Dynamic PWM Feedback Control for Vehicle Power Supply Voltage Stability
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Solution Overview
Problem
Existing power supply circuits in vehicles face challenges in stabilizing output voltage due to variations in battery voltage and load conditions, leading to potential oscillations and system malfunctions.
Innovation Solution
The power supply circuit dynamically adjusts the gain and phase of the PWM feedback control unit by using a digital circuit configuration with a parameter controller that changes current feedback controller parameters based on battery voltage and load current variations, optimizing bandwidth for stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed parameters are used in the PWM feedback control unit, then the circuit structure is simple, but the output voltage becomes unstable when battery voltage varies
Solution Approach 1:
The patent applies dynamics by making the feedback control parameters variable rather than fixed. The controller dynamically adjusts the gain and phase parameters of the PWM feedback control unit based on the detected battery voltage level. This allows the system to adapt to varying battery conditions and maintain stable output voltage, resolving the contradiction between simplicity and stability.
Solution Approach 2:
The patent changes the parameters of the feedback control unit according to battery voltage conditions. Specifically, different gain and phase parameters are selected based on whether the battery voltage is above or below a threshold value. This parameter adaptation enables the system to maintain optimal performance across varying battery conditions without requiring a completely complex reconfiguration.
2Reliability
If the feedback control parameters are adjusted dynamically, then the output voltage stability is improved, but the control circuit complexity increases
Solution Approach 1:
The patent segments the battery voltage operating range into distinct regions (above threshold and below threshold). For each region, pre-determined optimal parameters are applied. This segmentation approach simplifies the control logic compared to continuous adjustment, as the controller only needs to detect which region the current voltage falls into and apply the corresponding parameter set.
Solution Approach 2:
The patent implements feedback by continuously monitoring the battery voltage and using this information to adjust the feedback control parameters. The detected voltage level feeds back to the controller, which then selects appropriate gain and phase parameters to maintain stable output. This closed-loop feedback mechanism ensures stability without requiring overly complex open-loop control circuits.
3Speed
If the bandwidth is increased for fast response, then the transient response is improved, but oscillations may occur
Solution Approach 1:
The patent changes the bandwidth parameter of the feedback control unit based on battery voltage conditions. By adjusting the bandwidth along with gain and phase parameters, the system achieves fast transient response when needed while preventing oscillations through appropriate parameter selection. This dynamic parameter adjustment resolves the contradiction between speed and stability.
Data Source
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AI summary
An object of the present invention is to provide a power supply voltage stabilizing method that can suppress the performance of a switching power supply from being deteriorated even when a battery voltage varies and/or load conditions change. In a power supply voltage stabilizing method of a switching power supply including an output power MOS to which a battery voltage is supplied and a PWM feedback control unit that controls the output power MOS, the PWM feedback control unit includes a voltage feedback controller that controls on the basis of a power supply voltage output from the switching power supply and a current feedback controller that controls on the basis of a current output from the switching power supply. A variation in the battery voltage and/or a change in the load condition of the switching power supply are/is detected, and the bandwidth of the PWM feedback control unit is dynamically changed in accordance with the result of the detection.