Design of wind-solar hybrid LED lighting controller based on new substrate packaging technology

1 Introduction

At present, the wind-solar hybrid system is developing rapidly, and there are many types of wind-solar hybrid controllers, but there are not many systems that can really achieve good economy, reliability and safety. One of the main reasons is that there is no good control system. The wind-solar hybrid lighting controller works in an outdoor environment and is the core of the wind-solar hybrid system. The technical requirements for the controller are high. On the premise of meeting the use function, the control must be intelligent, reliable, long-life and stable.

After the battery is fully charged, the conventional photovoltaic controller will start the open circuit protection mode, disconnecting the charging circuit between the solar panel and the battery to protect the battery. However, for the wind-solar complementary lighting system, the wind turbine cannot be directly open-circuited for protection when the battery is overcharged. Generally, a load unloader is used to brake the wind turbine.

This paper conducts an in-depth study on the existing problems in the engineering application of wind-solar complementary lighting systems, and combines years of practical experience to propose a design method for a wind-solar complementary LED lighting controller based on a new substrate package. The method uses novel circuits and special circuit packaging methods to effectively solve the brake failure problem that occurs in the current wind-solar complementary lighting system, and improves the reliability of the wind-solar complementary lighting system.

2 System Configuration

As shown in Figure 1, the wind-solar complementary lighting system consists of five major parts: wind turbines, solar panels, batteries, controllers, and unloaders.

In the whole system, the functions of the controller mainly include battery charge and discharge management, LED light on and off and full power/half power control, fan charging and unloading control, system hardware and software protection, etc.

3 System Design

3.1 Controller Principle

The wind-solar hybrid controller is divided into control circuit and power circuit according to the functional modules, as shown in Figure 2.

The control circuit includes a single-chip microcomputer, an AD conversion circuit, a display button circuit, an IO drive circuit, a hardware protection circuit and an interface circuit; the voltage and current signals of the battery, solar panel and LED lamp collected by the power circuit board are sent to the AD conversion circuit through the interface circuit, and the AD conversion circuit converts the signal into a signal that can be recognized by the single-chip microcomputer and sends it to the single-chip microcomputer, which processes the converted result and then gives a control instruction to the display button circuit and the IO drive circuit; the power circuit includes a battery circuit, a solar panel circuit, an LED lamp circuit, a wind turbine circuit, a load unloading comparison circuit, a fan load unloading circuit and an interface circuit, and the external device battery, solar panel and LED lamp are respectively connected to the battery circuit, the solar panel circuit and the LED lamp circuit, and the voltage signal output by the wind turbine circuit is sent to the load unloading comparison circuit, which compares it and sends a control instruction to the fan load unloading circuit.

3.2 Conventional unloading control method

In the wind-solar hybrid lighting system, when the battery is overcharged or the wind speed is too high, the wind turbine needs to be braked. The commonly used protection control method is to collect the wind turbine output voltage through the controller AD conversion circuit and determine whether the wind turbine is unloaded through a single limit comparison circuit.

As shown in Figure 3, Vcc-Wind and GND-Wind are the output terminals of the fan after rectification, LM393D is the comparison chip, and pin 2 is the reference voltage input terminal of the comparator. Pin 3 inputs the fan input voltage to pin 3 through the voltage divider resistors R23 and R24, TVS is a voltage stabilizing and anti-shock diode, and CIO is a filter capacitor. By comparing the voltage after rectification of the fan, the gate control model Gate Shunt outputs high and low levels to control whether to unload.

As shown in Figure 3, the single-limit comparator is very sensitive. Ideally, when the input voltage of the comparator reaches the reference voltage, the comparator switches the output state. However, in reality, the wind energy is more random, the voltage generated is intermittent, and the switching characteristics of the comparator are nonlinear, which will cause the comparator to switch frequently and have poor anti-interference ability.

At this time, the MOS switch tube that controls the fan unloading is in the on and semi-on state, and the MOS is easy to burn out, causing damage to the controller.

3.3 New unloading control method

As shown in Figure 4, according to the poor anti-interference ability of the single-limit comparator in Figure 3, we introduce a hysteresis comparison circuit, which is fed back to pin 3 through output pin 1. The output characteristic of the circuit is in two threshold intervals. The unloading function is switched between the two threshold points in this interval, and the working state is not switched frequently, which improves the stability of the comparator. Therefore, it has a certain anti-interference ability, where 12V is the power supply voltage of the comparator, RM1 is the pull-up resistor at the output end, R23.R25 are voltage divider resistors, and pin 2 is the reference voltage.

Through long-term tests and engineering applications, the unloading prediction system using hysteresis comparator circuit can perfectly protect the internal switching components of the controller, improve the stability of unloading performance, and meet the requirements of actual engineering applications.

4 Substrate packaging technology

Feed to pin 3, the output characteristic of the circuit is in two threshold intervals, and the unloading function is switched between the two threshold points in this interval, and the working state is not frequently switched, which improves the stability of the comparator, and thus has a certain anti-interference ability, where 12V is the power supply voltage of the comparator, RM1 is the pull-up resistor at the output end, R23.R25 is the voltage divider resistor, and pin 2 is the reference voltage. Through long-term tests and engineering applications, the unloading prejudgment system using the hysteresis comparator circuit can perfectly protect the internal switch components of the controller, improve the stability of the unloading performance, and meet the requirements of actual engineering applications.

In the wind-solar complementary lighting system, a large amount of energy conversion will be generated during the charging of batteries by solar panels and wind turbines, and part of the energy will be consumed as heat energy, which poses a great risk to the stability of the system circuit, especially in the hot summer when the outdoor temperature reaches 40 degrees. When the controller converts electricity or the fan unloads, a large amount of heat will be generated. If the heat cannot be dissipated in time, the electronic components inside the controller will change their characteristics as the temperature rises, causing the controller to burn out.

Through the controller circuit design specifications, the independent innovation design into aluminum substrate packaging circuit board, its unique metal aluminum plate, has good thermal conductivity. Electrical insulation performance and mechanical processing performance, can quickly dissipate the heat of excessive power loss of the controller when the wind speed is very high, can withstand the impact of high current and high temperature cycle, so that the wind-solar hybrid controller has the characteristics of high reliability, low cost, low power consumption, etc.

As shown in Figure 5, the controller's exterior is mainly composed of a housing 1, an aluminum substrate 2, and a heat sink 3. The aluminum substrate 2 is located at the bottom of the housing 1, and the heat sink 3 is tightly attached to the aluminum substrate 2. The contact surface between the aluminum substrate 2 and the heat sink 3 is coated with thermal conductive silicone grease, which can withstand high current and high temperature impact. The controller power circuit is directly welded on the aluminum substrate, and the aluminum substrate is connected to the heat sink to facilitate heat dissipation.

Through long-term tests and engineering applications, it has been found that the wind-solar hybrid controller packaged with an aluminum substrate has a heat dissipation performance 10 times that of a general controller, and can quickly dissipate heat and protect the controller.

5 Conclusion

The wind-solar hybrid LED lighting controller with new substrate packaging solves the damage caused by overspeed of wind turbines through new substrate packaging technology and access function of intelligent unloading module. This solution solves the problem of overspeed braking of wind turbines and rapid heat dissipation, and also improves the reliability and quality of wind and solar power supply.

At the same time, the control system can realize the control of the flow, so as to achieve a certain degree of peak shaving and valley filling, which not only alleviates the contradiction of electricity consumption, but also improves the power supply structure of the power grid.