the control signal to connect to a required connection of the potential divider to further vary the voltage received by the motor 152, and hence vary the motor speed. The speed controller 230 comprises a speed controller comparator 231 and a reference feedback controller 232. The reference feedback controller acts a reference signal generator. The comparator 231 and reference feedback controller 232 operation is described with reference to Figure 4.

Figure 4 shows an arrangement of a speed controller 230 when the motor driver 220 functions in a VVCF (variable voltage constant frequency) mode. Figure 4 is a schematic view of the internal modules of the speed controller 230. As shown in Figure 4, the comparator 231 receives a reference speed ω_ref and a measured speed ω. The speed controller 230 receives a reference speed from the temperature controller 250 and receives a measured speed is received from a speed sensor 240. The comparator 231 generates a speed error ε_ω. The reference feedback controller 232 (i.e. a reference signal generator) receives the speed error (i.e. speed error signal) and generates an appropriate reference voltage signal V_ref. The reference feedback controller is configured to compensate for the speed error by varying the motor voltage set point i.e. by varying the reference voltage. The reference frequency f_ref and hence frequency of the motor are kept constant. The reference frequency is set to a nominal frequency f_N. The nominal frequency in the embodiment of Figure 4 may be mains frequency e.g. 50Hz or any other suitable frequency.

The speed controller 230 further comprises a switch controller 234. The switch controller 234 generates and provides a control signal to the switch assembly 280 to cause movement of the switch member 282. The switch controller 234 receives an error signal ε_ω and an output signal from the feedback controller. The switch controller 234 determines the position of the switch member 282 based on the error signal ε_ω and the reference voltage V_ref. The switch controller 234 is further configured to generate a control signal S_tap based on the speed error ε_ω and determined reference voltage V_ref to cause the switch member 282 to connect to an appropriate connection in the potential divider 153 to vary the voltage received by the multi speed motor, and thus vary the speed of the multi speed motor. The S_tap signal can be HIGH, MED or LOW. HIGH corresponds to a high speed position of the switch 282, MED corresponds to a medium speed position of the switch 282 and LOW corresponds to a low speed position of the switch 282. These positions will be described in more detail with respect to Figures 7a, 7b and 7c below. Further detailed operation of the switch controller 234 and switch assembly will be described later with respect to Figure 8.

As discussed earlier with reference to Figure 2a, the thermostat apparatus 200 comprises a speed sensor 240. The speed sensor 240 is configured to provide a motor speed ω (i.e. fan speed) signal to the speed controller 230. In an embodiment the speed sensor 240 comprises a tachometer. The tachometer may be positioned in the fan assembly 150. The tachometer may be positioned in the motor 152 or on the fan 154 or on the drive shaft that connects the motor to the fan. The tachometer is configured to measure the speed of the motor (or fan) and returns a measured speed value in revolutions per min. The tachometer measures the actual rotational speed of the motor. Preferably the speed sensor 240 comprises a tachometer. Alternatively if a tachometer is not available then a back EMF detection can be used. The back EMF detection process is described later in the description of alternative embodiments. Preferably a direct speed sensor is used such as a tachometer or accelerometer.

The temperature controller 250 is in electrical communication with a temperature sensor 180. The temperature sensor 180 is located within the space 102. The temperature sensor 180 may be located within the thermostat apparatus casing 260. The temperature sensor 180 is any suitable type of temperature sensor such as a thermistor or thermometer or a thermocouple or a temperature sensing IC.

Referring to Figure 5, there is illustrated an embodiment of the temperature controller 250 and the components or modules of the temperature controller 250. Figure 5 shows an exemplary architecture of the temperature controller 250. The temperature controller 250 is configured to generate a reference speed ω_ref based on a difference between a reference temperature and a measured temperature. The temperature controller 250 comprises a temperature comparator 252. The temperature controller 250 receives a reference temperature T_ref from the user interface 202. The temperature controller receives a measured temperature T_room from the temperature sensor 180. The temperature comparator 252 compares the magnitude between the reference temperature and the measured temperature. Specifically the temperature comparator 252 determines the difference between the reference temperature T_ref and the measured temperature T_room. The temperature comparator 252 generates a temperature error signal. The temperature controller 250 further comprises a temperature feedback controller 254 and a hysteresis controller 256. The temperature feedback controller 254 generates a reference speed ω_ref by minimizing the error signal. If the reference temperature is higher than the measured temperature of the room, then the temperature controller 250 (and temperature feedback controller 254) reduces the reference speed. Conversely if the reference temperature is less than the measured temperature then the temperature controller 250 increases the reference speed.

The temperature controller 250 is further configured to generate an actuation signal S_valve and transmit the actuation signal S_valve to the valve 170. The actuation signal S_valve comprises state information relating to the state of the valve 170. The state information includes an ON state and an OFF state. As illustrated in Figure 7a, 7b and 7c the temperature controller 250 further comprises a hysteresis controller 256. The hysteresis controller 256 outputs the actuation signal S_valve based on the temperature error signal (i.e. the difference between the reference temperature and the measured temperature) . In the ON state the valve 170 is opened to allow chilled water to enter the heat exchanger 130. In the OFF state the valve 170 is closed and prevents flow of chilled water to the heat exchanger 130.

In examples where the temperature controller 250 is arranged to operate with a system which has both a cooling valve 170c and heating valve 170h so as to provide either a cooling or heating function, the temperature controller is further arranged to be implemented with, or is connected with, a valve management logic arrangement 290 as shown in Figure 2b which provides an additional input of a heating or cooling command in addition to the actuation signal S_valve. As shown in Figure 2b and as described earlier, the logic arrangement, which can be implemented by logic gates circuits, hardware, software or a combination thereof is arranged to process the input signal such that either the cooling valve or the heating valve is actuated when the actuation signal S_valve is also inputted.

The hysteresis controller 256 is adapted to generate an ON state if the measured temperature T_room is greater than an upper threshold and an OFF state if generated if the measured temperature T_room is less than a lower threshold. The upper threshold relates to a predetermined upper value in a temperature hysteresis band and the lower threshold value relates to a predetermined lower value in a temperature hysteresis band. Figure 6 shows an example hysteresis band 258. The hysteresis band is constructed about the reference temperature T_ref as shown in Figure 6. The hysteresis band includes an upper threshold value T_H and a lower threshold value T_L. The upper and lower thresholds are predefined to achieve a desired hysteresis band. The upper and lower thresholds are selected based on the requirements for a temperature regulation system 100.

Figure 6 shows an example operation of the hysteresis controller 256. Figure 6 shows a plot of the measured temperature relative to the hysteresis band 258 for a time period. When the temperature crosses above the upper threshold T_H, an actuation signal S_valve is generated including an ON state. When the temperature drops below the lower threshold T_L, an actuation signal S_valve is generated including an OFF state. The hysteresis controller 256 reduces false switching of the valve 170 and reduces flutter in the valve due to any rapidly changing temperatures. Furthermore, the reduction of false switching of the valves 170 will also maximize the lifespan of the valve as frequent switching of the valves will reduce the lifespan of the valves.

Referring again to Figure 2a, the thermostat apparatus 200 further includes an AC load current sensor 272 (I_AC) . This sensor measures the current drawn by the motor driver 220. The AC load current sensor 272 may generate an alarm or disable the motor driver 220 if the current drawn is below a first threshold or preferably, when the current drawn is greater than a second threshold. This is advantageous as the motor will be protected if the current drawn exceeds a certain threshold and reduces the risk of damage to the motor. The AC load current sensor is any suitable type of current sensor such as for example a resistive current sensor a Hall effect IC current sensor or a current transformer.

The thermostat apparatus 200 further includes an AC grid voltage sensor 274. The AC grid voltage sensor 274 measures the grid voltage V_AC and provides the grid voltage to the motor driver 220. The AC grid voltage sensor 274 is useful if a power factor corrector is used in the motor driver. Based on the sampled voltage the RMS (root mean square) grid voltage and grid frequency are determined. The AC grid voltage sensor 274 is any suitable voltage sensor, such as for example a non-isolated resistive divider network with a differential amplifier. Alternatively the AC grid voltage sensor 274 may be implemented using isolated methods, such as optically isolated sigma-delta modulator, a voltage transformer based voltage sensor or a linear optocoupler or any other suitable sensor.

The thermostat apparatus 200 further includes an AC motor voltage sensor 276. The AC motor voltage sensor 276 is configured to measure a motor voltage V_motor. It provides the motor voltage value or signal to the motor driver 220 and the speed sensor. Based on the sampled voltage signal, the RMS motor voltage and frequency to be supplied to the motor are determined. The AC motor voltage sensor 276 may be implemented as any suitable voltage sensor. For example the AC motor voltage sensor 276 may include a sensor that is similar in structure and function as the AC grid voltage sensor 274.

As shown in Figure 2a, the thermostat apparatus 200 comprises an AC load current sensor 278. The AC load current sensor 278 measures the motor current I_motor drawn by the motor 152. Operation of the motor driver 220 will be disabled if the motor current I_motor rating exceeds its power rating to protect the motor driver 220.

Referring to Figures 7a, 7b and 7c, there are shown three circuit schematics relating to a HIGH, MED and LOW switch position respectively. Figure 7a shows a circuit schematic for when the switch member 282 is in a HIGH position. The switch member 282 is moved to a high position because the speed controller 230 has outputted a high S_tap signal. As seen in Figure 7a, the switch member 282 is configured to connect to one winding 153c of the motor. Therefore the stator voltage (i.e. voltage that will drive the stator) is defined by V_s ＝ V_AC –V_x. The stator voltage is the supply voltage V_AC minus the voltage across the motor driver V_x. As seen in Figure 7a the other windings are shown in faint line, to denote that there is no current flowing through those windings due to the position of switch member 282 bypassing the other windings.

Figure 7b shows a switch member 282 being in the MED position. In the MED position switch 282 connects the motor driver across two

windings

153b and 153c. The two windings are positioned in series to act as a potential divider. The voltage across each winding reduced. The voltage at the stator V_s is defined by the following formula for the MED position: V_s ＝ V_AC – [V_x + I_s (Z_med) ] . Z_med corresponds to a winding, and the winding is represented as an impedance. The “medium” winding is represented as a Z_med. In configuration shown in Figure 2a, the stator receives less voltage across it as compared to when the switch is in the HIGH position. Therefore the speed of the motor 152 is less when the switch is in the MED position as compared to when the switch is in the HIGH position.

Figure 7c shows a switch member 282 in a LOW position. In the LOW position the switch connects the motor driver 220 output across three

windings

153a, 153b, 153c. The three windings are positioned in series to act as a potential divider. The voltage across each winding is reduced i.e. the voltage is split across the windings and therefore the stator sees less voltage across the stator. When the switch member 282 is in the low position the stator voltage V_s is defined by V_s ＝ V_AC – [V_x + I_s (Z_low + Z_med) ] . Z_low corresponds to a winding and is represented as an impedance. The “low” winding is represented as Z_low. In the LOW configuration as shown in Figure 7c the voltage across the stator is lower than when the switch member 282 is in a MED position and when in a HIGH position. In the LOW configuration the voltage across the stator is the smallest thus reducing the speed the most.

An advantage of such a method is that the output voltage rating of the motor driver 220 does not need to cover the entire operating range of the multi speed motor to control the speed. Some of the voltage that is supplied to the motor is reduced by the potential divider 153, i.e. by the impedances Z_low and Z_med. Therefore the voltage rating of the motor driver can be more flexible than strictly matching the voltage rating of the motor 152.

The function of the switch controller 234 will now be described in more detail with respect to Figure 8. Figure 8 shows a method of operation of the switch controller 234. The switch controller 234 determines the position of the switch member 282. The position of the switch member 282 changes the connection between the motor driver 220 output and the desired speed winding in the motor (i.e. the potential divider 153) . The method begins at step 701 which comprises outputting a HIGH S_tap signal, meaning a control signal that includes information relating to a HIGH speed position. A HIGH S_tap signal would cause the switch member 282 to connect directly to the stator winding. At step 702 the switch controller 234 employs a delay of a predetermined time. The delay can be between 2 to 10 seconds.

At step 703 the speed controller 234 determines if the speed error ε_ω is greater than a predetermined threshold. If the speed error ε_ω is not greater than a threshold then this denotes that the reference speed and measured speed are closely aligned and the current speed setting should be maintained. If the speed error is not greater than a predetermined threshold the method loops back to after step 701 at this stage. If the speed error ε_ω is greater than a predetermined threshold then a check of the reference voltage V_ref is conducted at step 704. At step 704, the speed controller checks if the reference voltage V_ref has reached its lowest value. The V_ref value is generated by the reference feedback controller 232.

If the V_ref value has reached its lowest value the method 700 proceeds to check the position of the switch based on the switch control signal value, at step 705. The V_ref lowest value is predefined depending on the motor parameters and motor driver parameters. At step 705 the method determines if S_tap is HIGH. If yes then at step 706 the switch controller 234 outputs a S_tap ＝ MED output causing the switch 282 to move to the MED position (as described in Figure 7b) . If at step 705, the S_tap value is not HIGH, then the switch controller checks if the S_tap value is MED at step 707. If yes then at step 708 the switch controller 234 changes the S_tap value to equal LOW, causing the switch member 282 to move to a LOW position (as shown in Figure 7c) . If at step 707 the controller 234 determines that S_tap is not MED, then the method returns, at step 709, back to the delay at step 702.

Similarly referring again to step 704, if the V_ref value is determined not to be at its lowest, the method proceeds to step 710 and checks if the reference voltage V_ref has reached its highest value. The highest value is a predetermined value. If no, then the method proceeds to step 711 which returns the method back to step 702. If the reference voltage has reached its highest value, then the method proceeds to step 712. At step 712 the method determines if the switch control signal S_tap is LOW. If yes, then the method proceeds to step 713 where the switch controller 234 outputs a MED switch control signal i.e. S_tap＝ MED. Following step 713 the method returns to start at step 702.

If at step 712 the switch controller 234 determines a no, i.e. S_tap is not equal to low, then the method proceeds to step 714 where the controller checks if S_tap ＝ MED. If no, then method proceeds to step 715 and returns to the start at step 702. If at step 714 S_tap ＝ MED is true i.e. a yes determination, then the method proceeds to step 716 where the switch controller outputs a S_tap ＝ HIGH output causing the switch member 282 to move to a HIGH position (as shown in Figure 7a) . The method returns to step 702.

The method described above and with respect to Figure 8 is repeated constantly during operation. The method can be repeated at any suitable time period like every few milliseconds or every few seconds. The repetition of the method can be predetermined depending on the level of speed control required in the thermostat 200 and the temperature regulation apparatus 100. Alternatively the method may be executed and repeated in real time.

The speed of the multi speed motor 152 is determined by the magnitude of the voltage received by the stator. As explained earlier the motor driver 220 provides a drive voltage based on a reference voltage from the speed controller. In the thermostat apparatus as per the present disclosure the position of the switch member 282 further affects the drive voltage. The drive voltage is affected according to whether the switch member 282 is in a LOW, MED or HIGH position. The speed controller 230 is the component that affects the speed of the motor 152 since the speed controller 230 generates a reference signal comprising the reference voltage, and the speed controller 230 also generates a switch control signal to control the position of the switch. The reference signal and the switch control signal are generated based on at least the difference between the reference speed and the measured speed.

Figure 9 illustrates an embodiment of the switch assembly 280. The switch assembly 280 comprises a moveable switch member 282. Figure 9 shows an embodiment of the switch assembly 280 wherein the moveable switch member comprises a pair of relays. In the illustrated embodiment the switch member 282 comprises a pair of single pole double throw relays 284, 286. For a multi speed motor that comprises N speed windings, (N-1) speed pole double throw relays can be used. Figure 9 further illustrates that the switch assembly 280 comprises a relay controller 288 that controls the operation of each

relay

284, 286. The relay controller outputs a first relay control signal S₁ and a second relay controller signal S₂. The relay controller 288 may be a software based controller or can be a digital electronic or an analog electronics based controller. The relay controller 288 comprises a truth table that defines the switching relationship of the first and

second relays

284, 286. The relay controller 288 provides a control signal to the first relay 284 and second relay 286 based on the truth table and the received switch control signal S_tap.

Referring to Figure 9, each

relay

284, 286 includes a member that is moveable between a first position (A) and a second position (B) . Each relay control signal S₁, S₂ comprises information regarding which position the member of each relay is required to move. The truth table controls the operation of the relay depending upon the switch control signal information.

Figure 10 shows a truth table that is implemented in the relay controller 288. The truth table may be stored in an memory unit associated with the relay controller 288 and controls operation of the relay controller 288. As seen in Figures 9 and 10, when the relay controller 288 receives a switch control signal as high (i.e. S_tap ＝ HIGH) , a first relay signal (S₁) is outputted as an A. The first relay moves to an A position and this corresponds to the switch member being in the HIGH position. This causes the motor driver output 220 to connect directly to the stator, as shown in Figure 7a. If the switch control signal is MED (i.e. S_tap ＝ MED) , then a first relay signal (S₁) outputs a B and the second relay signal (S₂) outputs an A. The first relay member moves to a second position and the second relay member moves to the first position, which corresponds to the switch member being in a MED position. This causes the motor driver 220 output to connect to medium impedance Z_med and stator, as shown in Figure 7b. If the switch control signal is LOW (i.e. S_tap ＝ LOW) , then a first relay signal (S₁) outputs B and the second relay signal (S₂) outputs B too. The first relay member and second relay member are located at the second position, which corresponds to the switch member being in a LOW position. This causes the motor driver 220 output to connect to the low impedance, medium impedance and stator, as shown in Figure 7c.

The thermostat apparatus as described herein, that includes a speed controller 230 and switch assembly 280 is advantageous because it widens or expands the range of rotational speeds that can be achieved by the multi speed motor. As explained earlier in prior art thermostats discrete speed selections of a motor are possible, such as for example High, Medium and Low only. This can be because the motor is constructed with three windings. Prior art thermostats act as a switch that connect the mains supply voltage/power to a particular speed winding. The temperature regulation in prior art thermostats relies mainly on the control of heat exchanger rather than based on the speed of the fan. The fan speed is controlled to a user selected speed.

The present disclosure and thermostat apparatus 200 is advantageous because it is an active line thermostat and controls the speed of the motor via the motor driver and speed controller. The motor driver directly varies the electrical supply to the multi speed motor 152 and hence delivers a greater flexibility in speed selection. The motor driver functions similar to a variable output impedance device which is more versatile and flexible. Additionally the use of the potential divider 153 (i.e. the speed windings) allows further control of the voltage supplied by the motor driver. The thermostat apparatus 200 and the temperature regulation system regulates the temperature of a space by controlling the operation of the valve and the fan speed. The thermostat apparatus 200 and the temperature regulation system 100 can be set in an automatic mode, where the temperature of the space can be automatically regulated. In an automatic mode a user cannot set the fan speed. The thermostat apparatus 200 and the temperature regulation system may function in a manual mode, a user can select a fan speed through the user interface 202. For example a high speed corresponds to 100％speed, a medium speed corresponds to 77％fan speed and low speed corresponds to 60％speed. A user can customize the speed levels such as the low speed can be as a low as 40％of the maximum speed. In a manual mode the motor driver outputs a driving voltage based on the user input and the switch assembly 280 is also controlled based on the user input. The automatic mode is a preferred operation mode for temperature regulation.

As described earlier the speed sensor 240 includes a tachometer or any other suitable sensor that determines the rotational speed of the motor (i.e. the rotor or fan) . The speed sensor 240 comprises a lookup table that relates the motor speed ω with the supply voltage (V) and supply frequency (f) . The supplied voltage and supplied frequency are supplied by the motor driver 220. The lookup table created can be stored in the speed controller 230 or in the motor driver 220.

The lookup table may alternatively be stored in a memory unit that is in communication with either the speed controller 230 or the motor driver 220. The lookup table is created during a speed sensor calibration process. Figure 11 shows an embodiment of the calibration method. The calibration method 300 shown in Figure 11 is a calibration method that relates to a tachometer speed sensor. The method is executed by the speed sensor 240.

Referring to Figure 11, the method begins at step 302 wherein the calibration is initialized. The user can initiate the calibration method via the user interface 202. Alternatively the speed controller or motor driver or some other suitable component in the thermostat apparatus 200 is configured to initiate the calibration process during start up.

At step 304 the set point of the motor driver 220 is set to max. At step 304 the speed controller 230 is configured to provide a reference signal that comprises a maximum value reference voltage and a maximum value reference frequency. The motor driver 220 consequently generates a drive signal that includes a maximum value voltage and a maximum value frequency.

At step 306 the speed sensor 240 (in this example a tachometer) is configured to read out the rotational speed of the motor (i.e. rotor or fan) . At step 308 a lookup table is created by the speed controller or the motor driver. At step 308 the driving voltage value, the driving current value and the driving frequency value that relate to the measured rotational speed are stored in the table. The driving voltage, driving current and driving frequency are stored such that they relate to and are linked to the measured rotational speed.

At step 310 the reference signal (i.e. the reference voltage and reference frequency) are decremented. This causes a corresponding decrement in the driving signal (i.e. driving voltage and/or driving frequency) . The parameters that are decremented are based on the mode of the motor driver 220. At step 312 a check for if the set point is greater than the minimum threshold value is performed. The check can be performed by the speed controller 230 or the motor driver 220. If the reference signal value and/or the driving signal value is less than a minimum threshold then the calibration process is complete, as shown at step 314. The thermostat apparatus 200 resumes normal operation. If the reference signal value and/or driving signal value is greater than the minimum threshold then the method proceeds to step 316 where the drive signal is transmitted to the motor 152 and the method awaits until the motor 152 reaches a steady state. Once steady state is reached the method proceeds to repeat steps 306 to 312 until the calibration method is complete. The minimum threshold value is different for each mode of the motor driver. The table below illustrates examples of the ratios of the maximum (Max) drive voltage and frequency, the minimum threshold values (Min) and the step size for decrementing (Step-size) . These values are denoted as ratios of a nominal voltage V_N and frequency f_N. In the thermostat apparatus 200 only the voltage is incremented since the motor driver functions in a VVCF mode. See table below:

As a person skilled in the art would appreciate, these values in above Table are example values. There could be other values which will depend on some extrinsic factors, such as the specification of the motor or required resolution of the table. For example, the motor can be underdriven with the voltage lower than 50％of V_N or the frequency lower than 50％of f_N. If higher resolution is preferred, the step-size can be reduced, for example, to 1％.

Figure 12 shows an embodiment of the method 400 for regulating the temperature of a space using a temperature regulation system, wherein the temperature regulation system comprises a thermostat apparatus in electronic communication with a multi speed motor. The method 400 comprises the step 402 of initializing the system 100. At step 404 the temperature of the space is sampled using a temperature sensor. At step 406 the temperature controller 250 is activated. The temperature controller 250 functions as described earlier to generate a reference speed ω_ref and transmit the reference speed to a speed controller 230. The temperature controller 250 may alternatively or in combination with generating a reference speed, also generate an actuation signal S_valve to open or close the valve 170. At step 408 the speed sensor determines a measured motor speed and provides the measured motor speed ω to the speed controller 230. The speed controller 230 generates a reference signal comprising a reference voltage and a reference frequency at step 410 and provides the reference signal to the motor driver 220. At step 412 the motor driver is regulated to generate an appropriate driving signal that comprises a driving voltage to control the motor 152. At step 414 the switch assembly 280 is controlled by a switch control signal provided by the speed controller 230. The speed controller 230 generates and transmits a switch control signal based on the difference between a measured speed and reference speed. The switch is positioned between either a HIGH, MED or LOW position depending on the motor speed required. The steps 404-414 are repeated to control the temperature in a space.

Figure 13 shows a further embodiment of a method 500 for regulating the temperature of a space using a temperature regulation system that comprises a thermostat apparatus in electronic communication with a multi-speed motor, wherein the method comprises the steps of: receiving a measured temperature from a temperature sensor at step 502, receiving a reference temperature from a user at step 504. Step 506 comprises determining a difference between the reference temperature and the measured temperature. Step 508 comprises determining a reference speed based on the difference between the reference temperature and the measured temperature. Step 510 comprises determining a measured speed of the multi speed motor from a speed sensor 240. Step 512 comprises determining a difference between the reference speed and the measured speed. Step 514 comprises generating a reference signal based on the difference between the reference speed and the measured speed by a speed controller 230. Step 516 comprises generating a drive signal based on the reference signal. At step 518 a switch control signal is generated and transmitted to the switch assembly 280. The speed controller 230 preferably generates the switch control signal but alternatively this may be generated by the motor driver. Finally step 520 comprises transmitting the drive signal to the multi speed motor to drive the multi speed motor. The method described in Figure 14 is preferably implemented by the thermostat apparatus 200 and its components. The method 500 causing regulation of the temperature of a space. The method 500 further continuously controls the motor and continuously adjusts the driving signal (i.e. driving voltage and/or driving frequency) to the motor to provide improved or better control of the motor and improved temperature control. This method 500 can be repeated by the thermostat apparatus 200.

The thermostat apparatus 200 is advantageous because the use of the switch assembly broadens or expands the range of rotational speed for the multi speed motor. By using an integrated or internal potential divider 153 in the motor, the power rating of any passive elements is reduced to handle the full power level of the motor. The power rating requirement of the motor driver can be reduced by using the potential divider 153 which can also result in a smaller thermostat apparatus 200. The rotational speed of the multi speed motor 152 is adjusted in a step less manner by varying the drive voltage and the position of the switch member 282. This increases the versatility of the air flow supplied to the space and allows for improved temperature control of the space. The connections of the thermostat apparatus 200 (i.e. the active line thermostat) are compatible with a traditional prior art thermostat.

The thermostat apparatus 200 allows for additional functional modes of the temperature regulation system 100. The temperature regulation system 100 can function in a pre-cooling mode or a fresh air supply mode. In the pre cooling mode, the fan speed is lower than conventional low speed, approximately 50％of the full speed. In this mode the valve is maintained in an open position to cool air travelling through the passage 120. The main purpose of this mode is to cool the room slowly and prevent excessive energy from being wasted.

In the fresh air supply mode the fan speed is also lowered than a conventional low speed, such as approximately 50％of full speed. The valve 170 is closed to prevent chilled water entering the heat exchanger 130. The purpose of this mode is to maintain a minimum airflow to provide ventilation. In a normal automatic mode the thermostat apparatus 200 can function as described earlier.

In an alternative embodiment the heat exchanger 130 comprises a plate type heat exchanger that includes a plurality of plates located adjacent each other. In a further alternative the heat exchanger may be a plate and shell type heat exchanger, or a phase change heat exchanger or a micro-channel heat exchanger or a direct contact heat exchanger or a pass over heat exchanger or any other suitable heat exchanger that can be used to cool air through the passage 120.

In an alternative embodiment the thermal exchange material is a coolant such as a hydraulic fluid. The thermal exchange material may comprise a fluid or gas or liquid coolant. The thermal exchange material is preferably a fluid that is cooler than the operating temperature range of the room. The thermal exchange material is configured to cool air flowing across the heat exchanger. In a further alternative embodiment the thermal exchange material may be a hot fluid or hot gas that is configured to heat air flow across the heat exchanger.

In an alternative embodiment the valve 170 is a proportional valve. The proportional valve includes a moveable member that can move between an open position and a closed position. The moveable member can also be moved between any intermediate position between the open and closed position such that the moveable member can be partially open. The proportional valve allows any suitable or predetermined volume of thermal exchange material to be delivered to the heat exchanger. The actuation signal, generated by the temperature controller, comprises position information for the moveable member. The actuation signal causes the moveable member to move to a predetermined position between a fully open position and a fully closed position. The valve member position information is related to a temperature difference between the reference temperature and measured temperature. The valve member position information may be predetermined and stored in a look up table. The temperature controller is configured to generate an actuation signal with the appropriate valve member position information based on the difference between the reference temperature and the measured temperature. The temperature controller is configured to select the valve member position information from the look up table and encode it into the actuation signal.

In a further alternative embodiment the valve 170 may be any other suitable electronically activated valve such as an electromechanical check valve or an electromechanical butterfly valve or any other type of electronically activated or controllable valve. In an alternative embodiment the temperature regulation system 100 may comprise a plurality of valves between the reservoir and the thermal exchanger.

In an alternative embodiment the fan assembly comprises a fan, a linear motor and a crank assembly. The linear motor is connected to the fan via the crank assembly to drive the fan in a rotary or rotational motion. A linear motor can be used instead of a standard rotational motor since a linear motor may be smaller or may be easier to control. In this alternative embodiment the fan assembly may also include a linear “fan” in the form of a piston or plunger that is driven by the motor. The linear piston or plunger imparts pressure onto the air flow to push chilled air out of the outlet duct 112.

In an alternative embodiment the speed sensor 240 is configured to determine or predict the measured speed (i.e. motor speed) based on back EMF generated by the multi speed motor 152. Due to mechanical inertia in the motor 152 and fan 154, the rotor of the motor continues rotating for several cycles and generates a back EMF that can be detected. Figure 14 shows a graph of the back EMF (i.e. back voltage) that is generated by the motor 152. The speed sensor 240 comprises a zero crossing detector that is configure to detect a zero crossing of the back EMF signal. A square pulse is generated during zero crossing points, as seen in Figure 14. The period of the back EMF equals the time duration between two consecutive rising edge signals. The rotational speed can be estimated using the following formula:

ω_m＝ω

ω_m is the mechanical rotational speed of the rotor in rad s-1,

t_b is the measured period of back-EMF in s,

P is the number of motor pole-pair.

The speed sensor 240 is configured to generate a measured speed using the above formula. The speed sensor 240 generates a signal that includes information that denotes the speed of the motor. The speed that is estimated using the back EMF method is the rotational speed of the motor 152. For back EMF detection of speed the speed sensor 240 may be calibrated using a similar method to that described in Figure 11. The method of calibration comprises the steps of initializing the calibration, adjusting the reference signal (reference voltage and reference frequency) to a maximum value. Following this any power to the motor is switched off such that the motor functions as a generator generating a back EMF. The rotational speed of the motor is estimated using the formula above that relates speed to the period of the back EMF. A lookup table is created that relates the driving voltage, driving current and driving frequency to the rotational speed. The reference voltage and reference frequency are decremented by a step size, thus causing the driving voltage and driving frequency to be decremented too. The calibration method checks if the reference voltage and/or reference frequency is less than a minimum threshold. If no then the calibration process is ended once a specific number of decrements have taken place. If yes, then a driving signal is supplied to the motor and the system waits until the motor returns to a steady state before repeating the process. Other calibration methods are also contemplated.

In a further alternative the potential divider 153 may be incorporated into the thermostat apparatus rather than as part of the motor. The potential divider 153 may include inductors or resistors or any other suitable electrical components and may be positioned in the thermostat casing 260. The potential divider 153 would connect to the drive winding of an electrical motor. The potential divider 153 allows for improved speed control as described earlier. In a further alternative embodiment the motor driver and speed controller may be integrated with other. The thermostat apparatus may comprise a single controller that includes the functionalities of the speed controller 230 and motor driver 220.

In the foregoing specification the components of the thermostat apparatus and any sub components such as comparators, generators, controllers etc may be implemented with analog electronic parts such as resistors, inductors, capacitors, opamps, MOSFETS, transistors and so on. Alternatively the thermostat apparatus and any sub components such as comparators, generator, controllers etc may be implemented with digital electronic components such as logic gates. In a further alternative some or all of these components may be implemented as software modules that are stored in a memory unit and executed by a hardware processor residing in the thermostat apparatus casing. The thermostat apparatus may comprise a non-transitory computer readable medium such as a memory unit, that comprises computer readable instructions that are executable by a processor.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a, " "an" and "the" are intended to include plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" or "comprising, " when used in this specification, specify the presence of stated features, integers, steps, operations, elements components and/or groups or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups or combinations thereof.

As used herein, the term "and/or" includes any and all possible combinations or one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative ( "or" ) .

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and claims and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

It will be understood that when an element is referred to as being "on, " "attached" to, "connected" to, "coupled" with, "contacting, " etc., another element, it can be directly on, attached to, connected to, coupled with and/or contacting the other element or intervening elements can also be present. In contrast, when an element is referred to as being, for example, "directly on, " "directly attached" to, "directly connected" to, "directly coupled" with or "directly contacting" another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed "adjacent" another feature can have portions that overlap or underlie the adjacent feature.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

A thermostat apparatus for use with or as part of a temperature regulation system, the temperature regulation system including at least a multi speed motor coupled to a fan, wherein the thermostat apparatus comprises；

a motor driver being electrically coupled to a power supply and configured to receive a power supply signal from the power supply,

a switch assembly disposed between the motor driver and the multi speed motor, the switch assembly being electrically coupled to the motor driver and electrically coupled to a potential divider, wherein the potential divider being electrically coupled to the multi speed motor,

a speed controller in electronic communication with the motor driver, the speed controller configured to provide a reference signal to the motor driver, the reference signal being based on a difference between a reference speed and a measured speed of the multi speed motor,

the reference speed being based on the difference between a measured temperature and a reference temperature, and the reference temperature being set by a user,

the motor driver being configured to generate the drive signal based on the received reference signal, the motor driver further configured to transmit the drive signal to the multi speed motor via the switch assembly,

wherein the speed controller further configured to generate and transmit a switch control signal to the switch assembly, and；

the switch assembly configured to connect one of a plurality of connections of the potential divider.
A thermostat apparatus in accordance with claim 1, wherein the drive signal that is provided to the multi speed motor comprises a drive voltage and a drive frequency, the reference signal comprises a reference voltage and a reference frequency, and wherein the drive voltage being adjusted based on the reference voltage.
A thermostat apparatus in accordance with claim 2, wherein the speed of the multi speed motor being based on the drive voltage and the connection between the switch assembly and the one of the plurality of connections of the potential divider.
A thermostat apparatus in accordance with claim 1, wherein the speed controller comprises a comparator configured to determine a speed error, wherein the speed error being the difference between reference speed and the measured speed, and the speed controller configured to generate the reference signal based on the speed error.
A thermostat apparatus in accordance with claim 1, wherein the speed controller comprises a reference signal generator, the reference signal generator being configured to generate a reference signal based on the speed error, the reference signal generator generating a reference voltage and the reference frequency being a nominal frequency.
A thermostat apparatus in accordance with claim 1, wherein the speed controller comprises a switch controller that is configured to generate the switch control signal, the switch control signal being based on the difference between the reference speed and the measured speed and/or the reference signal.
A thermostat apparatus in accordance with claim 1, wherein the potential divider comprises one or more impedances and the plurality of connections, each connection corresponding to one of the impedances.
A thermostat apparatus in accordance with claim 7, wherein the potential divider comprises three impedances and three connections, each connection corresponding to each impedance, and wherein the impedances are inductors or resistors or windings of the multi speed motor.
A thermostat apparatus in accordance with claim 7, wherein one of the connections relates to a high supply voltage, one connection relates to a medium supply voltage and one connection relates to a low supply voltage, the switch assembly comprising an electrically actuable moveable member, the moveable member connectable to one of the high, medium or low supply voltage connections based on the switch control signal.
A thermostat apparatus in accordance with claim 9, wherein the potential divider affects the drive voltage based on the position of the moveable member of the switch,

wherein in a high supply voltage connection the switch assembly coupling the motor driver to the multi speed motor through one impedance,

wherein in a medium voltage connection the switch assembly coupling the motor driver being to the multi speed motor through more impedances than the high voltage connection, but less impedances than the low voltage connection, and；

wherein in a low voltage connection the switch assembly coupling the motor driver to the multi speed motor through more impedances than the medium voltage connection and the high voltage connection.
A thermostat apparatus in accordance with claim 1, wherein the switch assembly comprises a plurality of double throw relays, the number of relays in the switch assembly being equal to one less than the number of impedances in the potential divider or one less than the number of windings of the multi speed motor.
A thermostat apparatus in accordance with claim 11, wherein the switch assembly comprises a relay controller that is configured to generate and transmit a relay control signal to each of the plurality of double throw relays to actuate the relay between a first position and a second position, the relay control signal being generated based on switch control signal.
A thermostat apparatus in accordance with claim 1, wherein the thermostat apparatus comprises a speed sensor in electronic communication with the speed controller, the speed sensor configured to determine and transmit a measured speed to the speed controller, and wherein the measured speed corresponds to a motor speed and wherein the speed sensor is a tachometer that is configured to measure instantaneous motor speed.
A thermostat apparatus in accordance with claim 1, wherein the thermostat apparatus further comprises a temperature controller, the temperature being configured to generate the reference speed and transmit the reference speed to the speed controller, wherein the reference speed is generated based on a difference between a reference temperature and a measured temperature,

wherein the temperature controller is adapted to receive a reference temperature from a user interface, the temperature controller is further adapted to receive a measured temperature from a temperature sensor, the measured temperature relates to the temperature of a space,

wherein the temperature controller is configured to increase the magnitude of the reference speed if the measured temperature is greater than the reference temperature； and；

wherein the temperature controller is configured to decrease the magnitude of the reference speed if the measured temperature is less than the reference temperature.
A temperature regulation system for regulating the temperature of a space, the temperature regulation system comprising:

a fan assembly including a fan and a multi speed motor, the multi speed motor being connected to the fan and configured to drive the fan at a speed,

a thermostat apparatus in electrical communication with the multi speed motor and configured to control the multi speed motor,

the thermostat apparatus further comprising；

a motor driver being electrically coupled to a power supply and configured to receive a power supply signal from the power supply,

a switch assembly disposed between the motor driver and the multi speed motor, the switch assembly being electrically coupled to the motor driver and electrically coupled to a potential divider, wherein the potential divider being electrically coupled to the multi speed motor,

a speed controller in electronic communication with the motor driver, the speed controller configured to provide a reference signal to the motor driver, the reference signal being based on a difference between a reference speed and a measured speed of the multi speed motor,

the reference speed being based on the difference between a measured temperature and a reference temperature, and the reference temperature being set by a user,

the motor driver being configured to generate the drive signal based on the received reference signal, the motor driver further configured to transmit the drive signal to the multi speed motor via the switch assembly,

wherein the speed controller further configured to generate and transmit a switch control signal to the switch assembly, and；

the switch assembly configured to connect one of a plurality of connections of the potential divider.
A temperature regulation system in accordance with claim 15, wherein the temperature regulation system further comprises

a reservoir adapted to hold a thermal exchange material,

a heat exchanger in fluid communication with the reservoir, wherein the heat exchanger is adapted to receive the thermal exchange material from the reservoir,

a valve located between the heat exchanger and the reservoir, the valve being selectively moveable between an open position and a closed position, wherein in an open position the valve allows passage of the thermal exchange material from the reservoir to the heat exchanger and in a closed position the valve preventing the passage of the thermal exchange material from the reservoir to the heat exchanger,

a temperature sensor located within the space and configured to measure the temperature of the space to generate a measured temperature, the temperature sensor being in electrical communication with the thermostat apparatus to transmit the measured temperature to the thermostat apparatus,

a user interface adapted to communicate with a user and wherein the user interface is further adapted to receive a reference temperature from the user.
A temperature regulation system in accordance with claim 15, wherein the drive signal that is provided to the multi speed motor comprises a drive voltage and a drive frequency, the reference signal comprises a reference voltage and a reference frequency, and wherein the drive voltage being adjusted based on the reference voltage and wherein the speed of the multi speed motor being based on the drive voltage and the connection between the switch assembly and the one of the plurality of connections of the potential divider.
A temperature regulation system in accordance with claim 15, wherein the speed controller comprises a comparator configured to determine a speed error, wherein the speed error being the difference between reference speed and the measured speed, and the speed controller configured to generate the reference signal based on the speed error,

the speed controller further comprises a reference signal generator, the reference signal generator being configured to generate a reference signal based on the speed error, the reference signal generator generating a reference voltage and the reference frequency being a nominal frequency.
A temperature regulation system in accordance with claim 15, wherein the speed controller comprises a switch controller that is configured to generate the switch control signal, the switch control signal being based on the difference between the reference speed and the measured speed and/or the reference signal.
A temperature regulation system in accordance with claim 15, wherein the potential divider comprises one or more impedances and the plurality of connections, each connection corresponding to one of the impedances.
A temperature regulation system in accordance with claim 20, wherein the potential divider comprises three impedances and three connections, each connection corresponding to each impedance, and wherein the impedances are inductors or resistors or windings of the multi speed motor.
A temperature regulation system in accordance with claim 20, wherein one of the connections relates to a high supply voltage, one connection relates to a medium supply voltage and one connection relates to a low supply voltage, the switch assembly comprising an electrically actuable moveable member, the moveable member connectable to one of the high, medium or low supply voltage connections based on the switch control signal.
A temperature regulation system in accordance with claim 22, wherein the potential divider affects the drive voltage based on the position of the moveable member of the switch,

wherein in a high supply voltage connection the switch assembly coupling the motor driver to the multi speed motor through one impedance,

wherein in a medium voltage connection the switch assembly coupling the motor driver being to the multi speed motor through more impedances than the high voltage connection, but less impedances than the low voltage connection, and；

wherein in a low voltage connection the switch assembly coupling the motor driver to the multi speed motor through more impedances than the medium voltage connection and the high voltage connection.
A temperature regulation system in accordance with claim 15, wherein the switch assembly comprises a plurality of double throw relays, the number of relays in the switch assembly being equal to one less than the number of impedances in the potential divider or one less than the number of windings of the multi speed motor.
A temperature regulation system in accordance with claim 24, wherein the switch assembly comprises a relay controller that is configured to generate and transmit a relay control signal to each of the plurality of double throw relays to actuate the relay between a first position and a second position, the relay control signal being generated based on switch control signal.
A temperature regulation system in accordance with claim 15, wherein the thermostat apparatus comprises a speed sensor in electronic communication with the speed controller, the speed sensor configured to determine and transmit a measured speed to the speed controller, and wherein the measured speed corresponds to a motor speed and wherein the speed sensor is a tachometer that is configured to measure instantaneous motor speed.
A temperature regulation system in accordance with claim 15, wherein the thermostat apparatus comprises a temperature controller, the temperature being configured to generate the reference speed and transmit the reference speed to the speed controller, wherein the reference speed is generated based on a difference between a reference temperature and a measured temperature,

wherein the temperature controller is adapted to receive a reference temperature from a user interface, the temperature controller is further adapted to receive a measured temperature from a temperature sensor, the measured temperature relates to the temperature of a space,

wherein the temperature controller is configured to increase the magnitude of the reference speed if the measured temperature is greater than the reference temperature； and；

wherein the temperature controller is configured to decrease the magnitude of the reference speed if the measured temperature is less than the reference temperature.
A method for regulating a temperature of a space using a temperature regulation system, wherein the temperature regulation system comprises a thermostat apparatus in electronic communication with a multi speed motor, wherein the method for regulating a temperature comprises the steps of:

receiving a measured temperature from a temperature sensor,

receiving a reference temperature

determining a difference between the reference temperature and the measured temperature,

determining a reference speed based on the difference between the reference temperature and the measured temperature,

determining a measured speed of the multi speed motor from a speed sensor,

determining a difference between the reference speed and the measured speed,

generating a reference signal based on the difference between the reference speed and the measured speed,

generating a drive signal based on the reference signal,

generate and transmit a switch control signal to a switch assembly, the switch control signal causing the switch assembly to connect to one of a plurality of connections of a potential divider,

transmit the drive signal to the multi speed motor via the switch assembly.