Multi-phase Controller Heterodyne Feedback for Motor Frequency Control
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Solution Overview
Problem
Existing synchronous motor controllers are limited by high complexity and cost due to the need for multiple digital signal processors to achieve variable speed operation beyond 3 kHz, as they rely on pulse width modulation and high-speed feedback sensing, which restricts frequency control range and increases hardware and software requirements.
Innovation Solution
A multi-phase, multi-frequency controller using heterodyne signal conversion with a voltage controlled oscillator feedback arrangement, employing a 3-phase ring oscillator and phase lock loop techniques to generate and control baseband frequency signals, reducing the burden on microprocessors by eliminating high-speed frequency generation requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pulse width modulation and high-speed feedback sensing are used to achieve variable speed operation, then frequency control capability is improved, but device complexity and cost increase due to multiple digital signal processors
Solution Approach 1:
The patent extracts the high-speed frequency generation function from the microprocessor and implements it through a dedicated voltage controlled oscillator and heterodyne conversion circuitry. This separation allows the microprocessor to focus on control logic while the oscillator handling handles frequency synthesis, reducing overall system complexity despite expanded frequency capabilities
Solution Approach 2:
The patent introduces a heterodyne conversion intermediary that translates high-frequency oscillator output into usable motor control signals. This intermediary circuitry enables the system to achieve wide frequency control range without requiring the microprocessor to directly generate all control frequencies, thereby managing complexity
2Speed
If multiple digital signal processors are employed to increase output frequency beyond 3 kHz, then frequency control range is improved, but expense and complexity substantially increase
Solution Approach 1:
The patent replaces the mechanical approach of using multiple digital signal processors with an electronic oscillation-based system. A single voltage controlled oscillator generates the required frequencies through heterodyne conversion, eliminating the need for multiple processors and their associated complexity while achieving frequencies beyond 3 kHz
Solution Approach 2:
The patent changes the fundamental parameter of frequency generation from digital signal processing to analog oscillation with heterodyne conversion. The voltage controlled oscillator can be tuned across a wide frequency range by adjusting its control voltage, enabling high-speed operation without the complexity of multiple digital processors
3Measurement precision
If pulse width modulation is used for motor control, then precise voltage control is achieved, but high-speed feedback sensing and error calculation requirements increase microprocessor burden
Solution Approach 1:
The patent extracts the high-speed feedback sensing and error calculation functions from the microprocessor and implements them through dedicated hardware circuits including comparators and heterodyne conversion circuitry. This allows precise voltage control through PWM while relieving the microprocessor of time-critical operations
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 approach enables precise control of AC output voltage for synchronous motors, expanding the frequency control range and reducing hardware and software needs, allowing for seamless integration with faster pulse width modulators and achieving frequencies beyond 100 kHz without controller changes.
Implementation Method 1
A multi-phase, multi-frequency controller using heterodyne signal conversion with a voltage controlled oscillator feedback arrangement
Implementation Method 2
Feedback and closed loop control is provided by frequency and phase discriminators using phase lock loop techniques
Data Source
AI summary
Reference signals are combined with a chop frequency signal in a pulse width modulator (PWM) to provide plural inputs to a multi-phase H-bridge amplifier. Also provided to the bridge amplifier is a high voltage DC input which is converted by the pulsed inputs to the bridge amplifier to a variable AC voltage for driving a motor. The AC drive voltage is also provided to a variable frequency voltage-controlled oscillators (VCOs) in a feedback arrangement, with the variable frequency VCO outputs heterodyned with each of plural outputs of a multi-phase ring oscillator to provide plural baseband signals having a constant phase relationship at a high frequency. The baseband signals form the aforementioned reference signals provided to the PWM in the feedback arrangement with closed loop control and frequency and phase discrimination using phase lock loop techniques for synchronous motor control over a range of DC-100 kHz with 0-25 MHz VCOs.