Introduction: Formula Student Racing - Shutdown Circuit
Shutdown circuit is part of the low-voltage systems and its purpose is to power the AIRs and Pre-charge circuitry. According to rule EV 6.1.2, The shutdown circuit must consists a series path of normally closed shutdown buttons, inertia switch and brake-over-travel switch (BOTS) along with normally open master switches, insulation Monitory Device(IMD), Battery Management System (BMS) and the High-Voltage Disconnect(HVD) interlocks. The BSPD is also a part of this series path and can open the shutdown circuit in case of any plausibility in accordance with rule T 11.6.1.
The shutdown circuit only allows power to the Accumulator Isolation Relay (AIRs) on the condition that both the IMD and BMS are in a working state without any faults. When the rear-reset and cockpit-reset buttons are pressed, shutdown circuit provides power to the AIRs.
If the shutdown circuit is opened, then it will cause Tractive System voltage to fall below 60 V DC hence causing all accumulator current to stop, in accordance with rule EV 6.1.5. If the shutdown is opened by either the IMD or BMS then it can only be closed if the fault is resolved followed by pressing of the rear-reset button which is inaccessible to the driver, hence is pressed by another member present near the vehicle complying with rule EV 6.1.6.
COMPONENTS USED:
The devices which are a part of the Shutdown circuit are: These are in compliance with EV 6.1.2
• 2 Master Switches (MS)
• 3 Shut Down Buttons (SDBs)
• Insulation Monitoring Device (IMD)
• Inertia Switch (IS)
• Brake System Plausibility Device (BSPD)
• Brake Over Travel Switch (BOTS)
• Interlocks
• Cockpit and Rear Reset Buttons
Component and their Functions:
Main Switch (for control and tractive-system; CSMS, TSMS): (Normally open)
Brake over travel switch (BOTS): (Normally closed)
Shutdown buttons (SDB): Normally closed
Insulation Monitoring Device (IMD): Normally open
Battery Management System (BMS): Normally open
Inertia Switch: Normally closed
Interlocks: Closed when circuits are connected
Brake System Plausibility Device: Normally Closed
List of switches in the shutdown circuit
COMPONENT DESCRIPTION:
MASTER SWITCH:
These are manually triggered switches in the shutdown circuit, complying with rule T 11.2.1.
SHUTDOWN BUTTONS:
The car uses three shutdown buttons each button must be push-pull or push-rotate type according to rule T 11.4.2.
INERTIA SWITCH:
The car uses Sensata resettable crash sensors. These resettable crash sensors can be installed to directly shut down the main contactor upon vehicle impact, reducing the risk of fire and electrical shock in post-crash situations.
REFERENCES:
EV 6.1.2
The shutdown circuit is defined as a series connection of at least two master switches, three shutdown buttons, the BOTS, see T 6.2, the IMD, the inertia switch, see T 11.5, the BSPD, see T 11.6, all required interlocks and the AMS.
T 11.6.1
A standalone non-programmable circuit, the BSPD, must open the shutdown circuit, see EV 6.1 and CV 4.1, when hard braking occurs, whilst • [EV ONLY] ≥5 kW power is delivered to the motors. • [CV ONLY] the throttle position is more than 25 % over idle position. The shutdown circuit must remain open until power cycling the LVMS or the BSPD may reset itself if the opening condition is no longer present for more than 10 s.
EV 5.8.6
The AMS must switch off the TS via the shutdown circuit, if critical voltage, temperature or current values according to the cell manufacturer’s datasheet or these rules persistently occurs for more than: • 500 ms for voltage and current values • 1 s for temperature values The accuracy, noise and sample rate of the measurement must be taken into account.
EV 6.3.6
In case of an insulation failure or an IMD failure, the IMD must open the shutdown circuit. This must be done without the influence of any programmable logic. See also EV 6.1.6 regarding the re-activation of the TS after an insulation fault.
EV 6.1.5
If the shutdown circuit is opened, the TS must be shutdown by opening all AIRs and the voltage in the TS must drop to below 60 VDC and 25 VACRMS in less than five seconds. All accumulator current flow must stop immediately. The action of opening the AIRs may be delayed by ≤250 ms to signal the action to the motor controllers and reduce the TS current before the AIRs are opened. The AIR supply must be abruptly switched off before reaching the minimum AIR supply voltage.
EV 6.1.6
If the shutdown circuit is opened by the AMS or the IMD, it has to be latched open by a non-programmable logic that can only be manually reset by a person at the vehicle who is not the driver.
T11.2.1
Master switches must be a mechanical switch of the rotary type, with a red, removable handle. The handle must have a width of at least 50mm and must only be removable in electrically open position. They must be direct acting, i.e. they must not act through a relay or logic.
T11.4.2
Each shutdown button must be a push-pull or push-rotate mechanical emergency switch
where pushing the button opens the shutdown circuit.
Ordering the PCBs
Now we have got the PCB design and it’s time to order the PCB’s. For that, you just have to go to JLCPCB.com, and click on “QUOTE NOW” button.
JLCPCB are also sponsor of this project. JLCPCB (ShenzhenJLC Electronics Co., Ltd.), is the largest PCB prototype enterprise in China and a high-tech manufacturer specializing in quick PCB prototype and small-batch PCB production. You can order a minimum of 5 PCBs for just
$2.
To get the PCB manufactured, upload the gerber file you downloaded in the last step. Upload the.zip file or you can also drag and drop the gerber files.
After uploading the zip file, you’ll see a success message at the bottom if the file is successfully uploaded.
You can review the PCB in the Gerber viewer to make sure everything is good. You can view both top and bottom of the PCB.
After making sure our PCB looks good, we can now place the order at a reasonable price. You can order 5 PCBs for just $2 but if it’s your first order then you can get 10 PCBs for $2.
To place the order, click on “SAVE TO CART” button.
My PCBs took 2 days to get manufactured and arrived within a week using DHL delivery option. PCBs were well packed and the quality was really good.
The shutdown circuit only allows power to the Accumulator Isolation Relay (AIRs) on the condition that both the IMD and BMS are in a working state without any faults. When the rear-reset and cockpit-reset buttons are pressed, shutdown circuit provides power to the AIRs.
If the shutdown circuit is opened, then it will cause Tractive System voltage to fall below 60 V DC hence causing all accumulator current to stop, in accordance with rule EV 6.1.5. If the shutdown is opened by either the IMD or BMS then it can only be closed if the fault is resolved followed by pressing of the rear-reset button which is inaccessible to the driver, hence is pressed by another member present near the vehicle complying with rule EV 6.1.6.
COMPONENTS USED:
The devices which are a part of the Shutdown circuit are: These are in compliance with EV 6.1.2
• 2 Master Switches (MS)
• 3 Shut Down Buttons (SDBs)
• Insulation Monitoring Device (IMD)
• Inertia Switch (IS)
• Brake System Plausibility Device (BSPD)
• Brake Over Travel Switch (BOTS)
• Interlocks
• Cockpit and Rear Reset Buttons
Component and their Functions:
Main Switch (for control and tractive-system; CSMS, TSMS): (Normally open)
Brake over travel switch (BOTS): (Normally closed)
Shutdown buttons (SDB): Normally closed
Insulation Monitoring Device (IMD): Normally open
Battery Management System (BMS): Normally open
Inertia Switch: Normally closed
Interlocks: Closed when circuits are connected
Brake System Plausibility Device: Normally Closed
List of switches in the shutdown circuit
COMPONENT DESCRIPTION:
MASTER SWITCH:
These are manually triggered switches in the shutdown circuit, complying with rule T 11.2.1.
SHUTDOWN BUTTONS:
The car uses three shutdown buttons each button must be push-pull or push-rotate type according to rule T 11.4.2.
INERTIA SWITCH:
The car uses Sensata resettable crash sensors. These resettable crash sensors can be installed to directly shut down the main contactor upon vehicle impact, reducing the risk of fire and electrical shock in post-crash situations.
REFERENCES:
EV 6.1.2
The shutdown circuit is defined as a series connection of at least two master switches, three shutdown buttons, the BOTS, see T 6.2, the IMD, the inertia switch, see T 11.5, the BSPD, see T 11.6, all required interlocks and the AMS.
T 11.6.1
A standalone non-programmable circuit, the BSPD, must open the shutdown circuit, see EV 6.1 and CV 4.1, when hard braking occurs, whilst • [EV ONLY] ≥5 kW power is delivered to the motors. • [CV ONLY] the throttle position is more than 25 % over idle position. The shutdown circuit must remain open until power cycling the LVMS or the BSPD may reset itself if the opening condition is no longer present for more than 10 s.
EV 5.8.6
The AMS must switch off the TS via the shutdown circuit, if critical voltage, temperature or current values according to the cell manufacturer’s datasheet or these rules persistently occurs for more than: • 500 ms for voltage and current values • 1 s for temperature values The accuracy, noise and sample rate of the measurement must be taken into account.
EV 6.3.6
In case of an insulation failure or an IMD failure, the IMD must open the shutdown circuit. This must be done without the influence of any programmable logic. See also EV 6.1.6 regarding the re-activation of the TS after an insulation fault.
EV 6.1.5
If the shutdown circuit is opened, the TS must be shutdown by opening all AIRs and the voltage in the TS must drop to below 60 VDC and 25 VACRMS in less than five seconds. All accumulator current flow must stop immediately. The action of opening the AIRs may be delayed by ≤250 ms to signal the action to the motor controllers and reduce the TS current before the AIRs are opened. The AIR supply must be abruptly switched off before reaching the minimum AIR supply voltage.
EV 6.1.6
If the shutdown circuit is opened by the AMS or the IMD, it has to be latched open by a non-programmable logic that can only be manually reset by a person at the vehicle who is not the driver.
T11.2.1
Master switches must be a mechanical switch of the rotary type, with a red, removable handle. The handle must have a width of at least 50mm and must only be removable in electrically open position. They must be direct acting, i.e. they must not act through a relay or logic.
T11.4.2
Each shutdown button must be a push-pull or push-rotate mechanical emergency switch
where pushing the button opens the shutdown circuit.
Ordering the PCBs
Now we have got the PCB design and it’s time to order the PCB’s. For that, you just have to go to JLCPCB.com, and click on “QUOTE NOW” button.
JLCPCB are also sponsor of this project. JLCPCB (ShenzhenJLC Electronics Co., Ltd.), is the largest PCB prototype enterprise in China and a high-tech manufacturer specializing in quick PCB prototype and small-batch PCB production. You can order a minimum of 5 PCBs for just
$2.
To get the PCB manufactured, upload the gerber file you downloaded in the last step. Upload the.zip file or you can also drag and drop the gerber files.
After uploading the zip file, you’ll see a success message at the bottom if the file is successfully uploaded.
You can review the PCB in the Gerber viewer to make sure everything is good. You can view both top and bottom of the PCB.
After making sure our PCB looks good, we can now place the order at a reasonable price. You can order 5 PCBs for just $2 but if it’s your first order then you can get 10 PCBs for $2.
To place the order, click on “SAVE TO CART” button.
My PCBs took 2 days to get manufactured and arrived within a week using DHL delivery option. PCBs were well packed and the quality was really good.
