Sigma-Delta Modulator for Motor Supply Voltage Compensation
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Solution Overview
Problem
Existing control apparatuses for load supply devices are complex and costly in terms of semiconductor chip area due to the need for costly digital resources to compensate for variations in supply voltage, particularly in motor control systems.
Innovation Solution
A control apparatus utilizing a sigma-delta converter to generate a pulse-density modulation signal that compensates for supply voltage variations, reducing the complexity and silicon area requirements by using a feedback circuit and analogue-digital conversion to produce a signal proportional to the inverse of the supply voltage digital signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a circuit with analogue-digital converter and multiplication blocks is used to compensate for supply voltage variations, then the compensation accuracy is improved, but the device complexity and silicon area increase significantly
Solution Approach 1:
The patent extracts the complex multiplication and inversion operations from the control circuit by removing the need for block 61 (inversion and multiplication by constant K) and block 62 (multiplication of digital signal). Instead, a simplified sigma-delta modulator is used that directly generates the compensated signal through feedback, eliminating the need for expensive digital resource occupation and large silicon area while maintaining compensation accuracy.
Solution Approach 2:
The patent applies feedback principle by using the output signal of the sigma-delta modulator to adjust the control signal in real-time. The feedback loop continuously monitors the supply voltage variations and automatically compensates for them, replacing the complex open-loop multiplication and inversion circuitry with a simpler closed-loop system that achieves the same compensation effect with reduced complexity.
2Reliability
If a look-up table or real-time inversion circuit is used to compensate for supply voltage variations, then the compensation performance is improved, but the silicon area occupation increases
Solution Approach 1:
The patent replaces expensive, area-intensive components (look-up tables and real-time inversion circuits) with a simpler, more economical sigma-delta modulator implementation. The modulator uses basic integrator and comparator circuits that occupy minimal silicon area while providing the necessary compensation performance, effectively substituting high-cost components with low-cost alternatives.
3Manufacturing precision
If digital multiplier and PWM converter are used for motor control, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The patent merges the voltage compensation function with the existing PWM control circuitry by integrating the sigma-delta modulator into the control signal path. The modulator combines the supply voltage compensation with the motor control signal generation in a single unified circuit, eliminating the need for separate compensation circuits and reducing overall device complexity while maintaining control precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively stabilizes the phase currents of an electric motor by maintaining consistent operation despite supply voltage variations, minimizing the impact on the motor's performance and reducing the overall circuit complexity and resource usage.
Implementation Method 1
a sigma-delta converter (10) capable of converting to a pulse-density modulation digital signal (SDout) the digital signal (SDin) present at the input terminal (IN)
Implementation Method 2
The converter 10 comprises a feedback circuit 11 capable of providing a signal SDfb at the input terminal IN in response to the value of the output signal SDout
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A control apparatus for a supply device (5) of a load (2), the supply device is of switching type and is connected between a supply voltage (Vdd) and a reference voltage (GND). The apparatus comprises a sigma-delta device (10) having an input terminal at which is present a first digital signal (SDin), and being capable of providing a pulse-density modulation signal (Sdout) at the output terminal; the sigma-delta device comprises a feedback circuit (11) capable of sending to the input terminal (IN) of the sigma-delta device (10) a second digital signal (SDfb) whose value depends on the value of the output signal (SDout), and the apparatus comprises means (20) capable of digitalizing said supply voltage and of providing a further digital signal (Sg). The feedback circuit (16) comprises a terminal (Ext) capable of receiving the further digital signal (Sg), and the sigma-delta device has a gain (G) such that the output digital signal (Sdout) is proportional to the inverse of said further digital signal (Sg). (Fig. 2)