3.5 Battery control

Version 3.2 by Admin on 2024/11/21 17:06

3.5.1 Charge control

There are two relays that serve charging the battery: a charging relay and an allow charging relay. With the help of the allow charging relay, the BMS commands the charger to start or stop charging.

The board supports two charge control algorithms:

charging is always allowed;
charging is allowed when there is a signal “Charger connected”.

If you select the "charging is always allowed" algorithm, the charging relay and the allow charging relay are always closed. If at least one of the errors appears:

Overvoltage;
Overcurrent;
High temperature;
Low temperature;
HYG offline (optional);
Combilift offline (optional);
Spirit offline (optional);
Spirit charger error (optional);
Short circuit (optional);
Contactor high temperature (optional);
CH contactor cycles error;
Critical error,

both relays are open (no current flows).

When the algorithm "charging is allowed when there is a signal “Charger connected”" is selected, the relay control is performed as follows:

If there is a signal “Charger connected” and there are no errors (see the list above), then through the delay time T_on the charging relay and the allow charging relay close;
If the signal “Charger connected” disappears, the allow charging relay opens and after the delay time T_off the charging relay opens;
If in the process of charging the voltage on the cell exceeds the EV level, the allow charging relay opens (while the charging relay remains closed);
If errors in the list above occur the charging relay and allow charging relay open.

Note: When errors occur in the system, the charging relay opens either immediately or with the delay T_off (depends on the settings described below).

When the power down request occurs, the allow charging relay opens immediately and the charging relay opens after the delay T_off. Reclosing the charging relay and allow charging relay is performed if the power down request is removed.

To change the parameters of the battery charge control algorithm, select the menu "Cells → Charging control":

In this section:

Enable – a flag to activate the charge control;
Charging algorithm:
- Always on – charging is always allowed;
- On charger connected – charging is allowed when there is a signal “Charger connected”;
- On charge request – charging is allowed when there is a signal “Charge request”;
Current indicating charging – a current level to generate the "Charging current present" signal, A;
Current indicating no charging – a current level to clear the "Charging current present" signal, A;
Delay before starting charging – a time delay T_on before closing the charging relay and the allow charging relay, second;
Delay before stopping charging – a time delay T_off before opening the charging relay, second;
Use specific delays before stopping charging (on errors) – a flag to enable manual settings of time delays T_off for specific errors;
Switch off the charging relay on errors without delay – a flag to protectively open the charging relay without delay. In the opposite case, when an error is detected, the charging relay opens always with the delay “Delay before stopping charging”;
Control the precharging relay – a flag that allows control of the precharging relay;
Voltage to clear the “Ready to charge” (hence, the “Allow charging”) signal – a threshold voltage level on the cell, V; if the voltage of any cell is above this level, the “Ready to charge” signal is cleared;
Voltage to reset the “Ready to charge” (hence, the “Allow charging”) signal – a tolerant voltage level on the cell, V; if all cell voltages are below the tolerant level, the “Ready to charge” signal is set;
Delay before recharging – a time after which the previously opened the allow charging relay closes again, minute; to disable the operation by timeout set "Delay before recharging" to 0.

Note: The allow charging relay closes under two independent conditions:
1) the voltage on the cells reaches the Voltage to reset the “Ready to charge" level and
2) the "Delay before recharging" time has passed since the opening of the allow charging relay.

3.5.2 Discharge control

The board has a discharging relay to connect battery to the load.

The board supports two algorithms to control battery discharging:

load is always connected;
load is connected when there is no signal “Charger connected”.

When the algorithm "load is always connected" is selected, the discharging relay is always closed. If at least one of the errors appears:

Undervoltage;
Overvoltage (optional);
Overcurrent;
High temperature;
Low temperature (optional);
HYG offline (optional);
Combilift offline (optional);
Spirit offline (optional);
Spirit charger error (optional);
Short circuit (optional);
Contactor high temperature (optional);
DCH contactor cycles error;
Critical error

the discharging relay opens.

If you select the algorithm "load is connected when there is no signal “Charger connected”" control relay is as follows:

if there is no signal “Charger connected”, the charging relay is opened and there are no errors (see the list above), then through the delay time T_on the discharging relay closes;
If the signal “Charger connected” appears or errors occur (see the list above), then after the delay time T_off the discharging relay opens.

Note: In case of errors in the system operation, the opening of the discharging relay is performed either immediately or with a delay T_off (depends on the settings described below).

The board supports controlling the precharging relay. The duration of switching on the precharging relay before closing the discharging (load) relay is adjusted.

When the power down request occurs, the discharging relay opens after delay T_off. Reclosing the discharging relay is performed if the power down request is removed.

To change the parameters of the battery discharge control algorithm, select the menu "Cells → Discharging control":

In this section:

Enable – a flag to activate the discharge control;
Discharging algorithm:
- Always on – load is always connected;
- On charger disconnected – load is connected when there is no signal “Charger connected”;
- On discharge request – load is connected when there is a signal “Discharge request”;
Current indicating discharging – a current level to generate the "Discharging current present" signal, А;
Current indicating no discharging – a current level to clear the "Discharging current present" signal, А;
Delay before starting discharging – a time delay T_on before closing the discharging relay, second;
Delay before stopping discharging – a time delay T_off before opening the discharging relay, second;
Use specific delays before stopping discharging (on errors) – a flag to enable manual settings of time delays T_off for specific errors;
Switch off the discharging relay on errors without delay – a flag to protectively open the discharging relay without delay. In the opposite case, when an error is detected, the discharging relay opens always with the delay “Delay before stopping discharging”.
Precharge time – a duration of closing the precharge relay before closing the discharging relay, millisecond;
Voltage to clear the “Ready to discharge” signal – a threshold voltage level on the cell, V; if the voltage of any cell is below this level, the “Ready to discharge” signal is cleared;

Voltage to reset the “Ready to discharge” signal – a tolerant voltage level on the cell, V; if all cells voltages are above the tolerant level, the “Ready to discharge” signal is set;