The hysteresis control technique keeps the output current within a set band by switching ON or OFF when the current crosses upper or lower limits.
Execution Sample
Power Electronics
ref_current = 5.0
band = 0.5
upper_limit = ref_current + band
lower_limit = ref_current - band
if current > upper_limit:
switch = 'OFF'elif current < lower_limit:
switch = 'ON'
This code checks if the current is outside the hysteresis band and switches the device ON or OFF accordingly.
Analysis Table
Step
Measured Current (A)
Condition
Action
Switch State
1
4.6
4.6 > 5.5? No; 4.6 < 4.5? No
No switch change
Maintains previous state
2
5.6
5.6 > 5.5? Yes
Switch OFF
OFF
3
5.3
5.3 > 5.5? No; 5.3 < 4.5? No
No switch change
OFF
4
4.4
4.4 > 5.5? No; 4.4 < 4.5? Yes
Switch ON
ON
5
4.8
4.8 > 5.5? No; 4.8 < 4.5? No
No switch change
ON
6
5.7
5.7 > 5.5? Yes
Switch OFF
OFF
7
5.0
5.0 > 5.5? No; 5.0 < 4.5? No
No switch change
OFF
8
4.3
4.3 > 5.5? No; 4.3 < 4.5? Yes
Switch ON
ON
9
4.9
4.9 > 5.5? No; 4.9 < 4.5? No
No switch change
ON
10
5.6
5.6 > 5.5? Yes
Switch OFF
OFF
💡 Process repeats continuously to keep current within hysteresis band.
State Tracker
Variable
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Step 7
Step 8
Step 9
Step 10
Measured Current (A)
4.6
5.6
5.3
4.4
4.8
5.7
5.0
4.3
4.9
5.6
Switch State
ON (assumed)
OFF
OFF
ON
ON
OFF
OFF
ON
ON
OFF
Key Insights - 3 Insights
Why does the switch not change state when the current is within the hysteresis band?
Because the current is between the upper and lower limits, the control maintains the previous switch state to avoid rapid switching, as shown in steps 1, 3, 5, 7, and 9 in the execution_table.
What happens when the current exceeds the upper limit?
The switch turns OFF immediately to reduce the current, as seen in steps 2, 6, and 10 where the current is above 5.5A and the switch changes to OFF.
Why is there a lower limit in hysteresis control?
The lower limit prevents the switch from turning ON too early, avoiding rapid switching. When current falls below 4.5A, the switch turns ON, as in steps 4 and 8.
Visual Quiz - 3 Questions
Test your understanding
Look at the execution_table at step 4. What is the switch state after the action?
AON
BOFF
CNo change
DUndefined
💡 Hint
Refer to the 'Switch State' column at step 4 in the execution_table.
At which step does the current first exceed the upper limit causing the switch to turn OFF?
AStep 1
BStep 4
CStep 2
DStep 5
💡 Hint
Check the 'Condition' column for current > 5.5 in the execution_table.
If the hysteresis band was increased to 1.0 A, how would the switch behavior change at step 2?
ASwitch would still turn OFF
BSwitch would remain ON
CSwitch would toggle ON and OFF rapidly
DSwitch state would be undefined
💡 Hint
Look at the 'upper_limit' calculation and compare with current at step 2 in variable_tracker.
Concept Snapshot
Hysteresis control keeps output current within a band around a reference.
Switch turns ON if current < lower limit.
Switch turns OFF if current > upper limit.
Prevents rapid switching by allowing a band gap.
Common in power electronics for stable current control.
Full Transcript
Hysteresis control technique works by measuring the output current and comparing it to a reference current with an allowed band. If the current goes above the upper limit, the switch turns OFF to reduce current. If it falls below the lower limit, the switch turns ON to increase current. When the current is within the band, the switch state remains unchanged to avoid rapid switching. This cycle repeats continuously to maintain current stability. The execution table shows step-by-step current measurements, conditions checked, actions taken, and switch states. Key moments clarify why the switch does not change state inside the band and the role of upper and lower limits. The visual quiz tests understanding of switch states at specific steps and effects of changing the band size.