HK1132852A - System for control of lights and motors - Google Patents

Description

Control system for light and motor

RELATED APPLICATIONS

This application claims priority to commonly assigned U.S. provisional application No.60/687,689, entitled "same as this application," filed 6/2005, the entire contents of which are hereby incorporated by reference.

Technical Field

The present invention relates to a device for independently controlling a motor, such as a fan motor, and a light source, which is included in the same housing as the motor and is coupled to the motor. The invention also relates to a communication scheme for communicating over a power line to control loads such as a fan motor and lights.

Background

It is often desirable to include both the lamp and the fan motor in a single housing. Since the lamp and the fan motor are usually connected in parallel, the lamp and the fan motor are usually controlled together by a switch remote from the lamp and the motor. Fig. 1A shows a prior art light and fan motor control system 10. The system 10 includes a persistent switch 12 coupled between an Alternating Current (AC) voltage source 14 in a housing 19 and two loads, namely a fan motor 16 and a lighting load 18. The fan motor 16 and the lighting load 18 are connected in parallel such that when the switch 12 is closed, both the fan motor 16 and the lighting load 18 are on, and when the switch 12 is open, both the fan motor 16 and the lighting load 18 are off.

There are also a number of solutions for independent control of the fan motor and lighting load from a remote location, such as a wallstation. FIG. 1B shows a prior art light and fan motor control system 20 having a dual light and fan speed control 22 coupled to an AC voltage source 14. The dual light and fan speed control 22 has two outputs: a first output coupled to the fan motor 16 and a second output coupled to the lighting load 18 to provide independent control of the load. Also, the dual light and fan speed control 22 includes a fan speed circuit to adjust the speed at which the fan motor 16 rotates and a dimmer circuit to vary the intensity of the lighting load 18. The dual light and fan speed control 22 is typically housed in a standard electrical wallbox (electric wallbox) and includes a user interface for allowing a user to independently control the lighting load and the fan motor.

However, the dual light and fan speed control 22 requires two separate wires to be connected between the lamp and the fan motor. If these two connections cannot be made between the wall box and the housing containing the lamp and the fan motor, independent control of the lighting load 18 and the fan motor 16 would not be possible. Also, in the control system 20 of FIG. 1B, only one dual light and fan speed control 22 is possible, and thus, only one user interface is possible to effect adjustments to the intensity of the lighting load 18 and the speed of the fan motor 16. Control of the fan motor 16 and the lighting load 18 from more than one location is not possible in this system.

Fig. 1C shows a prior art Power Line Carrier (PLC) control system 30. Power line carrier control systems utilize power system wiring to transmit high frequency control signals (i.e., line frequencies much greater than 50Hz or 60 Hz). All devices of the PLC system 30 are coupled across the AC power source 32 (from hot side to neutral side) to receive power and information from the same wiring. The system 30 includes a PLC fan motor controller 34 coupled to a fan motor 36, a PLC lighting controller 38 coupled to a lighting load 40, and a remote control keypad 42. The remote control keypad 42 is used to transmit messages over the power lines to the PLC fan motor controller 34 and the PLC lighting controller 38 to control the respective loads. One example of a communication protocol employing power line carrier technology for a home automobile is industry standard X10. The X10 protocol employs voltage carrier technology (voltage carrier technology) to transmit messages between devices connected to a power system. By the voltage carrier technique, messages are transmitted on a reference voltage signal between the hot terminal and the neutral connection of the AC power supply 32 or between the hot terminal and a ground terminal of the AC power supply 32. Devices in the X10 system communicate using a house address (house address) and a cell address.

However, the existing power line carrier system has some limitations. For example, all devices in a PLC system require a neutral connection. Meanwhile, since the X10 protocol utilizes a voltage carrier technology, communication messages are transmitted through the power system, and communication signals are also difficult to isolate from other devices connected to the power system. Finally, the X10 protocol is not a "reliable" communication scheme since no acknowledgement message is sent to the transmitting device when the receiving device receives an invalid message.

Thus, there is a need to provide a reliable means of remotely controlling the fan motor and lighting load independently in the same housing. Since a user may wish to place the fan motor and attached lamp in a location where there was previously only one lamp, which was controlled by a standard Single Pole Single Throw (SPST) wall switch, it is also desirable to be able to use a two wire control device to independently control the fan motor and attached lamp. A two-wire device is a control device with only two electrical connections, i.e. one electrical connection for the AC mains voltage and the other electrical connection for the fan/lamp, and which has no neutral line connection. As shown in fig. 1A, such systems typically include only a switch 12 electrically connected in series between an AC power source 12 and a load, and no neutral connection is made in the electrical wallbox in which the switch is installed. Because of the need to employ existing building wiring (building wiring) for independent control of the fan motor 16 and lighting load 18, it is necessary to develop a device that enables independent control through existing building wiring consisting of a single wire that connects a wall controller, i.e., a dual light and fan speed control 22, to the housing of the fan motor 16 and lighting load 18.

Systems known in the art provide a coding/communication scheme for independently controlling the fan motor and the lamp. However, many of these systems are unreliable, are unstable to operation, are noisy, and require a neutral connection. There is a need to provide a simple and reliable communication scheme for independently controlling the fan motor and the lamp without the need for a neutral connection.

Disclosure of Invention

The present invention provides a system for communicating between a first control circuit portion and a remote second control circuit portion over the power wiring of a building. The first control circuit portion has a user executable control (user operable control) for remotely controlling the electrical load controlled by the second control circuit portion. The system includes a transmitter in a first circuit portion and a receiver in a second circuit portion. A transmitter in the first circuit portion is for transmitting control information to the second circuit portion over the power wiring, and a receiver in the second circuit portion is for receiving control information for controlling the load transmitted by the first circuit portion over the power wiring. The first and second circuit portions each include a current responsive element coupled to the building power wiring to establish a current signal loop in the building power wiring between the first and second control circuit portions to exchange control information. The electrical load preferably comprises an electric motor.

The invention further provides a two wire load control system for controlling power delivered to an electrical load from an AC voltage source. The two-wire load control system includes a load control device and a two-wire remote control device. The load control device is coupled to the electrical load for controlling the load. The load control device includes a first current responsive element operatively coupled in series electrical connection between an AC power source and an electrical load, and a first communication circuit coupled to the first current responsive element to receive a message signal. The two-wire remote control device includes a second current responsive element operatively coupled in series electrical connection between the AC power source and the electrical load, and a second communication circuit coupled to the second current responsive element for transmitting the message signal. The first and second current responsive elements are for conducting a communication loop current. The first communication circuit is configured to transmit a message signal via the communication loop current, and the second communication circuit is configured to receive the message signal via the communication loop current. Preferably, the first and second communication circuits are each for transmitting and receiving the message signal over the communication loop current.

According to another embodiment of the present invention, a two-wire load control system for controlling power delivered from an AC voltage source to a plurality of electrical loads includes a load control device, a two-wire remote control device, and a capacitor electrically connected in parallel with the plurality of loads. The plurality of loads and the AC voltage source are coupled together at a common neutral connection. The load control device is coupled to the plurality of loads and is configured to independently control each of the plurality of loads. The load control device includes a first current responsive element electrically connected in series between an AC power source and the plurality of loads, and a first communication circuit coupled to the first current responsive element to receive a message signal for controlling the plurality of loads. The two-wire remote control device includes a second current responsive element electrically connected in series between the AC power source and the plurality of loads, and a second communication circuit coupled to the second current responsive element for transmitting a message signal for controlling the plurality of loads. The capacitor, the AC power source, the first current responsive element, and the second current responsive element are for conducting a communication loop current. The second communication circuit is used for transmitting a communication signal to the first communication circuit through the communication loop current.

The invention further includes a method for communicating between a first control circuit portion having a first current responsive element and a remote second control circuit portion having a second current responsive element through the power wiring of a building to control the operation of a motor, the first control circuit portion having a user-executable control for remotely controlling the motor controlled by the second control circuit portion, the method comprising the steps of: (1) coupling the first current responsive element to the power wiring; (2) coupling the second current responsive element to the power wiring; (3) establishing a current signal loop in the power wiring between the first and second current responsive elements; (4) transmitting control information from the first control circuit portion to the second control circuit portion through the power wiring; and (5) receiving a control signal at the second circuit portion to control the motor.

Further, the present invention provides a method for transmitting digital messages from a two-wire remote control device to a load control device for independent control of power delivered from an AC voltage source to a plurality of loads. The method comprises the following steps: (1) electrically connecting the two-wire remote control device in series between an AC power source and a load control device; (2) electrically connecting a capacitor in parallel to both ends of the plurality of loads; (3) conducting a communication loop current through the AC power source, the two-wire remote control device, the load control device, and the capacitor; and (4) transmitting the digital message from the two-wire remote control device to the load control device over a current loop.

The present invention further provides a method for assigning a system address to a control device in a load control system to control power delivered to an electrical load from an AC voltage source. The method comprises the following steps: (1) electrically connecting the control device in series between the electrical load and the AC voltage source through the power wiring such that a load current may flow from the AC voltage source through the control device to the electrical load through the power wiring; (2) applying power to the control device; (3) subsequently transmitting an address initiation request over the power wiring; and (4) receiving a system address through the power wiring.

In accordance with another aspect of the present invention, a method of filtering a received message signal having a sequence of samples includes the steps of: (1) examining a set of N-sequence samples of the received message signal; (2) determining a median value of the N sequence of samples; (3) providing the median as an output sample; and (4) repeating the steps of testing a set of N series samples, determining a median value, and providing a median value.

Also, the present invention provides a method of transmitting a message signal from a first control device to a second control device. The message signal comprises a sequence of samples. The method comprises the following steps: (1) transmitting the message signal from a first control device; (2) receiving the message signal at a second control device; (3) examining a set of N-sequence samples of the received message signal; (4) determining a median value of the N sequence of samples; (5) providing the median as an output sample; and (6) repeating the steps of testing a set of N series samples, determining a median value, and providing a median value.

Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.

Drawings

The invention will be described in more detail with reference to the accompanying drawings, in which:

FIG. 1A is a simplified block diagram of a prior art electric light and motor control system;

FIG. 1B is a simplified block diagram of a prior art lamp and motor control system including dual light and motor speed control;

FIG. 1C is a simplified block diagram of a prior art power line carrier control system for controlling an electric motor and an electric light;

FIG. 2 is a simplified block diagram of a system for controlling an electric lamp and a motor in accordance with the present invention;

fig. 3 is a simplified block diagram of a wallstation of the system of fig. 2;

FIG. 4 is a simplified block diagram of the light/motor control of the system of FIG. 2;

fig. 5A shows a first example of the system of fig. 2 showing a current loop for communication between the wallstation and the light/motor control unit;

FIG. 5B illustrates a second example of a system for independently controlling a lighting load and a motor load to indicate an optimal communication loop current;

FIG. 5C is a simplified block diagram of a system for controlling multiple loads according to another embodiment of the present invention;

FIG. 6A shows an example of waveforms for the system of FIG. 2;

FIG. 6B shows a portion of a transfer message of the system of FIG. 2;

FIG. 7 shows a simplified block diagram of the communication circuit of the system of FIG. 2;

FIG. 8 shows a simplified flow diagram of the flow of a receiver program (receiverroute) implemented in the controller of the system of FIG. 2;

9A, 9B and 9C show waveforms illustrating the operation of the median filter of the receiver program of FIG. 8;

FIG. 9D is a simplified flow diagram of the flow of the median filter of the receiver routine of FIG. 8; and

fig. 10A and 10B show a simplified flow chart of the automatic address algorithm of the system of fig. 2.

Detailed Description

The foregoing summary, as well as the following detailed description of preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings an embodiment that is presently preferred, in which like numerals represent similar parts throughout the several views of the drawings. It should be understood, however, that the invention is not limited to the particular methods and instrumentalities disclosed.

It is well known that the lamp and the fan motor are usually encased in the same housing (housing). It is desirable to be able to independently control the lamp and the fan motor from the same remote location, such as by a wallstation. However, the two circuits used to control the lamp and the fan motor are typically different. The lamp is controllable by a series switch, usually by a phase angle dimmer. The fan MOTOR may be controlled by a parallel switch in parallel with the fan MOTOR, as disclosed in commonly assigned co-pending U.S. patent application entitled "METHOD AND DAPPARUTUS FOR QUIET VARIABLE MOTOR SPEED CONTROL" filed on 6.2006, U.S. Pat. No.04-11701-P2, the entire contents of which are incorporated herein by reference.

A block diagram of a system 100 for independently controlling light and a fan motor according to the present invention is shown in fig. 2. The system includes a plurality of wallstations 104 connected in series between an AC voltage source 102 and a light/motor control unit 105 by building power wiring to form a power loop. The light/motor control unit 105 is used to control the speed of the fan motor 106 and the intensity of the lighting load 108. The fan motor 106 and the lighting load 108 are preferably both mounted in a single housing 109 (sometimes referred to as a "cover").

In the system 100 of fig. 2, it is desirable to provide substantially all of the AC voltage from the AC voltage source 102 to the light/motor control unit 105 for operation of the fan motor 106 and the lighting load 108. Since the wallstations 104 are in series electrical connection, it is desirable to minimize the voltage drop across each wallstation 104. Thus, it is not desirable to apply a significant voltage across each wallstation 104 in order to charge the internal power source to power the low voltage circuitry of the wallstation.

A simplified block diagram of the wallstation 104 is shown in fig. 3. The power supply 110 is connected in series between the first electrical terminal H1 and the second electrical terminal H2. The power supply 110 provides a Direct Current (DC) voltage, Vcc, to power the controller 112 and the communication circuit 116. The operation of the POWER SUPPLY 110 is described in more detail in commonly assigned co-pending U.S. patent application serial No. 05-12142-P2 entitled POWER SUPPLY FOR a LOAD CONTROL DEVICE, filed on 6.6.2006, which is incorporated herein by reference in its entirety.

The controller 112 is preferably a microcontroller, but may be any suitable processing device, such as a Programmable Logic Device (PLD), a microprocessor, or an Application Specific Integrated Circuit (ASIC). The user interface 114 includes a plurality of buttons for receiving input from a user and a plurality of Light Emitting Diodes (LEDs) for providing visual feedback to the user. The controller 112 receives control inputs from the buttons of the user interface 114 and controls the operation of the LEDs. The operation of the LED is described in more detail in commonly assigned, co-pending U.S. patent application 11/191,780 entitled "APPARATUS AND METHOD FOR DISPLAYING operation ON STATUS INDICATORS", filed ON 28.7.2005, the entire contents of which are incorporated herein by reference.

The controller 112 is coupled to the communication circuitry 116 to transmit control information to and receive control information from the light/motor control unit 105 and other wallstations 104 of the system 100. The communication circuitry 116 transmits and receives the control information via the communication transformer 118 over the power wiring coupled from the AC voltage source 102 to the wallstation 104 and the light/motor control unit 105. The communications transformer 118 has a primary winding 118A electrically connected in series with terminals H1 and H2 of the wallstation 104, and a secondary winding 118B coupled to the communications circuit 116.

The wallstation 104 further includes an air gap switch 117 in series with the power supply 110. When the air-gap switch 117 is open, all devices of the system 100 are powered down because all devices of the system 100 are coupled in the power loop. To ensure safety when servicing a load, i.e. replacing the bulb cover, the wallstation 104 is preferably coupled to a hot wire (hot line) of the power wiring so that it is not provided to the cover when the air gap switch 117 is open. However, the wallstation 104 may also be coupled to a neutral.

A simplified block diagram of the light/motor control unit 105 is shown in fig. 4. The light/motor control unit 105 includes a HOT (HOT) terminal H, a neutral terminal N, a dimmed HOT (dimmed HOT) terminal DH connected to the lighting load 108, and a fan motor HOT terminal MH connected to the fan motor 106. The light/motor control unit 105 includes a dimmer circuit 150 for controlling the intensity of the lighting load 108 and a fan motor control circuit 152 for controlling the speed of the fan motor 106. The dimmer circuit 150 utilizes semiconductor switches (not shown) to control the amount of current conducted to the lighting load 108, and thus the intensity of the lighting load. The on-time of the semiconductor switch is controlled by the controller 154 using standard phase-control dimming techniques well known to those skilled in the art.

The motor voltage detection circuit 156 determines the zero crossing of the motor voltage across the fan motor 106 and provides a control signal to the controller 154, and the controller 154 operates the fan motor control circuit 152 accordingly. The zero-crossing of the motor voltage is defined as the time at which the motor voltage changes from positive to negative or negative to positive at the beginning of each half-cycle of the motor voltage. The operation of the fan motor control circuit 152 with the motor voltage detection circuit 156 is described in more detail in the aforementioned U.S. patent application attorney docket number 04-11701-P2.

The controller 154 is coupled to a communication circuit 158, which communication circuit 158 transmits and receives control information over the power wiring via a communication transformer 160. The communication transformer 160 is a current transformer having a primary winding 160A connected in series with the hot terminal H of the electro-mechanical/optical control unit 105 and a secondary winding 160B coupled to the communication circuit 158.

A power supply 162 is coupled to the load side of the communication transformer 160 and generates a DC voltage Vcc to power the controller 154 and other low voltage circuitry. Two diodes 164A and 164B are provided so that the power supply is used to charge only during the positive half cycle. The power supply 162 preferably includes a capacitor (not shown) having a capacitance value of about 680 muf. Capacitor 165 is coupled between the cathode of diode 164A and neutral terminal N and preferably has a capacitance value of 2.2 μ F.

A capacitor 166 is connected in parallel with power supply 162 between the load terminal of communication transformer 160 and the cathode of diode 164A. The capacitor 166 completes the communication loop with the wallstation 104 and isolates the communication transformer 160 from the high impedance of the fan motor 106, especially when the fan motor 106 is off. The capacitor 166 is sized to deliver a loop current carrier signal modulated with the control information while also blocking 50/60 cycles of power from the AC voltage source 102. The capacitor 166 preferably has a capacitance value of 10 nF.

A zero crossing detection circuit 168 is coupled between the load terminal and the neutral terminal N of the communications transformer 160 for providing a signal representative of the zero crossing of the AC voltage source 102 to the controller 154. The zero-crossing of the AC voltage is defined as the time at which the AC voltage transitions from positive to negative or negative to positive at the beginning of each half-cycle of the AC voltage source 102. The controller 154 determines when to turn on or off the semiconductor switches of the dimmer circuit 150 every half cycle by timing from each zero-crossing of the AC supply voltage.

The control system 100 preferably uses current-carrier technology for communication between the wallstation 104 and the light/motor control unit 105. Fig. 5A shows a first example of a system 100 for independently controlling a lighting load 108 and a fan motor 106, the lighting load 108 and fan motor 106 illustrating a current loop 172 for communicating between the wallstation 104 and the light/motor control unit 105. The load current for powering the lighting load 108 and the fan motor 106 flows through the primary winding 118A of the communications transformer 118 of the wallstation 104 and the primary winding 160A of the communications transformer 160 of the light/motor control unit 105. Since the AC voltage source 102, wallstation 104, and light/motor control unit 105 are all located at different locations, a portion of the building power wiring 170 exists between these system elements. The communication loop current 172 flows through the AC voltage source 102, the communication transformer 118 of the wallstation 104, the communication transformer 160, and the capacitors 165 and 166 of the light/motor control unit 105. The capacitor 161 completes the communication loop and isolates the communication loop from the fan motor 106. The isolation is necessary because of the high impedance that the fan motor 106 has when it is off, and because the inductive nature of the fan motor causes a decay in the communication loop current 172.

After the controller 112 receives user actuation control information from the actuation buttons of the user interface 114 (fig. 3), the communication circuit 116 transmits a communication message from the controller via the communication transformer 118, the communication transformer 118 coupling the control information to the hot wire. Since the same current flows through the primary winding 118A of the transformer 118 in the wallstation and the primary winding 160A of the transformer 160 in the light/motor control unit 105, the communication loop current 172 inductively generates an output message on the secondary winding 160B of the transformer 160. The output message is received by the communication circuit 158 of the light/motor control unit 105 and then provided to the controller 154 to control the fan motor control circuit 152 and the dimmer circuit 150.

Fig. 5B illustrates an example of a second system 180 for independently controlling the lighting load 108 and the fan motor 106 that indicates that the lighting load 108 and the fan motor 106 do not have an optimal communication loop current 182 flowing through the AC voltage source 102, the fan motor 106, or the lighting load 108. It is noted that in this configuration, the hot side of the AC voltage source 102 is provided at the hood, i.e., at the mounting enclosure 109 (fig. 2) of the fan motor 106 and the lighting load 108. The system 180 comprises a light/motor control unit 184, which light/motor control unit 184 comprises an additional communication terminal C and a capacitance 186 coupled between said terminal C and a neutral terminal N. In the layout of system 180, terminal C is connected to the hot terminal of AC voltage source 102 to complete the communication loop through capacitor 186 so that communication loop current 182 does not flow through AC voltage source 102. The capacitor 186 is used to terminate the communication loop, thereby preventing data from passing between the wallstation 104 and the light/motor control unit 184 when entering the power system. The capacitor 186 is sized to transmit a loop current carrier signal containing control information while also blocking 50/60 cycles of power from the AC voltage source. The capacitor 186 preferably has a capacitance value of 10 nF.

Fig. 5C is a simplified block diagram of a system 189 for controlling multiple loads according to another embodiment of the present invention. The three light/motor control units 105 are electrically connected in parallel. Each light/motor control unit 105 is coupled to a fan motor (not shown) and/or a lighting load (not shown). A communication loop current 189 flows through the wallstation 104 and communication currents 189A, 189B, and 189C flow through each of the opto/electromechanical control units 105. The magnitude of each of the communication currents 189A, 189B, and 189C is about one-third the magnitude of the communication current 189. Each wallstation 104 is used to control all fan motors to be consistent and all lighting loads to be consistent. If the air gap switch 117 of any of the wallstations 104 is opened, power is removed from all of the wallstations 104 and the light/motor control unit 105 on the loop.

The message information may be modulated on the hot wire in any suitable modulation method, such as Amplitude Modulation (AM), Frequency Modulation (FM), Frequency Shift Keying (FSK), or double phase shift keying (BPSK). Fig. 6A shows an example of transmitted and received signals of the control system 100. The transmission message signal 190 is provided by, for example, the controller 112 to the communication circuitry 116 of the wallstation 104. The transmission message signal 190 is modulated on a carrier wave, e.g., frequency modulated on a carrier wave, by the communication circuit 116 to produce a modulated signal 191. The modulated signal 191 is susceptible to noise during transmission and, thus, a noise modulated signal 192 (which includes some noise 192A) is received by the communication circuitry 158, e.g., the light/motor control unit 105. Accordingly, the communication circuitry 158 may provide a noise demodulation message 193 to the controller 154 of the light/motor control unit 105. To avoid generating noisy demodulated messages 193 and to obtain desired received messages 194, a suitable method for modulation, demodulation, and filtering is provided in accordance with the present invention (described in more detail below).

According to fig. 6B, the transmission message signal 190 has three parts: a preamble 196, a synchronization code 197, and a message code 198. The preamble 196 is a kilobits (kbits) in length and is used to coordinate demodulation and decoding of the received signal. The synchronization code 197 is an orthogonal pseudorandom code with low cross-correlation and is n bits (n bits) in length that all devices in the loop of the system 100 attempt to detect in real time. The synchronization code also serves as an address. The presence of the synchronization code indicates that its subsequent message code 198 contains a message. Finally, the message code 198 is a forward error correction code, m bits long (m bits), and is received after the synchronization code. The bitstream is not decoded in real time but is passed to a message parser.

Fig. 7 shows a simplified block diagram of the communication circuitry 158 of the electro-mechanical/optical control unit 105. The communication circuit 158 is coupled to a transformer 160, which transformer 160 together with a capacitor 202 is used as a tuning filter for transmitting substantially only signals having a frequency substantially at the transmission frequency of the modulated signal 192, i.e. between 200kHz and 300 kHz. The voltage across the capacitor 202 is provided to a voltage clamp 204 (voltagecamp) for protection at transient high voltages. Demodulator 206 receives modulated message signal 192 and generates a demodulated received message signal 193 using standard demodulation techniques known to those skilled in the art. The demodulated message signal 193 is provided to the receiver program 208 of the controller 154, which controller 154 will be described in more detail below with reference to fig. 8.

Fig. 7 also shows a transmitter portion of the communication circuitry 158. The controller 154 executes the code generator 210 to generate the synchronization code 197 and the message code 198 of the transmitted message 190. Alternatively, the controller 154 may use a look-up table (look-up table) to generate the synchronization codes 197 and message codes 198 based on the required information transmitted to control the fan motor 106 and the lighting load 108.

In a preferred embodiment, the encoded signal is thereafter encoded in Manchester encoder 212. With manchester encoding, a bit of data is represented as a transition from a high state to a low state or vice versa, as is well known to those skilled in the art. Although manchester encoding has been shown, other digital encoding schemes may be used. The encoded signal is then modulated on a carrier by a modulator 214 using a modulation method such as AM, FM, or BPSK. After amplification by the power amplifier 218, the modulated signal is coupled to a tuned filter (including the capacitor 202 and the transformer 160) and transmitted as a current signal on the hot wire. The communications circuitry 158 of the electro-mechanical/optical control unit 105 as described above and illustrated by fig. 7, the communications circuitry 116 of the wallstation 104 would have the same implementation.

Fig. 8 shows a simplified block diagram of a process of the receiver program 208 implemented in the controller 154. The demodulated signal 193 (i.e., the input to the receiver program 208) is first filtered by the pipeline multi-pass median filter 220. The waveforms shown in fig. 9A, 9B and 9C illustrate the operation of the median filter 220. Fig. 9A shows an example of an original manchester encoded stream 250, i.e., the stream generated by manchester encoder 212 of controller 154 prior to transmission, of manchester encoded stream 250.

The original manchester encoded stream 250 may be corrupted by noise during transmission such that the noisy manchester encoded stream 252 (with noise pulses 252A) shown in fig. 9B is provided to the controller of the receiving device. The amplitude of the transmitted current carrier signal (about 5mA) is much smaller than the amplitude of the current used by the lighting load 108 and the fan motor 106 (about 5A). Since the semiconductor switches of the dimmer circuit 150 employ phase-control dimming to control the power delivered to the lighting load 108, large current pulses through the lighting load 108 are included in the communication transformers 118 and 160. These large current pulses cause damage to the modulated signal 191 and are detected as binary impulse noise in the demodulated bit stream. This is shown in noisy manchester encoded stream 252 by a plurality of noise pulses 252A, which plurality of noise pulses 252A are not in the original manchester encoded stream 250.

Most types of interference will only cause momentary shifts in the detection threshold. The resulting signal is very similar to digital scattering noise and statistically similar to a "random reporter's waveform". Thus, it is instantaneous in nature and can be modeled as the first order (first order) of the poisson process.

The median filter 220 is used to remove noise interference to produce a filtered manchester encoded stream 254 as shown in fig. 9C. The median filter 220 is ideally suited to filter the binary stream as shown in fig. 9B. The median filter of order N has a sliding window of width W samples defined by:

w is 2N + 1. (equation 1)

The median filter 220 holds any "root signal" that passes through the window. A root signal is defined as any signal having a constant region of N +1 points or more with a single growing or decreasing boundary. By this definition, the root signal cannot contain any pulses or vibrations, i.e. signals having a width smaller than N + 1. When the corrupted binary signal passes through the median filter, the filter removes the pulse in the region where the signal should be a binary 0 or a binary 1.

Fig. 9D is a simplified block diagram of a median filter according to the present invention. The median filter 200 checks W samples of the corrupted manchester encoded stream 252 at one time instant. For the third order median filter, seven samples were examined as follows

W_(N＝3)2N + 17. (equation 2)

After the median filter 220 has completed processing the previous W samples, it discards the nth sample, i.e., the first of the W samples received by the median filter at step 260. In step 262, the median filter 220 shifts up the samples, leaving the first of the W samples empty and enabling it to receive new samples. In step 266, the median filter 220 receives a new input sample 264 from the corrupted manchester encoded stream 252 and moves that sample into the first position of the W sample sequence.

Then, in step 268, the median filter 200 determines the median of the W samples. According to the first embodiment of the present invention, the median filter 200 groups (i.e., arranges in order) 1's and 0's of W samples and determines the values of the intermediate samples. For example, if the current W samples are

1011001，

The median filter 220 will group these 1's and 0's to form a sorted sample stream

0001111。

The median value of this sorted sample stream is 1 because its median or median value is 1.

According to the second embodiment of the present invention, in step 268, the median filter 220 counts the number of 1's in the W samples to determine the median thereof. For the nth order median filter, if the count of 1 is greater than or equal to the value of N +1, its median is 1. Otherwise, the value is 0. Thus, for the third order median filter, if there are four 1 s in the W samples, then its median is equal to 1. Thus, the width W of the median filter 220 must always be odd, i.e., 2N + 1. The median filter 220 is preferably implemented as a look-up table that counts 1's, returns a 1 if the count is greater than or equal to N +1, and returns a 0 otherwise. By using the look-up table, the filtering process is completed in several instruction cycles, thus making the calculations on the microcontroller exceptionally fast.

Finally, in step 270, the median filter 220 provides the median determined in step 268 as the output sample 272 to form the filtered Manchester encoded stream 254 (as shown in FIG. 9C). The median filter 220 removes noise pulses 252A from the corrupted manchester encoded stream 252. As a result of the filtering, the rising and falling edges of the filtered Manchester encoded stream 254 may occur at different times than the rising and falling edges of the original Manchester encoded stream 250. Since data is encoded in Manchester encoded stream 250 by generating a rising edge or a falling edge during a predetermined time, it is not critical that rising and falling edges be generated in filtered Manchester encoded stream 254 when decoding. It is only important to remove the false rising and falling edges from the encoded stream.

Referring to FIG. 8, after one or more passes through the median filter 220, the signal passes through a Manchester decoder 222 to generate a digital bit stream from the received Manchester encoded bit stream. The decoded signal and the pseudo-random orthogonal synchronization code 224 are supplied to a cross correlator 226. The output of the cross correlator 226 is integrated by an integrator 228 and provided to a threshold detector 230. This process occurs in real time with the output of the receiver program 208 being updated at the bit rate of the sequence.

In cross correlator 226, the bit stream from manchester decoder 222 and pseudorandom orthogonal synchronization code 224 are input to an exclusive nor (XNOR) logic gate. The number of 1's in the output of the XNOR gate is counted for integration in integrator 228. A look-up table is used to count 1's during the integration process. Since the codes are orthogonal, unless the codes match, the correlation will be small. The agreement need not be a complete agreement, but only approximately, such as 75% agreement.

If the synchronization code is detected in step 232, the next M decoded bit from Manchester decoder 222 (i.e., message code 198) is saved in step 234. Forward error correction message code 236 is then compared to the M decoded bits to find the best match to determine the instruction of step 238 and executed in step 240. This step is known as the most approximate decoding and is well known to those skilled in the art. If the synchronization code is not detected, the data is lost and the process exits in step 232.

Upon receiving the decoded message, the controller will transmit an Acknowledgement (ACK) to the device that sent the received message. The ACK is sent to facilitate a reliable communication scheme.

The devices in system 100 for independently controlling the lamp and fan motor each communicate using a system address. To establish the system address used, the wallstation 104 and the light/motor control unit 105 execute an auto-addressing algorithm in the case of power supply. Fig. 10A and 10B show simplified block diagrams of the auto-addressing algorithm.

Since the devices in the system 100 are connected in a loop topology, it is possible to have all devices powered at the same time by toggling (i.e., opening and then closing) the air gap switch 117 of one of the wallstations 104. After power is applied in step 300, the devices in the system 100 will enter an addressing mode in step 302, which means that the devices are adapted to join the addressing algorithm and will communicate with other devices of the system by using the broadcast system address 0. In the addressing mode, the devices use a random backoff time on transmission to minimize the possibility of collisions due to the possible presence of many unaddressed devices in the system. After a suitable timeout period, e.g. 20 seconds, the device leaves the addressing mode.

First, in step 304, the current device determines whether all devices in the system have a system address. In particular, after power-on, all devices that do not have a system address will transmit an address initiation request. In step 304, the device waits a predetermined amount of time to determine whether to transmit any address initiation requests. If, in step 304, the device determines that all devices in the system have a system address, then, in step 306, the device transmits the system address to all devices.

If all devices in the system do not have a system address in step 304, the current device transmits a query message to each device in step 308. The devices in the system will respond to the inquiry message by transmitting the system address and its device type (i.e., wallstation 104 or light/motor control unit 105). In step 310, the current device determines whether the system 100 is an "active" system. An active system includes at least one wallstation 104 and at least one light/motor control unit 105 and does not have more than one system address, i.e., no two devices in the system have different system addresses. If the system is a valid system in step 310, the current device determines whether all devices in the system 100 have system addresses in step 312. If at least one device has a system address, the current device saves the received address as the system address in step 314 and transmits the received address in step 316.

In step 312, if no device has a system address, the current device attempts to select a new system address. In step 318, the device selects a random address M, i.e. an address randomly selected from the allowed addressing, as a system address alternative. For example, there may be 15 possible system addresses, i.e., 1 to 15. Since there may be a neighboring system that already has an assigned address M, the device transmits a "ping", i.e. a query message, and verifies the availability of this address using address M in step 320. If in step 322 any device responds to the ping, i.e. the address M has been allocated, the device starts to step through all available system addresses. If all available system addresses have not been tried in step 324, the device selects the next available address in step 326 (e.g., by adding a system address alternative) and transmits another ping in step 320. Otherwise, the process exits. Once the appropriate address M is verified as available, i.e., no device response in step 322, the current device sets the system address alternative as the system address in step 328 and transmits the address M on broadcast channel 0 in step 316. Thus, all unaddressed devices that are in addressing mode then save the address M as a system address. The process is then exited.

If the system 100 is not a valid system in step 310, all system devices currently having a system address exit the addressing mode in step 330. If the address assignment is made only once in step 332, the device transmits another query message in step 308. Otherwise, the process exits.

Address reset is included as a recovery method that performs address reselection for all devices in the system 100. Upon power-up, i.e., when all devices in the system are in the addressing mode, the user may enter a particular key sequence through the user interface 114 of the wallstation 104. Upon receiving this input from the user interface 114, the controller 112 of the wallstation 104 transmits a message signal containing a "reset address" instruction to all devices over the power wiring. When a device in addressing mode receives the reset address instruction, the device will self-set to a no address state, i.e. the device will only respond to messages transmitted at broadcast system address 0 when in addressing mode. The address assignment algorithm then continues to run as if all devices in the system 100 did not have a system address.

Although "device" and "unit" are used to describe the elements of the system for controlling the lamp and fan motor of the present invention, it should be noted that each of the "device" and "unit" described herein need not be entirely contained within a single housing or structure. For example, the light/fan motor control unit 105 may include a controller in a wall-mounted device and a fan motor control circuit in a separate location, for example, in the housing of the fan motor and electric light. Likewise, one "device" may also be included in another "device".

Although the present invention has been described in conjunction with specific embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. Accordingly, the invention is not limited by the specific disclosure herein, but only by the appended claims.

Claims (50)

1. A system for communicating between a first control circuit portion and a remote second control circuit portion over building power wiring, the first control circuit portion having user-executable controls for remotely controlling electrical loads controlled by the second control circuit portion, the system comprising:

a transmitter in the first circuit portion for transmitting control information to the second circuit portion through the power wiring;

a receiver in the second circuit portion for receiving the control information for controlling a load transmitted by the first circuit portion through the power wiring; and wherein

The first and second circuit portions each include a current responsive element coupled with the building power wiring for establishing a current signal loop in the building power wiring between the first and second control circuit portions for exchanging the control information, and wherein the electrical load includes an electrical machine.

2. The system of claim 1 wherein each of said current responsive elements comprises a current transformer having a winding coupled with said building power wiring for establishing a current signal loop in said building power wiring between said first and second circuit portions for exchanging said control information.

3. The system of claim 2, wherein the transmitter provides a modulated carrier signal onto the signal loop, wherein the carrier signal is modulated with the control information.

4. The system of claim 3, wherein the receiver receives the modulated carrier signal, demodulates the carrier signal, and generates a detection signal containing the control information.

5. The system of claim 4, wherein the transmitter comprises a code generator for generating the control information in a coded form and a modulator for modulating the coded control information onto the carrier signal.

6. The system of claim 5, wherein the code generator comprises a pseudo-random orthogonal code generator.

7. The system of claim 6, wherein the encoded control information comprises a first portion for providing synchronization data for synchronizing a decoding operation, a second portion containing a synchronization code, and a third portion containing message information for controlling the motor.

8. The system of claim 7, wherein the receiver comprises a median filter for removing an impulse noise signal from the modulated carrier signal.

9. The system of claim 6, wherein the code generator comprises a forward error correction code generator.

10. The system of claim 1, wherein the electrical load further comprises an electric light, the electric light and the electric motor being independently controllable by the control information.

11. A method for communicating over building power wiring between a first control circuit portion having a first current responsive element and a remote second control circuit portion having a second current responsive element to control operation of an electrical load including an electrical machine, the first control circuit portion having a user-executable control for remotely controlling the electrical machine controlled by the second control circuit portion, the method comprising the steps of:

coupling the first current responsive element to the power wiring;

coupling the second current responsive element to the power wiring;

establishing a current signal loop in the power wiring between the first and second current responsive elements;

transmitting control information from the first control circuit portion to the second control circuit portion through the power wiring; and

receiving the control information for controlling the motor at the second circuit portion.

12. The method of claim 11, wherein the step of establishing a current signal loop in building power wiring comprises the steps of:

providing first and second current transformers to said first and second current responsive elements, respectively, said first and second current transformers having windings, respectively; and

coupling the windings of the first and second current transformers to the power wiring.

13. The method of claim 12, wherein the transmitting step comprises the steps of:

modulating a carrier signal with the control information; and

a modulated carrier signal is coupled onto the signal loop.

14. The method of claim 13, wherein the receiving step comprises the steps of:

demodulating the modulated carrier signal; and

and generating a detection signal containing the control information.

15. The method of claim 12, wherein the transmitting step comprises the steps of:

encoding the control information;

modulating a carrier signal with the encoded control information; and

a modulated carrier signal is coupled onto the signal loop.

16. The method of claim 15, wherein the encoding step comprises the steps of:

the control information is encoded with a pseudo-random orthogonal code.

17. The method of claim 16, wherein the encoding step comprises the steps of:

the control information is encoded such that the control information has a first portion for providing synchronization data for synchronizing a decoding operation, a second portion containing a synchronization code, and a third portion containing message information for controlling the motor.

18. The method of claim 17, wherein the receiving step comprises the steps of:

median filtering the modulated carrier signal at the second control circuit portion to remove impulse noise signals from the modulated carrier signal.

19. The method of claim 15, wherein the encoding step comprises encoding the control information as a forward error correction code.

20. The method of claim 12, wherein the electrical load further comprises an electric lamp, the method further comprising the steps of:

the motor and the electric lamp are independently controlled with the control information.

21. A load control system for controlling power delivered to an electrical load from an ac voltage source, the system comprising:

a load control device coupled to the electrical load for controlling the load, the load control device comprising a first current responsive element operatively connected in series electrical connection between the ac power source and the electrical load and a first communication circuit coupled with the first current responsive element for receiving a message signal; and

a two-wire remote control device including a second current responsive element operatively electrically connected in series between the ac power source and the electrical load and a second communication circuit coupled with the second current responsive element for transmitting the message signal, the second current responsive element electrically connected in series with the first current responsive element; and

wherein the first and second current responsive elements are for conducting a communication loop current, the first and second communication circuits being for transmitting and receiving the message signal through the communication loop current, respectively.

22. The system of claim 21, wherein the first communication circuit of the load control device and the second communication circuit of the two-wire remote control device are each operable to transmit and receive the message signal through the communication loop current.

23. The system of claim 22, wherein the first current responsive element comprises a first current transformer having a primary winding electrically connected in series between the ac power source and the electrical load and a secondary winding coupled to the first communication circuit; and

the second current responsive element comprises a second current transformer having a primary winding electrically connected in series between the ac power source and the electrical load and a secondary winding coupled to the second communication circuit.

24. The system of claim 23, wherein the first and second communication circuits each include a code generator for generating a coded signal from the message signal using manchester encoding and a modulator for modulating the communication current loop with the coded signal to produce a modulated signal.

25. The system of claim 24, wherein the first and second communication circuits each comprise a demodulator for demodulating the modulated signal to generate a detected encoded signal and a median filter for removing impulse noise signals from the detected encoded signal.

26. The system of claim 22, wherein the load control device is coupled with a plurality of electrical loads, and the load control device is configured to individually control each of the plurality of electrical loads.

27. The system of claim 27, wherein the plurality of electrical loads comprise motors and lamps.

28. The system of claim 22, wherein the electrical load and the ac voltage source are coupled at a common neutral connection, and the load control device is coupled with the common neutral connection.

29. The system of claim 28, wherein the load control device includes a capacitance coupled between the first current responsive element and the common neutral connection such that the communication loop current does not flow through the electrical load.

30. The system of claim 22, wherein the remote control device includes a plurality of status indicators for providing an indication of the status of the electrical load.

31. The system of claim 30, wherein the first and second communication circuits are adapted to transmit and receive status signals.

32. The system of claim 22, wherein the remote control device and the load control device are configured to transmit the message signal using a system address; and

wherein the remote control device and the load control device are to receive the system address in response to supplying power to the remote control device and the load control device, respectively.

33. The system of claim 32, wherein the remote control device comprises an air-gap switch such that when the air-gap switch is open, the power is removed from the remote control device and the load control device, and when the air-gap switch is closed, the power is supplied to the remote control device and the load control device.

34. The system of claim 22, further comprising a plurality of two-wire remote control devices, each of the two-wire remote control devices including a respective current responsive element operatively connected in series electrical connection between the ac power source and the electrical load and a respective communication circuit coupled with the respective current responsive element for transmitting and receiving the message signal.

35. The system of claim 22, further comprising:

a plurality of two-wire remote control devices, each of the two-wire remote control devices including a current responsive element operatively connected electrically in series between the AC power source and the electrical load and a communication circuit coupled with the current responsive element for transmitting the message signal.

36. The system of claim 22, further comprising:

a plurality of load control devices, each of the load control devices coupled to the electrical load for controlling the load, each of the load control devices including a current responsive element operatively connected in series electrical connection between the alternating current power source and the electrical load and a communication circuit coupled with the current responsive element for receiving a message signal.

37. A two-wire load control system for controlling power delivered from an ac voltage source to a plurality of electrical loads, the plurality of loads and the ac voltage source coupled at a common neutral connection, the system comprising:

a load control device coupled to the plurality of loads, the load control device for individually controlling each of the plurality of loads; the load control device includes a first current responsive element electrically connected in series between the ac power source and the plurality of loads and a first communication circuit coupled with the first current responsive element for receiving a message signal for controlling the plurality of loads;

a two-wire remote control device including a second current responsive element electrically connected in series between the ac power source and the plurality of loads and a second communication circuit coupled with the second current responsive element for transmitting message signals for controlling the plurality of loads;

a capacitor electrically connected in parallel with the plurality of loads;

wherein the capacitor, the AC power source, the first current responsive element, and the second current responsive element are to conduct a communication loop current, the second communication circuit to transmit a communication signal to the first communication circuit through the communication loop current.

38. A method for communicating digital messages from a two wire remote control device to a load control device for independent control of power delivered from an ac voltage source to a plurality of loads, the method comprising the steps of:

electrically connecting the two-wire remote control device in series between the AC power source and the load control device;

electrically connecting a capacitor across the plurality of loads in parallel;

conducting a communication loop current via the AC power source, the two-wire remote control device, the load control device, and the capacitance, the loop current having; and

transmitting the digital message from the two-wire remote control device to the load control device over the current loop.

39. The method of claim 32, further comprising the steps of:

independently controlling each of the plurality of loads in response to the digital message.

40. A method for assigning a system address to a first control device in a load control system to control an amount of power delivered from an ac voltage source to an electrical load, the method comprising the steps of:

electrically connecting the first control device in series between the electrical load and the ac voltage source through an electrical wiring such that a load current flows from the ac voltage source to the electrical load via the first control device through the electrical wiring;

electrically connecting a second control device in series between the electrical load and the alternating voltage source through an electrical wiring, the second load control device being connected in series with the first control device such that the load current flows from the alternating voltage source to the electrical load through the electrical wiring via the second control device;

supplying power to the first and second control devices;

subsequently transmitting an address initiation request over the power wiring; and

receiving the system address through the power wiring.

41. The method of claim 40, further comprising the steps of:

selecting a random address as the system address;

subsequently storing the random address as the system address in a memory; and

transmitting the system address through the power wiring.

42. The method of claim 41, further comprising the steps of:

transmitting a query message over the power wiring using the random address; and

determining whether the second control device responds to the query message.

43. The method of claim 40, further comprising the steps of:

storing the system address in a memory in response to the step of receiving the system address.

44. The method of claim 40, further comprising the steps of:

determining whether the control device has the system address stored in memory; and

the system address is then transmitted over the power wiring.

45. The method of claim 40, further comprising the steps of:

entering an addressing mode in response to said step of supplying power to the control device.

46. The method of claim 45, further comprising the steps of:

exiting the addressing mode after a predetermined time after the step of entering the addressing mode.

47. A method of transmitting a message signal from a first control device to a second control device, the message signal comprising a sequence of samples, the method comprising the steps of:

transmitting the message signal from the first control device;

receiving the message signal at the second control device;

examining a set of N-sequence samples of the received message signal;

determining a median of the N sequence of samples;

providing the median as an output sample; and

repeating the steps of testing a set of N series samples, determining a median value, and providing a median value.

48. The method of claim 47, wherein the repeating step further comprises examining a new set of N-sequence samples of the received message signal;

wherein the new set of N sequence samples is determined by discarding an Nth sample of the N sequence of samples and shifting a sequence of samples of the received message signal.

49. A method of filtering a received message signal comprising a sequence of samples, the method comprising the steps of:

examining a set of N-sequence samples of the received message signal;

determining a median of the N sequence of samples;

providing the median as an output sample; and

repeating the steps of testing a set of N series samples, determining a median value, and providing a median value.

50. The method of claim 49, wherein said repeating step further comprises examining a new set of N-sequence samples of said received message signal;

wherein the new set of N sequence samples is determined by discarding an Nth sample of the N sequence of samples and shifting a sequence of samples of the received message signal.