*6.1. Control System*

In this study, the core of control system is selected as MSP4305438A (Texas Instruments, Dallas, TX, USA). The microcontroller is a reduced instruction set computer (RISC) with a 16-bit mixed-signal processor, which has a high processing power, a fast computing speed and an efficient development environment. The microcontroller can operate stably in a low-temperature environment (−50 ◦C) and was used multiple times in monitoring in Antarctica and the Arctic Ocean [4]. The control system has 11 sets of I/O ports, which can monitor the voltage and current of wind turbine, PV array and batteries in real time, and realizes the control strategy of the power system. Terminal names and general descriptions of the electrical interface of the control system are shown in Table 8.


**Table 8.** Terminal names and general descriptions of the electrical interface of the control system.

### *6.2. DC*/*DC Conversion Circuit and Power Supply Circuit*

The DC/DC conversion circuit and power supply circuit are shown in Figure 13. In this study, the DC/DC conversion circuit can provide better stability to the proposed power system over wide ranges of input and output voltages, and enable more stable and accurate current limiting operation. A thermal shutdown in this circuit is implemented to prevent damages owing to excessive heat.

**Figure 13.** The DC/DC conversion circuit and power supply circuit.

The output voltage of DC/DC conversion circuit can be set by external resistors and the resistors are calculated as follows.

$$R\_2 = V\_{nf} / 70 \mu A \tag{23}$$

$$R\_3 = R\_2 \Big(12/V\_{ref} - 1\Big)\tag{24}$$

where *R*2 and *R*3 are external resistors; *Vref* is the reference voltage set inside the circuit (1.238 V). The resistances of *R*2 and *R*3 are 18 KΩ and 156 KΩ, respectively. Other relevant parameters of the DC/DC conversion circuit can be seen in Table 9.


**Table 9.** Relevant parameters of the DC/DC conversion circuit.

The power supply circuit includes a primary voltage-regulator and a secondary voltage-regulator. Primary voltage-regulator is designed by LT1129 (Analog Devices Inc., Norwood, MA, USA), which can generate 3.3 V at supply of 12 V for MCU, some sensors and some detection circuits in this power system. LM78M05 (Texas Instruments, Dallas, TX, USA) is selected as the core of the secondary voltage-regulator, which can generate 5 V at supply of 12 V to fulfill the requirements of the amplifier. Relevant parameters of the power supply circuit can be seen in Table 10.


**Table 10.** Relevant parameters of the power supply circuit.
