DIY tooling for high-voltage insulation testing products (2) Schematic drawing
Latest update time：2021-06-24
Reads：
I did an online technology sharing and exchange on Tuesday night this week. I felt very novel and a little nervous. It was a good experience and I also found a lot of shortcomings. I will make improvements in the future and keep up the good work.
I would like to add a note. In the previous article on the relay drive circuit of MODEL 3, the last circuit diagram is wrong. The correct one is as follows: the power supply of the relay coil is directly connected to VCC.
This time I will continue to introduce the previous production of the tooling board. The current progress is that the PCB has been processed and the components will be welded after receiving it. First, feel what the board looks like, as shown in the picture below: the board size is 100mm*100mm and the thickness is 1.6mm, two-layer board.
First of all, give the tooling board a resounding name -
Daliwan No. 1.
This name comes from a battle game that I have played for ten years. I still play it occasionally, which is a bit far-fetched.
The functional topology diagram of the tooling board is as follows: before and after the switch of each relay, a combination of resistors and capacitors are arranged to simulate the insulation resistance and Y capacitance. Among them, ① and ③ are fixed resistors and capacitors, used to simulate the battery pack and charging port. The situation at ② is an adjustable resistor, but the capacitance is fixed, which is used to simulate the situation of the entire vehicle.
Let's start designing the schematic diagram and selecting components. The entire schematic diagram is shown below. It looks relatively simple and clear. A total of four types of components are used: connectors, switches, resistors, and capacitors.
The basic requirements of this high-voltage tooling board have been introduced in the previous article. The following is a one-to-one corresponding schematic diagram.
Simulate relay behavior
As analyzed earlier, in order to adapt to the series and parallel combination of various relays, 6 relays need to be connected in the form of the figure below.
Here we sample a manual switch for simulation. This switch uses a commonly used boat-shaped switch, which is simple and convenient to operate manually. It has two options: red and black. It is a 2-pin package with a spacing of 5mm. The body is made of plastic to avoid the risk of electric shock.
Simulate insulation resistance and Y capacitance
According to the position of the relay, there are three places that need to be simulated, namely ①②③ in the functional topology diagram; the circuits at ①③ are the same. The circuit of a bridge arm is as follows: the insulation resistance uses five 2MΩ/1206 resistors in series, and the total is 10MΩ. One of the resistors has a withstand voltage of 200V, adding up to a total of 1000V; the Y capacitor uses four 220nF/1210 capacitors connected in series, with a total capacitance of 55nF. The withstand voltage of a single capacitor is 250V, and the sum is also 1000V.
The insulation resistance at position ② is designed to be adjustable, but the capacitance is fixed, as shown below: The Y capacitor uses four 1uF/1812 capacitors, two in series and two in parallel. The total is still 1uF. The withstand voltage of a single capacitor is 500V. After being connected in series is 1000V. The insulation resistance is adjustable, mainly for accuracy testing. The resistance value is adjustable from 10KΩ to 10MΩ; the switch here also uses the boat-shaped switch above.
Analog high voltage interface
This is to lead the high-voltage points at the front and rear of the relay to the connector, as shown in the figure below: Each high-voltage sampling point has two external connection ports for product selection.
The connector is of the type shown in the picture below, which can be directly connected to the outside without terminal blocks; the actual chosen one is a 2PIN package with a 5mm pin spacing.
I am going to introduce the welding of PCB and physical object later. I will write an article on this content after the board comes back.
Summarize:
I have been writing this since I came back from working overtime, and it is almost early in the morning, so I have gone to bed; all the above are for reference only.
京公网安备 11010802033920号