Load control device for light-emitting diode light source

Abstract

The load control device can control the amount of power delivered to the electrical load using a feedback signal representing the average amplitude of the load current conducted through the electrical load. The feedback signal can be generated based on a sensed signal that is electrically isolated from the line voltage input of the load control device. Depending on the operating characteristics of the electrical load, different techniques can be used to generate the feedback signal. In one example technique, the sensed signal can be integrated and filtered to obtain the feedback signal. In another example technique, the sensed signal can be used in combination with the input power of the load control device and the efficiency parameter of the load control device to obtain the feedback signal. In yet another example technique, the values ​​obtained from the aforementioned two techniques can be mixed together to obtain the feedback signal.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 712,109, filed Jul. 30, 2018, the entire disclosure of which is incorporated herein by reference. Background of the Invention

[0003] Light - emitting diode (LED) light sources (e.g., LED light engines) are commonly used to replace or substitute for conventional incandescent, fluorescent, or halogen lamps, etc. An LED light source may include a plurality of light - emitting diodes mounted on a single structure and disposed in a suitable housing. Compared with incandescent, fluorescent, and halogen lamps, LED light sources are generally more efficient and provide a longer service life. To properly illuminate, an LED driver control device (e.g., an LED driver) can be coupled between an alternating - current (AC) source and the LED light source to regulate the power supplied to the LED light source. The LED driver can regulate the voltage supplied to the LED light source to a specific value, or regulate the current supplied to the LED light source to a specific peak - current value, or can regulate both the current and the voltage.

[0004] LED light sources are typically rated to be driven via one of two different control techniques: a current - load control technique or a voltage - load control technique. An LED light source rated for the current - load control technique is also characterized in that the peak - amplitude current of the current passing through the LED light source should be regulated to a rated current (e.g., about 350 milliamperes) to ensure that the LED light source is illuminated to an appropriate intensity and color. In contrast, an LED light source rated for the voltage - load control technique is characterized in that the voltage across the LED light source should be regulated to a rated voltage (e.g., about 15 volts) to ensure the normal operation of the LED light source. Generally, each LED string in an LED light source rated for the voltage - load control technique includes a current - balance adjustment element to ensure that each parallel branch has the same impedance, such that the same current is drawn in each parallel string.

[0005] The light output of an LED light source can be dimmed. Different methods for dimming an LED include Pulse Width Modulation (PWM) techniques and Constant Current Reduction (CCR) techniques. Pulse width modulation dimming can be used for LED light sources controlled in a current or voltage load control mode / technique. In pulse width modulation dimming, a pulse signal with a varying duty cycle is supplied to the LED light source. If the LED light source is controlled using a current load control technique, the peak current supplied to the LED light source will remain constant during the on-time of the duty cycle of the pulse signal. However, as the duty cycle of the pulse signal varies, the average current supplied to the LED light source also varies, thereby varying the intensity of the light output of the LED light source. If the LED light source is controlled using a voltage load control technique, the voltage supplied to the LED light source will remain constant during the on-time of the duty cycle of the pulse signal, facilitating the achievement of a desired target voltage level, and the duty cycle of the load voltage is varied to adjust the intensity of the light output. Constant current reduction dimming is typically only used when controlling an LED light source using a current load control technique. In constant current reduction dimming, current is continuously supplied to the LED light source, but the DC magnitude of the current supplied to the LED light source varies to adjust the intensity of the light output. Examples of LED drivers are described in more detail in the commonly assigned U.S. Patent No. 8,492,987 issued on July 23, 2010, and U.S. Patent Application Publication No. 2013 / 0063047 published on March 14, 2013, both titled "LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHT SOURCE", the entire disclosure of which is incorporated herein by reference. SUMMARY OF THE INVENTION

[0006] This document describes a load control device for controlling the amount of power delivered to an electrical load. The load control device may include a load regulation circuit, a load sensing circuit, and a control circuit. The load regulation circuit may be configured to control the magnitude of the load current conducted through the electrical load to control the amount of power delivered to the electrical load across a power range. The load regulation circuit may include a transformer and an output inductor located on the secondary side of the transformer. The load regulation circuit may further include a winding that is magnetically coupled to and electrically isolated from the output inductor. The load regulation circuit may be configured to generate a sense signal via the winding, and the sense signal may indicate the voltage formed across the output inductor. The load sensing circuit may be configured to generate a load current feedback signal based on the sense signal, and the load current feedback signal may indicate the magnitude of the load current conducted through the electrical load. The control circuit may be configured to generate at least one drive signal based on the load current feedback signal during at least a first portion of the power range. The at least one drive signal may be used to control the load regulation circuit to adjust the average magnitude of the load current conducted through the electrical load. Different techniques may be used to generate the load current feedback signal based on the operating characteristics of the electrical load. In one example technique, the sense signal may be integrated and filtered to obtain the load current feedback signal. In another example technique, the sense signal may be used in combination with the input power of the load control device and the efficiency parameter of the load control device to obtain the load current feedback signal. In yet another example technique, values obtained from the foregoing two techniques may be mixed together to obtain the load current feedback signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a simplified block diagram of an example load control device, such as a light-emitting diode (LED) driver for controlling the intensity of an LED light source.

[0008] Figure 2 is a simplified schematic diagram of a forward converter and a load sensing circuit of an example LED driver.

[0009] Figure 3 is a simplified waveform diagram illustrating the operation of the LED driver when the forward converter operates in a continuous conduction mode (e.g., near high-end intensity) Figure 2 of the LED driver.

[0010] Figure 4 is a simplified waveform diagram illustrating the operation of the LED driver when the forward converter operates in a discontinuous conduction mode (e.g., near low-end intensity) Figure 2 of the LED driver.

[0011] Figures 5 to 7 is a simplified example flowchart of a load current measurement process that may be performed by the control circuit of the load control device to determine the magnitude of the load current conducted through the electrical load. Detailed implementation mode

[0012] Figure 1 is a simplified block diagram of an exemplary load control device (e.g., light-emitting diode (LED) driver 100) for controlling the amount of power delivered to an electrical load such as an LED light source 102 (e.g., LED light engine), and thus controlling the intensity of the light source. The LED light source 102 is shown as a plurality of LEDs connected in series, but depending on the particular lighting system, the LED light source 102 may include a single LED or a plurality of LEDs connected in parallel or a suitable combination thereof. The LED light source 102 may include one or more organic light-emitting diodes (OLEDs). The LED driver 100 may include a hot terminal H and a neutral terminal adapted to be coupled to an alternating current (AC) power source (not shown).

[0013] The LED driver 100 may include a radio frequency interference (RFI) filter circuit 110, a rectifier circuit 120, a boost converter 130, a load regulation circuit 140, a control circuit 150, a current sensing circuit 160, a memory 170, a communication circuit 180, and / or a power supply 190. The RFI filter circuit 110 may minimize the noise provided on the AC feed line. The rectifier circuit 120 may generate a rectified voltage V RECT . The boost converter 130 may receive the rectified voltage V RECT and generate a boosted direct current (DC) bus voltage V BUS across the bus capacitor C BUS . The boost converter 130 may include any suitable power converter circuit for generating a suitable bus voltage, such as a flyback converter, a single-ended primary inductor converter (SEPIC), a Cuk converter, or other suitable power converter circuits. The boost converter 120 may be used as a power factor correction (PFC) circuit to adjust the power factor of the LED driver 100 to a power factor of 1.

[0014] The load regulation circuit 140 may receive the bus voltage V BUS and control the amount of power delivered to the LED light source 102 across a power range. For example, the load regulation circuit may be at a low-end (e.g., minimum) intensity L LE (e.g., about 0.1 - 5%) and a high-end (e.g., maximum) intensity L HE(e.g., about 100%) to control the intensity of the LED light source 102. An example of the load regulation circuit 140 can be an isolated half-bridge forward converter. Examples of load control devices (e.g., LED driver 100) including forward converters are described in more detail in the co-owned U.S. Patent No. 9,253,829, filed on February 2, 2016, titled "LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHT SOURCE", the entire disclosure of which is incorporated herein by reference. The load regulation circuit 140 can also include, for example, a buck converter, a linear regulator, or any suitable LED driver circuit for adjusting the intensity of the LED light source 102.

[0015] The control circuit 150 can be configured to control the operation of the boost converter 130 and / or the load regulation circuit 140. An example of the control circuit 150 can be a controller. The control circuit 150 can include, for example, a digital controller or any other suitable processing device, such as a microcontroller, a programmable logic device (PLD), a microprocessor, an application-specific integrated circuit (ASIC), or a field-programmable gate array (FPGA). The control circuit 150 can generate a bus voltage control signal V BUS-CNTL , which can be provided to the boost converter 130 to adjust the bus voltage V BUS 's amplitude. The control circuit 150 can receive a bus voltage feedback signal V BUS-FB from the boost converter 130, which can indicate the amplitude of the bus voltage V BUS .

[0016] The control circuit 150 can generate at least one drive signal, such as drive signals V DRI , V DR2 . The drive signals V DRI , V DR2 can be provided to the load regulation circuit 140 for adjusting the amplitude of the load voltage V LOAD generated across the LED light source 102 and / or the amplitude of the load current I LOAD conducted through the LED light source 120, e.g., to control the intensity of the LED light source 120 to a target intensity L TRGT , the target intensity L TRGT can range from a low-end intensity L LE to a high-end intensity L HE . The control circuit 150 can adjust the operating frequency f DRI , V DR2 of the drive signals V op and / or the duty cycle DC INV (e.g., on-time TON ) to adjust the load voltage V LOAD and / or the load current I LOAD magnitude. Near the high-end intensity L HE , the load regulation circuit 140 can operate in a continuous operation mode (e.g., as will be described in more detail below). Near the low-end intensity L LE , the load regulation circuit 140 can operate in a discontinuous operation mode (e.g., as will be described in more detail below).

[0017] The control circuit 150 can receive one or more sensing signals from the load regulation circuit 140. For example, the load regulation circuit 140 can generate a first sensing signal V SENSE1 and a second sensing signal V SENSE2 . The control circuit 150 can receive the first sensing signal V SENSE1 from the load regulation circuit 140, and can be configured to determine the input power P BUS-FB of the load regulation circuit 140 in response to the bus voltage feedback signal V SENSE1 and the first sensing signal V IN . The LED driver 100 can also include a load sensing circuit 160 that receives the second sensing signal V SENSE2 and generates a load voltage feedback signal V V-LOAD and / or a load current feedback signal V I-LOAD . The load voltage feedback signal V V-LOAD can have an amplitude representative of the amplitude of the load voltage V LOAD , while the load current feedback signal V I-LOAD can have an amplitude representative of the average amplitude I LOAD of the load current I AVE . The control circuit 150 can generate a filter control signal V FC for controlling the load sensing circuit 160 (e.g., for controlling a part of the load sensing circuit 160). For example, the control circuit 150 can use the filter control signal V FC to control the generation of the load current feedback signal V I-LOAD . The control circuit 150 can be configured to receive the load voltage feedback signal V V-LOAD and / or the load current feedback signal V I-LOAD .

[0018] The control circuit 150 can control the drive signals V DR1 , VDR2 to adjust the magnitude of the load current I LOAD to a target load current I TRGT , thus in response to the first sensing signal V SENSE1 , the voltage feedback signal VV-LOAD and / or the load current feedback signal V I-LOAD (e.g., using a control loop) the amount of power delivered to the electrical load is controlled to a target power level (e.g., to control the intensity of the LED light source 102 to a target intensity L TRGT ). The control circuit can be configured to use different techniques, such as based on the position of the target power level within the power range of the light source 120 (e.g., based on the position of the target intensity L TRGT falling within the intensity range of the LED light source 120), to determine the average magnitude I LOAD of the load current I AVE . When the target power level is greater than a first power threshold (e.g., when the target intensity L TRGT is greater than a first threshold intensity L TH1 , such as a high threshold intensity, which can be about 60%), the control circuit 150 can be configured to use a first load current measurement technique to determine the average magnitude I LOAD of the load current I AVE . For example, when using the first load current measurement technique, the control circuit 150 can use the input power P IN of the load regulation circuit 140, the magnitude of the load voltage V LOAD (e.g., as determined from the load voltage feedback signal V V-LOAD ) and the efficiency η of the load regulation circuit 140 (e.g., a pre-determined efficiency parameter) to calculate the average magnitude I LOAD of the load current I AVE . When the target power level is less than a second power threshold (e.g., when the target intensity L TRGT is less than a second threshold intensity L TH2 , such as a low threshold intensity, which can be about 40%), the control circuit 150 can be configured to use a second load current measurement technique to determine the average magnitude I LOAD of the load current I AVE . For example, when using the second load current measurement technique, the control circuit 150 can determine the average magnitude I 1-LOAD of the load current I LOAD from the load current feedback signal V AVE .

[0019] When the target power level is less than or equal to the first power threshold and greater than or equal to the second power threshold (e.g., when the target intensity L TRGT is between the first threshold intensity L TH1 and the second threshold L TH2 ), the control circuit 150 can be configured to use both the first and second load current measurement techniques to determine the average magnitude I LOAD of the load current I AVEFor example, the control circuit 150 may be configured to appropriately mix the average magnitude I of the load current I determined using the first measurement technique LOAD and the average magnitude I of the load current I determined using the second load current measurement technique AVE to determine the average magnitude I of the load current I LOAD (e.g., as will be described in more detail below). The load regulation circuit 140 may transition between a continuous operation mode and a discontinuous operation mode at an intensity greater than the first threshold intensity L AVE to prevent the control circuit 150 from using the second load current measurement technique to determine the average magnitude I of the load current I when the load regulation circuit is operating in the continuous mode LOAD (e.g., as will be described in more detail below). The load regulation circuit 140 may transition between a continuous operation mode and a discontinuous operation mode at an intensity greater than the first threshold intensity L AVE . THI to prevent the control circuit 150 from using the second load current measurement technique to determine the average magnitude I of the load current I when the load regulation circuit is operating in the continuous mode LOAD (e.g., as will be described in more detail below). The load regulation circuit 140 may transition between a continuous operation mode and a discontinuous operation mode at an intensity greater than the first threshold intensity L AVE .

[0020] The control circuit 150 may be coupled to the memory 170. The memory 170 may store the operating characteristics of the LED driver 100 (e.g., the target intensity L TRGT , the low-end intensity L LE , the high-end intensity L HE , etc.). The communication circuit 180 may be coupled to, for example, a wired communication link or a wireless communication link, such as a radio frequency (RF) communication link or an infrared (IR) communication link. The control circuit 150 may be configured to update the target intensity L of the LED light source 102 TRGT and / or the operating characteristics stored in the memory 170 in response to a message (e.g., a digital message) received via the communication circuit 180. The LED driver 100 may be configured to receive a phase control signal from a dimmer switch to determine the target intensity L of the LED light source 102 TRGT . The power supply 190 may receive a rectified voltage V RECT and generate a direct current (DC) power supply voltage V cc to power the circuits of the LED driver 100

[0021] Figure 2 is a simplified schematic diagram of the forward converter 240 (e.g., the load regulation circuit 140) and the load sensing circuit 260 (e.g., the current sensing circuit 160) of an example LED driver 200 (e.g., the LED driver 100 shown in Figure 1 ). The LED driver 200 may also include a control circuit 250 that controls the forward converter 240 in response to the load sensing circuit 260 to adjust the current intensity L of the LED light source 202 PRES . The control circuit 250 may receive a bus voltage feedback signal V BUS-FB which may indicate the bus voltage V received by the forward converter 240BUS The amplitude. For example, the bus voltage feedback signal V BUS-FB can be generated by a resistive voltage divider including resistors R204, R206.

[0022] As Figure 2 shown, the forward converter 240 can include a half-bridge inverter circuit including two field effect transistors (FETs) Q210, Q212 for generating a high-frequency inverter voltage V BUS from the bus voltage V INV . The control circuit 250 can generate at least one drive signal (e.g., drive signals V DR1 , V DR2 ) to turn the FETs Q210, Q212 on and off. The drive signals V DR1 , V DR2 can be coupled to the gates of the respective FETs Q210, Q212 via a gate drive circuit 214 (e.g., which can include components with part number L6382DTR manufactured by ST Microelectronics). The forward converter 240 can include a transformer 220, and the inverter voltage V INV can be coupled to the primary winding of the transformer 220 through a DC-blocking capacitor C216 (e.g., which can have a capacitance of approximately 0.047 μF), such that a primary voltage V PRI can be generated across the primary winding.

[0023] The forward converter 240 can include a current sensing circuit 218 (e.g., including a sense resistor R219) coupled in series with the half-bridge inverter (e.g., in series with the first FET Q210 and the second FET Q212). The current sensing circuit 218 can generate a first sensing signal V SENSE in response to a sensed current I SENSE1 conducting through the sense resistor R219 (e.g., conducting through the half-bridge inverter). The control circuit 250 can receive the first sensing signal V SENSE1 , and can be configured to determine the magnitude of the sensed current I SENSE1 of the forward converter 240 in response to the first sensing signal V SENSE . The control circuit 250 can use the magnitude of the sensed current I SENSE to determine the input power P IN of the forward converter 240. The control circuit 250 can use the magnitude of the sensed current I SENSE to determine the input power P IN of the forward converter 240. For example, the control circuit 250 can use the magnitude of the bus voltage V BUS (e.g., which can be obtained from the bus voltage feedback signal V BUS-FBDetermined and / or stored in the memory 170) to calculate the input power P IN , for example, P IN =V BUS· I SENSE .

[0024] The secondary winding of the transformer 220 can generate a secondary voltage V SEC , and can be coupled to the AC terminals of a rectifier bridge 224 (e.g., a full-wave diode rectifier bridge) for rectifying the secondary voltage generated across the secondary winding. The positive DC terminal of the rectifier bridge 224 can be coupled to the LED light source 202 through an output inductor L226 (e.g., an energy storage inductor, which can be located on the secondary side of the transformer and can have an inductance of approximately 400 μH), such that the inductor current I L226 can be conducted through the output inductor L226, and a load voltage V LOAD can be generated across an output capacitor C228 (e.g., which can have a capacitance of approximately 3 μF). The transformer 220 can provide electrical isolation between the line voltage input (e.g., the hot terminal and the neutral terminal N) of the LED driver 200 and the LED light source 202.

[0025] The control circuit 250 can be configured to perform pulse width modulation (PWM) on the drive signals V DR1 , V DR2 to control the current intensity L PRES of the LED light source 202 towards a target intensity L TRGT , and the range of the target intensity L TRGT can be from a low-end intensity L LE to a high intensity L HE . The control circuit 250 can be configured to adjust the corresponding duty cycles DC1, DC2 of the drive signals V DR1 , V DR2 to adjust the current intensity L PRES . Near the high intensity L HE , the load regulation circuit 240 can operate in a continuous operation mode. The continuous operation mode can refer to a mode in which the inductor current I L226 can be continuous (e.g., the inductor current I L226 can continuously be higher than zero amperes). Near the low-end intensity L LE , the load regulation circuit 140 can operate in a discontinuous operation mode. The discontinuous operation mode can refer to a mode in which the inductor current I L226 can be discontinuous (e.g., during at least a part of the operation period of the drive signals V DR1 , V DR2 , the inductor current I L226 can reach approximately zero amperes).

[0026] The control circuit 250 can receive a load voltage feedback signal V from the load sensing circuit 260 V-LOAD and / or a load current feedback signal V I-LOAD . The load sensing circuit 260 can generate a load voltage feedback signal V SENSE2 and / or a load current feedback signal V V-LOAD in response to a second sensing signal V received from the load regulation circuit 240 I-LOAD . For example, the second sensing signal V SENSE2 can be magnetically coupled across the winding 230 of the output inductor L226 of the load regulation circuit 140 and can represent the magnitude of the inductive voltage V L226 generated across the output inductor. The winding 230 can be electrically isolated from the output inductor L226, and thus the load sensing circuit 260 (and thus the line voltage input of the LED driver 200) can be electrically isolated from the load regulation circuit 240 (and thus the LED light source 202).

[0027] When the target intensity L of the LED light source 202 TRGT is greater than a first threshold intensity L TH1 (e.g., about 60% of the maximum intensity of the lighting load), the control circuit 250 can be configured to determine the average magnitude I of the load current I from the load voltage feedback signal V using a first load current measurement technique V-LOAD LOAD AVE . The load sensing circuit 260 can include a peak detection circuit 270 for generating a load voltage feedback signal V from the second sensing signal V SENSE2 V-LOAD . When the FETs Q210, Q212 of the load regulation circuit 240 are non-conducting, the output inductor L226 is electrically coupled in parallel with the LED light source 202, and the magnitude of the inductor voltage VL 226 can be approximately equal to the load voltage V LOAD . When the FETs Q210, Q212 of the load regulation circuit 240 are non-conducting (e.g., when the magnitude of the inductor voltage V L226 can be approximately equal to the load voltage V LOAD ), the capacitor C272 can be configured to charge through the diode D274 and the winding 230 to reach the peak magnitude of the second sensing signal V SENSE2 . Due to the orientation of the diode D274, a negative voltage V NEG (e.g., a voltage with a negative polarity) may be generated at the node of the capacitor C272 and the diode D274 NEG . The negative voltage V POS ​​​(e.g., a voltage with a positive polarity). The positive voltage V POS can be filtered by a resistor-capacitor (RC) filter circuit including a resistor R276 (e.g., having a resistance of approximately 12.1 kΩ) and a capacitor C278 (e.g., having a capacitance of approximately 1000 pF). The load voltage feedback signal V V-LOAD can be generated at the node of the resistor R276 and the capacitor C278, and can have an amplitude (e.g., a DC amplitude) representative of the amplitude of the load voltage V LOAD . The control circuit 250 can use the input power P IN of the forward converter 240 (e.g., determined from the amplitude of the bus voltage V BUS and the first sensing signal V SENSE1 ), the amplitude of the load voltage V V-LOAD determined from the load voltage feedback signal V LOAD , and the efficiency η of the forward converter 240 to calculate the average amplitude I LOAD of the load current I AVE , e.g., I AVE = (η·P IN ) / V LOAD , where η·P IN can represent the output power P OUT of the load control device.

[0028] When the target intensity L TRGT of the LED light source 202 is less than a second threshold intensity L TH2 (e.g., approximately 40% of the maximum intensity of the lighting load), the control circuit 250 can be configured to determine the average amplitude I I-LOAD of the load current I LOAD using a second load current measurement technique from the load voltage feedback signal V AVE . The load sensing circuit 260 can include an integrator circuit 280 and a filter circuit 282 (e.g., a boxcar filter circuit) for generating the load voltage feedback signal V I-LOAD . The integrator circuit 280 can integrate the second sensing signal V SENSE2 , and can generate an integrated signal V INT , which can be approximately equal to or can be a scaled (e.g., a percentage) version of the inductor current I L226 . For example, the integrator circuit 280 can include an operational amplifier integrator. Since the amplitude of the inductor voltage V L226 can be a function of the derivative of the inductor current I L226 , the integration of the second sensing signal V SENSE2 can be approximately equal to or can be the inductor current I L226A scaled version (e.g., a percentage), where the scaling factor may depend on many factors, including the inductance of the output inductor L226, the number of turns of the winding 230, and / or the values of the components of the integrator circuit 280.

[0029] Load current I LOAD The average magnitude of I AVE May be approximately equal to the inductor current I L226 The average magnitude of I AVE . The filter circuit 282 may be configured to filter the integrated signal V INT To generate a load current feedback signal V I-LOAD , The load current feedback signal V I-LOAD May have a DC magnitude representing the average magnitude of the load current I LOAD Of I AVE . The filter circuit 282 may operate in various ways to improve the performance of the load control device. For example, when the forward converter 240 operates in discontinuous mode (e.g., near the low-end intensity L LE ), the load current I LOAD And / or the inductor current I L226 May reach approximately zero amperes during at least a portion of the operating period of the drive signals V DR1 , V DR2 (e.g., the inductor current I L226 And / or the load current I LOAD May include one or more pulses in discontinuous mode. The pulses of the load current I LOAD (e.g., and thus the pulses of the inductor current I L226 ) May be far apart, and the average magnitude of the integrated signal V INT Of I AVE May be so small that the control circuit 250 may not be able to properly sample and / or measure the average magnitude of the integrated signal V INT Of I AVE . The filter circuit 282 may be configured to filter (e.g., only filter) the integrated signal V during a filter window time period T L226 (e.g., a time window) around the pulses of the inductor current I FW . The filter circuit 282 may include a controllable switching device (e.g., a controllable switch 284), which may be turned on and off in response to a filter control signal V generated by the control circuit 250 INT . Thus, the control circuit 250 may control the controllable switch 284 to selectively pass the integrated signal V FC And non-conducting. In this way, the control circuit 250 can control the controllable switch 284 to selectively pass the integrated signal V INTCoupled to a filter (e.g., an RC filter) that includes a resistor R286 (e.g., having a resistance of approximately 510 Ω) and a capacitor C288 (e.g., having a capacitance of approximately 0.47 μF). A load current feedback signal V can be generated at the node of resistor R286 and capacitor C288 I-LOAD .

[0030] Since the control circuit 250 is generating drive signals V DR1 、V DR2 that cause the generation of pulses of inductor current I L226 , the control circuit 250 can generate a filter control signal V FC to cooperate with the drive signals V DR1 、V DR2 to turn the controllable switch 284 on and off. For example, the control circuit 250 can drive the filter control signal V FC high (e.g., towards the supply voltage V CC ) to turn the controllable switch 284 on at approximately the same time as any one of the drive signals V DR1 、V DR2 is driven high. The control circuit 250 can maintain the filter control signal V FW high within the filter window time period T FC , which can be at least as long as the length of each pulse of the inductor current I L226 (e.g., at least as long as the length of each pulse of the load current I LOAD ). At the end of the filter window time period T FW , the control circuit 250 can drive the filter control signal V FC low (e.g., towards zero volts) to turn the controllable switch 284 off. When the controllable switch 284 is on, the capacitor C288 can be charged, and when the controllable switch 284 is off, the capacitor C288 can maintain the amplitude of the load current feedback signal V I-LOAD substantially constant. As a result, when the filter control signal V FC is high, the amplitude of the load current feedback signal V I-LOAD can indicate the average amplitude I LOAD of the load current I WIN during the filter window (e.g., only during the filter window). The control circuit 250 can be configured to calculate the average amplitude I LOAD of the load current I WIN based on the average amplitude I FC of the load current I SW during the filter window and the current duty cycle DC LOAD of the filter control signal V AVE, for example, I AVE = DC SW ·I WIN .

[0031] When the amplitude of the filter control signal V FC is high, the filter control signal V FC can be used to reset the integrator circuit 280 at the end of the filter window. For example, the filter control signal VFC can be coupled to the integrator circuit 280 via an inverter circuit 289, which can be configured to generate an inverted signal VINV. When the filter control signal V FC is driven low (e.g., towards the circuit common) at the end of the filter window, the inverted signal V INV can be driven high to reset the inverter circuit 280.

[0032] When the target intensity L TRGT of the LED light source 2020 is less than or equal to a first threshold intensity L THI and greater than or equal to a second threshold intensity L TH2 , the control circuit 250 can be configured to use both the load voltage feedback signal V V-LOAD and the load current feedback signal V I-LOAD to determine the average magnitude of the load current I LOAD . For example, the control circuit 150 can be configured to appropriately mix the average magnitude of the load current I V-LOAD determined from the load voltage feedback signal V LOAD and the average magnitude of the load current I I-LOAD determined from the load current feedback signal V LOAD (e.g., as will be described in more detail below) to obtain an estimated average magnitude of the load current I LOAD .

[0033] Figure 3 is a simplified waveform diagram illustrating the operation of the LED driver 200 when the forward converter 240 operates in a continuous mode of operation (e.g., near the high-end intensity L HE ). The drive signals V DR1 , V DR2 can be characterized by a working frequency f OP and a working period T OP . During each period of the drive signals V DR1 , V DR2 , the control circuit 250 can drive one of the drive signals V ON within the on-time T Figure 3 (e.g., between times t1 and t2 in DR1 , V DR2 ) high (e.g., towards the supply voltage VCC ) to turn on the corresponding FETs Q210, Q212 during the conduction times at different times (e.g., FETs Q210, Q212 turn on at different times). Then, the control circuit 250 can drive the signals V Figure 3 to low during the remaining time of this period (e.g., between times t2 and t3 in DR1 ), V DR2 . During the next period of the drive signals V DR1 , V DR2 , the control circuit 250 can drive another one of the drive signals V ON (e.g., between times t3 and t4 in Figure 3 ) to high during the conduction time T DR1 , V DR2 to turn on the corresponding FETs Q210, Q212 during the conduction time.

[0034] When the high-side FET Q210 is on, the bus voltage V BUS can be coupled across the series combination of the capacitor C216 and the primary winding of the transformer 220, which allows the capacitor C216 to charge such that the magnitude of the primary voltage V PRI is about half of the magnitude of the bus voltage V BUS . Thus, the magnitude of the primary voltage V PRI across the primary winding of the transformer 220 can be equal to about half of the magnitude of the bus voltage V BUS (e.g., V BUS / 2 ). When the low-side FET Q212 is on, the capacitor C216 can be coupled across the primary winding such that the primary voltage V PRI can have a negative polarity and its magnitude is equal to half of the magnitude of the bus voltage V BUS .

[0035] When one of the high-side and low-side FETs Q210, Q212 is on, a secondary voltage V SEC can be developed across the secondary winding of the transformer 220. Since the secondary winding of the transformer 220 is coupled to the output inductor L226 and the LED light source 202 through the rectifier bridge 224, when any one of the FETs Q210, Q212 is on, a secondary voltage V SEC can be generated across the series combination of the output inductor L226 and the LED light source 202. At this time, the magnitude of the inductor voltage V L226 may be at the peak magnitude V L-PK , and the magnitude of the output inductor current I L226 conducted by the output inductor L226 may be relative to as Figure 3increases as shown in the figure. When the FETs Q210, Q212 are non-conducting, the output inductor L226 can be coupled in parallel with the LED light source 202, and the inductor voltage V L226 can have a negative peak amplitude of -V L-PK . Additionally, when the FETs Q210, Q212 are non-conducting, the inductor current I L226 can decrease with respect to time. Since the forward converter 240 operates in continuous mode, the amplitude of the inductor current I L226 does not reach zero amperes (e.g., during the corresponding operating periods of the drive control signals V DR1 , V DR2 , the amplitude of the inductor current I L226 will continuously be higher than zero amperes). In continuous mode, the operating period T DR of the drive signal V OP can be equal to the minimum operating period T MIN . The inductor current I L226 can be characterized by a peak amplitude I L-PK and an average amplitude I L-AVG . The control circuit 250 can increase and / or decrease the conduction time T DR1 of the drive control signals V DR2 , V ON (e.g., the duty cycle DC INV of the inverter voltage V INV ) to increase and decrease the average time I L of the output inductor current I L-AVG , and thereby increase and decrease the intensity of the LED light source 202 respectively.

[0036] Near the high-end intensity L HE (e.g., when the forward converter 240 operates in continuous mode), the control circuit 250 can use a first load current measurement technique to determine the average amplitude of the load current I V-LOAD from the load voltage feedback signal V LOAD . When the FETs Q210, Q212 are made non-conducting (e.g., at times t2 and t4 in Figure 3 ), the capacitor C272 of the peak detection circuit 270 can be charged to the peak amplitude of the second sense signal V SENSE2 to generate a load voltage feedback signal V V-LOAD across the capacitor C278. When any of the FETs Q210, Q212 is conducting, the capacitor C278 can hold the amplitude of the load voltage feedback signal V V-LOAD substantially constant (e.g., between times t3 and t4). The control circuit 250 can sample (e.g., sample periodically) the load voltage feedback signal VV-LOAD amplitude, and calculate the load current I LOAD average amplitude.

[0037] Figure 4 illustrates the operation of the LED driver 200 when the forward converter 240 operates in a discontinuous operation mode (e.g., near the low-end intensity L LE ). The control circuit 250 can generate the drive signals V OP (e.g., the same operation period as in Figure 3 ) but within a smaller length of the on-time T ON (e.g., compared to the on-time of Figure 3 ). DR1 V DR2 .

[0038] When any one of the high-side and low-side FETs Q210, Q212 is on, the amplitude of the inductor voltage V L226 can be at the peak amplitude V L-PK , and the amplitude of the output inductor current I L226 conducted by the output inductor L226 can increase with respect to time (e.g., between time t1 and t2 and / or between time t4 and t6). When the FETs Q210, Q212 are off, the amplitude of the inductor voltage V L226 can be at the negative peak amplitude -V L-PK , and the amplitude of the inductor current I L226 can decrease in amplitude with respect to time until the amplitude of the inductor current I L226 reaches approximately zero amperes (e.g., between time t2 and t3 and / or between time t5 and t6). Since the forward converter 240 operates in a discontinuous mode, the amplitude of the inductor current I OP can be at approximately zero amperes for the remainder of the current operation period T L226 (e.g., between time t3 and t4 and / or between t6 and t7). As Figure 4 shown, at the start of each period, the output inductor L226 can conduct a current pulse (e.g., a triangular pulse). Since the current pulses may be spaced more widely as the current intensity L PRES decreases towards the low-end intensity L LE , the average amplitude I L226 of the inductor current I L-AVG may become very small (e.g., much less than the peak amplitude I L226 of the inductor current I L-PK ).

[0039] At the low-end intensity L LEWhen the forward converter 240 is operating in a discontinuous operation mode, the control circuit 250 may use a second load current measurement technique (e.g., from the load current feedback signal V I-LOAD ) Determine the load current I LOAD The integrator circuit 280 of the load sensing circuit 260 can integrate the second sensing signal V SENSE2 To generate the integrated signal V INT , the integrated signal V INT Can be equal to or can be Figure 4 The inductor current I L226 is a scaled version of . Since the inductor current I L226 The average amplitude I L-AVG At the low end strength L LE may be very small (eg, close to zero amperes), the control circuit 250 may be configured to generate a filter control signal V FC To enable the filter circuit 282 to L226 The filter window time period T around the pulse FW During the filtering (eg, filtering only) of the integrated signal V INT The control circuit 250 can be connected with the driving signal V DR1 、V DR2 Collaboratively generate filter control signal V FC For example, the control circuit 250 may generate a filter control signal V FC As with the driving signal V DR1 、V DR2 Operation period T OP The control circuit 250 may be configured to provide a pulse width modulation signal with equal or similar time periods. The control circuit 250 may be configured to provide a pulse width modulation signal with equal or similar time periods at approximately the same time or slightly DR1 、V DR2 The time that any one of the Figure 4 The filter control signal V FC The amplitude of the filter is driven high. For example, the filter control signal V FC The filter window time period T FW can be approximately equal to the drive signal V DR1 、V DR2 The on time T ON In addition, the filter control signal V FC The filter window time period T FW Can be longer than the driving signal V DR1 、V DR2 The on time T ON twice, for example, until about the minimum operating period T of the driving signal MIN。The control circuit 250 may drive the amplitude of the filter control signal V to low at the end of the filter window time period T FW (e.g., at times t3 and t6 in Figure 4 ). When the filter control signal V FC is high, the filter circuit 282 may be configured to filter the integration signal V FC to generate a load current feedback signal V INT . When the filter control signal V I-LOAD is low (e.g., between times t3 and t4), the capacitor C288 of the filter circuit 280 may hold the amplitude of the load current feedback signal V FC substantially constant (e.g., the amplitude of the load current feedback signal V I-LOAD between times t3 and t4 is substantially similar to the amplitude of the load current feedback signal V 1-LOAD between times t1 and t2). The control circuit 250 may sample (e.g., periodically sample) the amplitude of the load current feedback signal V I-LOAD to determine the average amplitude of the load current I I-LOAD . LOAD

[0040] Figure 5 is a simplified example flowchart of a first load current measurement process 500 that may be performed by a control circuit (e.g., the control circuit 150 of the LED driver 100 and / or the control circuit 250 of the LED driver) of a load control device for controlling an electrical load (e.g., an LED light source, such as the LED light source 202). For example, the control circuit 250 may perform the first load current measurement process 500 to determine the average amplitude of the load current conducted through the electrical load (e.g., the load current I LOAD ) using a first load current measurement technique. The load control device may include a load regulation circuit (e.g., the load regulation circuit 140 and / or the forward converter 240), which in turn may include an output inductor. The output inductor may be magnetically coupled to a winding for generating a sense voltage that may be used to generate a load voltage feedback signal. The load voltage feedback signal may have an amplitude representing the amplitude of the load voltage generated across the electrical load (e.g., the load voltage feedback signal V V-LOAD ).

[0041] The control circuit may, for example, periodically perform the first load current measurement process 500 at 510 (e.g., when the target power level of the electrical load is above a high threshold). Additionally, the first load current measurement process 500 may be performed as part of another load current measurement process. At 512, the control circuit may determine the bus voltage V BUSamplitude. For example, at 512, the control circuit 250 can obtain from the bus voltage feedback signal V BUS-FB to determine the bus voltage V BUS amplitude. In addition, the control circuit 250 can call the target bus voltage from the memory at 512 (for example, for controlling the bus voltage control signal V BUS-CNTL ) to be used as the amplitude of the bus voltage V BUS . At 514, the control circuit can determine the sensed current I SENSE amplitude (for example, as shown in Figure 2 ). For example, when the second FET Q212 is conducting, the control circuit 250 can determine the sensed current I SENSE1 amplitude from the first sensed signal V generated by the current sensing circuit 218 at 514 SENSE . At 516, the control circuit can use the determined bus voltage V BUS amplitude and the determined sensed current I SENSE amplitude to calculate the input power P of the load control device IN , for example, P IN = V BUS ·I SENSE .

[0042] At 518, the control circuit can use the calculated input power P IN and the efficiency η of the power regulation circuit to calculate the output power P of the load control device OUT . For example, the efficiency η can be a predetermined value stored in the memory (such as the memory 170). At 520, the control circuit can determine the load voltage V V-LOAD amplitude, for example, by sampling and processing (such as scaling) the load voltage feedback signal V LOAD . At 522, before exiting the first load current measurement process 500, the control circuit can use the calculated output power P OUT and the determined load voltage V LOAD to calculate the load current I LOAD amplitude, for example, I LOAD = P OUT / V LOAD .

[0043] Figure 6FIG. 0 is a simplified example flowchart of a second load current measurement process 600 that may be performed by a control circuit (e.g., control circuit 150 of LED driver 100 and / or control circuit 250 of LED driver 200) of a load control device for controlling an electrical load (e.g., an LED light source, such as LED light source 202). For example, control circuit 250 may perform the second load current measurement process 600 to determine the average magnitude of the load current of the electrical load (e.g., load current I LOAD ) using a second load current measurement technique. The load control device may include a load regulation circuit (e.g., load regulation circuit 140 and / or forward converter 240), which in turn may include an output inductor. The output inductor may be magnetically coupled to a winding to generate a sense voltage that may be used to generate a load current feedback signal. The load current feedback signal may have a magnitude that represents the magnitude of the load current conducted through the electrical load (e.g., load current feedback signal V I-LOAD ).

[0044] The control circuit may periodically perform the second load current measurement process 600, e.g., at 610 (e.g., when the target power level of the electrical load is below a low threshold). Additionally, the second load current measurement process 600 may be performed as part of another load current measurement process. At 612, the control circuit may drive a filter control signal (e.g., filter control signal V FC ) high to enable a filter circuit (e.g., a boxcar filter circuit) to adjust the magnitude of the load current feedback signal. At 614, before driving the filter control signal low to disable the filter circuit from adjusting the magnitude of the load current signal at S616, the control circuit may wait for a period of time (e.g., filter window period T Figure 4 as shown FW ). At 618, the control circuit may determine the average magnitude of the load current I I-LOAD by, for example, sampling and processing (e.g., scaling) the magnitude of the load current feedback signal V LOAD .

[0045] Figure 7 FIG. 21 is a simplified flowchart of a third load current measurement process 700 that may be performed by a control circuit (e.g., control circuit 150 of LED driver 100 and / or control circuit 250 of LED driver 200) of a load control device for controlling an electrical load (e.g., an LED light source, such as LED light source 202). For example, the control circuit may perform the third load current measurement process 600 to use multiple load current measurement techniques (e.g., using Figure 5 and Figure 6The first and second load current measurement processes 500, 600 shown in determine the load current of an electrical load (e.g., the load current I described herein) LOAD ) of the average magnitude. The load control device may include a load regulation circuit (e.g., load regulation circuit 140 and / or forward converter 240).

[0046] The control circuit may, for example, periodically perform a third load current measurement process 700 at 710. For example, if the current intensity L of the LED light source at 712 PRES is greater than a first threshold intensity L THI (e.g., about 60% of the maximum intensity of the LED light source), the control circuit may use a first load current measurement technique at 714, for example, by performing a first load current measurement process 500 (e.g., as Figure 5 shown), to determine the average magnitude of the load current I LOAD . If the current intensity L of the LED light source at 716 PRES is less than a second threshold intensity L TH2 (e.g., about 40% of the maximum intensity of the LED light source), the control circuit may use a second load current measurement technique at 718, for example, by performing a second load current measurement process 600 (e.g., as Figure 6 shown) to determine the average magnitude of the load current I LOAD .

[0047] If the current intensity L of the LED light source at 712 PRES is less than or equal to the first threshold intensity L TH1 and at 716 is greater than or equal to the second threshold intensity L TH2 (e.g., if the current intensity L of the LED light source PRES is between the first threshold intensity L TH1 and the second threshold intensity L TH2 ), the control circuit may use both the first load current measurement technique and the second load current measurement technique, and combine the values determined from the first and second load current measurement techniques (e.g., a scaled version of the values) to determine the average magnitude of the load current I LOAD . For example, the control circuit may use the first load current measurement technique at 720 to determine a first value I LOAD for the average magnitude of the load current I LOAD1 , and use the second load current measurement technique at 722 to determine a second value I LOAD for the average magnitude of the load current I LOAD2 . At 724, the control circuit may determine a scaling factor α to calculate the average magnitude of the load current I LOAD . For example, the first value I LOAD1and a second value I LOAD2 can be mixed (e.g., linearly mixed) between a first threshold intensity L TH1 and a second threshold intensity L TH2 The scaling factor α can represent the current intensity L PRES as a percentage distance between the first threshold intensity L TH1 and the second threshold intensity L TH2 For example,

[0048] α = (L PRES - L TH2 ) / (L TH1 - L TH2 ).

[0049] At 726, the control circuit can calculate the average magnitude of the load current I based on two components obtained using the first and second load current measurement techniques and by applying the scaling factor α to those components. For example, LOAD

[0050] I LOAD = α · I LOAD1 + (1 - α)I LOAD2

[0051] where α · I LOAD1 and (1 - α)I LOAD2 can represent the corresponding parts of I LOAD and I LOAD1 used to calculate the average magnitude of the load current I LOAD2 After determining the average magnitude of the load current I LOAD at 714, 718, or 726, the third load current measurement process 700 can exit.

[0052] ​Although described with reference to LED drivers, one or more embodiments described herein can be used with other load control devices. For example, one or more embodiments described herein can be performed by various load control devices configured to control various types of electrical loads, such as, for example, an LED driver (e.g., an LED light engine) for driving an LED light source; a screw-in illuminator including a dimmer circuit and an incandescent or halogen lamp; a screw-in illuminator including a ballast and a compact fluorescent lamp; a screw-in illuminator including an LED driver and an LED light source; a dimmer circuit for controlling the intensity of an incandescent lamp, halogen lamp, electronic low voltage lighting load, magnetic low voltage lighting load, or other type of lighting load; an electronic switch, a controllable circuit breaker, or other switching device for turning an electrical load or appliance on or off; a plug-in load control device, a controllable electrical outlet, or a controllable electrical panel for controlling one or more plug-in electrical loads (e.g., a coffee maker, a space heater, other household appliances, etc.); a motor control unit for controlling a motor load (e.g., a ceiling fan or an exhaust fan); a drive unit for controlling an electric curtain or a projection screen; electric interior or exterior blinds; a thermostat for a heating and / or cooling system; a temperature control device for controlling a heating, ventilation, and air conditioning (HVAC) system; an air conditioner; a compressor; an electric baseboard heater controller; a controllable damper; a humidity control unit; a dehumidifier; a water heater; a pool pump; a refrigerator; a freezer; a television or computer monitor; a power supply; an audio system or amplifier; a generator; a charger, such as an electric vehicle charger; and an alternative energy controller (e.g., a solar, wind, or thermal energy controller). A single control circuit can be coupled to and / or adapted to control multiple types of electrical loads in a load control system.

Claims

1. A load control device for controlling the amount of power delivered to an electrical load, the load control device comprising: A load regulation circuit configured to control the magnitude of a load current conducted through the electrical load to control the amount of power delivered to the electrical load across a power range, the load regulation circuit including a transformer and an output inductor located on a secondary side of the transformer, the load regulation circuit further including a winding magnetically coupled to and electrically isolated from the output inductor, the load regulation circuit being configured to generate a sense signal via the winding, wherein the sense signal indicates a voltage formed across the output inductor; A load sensing circuit configured to generate, based on the sense signal: A load current feedback signal indicative of the magnitude of the load current conducted through the electrical load; and A load voltage feedback signal indicative of a load voltage formed across the electrical load; and A control circuit configured to: Receive both the load current feedback signal and the load voltage feedback signal; and Generate at least one drive signal based on the load current feedback signal during at least a first portion of the power range, the at least one drive signal being generated to control the load regulation circuit to adjust an average magnitude of the load current conducted through the electrical load, wherein the load regulation circuit is configured to operate in a discontinuous mode, the load sensing circuit includes an integrator circuit configured to integrate the sense signal, and the load current feedback signal is generated based on the integrated sense signal; and wherein the load sensing circuit further includes a filter circuit configured to filter the integrated sense signal to produce the load current feedback signal, the filter circuit including a controllable switching device for controlling when the filter circuit filters the integrated sense signal to produce the load current feedback signal, the control circuit further being configured to cooperate with the at least one drive signal to turn the controllable switching device on and off.

2. The load control device according to claim 1, wherein, The control circuit is configured to turn the controllable switching device on approximately simultaneously with driving the at least one drive signal high.

3. The load control device according to claim 1, wherein, The control circuit is configured to maintain the controllable switching device on for at least a length of a pulse of the load current.

4. The load control device according to claim 1, wherein, The electrical load is characterized by a low power threshold, the first portion of the power range is below the low power threshold, and the control circuit is configured to cooperate with the at least one drive signal to turn the controllable switching device on and off within the first portion of the power range.

5. The load control device according to claim 4, wherein, The control circuit is configured to operate in a discontinuous mode within the first portion of the power range.

6. The load control device according to claim 4, wherein, The electrical load is further characterized by a high power threshold, and wherein, under the condition that the current power amount delivered to the electrical load is between the low power threshold and the high power threshold, the control circuit is configured to use a part of the integrated sensed signal filtered by the filter circuit to determine the average magnitude of the load current conducted through the electrical load.

7. The load control device according to claim 6, wherein, The part of the integrated sensed signal for determining the average magnitude of the load current is proportional to the percentage distance that the current power amount delivered to the electrical load is between the low power threshold and the high power threshold.

8. The load control device according to claim 1, wherein, During at least a second part of the power range, the control circuit is configured to determine the input power of the load regulation circuit, and the control circuit is further configured to determine the load current conducted through the electrical load based on the input power of the load regulation circuit, an efficiency parameter associated with the load regulation circuit, and the load voltage feedback signal.

9. The load control device according to claim 8, wherein, The load current is determined by calculating the product of the input power and the efficiency parameter and dividing the product by the magnitude of the load voltage indicated by the load voltage feedback signal.

10. The load control device according to claim 8, wherein, The load regulation circuit further includes an inverter that responds to the at least one drive signal, the inverter is configured to receive a bus voltage and is coupled to the primary winding of the transformer, and the load regulation circuit further includes a current sensing circuit configured to generate a second sensed signal indicating the sensed current conducted through the inverter, wherein the control circuit is configured to determine the input power of the load regulation circuit based on the magnitude of the sensed current and the magnitude of the bus voltage.

11. The load control device according to claim 8, wherein, The electrical load is characterized by a high power threshold, the second part of the power range is higher than the high power threshold, and the control circuit is configured to determine the load current conducted through the electrical load based on the input power, the efficiency parameter, and the load voltage feedback signal when the current power amount delivered to the electrical load is within the second part of the power range.

12. The load control device according to claim 11, wherein, The control circuit is configured to operate in a continuous mode within the second part of the power range.

13. The load control device according to claim 11, wherein, The electrical load is further characterized by a low power threshold, and wherein, under the condition that the current intensity of the electrical load is between the low power threshold and the high power threshold, the control circuit is configured to: Determine a first component of the load current based on the load voltage feedback signal; Determine a second component of the load current based on the load current feedback signal; and Determine the load current based on the weighted sum of the first component and the second component.

14. The load control device according to claim 13, wherein, The first component is determined by calculating the product of the input power and the efficiency parameter, dividing the product by the magnitude of the load voltage indicated by the load voltage feedback signal, and applying a first scaling factor to the result of the division.

15. The load control device according to claim 14, wherein, The load current feedback signal is determined by integrating the sensed signal via the integrator circuit and filtering the integrated sensed signal via the filter circuit, and wherein the second component is determined by applying a second scaling factor to the load current feedback signal.

16. The load control device according to claim 15, wherein, The first scaling factor and the second scaling factor are determined based on a percentage distance between the low power threshold and the high power threshold of the current power amount delivered to the electrical load.

17. The load control device according to claim 15, wherein, The control circuit is configured to turn on the controllable switching device approximately simultaneously with driving the at least one drive signal high and to maintain the controllable switching device on for at least the length of the pulse of the load current.

18. A load control device for controlling an amount of power delivered to a lighting load, the load control device comprising: A load regulation circuit configured to control an amplitude of a load current conducted through the lighting load to control the amount of power delivered to the lighting load, the load regulation circuit including an output inductor and a winding magnetically coupled to and electrically isolated from the output inductor, the load regulation circuit being configured to generate a sensed signal via the winding, wherein the sensed signal indicates a voltage formed across the output inductor; A load sensing circuit configured to generate a first feedback signal indicative of an amplitude of a load voltage formed across the lighting load and a second feedback signal indicative of an amplitude of the load current conducted through the lighting load based on the sensed signal; and A control circuit configured to generate at least one drive signal for controlling the load regulation circuit to adjust an average amplitude of the load current conducted through the lighting load, wherein: Under a condition that a current intensity of the lighting load is higher than a first threshold, the control circuit is configured to generate the at least one drive signal based on the first feedback signal; Under a condition that the current intensity of the lighting load is lower than a second threshold, the control circuit is configured to generate the at least one drive signal based on the second feedback signal; and Under a condition that the current intensity of the lighting load is between the first threshold and the second threshold, the control circuit is configured to generate the at least one drive signal based on a portion of the first feedback signal and a portion of the second feedback; wherein the load sensing circuit includes an integrator circuit and a filter circuit, and wherein the second feedback signal is generated by integrating the sensed signal via the integrator circuit and filtering the integrated sensed signal via the filter circuit; and Wherein, the filter circuit includes a controllable switching device configured to control when the filter circuit filters the integrated sensed signal to generate the load current feedback signal, and wherein the control circuit is further configured to cooperate with the at least one drive signal to turn the controllable switching device on and off to obtain the second feedback signal.

19. The load control device according to claim 18, wherein, The control circuit is configured to turn on the controllable switching device approximately simultaneously with driving the at least one drive signal high.

20. The load control device according to claim 19, wherein, The control circuit is configured to maintain the controllable switching device on for at least the length of the pulse of the load current.

21. The load control device according to claim 18, wherein, When the current intensity of the lighting load is higher than the second threshold, the control circuit is configured to determine the magnitude of the load current by multiplying the input power of the load regulation circuit by an efficiency parameter associated with the load regulation circuit and dividing the multiplied result by the magnitude of the load voltage indicated by the first feedback signal.

22. The load control device according to claim 21, wherein, The load regulation circuit further includes an inverter, a transformer coupled to the inverter, and a current sensing circuit. The inverter is configured to receive a bus voltage, the inverter responds to the at least one drive signal, and the current sensing circuit is configured to generate a second sensed signal indicative of a sensed current conducted through the inverter, and wherein the control circuit is configured to determine the input power of the load regulation circuit based on the magnitude of the sensed current and the magnitude of the bus voltage.

23. The load control device according to claim 18, wherein, When the current intensity of the lighting load is between the first threshold and the second threshold, the control circuit is configured to: Determine a first component of the load current conducted through the lighting load based on the first feedback signal; Determine a second component of the load current conducted through the lighting load based on the second feedback signal; And Determine the load current based on a weighted sum of the first component and the second component.

24. The load control device according to claim 23, wherein, The second feedback signal is generated by integrating the sensed signal via the integrator circuit and filtering the integrated sensed signal via the filter circuit, wherein the first component of the load current is determined by applying a first scaling factor to the first feedback signal.

25. The load control device according to claim 24, wherein, The control circuit is configured to turn on the controllable switching device approximately simultaneously with driving the at least one drive signal high and maintain the controllable switching device on for at least the length of the pulse of the load current.

26. The load control device according to claim 24, wherein, The second component is determined by multiplying the input power of the load regulation circuit by an efficiency parameter associated with the load regulation circuit, dividing the multiplied result by the magnitude of the load voltage indicated by the first feedback signal, and applying a second scaling factor to the divided result.

27. The load control device according to claim 26, wherein, The load regulation circuit includes an inverter, a transformer coupled to the inverter, and a current sensing circuit. The inverter is configured to receive a bus voltage and responds to the at least one driver signal. The current sensing circuit is configured to generate a second sensing signal indicative of a sensed current conducted through the inverter, and wherein the input power of the load regulation circuit is determined based on the magnitude of the sensed current and the magnitude of the bus voltage.

28. The load control device according to claim 26, wherein, The first scaling factor and the second scaling factor are determined based on a percentage distance of the current intensity between the first threshold and the second threshold.

29. A load control device for controlling an amount of power delivered to a lighting load, the load control device comprising: A load regulation circuit configured to generate a sensing signal and control an amplitude of a load current conducted through the lighting load to control the amount of power delivered to the lighting load. The load regulation circuit includes an output inductor and is configured to operate in a continuous mode when the inductor current conducted through the output inductor is continuous and in a discontinuous mode when the inductor current conducted through the output inductor is discontinuous. A load sensing circuit configured to generate: A first feedback signal indicative of an amplitude of a load voltage formed across the lighting load; And A second feedback signal indicative of an amplitude of the load current conducted through the lighting load; And A control circuit configured to: Receive both the first feedback signal and the second feedback signal; and Generate at least one driver signal that controls the load regulation circuit to adjust an average amplitude of the load current conducted through the lighting load, wherein: When the load regulation circuit operates in the continuous mode, the control circuit is configured to generate the at least one driver signal based on the first feedback signal; and When the load regulation circuit operates in the discontinuous mode, the control circuit is configured to generate the at least one driver signal based on the second feedback signal. Wherein, the load sensing circuit includes an integrator circuit configured to integrate the sensing signal, and the first feedback signal is generated based on the integrated sensing signal; and Wherein, the load sensing circuit further includes a filter circuit configured to filter the integrated sensing signal to produce the first feedback signal. The filter circuit includes a controllable switching device for controlling when the filter circuit filters the integrated sensing signal to produce the first feedback signal, and the control circuit is further configured to cooperate with the at least one driver signal to turn the controllable switching device on and off.

30. The load control device according to claim 29, wherein, The load regulation circuit is configured to generate the at least one drive signal based on the first feedback signal when a target intensity of the lighting load is higher than a high threshold, and to generate the at least one drive signal based on the second feedback signal when the target intensity of the lighting load is lower than a low threshold.

31. The load control device according to claim 30, wherein, The load regulation circuit is configured to generate the at least one drive signal based on both the first feedback signal and the second feedback signal when the target intensity of the lighting load is between the high threshold and the low threshold.

32. The load control device according to claim 29, wherein, The at least one drive signal is characterized by an operating period during which the inductor current conducted through the output inductor is continuously higher than zero amperes in the continuous mode, and the inductor current conducted through the output inductor reaches approximately zero amperes during at least a portion of the operating period of the at least one drive signal in the discontinuous mode.

33. The load control device according to claim 29, wherein, When the load regulation circuit operates in the discontinuous mode, the control circuit is further configured to generate the at least one drive signal based on the first feedback signal.

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