WO2014205805A1

WO2014205805A1 - Overload protection for vehicle hvac system

Info

Publication number: WO2014205805A1
Application number: PCT/CN2013/078433
Authority: WO
Inventors: Junmin Peng; Guohui Zhong; Zhiming Shen; Dan Wang; Gregory Robert Truckenbrod
Original assignee: Ingersoll Rand (China) Industrial Technologies; Thermo King Corporation
Priority date: 2013-06-28
Filing date: 2013-06-28
Publication date: 2014-12-31

Abstract

A vehicle HVAC system including a HVAC alternator and a method of operating a HVAC alternator are provided. The said system comprises: an output terminal of the HVAC alternator having an output voltage; a voltage regulator of the HVAC alternator having an input terminal; a first relay positioned between the input terminal and a vehicle battery; wherein the first relay is configured to have a first state and a second state, when the first relay is in the first state, the first relay is configured to allow the vehicle battery to provide a voltage to the input terminal of the voltage regulator, and when the first relay is in the second state, the first relay is configured to prevent the vehicle battery to provide a voltage to the input terminal of the voltage regulator. As a result, the HVAC alternator may be prevented from providing an output voltage that exceeds the predetermined high voltage threshold.

Description

OVERLOAD PROTECTION FOR VEHICLE HVAC SYSTEM

Field

The disclosure herein relates to an alternator, which may be configured to power a load, such as, for example, a vehicle heating, ventilation and air conditioning (HVAC) system. More particularly, this disclosure relates to methods and systems that are directed to prevent the HVAC alternator from providing a relatively high voltage that may damage the load.

Background

A vehicle HVAC system typically includes its own alternator to power the HVAC system. The alternator of the HVAC system (herein referred to as a HVAC alternator) is typically separated from an alternator of the vehicle. The HVAC alternator and the vehicle alternator generally have similar structures, whichcan include an exciter coil that may be regulated by a voltage regulator. Whenan excitation current passes through the exciter coil, the exciter coil can provide a magnetic field. When the rotor of the alternator rotates in the magnetic field provided by the exciter coil, the alternator can produce an output voltage to drive a load (such as, for example, the vehicle HVAC system). The voltageregulator can be configured to monitor the output voltage of the alternator. When the output voltage varies, the voltage regulator can be configured to regulate the excitation current accordingly so as to maintain a relatively stable output voltage from the alternator.

Typically, the HVAC system does not include a battery. To start the HVAC alternator, a battery of the vehicle may be used to provide the initial excitation current to the exciter coil.

Summary

Systems and methods to help prevent occurrence of a condition that may cause a relatively high output voltage from an alternator are provided. The alternator can be configured to provide power to, for example, a vehicle HVAC system.

In some embodiments, the HVAC alternator may include an output terminal supplying an output voltage, and a voltage regulator with an input terminal. The input terminal of the voltage regulator can be configured to be connected to a first relay. In some embodiments, the first relay can be a solid state relay.

In some embodiments, the first relay can be configured to have a first state and a second state. In some embodiments, when the first relay is in the first state, the first relay may be configured to allow a vehicle battery to provide a voltage to the input terminal of the voltage regulator so as to provide an excitation current to an exciter coil of the HVAC alternator. In some embodiments, when the first relay is in the second state, the first relay may be configured to prevent the vehicle battery to provide the voltage to the input terminal of the voltage regulator.

In some embodiments, the first relay may be configured to switch from the first state to the second state at a predetermined activation voltage applied to an input terminal of the first relay. In some embodiments, the predetermined activation voltage may be higher than a normal voltage of the vehicle battery and lower than a safe operation voltage high-threshold of a load, such as the vehicle HVAC system.

In some embodiments, the input terminal of the first relay may be connected to the output terminal of the HVAC alternator, so that the first relay can be activated when the output voltage of the HVAC alternator exceeds the predetermined activation voltage. Activation of the first relay can prevent an excitation current from being provided to the excitation coil of the HVAC alternator, causing the reduction of the output voltage of the HVAC alternator.

In some embodiments, the vehicle battery may be connected to the first terminal of the first relay through an ignition switch. In some embodiments, the HVAC alternator can be configured to be connected to a second relay. In some embodiments, the second relay can be configured to have a first state and a second state. In some embodiments, when the second relay is in the first state, the second relay may be configured to allow the first terminal of the first relay to be connected to the input terminal of the voltage regulator, and when the second relay is in the second state, the second relay may be configured to prevent the first terminal of the first relay from being connected to the input terminal of the voltage regulator.

Other features and aspects of the embodiments will become apparent by consideration of the following detailed description and accompanying drawings. Brief Description of the Drawings

Reference is now made to the drawings in which like reference numbers represent corresponding parts throughout.

Fig. 1 illustrates a schematic diagram of circuit that includes a HVAC alternator, a vehicle battery and a relay, according to one embodiment.

Fig. 2 illustrates a schematic diagram of circuit that includes a HVAC alternator, a vehicle battery, and a first and second relays, according to one

embodiment.

Fig. 3 illustrates a method of operating an alternator for a load, such as a HVAC system.

Detailed Description

A vehicle HVAC system typically carries its own alternator (HVAC alternator) to provide power to the HVAC system. The HVAC alternator may be driven by an engine of the HVAC system to provide the power. One type of alternatorincludes a rotatable exciter coil (rotor) and a stationary conductor coil (stator). When an excitation current is provided to the exciter coil, a magnetic field can be generated by the exciter coil. The rotation of the exciter coil can induce an output voltage in the conductor coil. The excitation current is provided to the exciter coil through a voltage regulator that may be integrated into the HVAC alternator. The voltage regulator can be configured to regulate the excitation current to the exciter coil. When the output voltage increases, the voltage regulator may reduce the excitation current so as to reduce the magnetic field. As a result, the output voltage can be reduced.

When the output voltage decreases, the voltage regulator may increase the excitation current to increase the magnetic field. As a result, the output voltage can be increased. The voltage regulator, therefore, can maintain the output voltage to be relatively constant.

When the HVAC alternator is initially started, the voltage regulator of the HVAC alternator may need to be powered. Because many vehicle HVAC systems typically do not have a battery, the power to the voltage regulator may be provided by the vehicle battery initially when the HVAC alternator starts. After the HVAC alternator starts, the voltage regulator may be powered by the output voltage of the HVAC alternator (self-excitation). The term self-excitation generally means that the voltage regulator is configured to sense the output voltage of the HVAC alternator, and regulate the excitation current (and the output voltage) based on the output voltage of the HVAC alternator.

An issue with using the vehicle battery to provide power to the regulator is that when the voltage of the vehicle battery drops below a certain voltage, the voltage regulator may overcompensate for the low voltage, causing the HVAC alternator output voltage to be relatively high (such as about the maximum voltage that the HVAC alternator can provide). For example, a typical vehicle battery voltage is about 24 volts. Under certain conditions, such as when the vehicle repeatedly starts or when the load on the vehicle battery is relatively high (such as in a rainy day), the vehicle battery voltage may drop to about 15 to 16 volts. When this condition happens, the voltage regulator of the HVAC alternator of the HVAC system may consider the voltage too low. Consequently, the voltage regulator may provide the maximum current to the exciter coil to try to correct the relatively low voltage, causing the output voltage of the HVAC alternator to be about the maximum voltage (e.g. about 50 volts). The relatively high output voltage may then damage the voltage regulator and/or components of the HVAC system.

Improvements can be made to help prevent/reduce the occurrence of the relatively high output voltage so as to help prevent/reduce damages to the voltage regulator and/or the components of the HVAC system.

Embodiments as described herein are generally directed to systems and methods to help prevent occurrence of a condition that may cause a relatively high output voltage from an alternator (e.g. HVAC alternator), so that a load (e.g. the vehicle HVAC system) may be protected from being damaged by the relatively high output voltage from the alternator. In some embodiments, an output terminal of the HVAC alternatormay be connected to an input terminal of a relay, such as a solid state relay. In some embodiments, the relay can be activated at a predetermined activation voltage. When an output voltage of the HVAC alternatorexceeds the predetermined activation voltage, the relay can be activated, causing an excitation current to an exciter coil of the HVAC alternator to be reduced or cut. As a result, the HVAC alternator may be prevented from providing an output voltage that exceeds the predetermined activation voltage. In some embodiments, the excitation current to the HVAC alternator can be initially provided by the vehicle battery. After initiation, a relay is activated to cut the vehicle battery from the HVAC alternator and the voltage regulator may be powered by the output voltage of the HVAC alternator in a self-excitation mode.

References are made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration of the embodiments in which the embodiments may be practiced. It is to be understood that the terms used herein are for the purpose of describing the figures and embodiments and should not be regarding as limiting the scope of the present application.

Fig. 1 illustrates a schematic circuit diagram that includes a HVAC alternator 100, a vehicle battery 130 and a first relay 120. The HVAC alternator 100 has an output terminal 121 that is configured to provide an output voltage B+ to power, for example, a vehicle HVAC system. The HVAC alternator 100 includes a voltage regulator 1 lOthat is configured to regulate an excitation current to an exciter coil 1 12. Generally, when the excitation current to the exciter coil 1 12 increases, the output voltage B+ of the HVAC alternator 100 may increase. When the excitation current to the exciter coil 1 12 decreases, the output voltage B+ of the HVAC alternator 100 may decrease. In a typical vehicle HVAC system, a normal/safe operation voltage range of the output voltage B+ may be between a low threshold of about 20V to a high-threshold of about 35 volts.

A first relay 120 is positioned between the vehicle battery 130 and an input terminal 1 14 of the voltage regulator 1 10. The first relay 120includes an input terminal 122 and a plurality of relay terminals: a first terminal (30), a second terminal (87a) and a third terminal (87). The first terminal (30) is connected to the vehicle battery 130 through a vehicle ignition switch 140. In a default state, the first terminal (30) is connected to the second terminal (87a). Since the second terminal (87a) is connected to the input terminal 1 14 of the voltage regulator 1 10, the vehicle battery 130 can be connected to the input terminal 1 14 of the voltage regulator 1 10 to provide a reference voltage and an excitation current to the exciter coil 1 12 through the ignition switch 140.

The first relay 120 can be activated by providing an input voltage that exceeds a predetermined activation voltage to the input terminal 122 of the first relay 120. When a voltage exceeding the predetermined activation voltage is applied to the input terminal 122, the first relay 120 is activated. In the activated state, the first terminal (30) is connected to the third terminal (87). The vehicle battery 130 is therefore prevented from being connected to the input terminal 1 14 of the voltage regulator 1 10. Also as illustrated in Fig. 1 , the input terminal 122 of the first relay 120 is connected to the outputterminal 121 supplying output voltage B+ of the HVAC alternator 100.

The vehicle battery 130 is connected to the vehicle ignition switch 140, which has an "on" state and an "off state. Fig. 1 illustrates the "off state. When the vehicle ignition switch 140 is at the "on" state, the vehicle battery 130 can be connected to the first terminal (30) of the first relay 120. When the vehicle ignition switch 140 is at the "off state, the vehicle battery 130 is generally prevented from being connected to the first terminal (30) of the first relay 120.

The predetermined activation voltage can be a voltage that is between a normal voltage of the vehicle battery (such as, for example, about 24 volts) and a relatively high voltage (such as, for example, about 35 volts) that may be still safe for a load (such as the HVAC system) of the HVAC alternator 100. The normal voltage of the vehicle battery may be a voltage that can be supplied by the vehicle battery without any load. The relatively high voltage can be the high-threshold safe operation voltage range for the load.

In operation, when the ignition switch 140 is switched to "on" state, the first relay 120 is still in the default statebecause the predetermined activation voltage is higher than the normal voltage of the vehicle battery 130. The terminal (30) is connected to the terminal (87a). Thus, the vehicle battery 130 is connected to the input terminal 1 14 of the voltage regulator 1 10 to provide the initial excitation current to the exciter coil 1 12, which can induce the output voltage B+ at the output terminal 121.

In some operational situations, the vehicle battery 130 can have a relatively low voltage (such as, for example, 15-16 volts), for example, when the vehicle repeatedly starts, or when the load on the vehicle battery 130 is relatively high (such as in a rainy day).

If the vehicle battery 130 has a relatively low voltage (such as about 15- 16 volts) when the ignition switch is turned on, the voltage regulator 1 10 may consider the initial voltage provided by the vehicle battery 130 too low due to, for example, the configuration of the voltage regulator 1 10. Consequently, the voltage regulator 1 10 may try to correct the relatively low voltage by providing a relatively high excitation current (e.g. a current that is about the maximum excitation current) to the exciter coil 1 12, causing the output voltage B+ to be relatively high (such as, for example, about 50 volts). This relatively high voltage may result failure of the load (such as the vehicle HVAC system) that is connected to the output terminal 121 due to the relatively high output voltage B+. The embodiment as illustrated in Fig. 1 may help prevent the output voltage B+ from providing the relatively high output voltage B+.

When the output voltage B+ exceeds the predetermined activation voltage (e.g. about 35 volts), the first relay 120 can be activated. As a result, the relay terminal (30) is connected to the relay terminal (87), thus preventing the vehicle battery 130 from being connected to the voltage regulator 1 10 so as to eliminate the condition causing the relatively high output voltage B+ due to the relatively low voltage of the vehicle battery 130. Since the vehicle battery 130 is no longer connected to the input terminal 1 14 of the voltage regulator 1 10, the excitation current to the exciter coil 1 12 may also be cut. The output voltage B+ can therefore be reduced.

In some embodiments, the output terminal 121 may be connected to the input terminal 1 14 of the voltage regulator 1 10 through a resistor network (not shown) to provide a reference voltage (e.g. the output voltage B+) and/or the excitation current to the voltage regulator 1 10. Therefore, after the HVAC alternator 100 is initially started by the vehicle battery 130, the voltage regulator 1 10 can be configured to regulate the output voltage B+ by monitoring the output voltage B+ (self-excitation). In the self-excitation mode, the voltage regulator 1 10 can response to the relatively high output voltage B+ by reducing the excitation current to the exciter coil 1 12. When the first relay 120 is activated, which generally prevents the vehicle battery 130 from providing the voltage to the input terminal 1 14 of the voltage regulator 1 10, the output voltage B+ can be configured to provide the reference voltage and the excitation current to the exciter coil 1 12.

The first relay 120 can be configured to have a predetermined turn-off voltage. The first relay 120 may switch from the activated state to the default state when the input terminal 122 of the first relay 120 is below the turn-off voltage. The predetermined turn-off voltage (such as, for example, about 20 volts) can be configured to be lower than the normal voltage of the battery (i.e. about 24 volts). After the first relay 120 is activated, the first relay 120 can remain in the active state because the output voltage B+ and/or the vehicle battery 130 is typically above the turn-off voltage. The first relay 120 can return to the default state when the ignition switch 140 is turned off and the HVAC alternator 100 is turned off so that the input terminal 122 of the first relay 120 loses voltage.

By setting the predetermined activation voltage, the first relay 120 can be activated when a situation causing the output voltage B+ to exceed the

predetermined activation voltage occurs. As a result, the excitation current provided to the exciter coil 120 may be reduced or cut, so that the output voltage B+ may be reduced. Thus, the load of the HVAC alternator 100 may be protected from the relatively high output voltage B+.

It is to be understood that other operation situations, such as when the voltage regulator 1 10 malfunctions, may also causes the output voltage B+ to exceed the predetermined activation voltage. Therefore, the embodiment as shown in Fig. 1 may also protect the load when the voltage regulator 1 10 malfunctions or when other operation situations causing the output voltage B+ to exceed the predetermined activation voltage occur.

It is to be appreciated that in some embodiments, the first relay 120 can be a solid state relay, with the understanding that the first relay 120 may be a non-solid state relay. A solid state relay can be configured to have a relatively precise activation voltage and a turn-off voltage compared to a non-solid state relay. For example, a solid state relay can be configured to be activated and/or turned off within about 0.5 volts from the predetermined activation voltage. Therefore, the protection offered by the embodiments as disclosed herein can occur in a relatively narrow voltage range. Other types of relay that have a relatively precise activation voltage and/or a turn-off voltage can also be used.

It is to be appreciated that the predetermined activation voltage of the first relay 120 is exemplary. The first relay 120 can be configured to be activated at other voltages.

Fig. 2 illustrates another schematic circuit diagram including an alternator 200, a vehicle battery 230, a first relay 220 and an optional second relay 250. The first relay 220 can be a solid state relay. The second relay 250 can be a solid state relay or a non-solid state relay. The HVAC alternator 200 has an output terminal 221 that can provide an output voltage B+ to power, for example, a vehicle HVAC system. The embodiment is generally configured to switch the alternator 200 from being excited by the vehicle battery to a self-excitation mode.

Thefirst relay 220 is positioned between the vehicle battery 230 and an input terminal 214 of a voltage regulator 210. The first relay 220 has a first terminal (30), a second terminal (87a) and a third terminal (87). In a default state of the first relay 220, the first terminal (30) is connected to the second terminal (87a). In the default state, when an ignition switch 240 of the vehicle is turned on, the vehicle battery 230 can be connected to the first terminal (30) through the second terminal (87a) of the first relay.

An optional second relay 250 can be positioned between the first relay 220 and the input terminal 214 of the voltage regulator 210, with the notion that the second relay 250 is not necessary in some embodiments. When the second relay 250 is not used, the first terminal (30) may be connected to the input terminal 214 directly.

The second relay 250 can be a solid state type relay or a non-solid state type relay. The second relay is configured to have a default state and an activated state. In the default state, a first terminal (30') is connected to a second terminal (87a'). In the default state, the first terminal (30) of the first relay 220 is prevented from being connected to the input terminal 214 of the voltage regulator 210. In the activated state, the first terminal (30') is connected to the third terminal (87'), which allows the first terminal (30') to be connected to the third terminal (87'). As illustrated, when the first relay 220 is in the default state and the second relay is in the activated state, the vehicle battery 230 can be connected to the input terminal 214 of the voltage regulator 210 through the ignition switch 240. The second relay 250 may be connected to, for example, an on/off switch for the HVAC system so that the second relay 250 switches from the default state to the activated state when the on/off switch of the HVAC system is turned on.

In some operation conditions, such as when the vehicle is initially started, the vehicle battery 230 may be in a relatively low voltage (e.g. about 15-16 volts). If the vehicle battery 230 is connected to the input terminal 214 of the voltage regulator 210, the voltage regulator 210 may consider the initial voltage too low. Consequently, the voltage regulator 210 may increase an excitation current, causing the output voltage B+ of the HVAC alternator 200 to be relatively high. The second relay 250 can be used to prevent the vehicle battery 230 from being

connected to the input terminal 214 of the voltage regulator 210 when the vehicle initially starts.

In operation, when the vehicle is initially started by turning on the switch 240, the solid state 220 is in the default state and the second relay is in the default state. As illustrated in Fig. 2, the vehicle battery 230 may be prevented from being connected to the input terminal 214 of the voltage regulator 210. Therefore, the voltage regulator 210 may not have power to generate the excitation current.

Consequently, the output voltage B+ at the output terminal 221 can be very low or zero volt.

After the vehicle starts, the second relay 250 can be switched to the activated state by, for example, a user turning on the on/off switch of the HVAC system.

When the second relay 250 is activated, the vehicle battery 230 can be connected to the input terminal 214 of the voltage regulator 210 so as to initiate the HVAC alternator 200.

The first relay 220 can be configured to be activated by a predetermined activation voltage. If the output voltage B+ exceeds the predetermined activation voltage, the first relay 220 can be activated. As a result, the output voltage B+ is connected to the input terminal 214 of the voltage regulator 210, so that the HVAC alternator 200 may be operated in a self-excitation mode. In some embodiments, the predetermined activation voltage can be a voltage that is about a normal output voltage (such as, for example, 26 volts) of the HVAC alternator 200 when the HVAC alternator 200 in a normal operation. After the HVAC alternator 200 is initiated by the vehicle battery 230, the HVAC alternator 200 can be switched from being excited by the vehicle battery 230 to the self-excitation mode when the HVAC alternator 200 operates normally by activating the first relay 220.

The output voltage B+ is connected to the input terminal 222 of the first relay 220 to maintain the first relay 220 in the activated state. When both the first relay 220 and the second relay 250 are in the activated state, the HVAC alternator 200 can continuously be operated in a self-excitation mode.

In some embodiments, the first relay 210 may be a solid state relay, with the appreciation that non-solid state relay can also be used. In some embodiments, the first relay 210 may have heat protection mechanism. In the self-excitation mode, when the output voltage B+ of the HVAC alternator 200 is relatively high, the relatively high output voltage B+ may cause the first relay 210 to overheat, which may activate the heat protection mechanism of the first relay 210. As a result, the first relay 210 may prevent current flow between the first terminal (30) and the third terminal (87), reducing/cutting the excitation current provided by the output voltage B+. As a result, the output voltage B+ can be reduced.

When the HVAC alternator 200 is turned off, the output voltage B+ is lost. Both the first relay 220 and the second relay 250 can return to the default state as illustrated in Fig. 2.

The embodiment as illustrated in Figs. 1 and 2 are exemplary. A general method 300 of operating an alternator of a load (such as a vehicle HVAC system)is illustrated in Fig. 3. At 310, if a vehicle ignition switch (e.g. the switch 140) is activated, a vehicle battery (e.g. the vehicle battery 130) is connected to a voltage regulator (e.g. the voltage regulator 120) to initiate a HVAC alternator (e.g. the HVAC alternator 100). At 320, the vehicle battery can provide a voltage to the excitation coil/voltage regulator. At 330 when an output voltage of the alternator exceeds a high-threshold of safe operation voltage (e.g. about 35 volts), the vehicle battery is prevented from providing the voltage to the HVAC alternator at 340.

When the output voltage of the alternator does not exceed the high-threshold of safe operation voltage, the output voltage is provided to a load at 350.

In some embodiments, the method may include connecting the voltage regulator of the HVAC alternator to the output of the HVAC alternator so that the HVAC alternator may work in a self-excitation mode, after, for example, the HVAC alternator is initiated by the vehicle battery. The self-excitation mode may help the HVAC alternator to reduce the relative high voltage output relatively quickly.

With regard to the foregoing description, it is to be understood that changes may be made in detail, without departing from the scope of the present invention. It is intended that the specification and depicted embodimentsare to be considered exemplary only, with a true scope and spirit of the invention being indicated by the broad meaning of the claims.

Claims

1. A vehicle HVAC system including a HVAC alternator, comprising:

an output terminal of the HVAC alternator having an output voltage;

a voltage regulator of the HVAC alternator having an input terminal;

a first relay positioned between the input terminal and a vehicle battery;

wherein the first relay is configured to have a first state and a second state, when the first relay is in the first state, the first relay is configured to allow the vehicle battery to provide a voltage to the input terminal of the voltage regulator, and when the first relay is in the second state, the first relay is configured to prevent the vehicle battery to provide a voltage to the input terminal of the voltage regulator.

2. The vehicle HVAC system of claim 1 , whereinthe first relay is configured to switch from the first state to the second state at a predetermined activation voltage applied to an input terminal of the first relay.

3. The vehicle HVAC system of claim 2, wherein the predetermined activation voltage is higher than a normal voltage of the vehicle battery and lower than a high-threshold of safe operation voltage of the vehicle HVAC system.

4. The vehicle HVAC system of claim 2, wherein the input terminal of the first relay is connected to the output terminal of the alternator.

5. The vehicle HVAC system of claim 1 , wherein the vehicle battery is connected to the first terminal of the first relay through an ignition switch.

6. The vehicle HVAC system of claim 1 , wherein the first relay is configured to have a first terminal, a second terminal and a third terminal;

when the first relay is in the first state, the first terminal is configured to be connected to the second terminal; and when the first relay is in the second state, the first terminal is configured to be connected to the third terminal.

7. The vehicle HVAC system of claim 6,

wherein the alternator is configured to be connected to a second relay;

the second relay is configured to have a first state and a second state,

when the second relay is in the first state, the second relay is configured to allow the first terminal of the first relay to be connected to the input terminal of the voltage regulator, and

when the second relay is in the second state, the second relay is configured to prevent the first terminal of the first relay from being connected to the input terminal of the voltage regulator.

8. A method of operating a HVAC alternator comprising:

providing a voltage to a voltage regulator of the alternator; and

when an output voltage of the alternator exceeds a high-threshold of safe operation, preventing the voltage from being provided to the voltage regulator.