Controller Modes

The brake/clutch controller offers a user selectable closed loop current controller and open loop voltage control and direct PWM ducty cycle control.

Controller modes

Set the controller mode by writing an enum to controller_0_mode or controller_1_mode:

Control mode	Description
`current`	Closed loop current controller.
`voltage`	Direct open loop voltage control.
`duty`	Direct open loop duty cycle control.
`test_l`	Inductance test controller.
`test_r`	Resistance test controller.

Controller mode: current

The current controller performs closed loop control of the load winding current.

The controller structure is:

In this case:

\(i_{cmd}\) is taken fron the JCS signal cmd_ch_0 or cmd_ch_1.
\(v_{cmd}\) is the voltage command output from the PI controller.
\(duty\) is generated by normalising \(v_{cmd}\) to the measured DC bus voltage as \(duty = {v_{cmd} \over v_{dc}}\).

Note: The switching mechanism employed is unipolar, in that it is implemented using a single high side MOSFET. However the PI controller may produce negative going voltage commands or commands clamped to zero. Some controller performance degradation should be expected when commands around this region are generated. Typical behaviour might manifest as a mechanism being faster to turn on than it is to turn off.

Configuration parameters

PI Current controller

Commands	Type	Required	Description
`controller_X_current_kp`	float32	Required	Channel X current controller proportional gain (A). `X` is channel 0 or 1.
`controller_X_current_ki`	float32	Required	Channel X current controller integral gain (A.s). `X` is channel 0 or 1.
`controller_X_limit_out_h`	float32	Required	Channel X current controller output and integrator upper limit (V). `X` is channel 0 or 1.
`controller_X_limit_out_l`	float32	Required	Channel X current controller output and integrator lower limit (V). `X` is channel 0 or 1.

To start the controller, set controller_X_mode to current to select the channel 0 or 1 current controller, then start the controller with a write to controller_X_start.

X is channel 0 or 1.

Controller mode: voltage

The voltage controller performs open loop control of the load winding voltage by transforming the incoming voltage command to a duty cycle.

The controller structure is:

In this case:

\(v_{cmd}\) is the voltage command taken fron the JCS signal cmd_ch_0 or cmd_ch_1.
\(duty\) is generated by normalising \(v_{cmd}\) to the measured DC bus voltage as \(duty = {v_{cmd} \over v_{dc}}\).

Voltage command

Commands	Type	Required	Description
`controller_X_limit_out_h`	float32	Required	Channel X voltage command output upper limit (V). `X` is channel 0 or 1.
`controller_X_limit_out_l`	float32	Required	Channel X voltage command output lower limit (V). `X` is channel 0 or 1.

To start the controller, set controller_X_mode to voltage to select the channel 0 or 1 duty cycle controller, then start the controller with a write to controller_X_start.

X is channel 0 or 1.

Controller mode: duty

The duty cylce controller performs open loop control of the load winding voltage by directly setting the duty cycle.

The controller structure is:

In this case:

\(duty_{cmd}\) is the voltage command taken fron the JCS signal cmd_ch_0 or cmd_ch_1.
An output duty cycle \(duty\) is generated by applying a scale and offset to the incoming JCS signal command as \(duty = duty_{cmd} * scale - offset\).

Note: The duty cycle output to the load is hard clamped to [1.0, 0.0].

Configuration parameters

Duty cycle command

Commands	Type	Required	Description
`controller_X_duty_scale`	float32	Optional	Channel X duty cycle controller command scale value. `X` is channel 0 or 1.
`controller_X_duty_offset`	float32	Optional	Channel X duty cycle controller command offset value. `X` is channel 0 or 1.

To start the controller, set controller_X_mode to duty to select the channel 0 or 1 duty cycle controller, then start the controller with a write to controller_X_start.

X is channel 0 or 1.

Controller mode: test_l

This controller mode attempts to determine load inductance (H) via frequency injection.

Parameters:

Command	Type	Required	Description
`controller_X_test_l_v_bias`	float32	Required	Channel X bias voltage (V). `X` is channel 0 or 1.
`controller_X_test_l_v_amplitude`	float32	Required	Channel X test square wave amplitude (V), centered around the bias voltage. `X` is channel 0 or 1.
`controller_X_test_l_freq_hz`	float32	Required	Channel X test square wave frequency (Hz). `X` is channel 0 or 1.
`controller_X_test_l_time_ms`	uint16	Required	Channel X test duration (ms). `X` is channel 0 or 1.

Once the parameters are written, set controller_X_mode to test_l to select the inductance test, then start the test with a write to controller_X_start. Poll the status of the test with a boolean read to command controller_X_is_running. The boolean value will be true if the controller is running (ie, the test is still running) and false if the controller is in any other state. Exit the test early with a write to command controller_X_stop.

Upon test completion read float32 from command controller_X_L. The test failed if the return value is 0.0f.

X is channel 0 or 1.

Controller mode: test_r

This controller mode attempts to determine the load resistance (Ohms) via Ohms law.

Parameters:

Command	Type	Required	Description
`controller_0_test_r_v_amplitude`	float32	Required	Channel X test voltage (V). `X` is channel 0 or 1.
`controller_0_test_r_time_ms`	uint16	Required	Channel X test duration (ms). `X` is channel 0 or 1.

Once the parameters are written, set controller_X mode to test_r to select the resistance test, then start the test with a write to controller_X_start. Poll the status of the test with a boolean read to command controller_X_is_running. The boolean value will be true if the controller is running (ie, the test is still running) and false if the controller is in any other state. Exit the test early with a write to command controller_X_stop.

Upon test completion read float32 from command controller_X_R. The test failed if the return values is 0.0f.

X is channel 0 or 1.