LED power supply

Abstract

This application relates to an LED power supply for supplying power to an external load, and includes a power supply unit, a sampling unit, and a judgment unit. The power supply unit provides load current to the load, wherein the load current has a first current value during a first time period and a second current value during a second time period. The sampling unit acquires the load voltage of the load, wherein the load voltage has a first voltage value during the first time period and a second voltage value during the second time period. The judgment unit determines whether the type of the load is an LED load or a resistive load based on the first and second voltage values ​​of the load voltage.

Description

Technical Field

[0001] This case involves the field of power supplies, specifically an LED power supply. Background Technology

[0002] For LED power supplies, the load is generally an LED load, but in some evaluation and testing scenarios, a resistive load is required. However, due to the significant difference in the volt-ampere characteristics of resistive and LED loads, LED power supplies must employ different startup strategies for each load; otherwise, startup abnormalities may occur. Specifically, if a startup strategy for an LED load is followed for a resistive load, the output voltage will be too low, triggering the LED power supply's undervoltage protection and preventing normal startup. Furthermore, for LED loads, excessive startup current will negatively impact startup. Therefore, LED power supplies must accurately distinguish between LED and resistive loads and adopt different startup strategies to achieve stable startup for different types of loads. However, as the output voltage range of LED power supplies continues to increase, existing LED power supply load type detection schemes are increasingly unable to differentiate between LED and resistive loads.

[0003] Therefore, it is necessary to develop an LED power supply to solve the problems faced by previous technologies. Utility Model Content

[0004] The purpose of this invention is to provide an LED power supply suitable for different power requirements. By changing the load current, different load voltages can be obtained, and the load type can be determined as an LED load or a resistive load based on the changes in the load voltage. This broadens the load detection range of the LED power supply, effectively improves the accuracy of load type detection, and shortens the load type detection time.

[0005] To achieve the above objectives, this application provides an LED power supply for supplying power to an external load, and includes a power supply unit, a sampling unit, and a determination unit. The power supply unit provides load current to the load, wherein the load current has a first current value during a first time period and a second current value during a second time period. The sampling unit acquires the load voltage of the load, wherein the load voltage has a first voltage value during the first time period and a second voltage value during the second time period. The determination unit determines whether the load type is an LED load or a resistive load based on the first and second voltage values ​​of the load voltage.

[0006] In some embodiments, the first current value is greater than the second current value.

[0007] In some embodiments, when the first voltage value is less than the second voltage value, the determination unit confirms that the type of the load is the LED load.

[0008] In some embodiments, when the first voltage value is greater than the second voltage value, the determination unit confirms that the type of the load is the resistive load.

[0009] In some embodiments, the first current value is less than the second current value.

[0010] In some embodiments, when the difference between the first voltage value and the second voltage value is less than a voltage threshold, the determination unit confirms that the type of the load is the resistive load.

[0011] In some embodiments, when the difference between the first voltage value and the second voltage value is greater than a voltage threshold, the determination unit confirms that the type of the load is the LED load. Attached Figure Description

[0012] Figure 1 This is the circuit architecture diagram of the LED power supply in this case;

[0013] Figure 2A for Figure 1 The diagram shows the load voltage waveform of the LED power supply when the load current is fixed and the connected load is a resistive load.

[0014] Figure 2B for Figure 1 The diagram shows the load voltage waveform of the LED power supply when the load current is fixed and the connected load is an LED load.

[0015] Figure 3 for Figure 1 The diagram shows the current waveform of an LED power supply in an embodiment where the load current is not constant.

[0016] Figure 4A and Figure 4B for Figure 3 The diagram shows the load voltage waveform of the LED power supply.

[0017] Figure 5 for Figure 1 The current waveform diagram of the LED power supply in another embodiment with a variable load current is shown; and

[0018] Figure 6A and Figure 6B for Figure 5 The diagram shows the load voltage waveform of the LED power supply.

[0019] The reference numerals in the attached figures are explained as follows:

[0020] 1: LED power supply

[0021] 2: Load

[0022] 3: Power Supply Unit

[0023] 4: Sampling Unit

[0024] 5: Judgment Unit

[0025] C: Capacitor

[0026] I1: First current value

[0027] I2: Second current value

[0028] V1: First voltage value

[0029] V2: Second voltage value

[0030] Vd: Voltage difference

[0031] t0, t1, t2: Time points Detailed Implementation

[0032] Some typical embodiments that embody the features and advantages of this invention will be described in detail in the following description. It should be understood that this invention can have various variations in different forms, all of which do not depart from the scope of this invention, and the descriptions and drawings therein are essentially for illustrative purposes and not for limiting this invention.

[0033] Please see Figure 1 , Figure 2A , Figure 2B , Figure 3 , Figure 4A and Figure 4B ,in Figure 1 This is the circuit architecture diagram of the LED power supply in this case. Figure 2A for Figure 1 The diagram shows the load voltage waveform of the LED power supply when the load current is fixed and the load is a resistive load. Figure 2B for Figure 1 The diagram shows the load voltage waveform of the LED power supply when the load current is fixed and the load is an LED load. Figure 3 for Figure 1 The diagram shows the load current waveform of an LED power supply in an embodiment where the load current is not constant. Figure 4A and Figure 4B for Figure 3 The diagram shows the load voltage waveform of the LED power supply. Figure 1 As shown, the LED power supply 1 in this case is used to supply power to an external load 2, wherein the type of load 2 can be a resistive load or an LED load.

[0034] The LED power supply 1 includes a power supply unit 3, a sampling unit 4, and a judgment unit 5. The power supply unit 3 includes at least one capacitor C to provide load current to the load 2. The sampling unit 4 is electrically connected to the load 2 and is used to acquire the load voltage of the load 2. The judgment unit 5 is electrically connected to the sampling unit 4 and is used to determine whether the load 2 is a resistive load or an LED load based on the received load voltage. Further, The load voltage variation over time when the load current is fixed and the load 2 is a resistive load is as follows: Figure 2A As shown. When load 2 is an LED load, the expression for the load voltage of load 2 is: Where V LED The load voltage of the LED load is given. With a fixed load current, the variation of the load voltage over time when load 2 is an LED load is as follows: Figure 2B As shown. For resistive loads, when the load current is stable, the load voltage depends on the resistance value R. Generally speaking, the larger the resistance R, the larger the load voltage of the resistive load. However, under the condition of a fixed load current, when the resistance of the resistive load is large, the load voltage of the resistive load is very close to that of the LED load within the load type detection time. Obviously, at this time, the LED power supply cannot distinguish whether the load is a resistive load or an LED load based solely on the detected load voltage.

[0035] This case uses a variable load current and determines whether the load of the LED power supply is a resistive load or an LED load based on the change in load voltage before and after the load current changes. Specifically, when the load current is not fixed, for example... Figure 3 As shown, during the first time period (i.e., from time t0 to time t1), the load current has a first current value I1, and the corresponding load voltage has a first voltage value V1; during the second time period (i.e., from time t1 to time t2), the load current has a second current value I2, and the corresponding load voltage has a second voltage value V2, wherein the first current value I1 is greater than the second current value I2. The determination unit 5 can determine whether the load 2 is an LED load or a resistive load based on the first voltage value V1 and the second voltage value V2 of the load voltage. In this embodiment, if the first voltage value V1 in the first time period is greater than the second voltage value V2 in the second time period, then... Figure 4A As shown, the judgment unit 5 confirms that the type of load 2 is a resistive load; if the first voltage value V1 in the first time period is less than the second voltage value V2 in the second time period, then... Figure 4B As shown, the judgment unit 5 confirms that the type of load 2 is an LED load.

[0036] In other embodiments, the difference between the first voltage value V1 in the first time period and the second voltage value V2 in the second time period can also be used as the basis for determining the load type. Figure 5 for Figure 1 The diagram shows the load current waveform of an LED power supply in another embodiment where the load current is not constant. Figure 6A and Figure 6B for Figure 5 The diagram shows the load voltage waveform of the LED power supply. In this embodiment, compared to... Figure 3 The first current value I1 of the load current in the first time period of the LED power supply 1 shown is greater than the second current value I2 of the load current in the second time period. In this embodiment, when the first current value I1 of the load current in the first time period of the LED power supply 1 is less than the second current value I2 of the load current in the second time period, that is, when the load current is as shown... Figure 5 In this case, further, when the difference Vd between the first voltage value V1 in the first time period and the second voltage value V2 in the second time period is less than the preset voltage threshold Vref, i.e., Vd < Vref, as... Figure 6A As shown, the judgment unit 5 confirms that the type of load 2 is a resistive load; when the difference Vd between the first voltage value V1 in the first time period and the second voltage value V2 in the second time period is greater than the preset voltage threshold Vref, that is, Vd > Vref, as shown. Figure 6B As shown, the judgment unit 5 confirms that the type of load 2 is an LED load. The voltage threshold Vref can be set according to actual needs, and is not limited in this case.

[0037] In summary, the LED power supply in this case obtains different load voltages by changing the load current, and determines whether the load type is an LED load or a resistive load based on the changes in load voltage. This broadens the load detection range of the LED power supply, effectively improves the accuracy of load type detection, and shortens the load type detection time.

Claims

1. An LED power supply for supplying power to an external load, characterized in that, Include: A power supply unit is used to provide a load current to the load, wherein the load current has a first current value during a first time period and a second current value during a second time period. A sampling unit is used to acquire a load voltage of the load, wherein the load voltage has a first voltage value during the first time period and a second voltage value during the second time period; as well as A determination unit is used to determine whether the load is an LED load or a resistive load based on the first voltage value and the second voltage value of the load voltage.

2. The LED power supply of claim 1, wherein, The first current value is greater than the second current value.

3. The LED power supply of claim 2, wherein, When the first voltage value is less than the second voltage value, the determination unit confirms that the type of the load is the LED load.

4. The LED power supply of claim 2, wherein, When the first voltage value is greater than the second voltage value, the determination unit confirms that the type of the load is the resistive load.

5. The LED power supply of claim 1, wherein, The first current value is less than the second current value.

6. The LED power supply of claim 5, wherein, When the difference between the first voltage value and the second voltage value is less than a voltage threshold, the determination unit confirms that the type of the load is the resistive load.

7. The LED power supply of claim 5, wherein, When the difference between the first voltage value and the second voltage value is greater than a voltage threshold, the determination unit confirms that the type of the load is the LED load.

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