Abstract: The present disclosure is constructed on the prior art inverter architecture, a pulse code width modulation (PCWM). This is an open loop motor control system without sensing its rotor position. The present disclosure employs a closed loop method to track the optimum efficiency motor operating point directly. A bench load test is conducted to gather information for an AI type control, which includes both load angle vs. voltage command charts and power factor vs. voltage command charts, with load levels as parameters for certain frequency command ranges. This way, the optimum efficiency motor operating points are generated a priori. The AI type control is mechanized to track the optimum efficiency motor operating points.

Abstract: The present disclosure is constructed on the prior art inverter architecture, a pulse code width modulation (PCWM). This is an open loop motor control system without sensing its rotor position. The present disclosure employs a closed loop method to track the optimum efficiency motor operating point directly. A bench load test is conducted to gather information for an AI type control, which includes both load angle vs. voltage command charts and power factor vs. voltage command charts, with load levels as parameters for certain frequency command ranges. This way, the optimum efficiency motor operating points are generated a priori. The AI type control is mechanized to track the optimum efficiency motor operating points.

Abstract: A detailed architectural and operational characteristic of a pulse code width modulation (PCWM) motor drive system is presented. The system can drive a three phase permanent magnet AC (PMAC) motor sinusoidally without sensing its rotor position. The system employs an ultrasonic carrier frequency (e.g., of approximately 20 kHz) to avoid annoying acoustic noise problems. While keeping the hardware construction at a minimum, it can provide the highest possible motor performance by satisfying various motor operating requirements. The system may include an AC to DC converter, an application specific integrated circuit (ASIC), a DC to DC step-down chopper, and a gate drive and power transistor circuitry to drive a three phase AC motor.

Abstract: An inverter for driving a motor, when a command frequency is given, the output voltage is increased as output current is increased as to optimize motor efficiency under varying load conditions. The inverter is comprised of a converter to convert an input ac voltage to a dc voltage, a current sensor to measure an output current for determining a load level of the motor, a voltage setting means to calculate a command voltage as a function of a command frequency and the measured current, an encoding means to issue on a real time basis bit patterns containing information on the command frequency and the command voltage, a decoding means to decode the bit patterns into a pulse width modulated (PWM) signal, a clock means to provide a timing signal for the encoding means and the decoding means, and an inverter to modulate the dc voltage by the PWM signal, thereby applying the motor input voltage to the motor.

Abstract: A software-based inverter has a logic portion which is preferably made of LSIs. The inverter is therefore low-cost, yet provides a more efficient, precise and sophisticated operation for the inverter-motor combination. The inverter permits independent frequency and voltage application within the maximum and minimum voltage/frequency envelopes for a substantially optimal inverter-motor performance under a given load condition. The higher harmonics associated with the signal modulation are limited to a range between 0.9 kHz to 1.5 kHz with the center frequency at 1.2 kHz so that the harmonics are substantially attenuated by motor windings compared to the signal having a frequency range of 10 Hz-120 Hz, thereby resulting in higher efficiency and lower noise and vibration levels for the inverter-motor combination.

Abstract: An electronic expansion valve comprising a stepping motor, motion conversion member for converting the rotational motion of the stepping motor to a screw motion, a valve pintle coupled to the motion conversion means to be rectilinearly displaced and having pistons at both ends of the valve pintle, of which the pistons are slidably supported on valve casing members, a valve body formed as an integral part of the valve pintle at an intermediate portion thereof, and a valve seat which has such an outer surface that when the valve pintle is displaced with respect to the valve seat in either direction, the cross sectional area and the shape of a passage defined between the valve seat and the valve pintle are smoothly varied. The valve can be used in refrigeration cycle with a compressor. Stable operation of the refrigeration cycle is obtained.

Abstract: A multi-mode water heating system wherein a capacity control mechanism is provide so that no additional heat source is required and via use of capacity control, either solar radiation energy or ambient air energy is selectively utilized dependent on the availability of sunshine. A system configuration is so arranged as to maximize the system seasonal coefficient of performance by a refrigeration cycle optimization which adjusts both a pump/compressor speed and pressure regulating valve opening.

Abstract: A water heating system comprising an outdoor heat exchanger including a heat collection chamber, solar collector panels, collector fins, an evaporator for passing refrigerant therethrough to perform the heat exchange between the refrigerant and the heat transferred from the panels and fins to evaporate the refrigerant. The panels, fins and evaporator are incorporated integrally in the heat collection chamber. A variable rotational speed compressor is connected to the outdoor heat exchanger for compressing the vaporized refrigerant from the evaporator. A heat exchanger disposed on the bottom side in the water storage tank passes the refrigerant vapor from the compressor to perform the heat exchange between the water in the tank and the refrigerant vapor to condense the refrigerant vapor.

Abstract: A heat pump air conditioning system with an active digital control of the refrigeration cycle thereof to improve the coefficient of performance. The system can incorporate solar collectors in parallel with the outdoor heat exchanger and a water storage tank in the system to maximize the utilization of solar heating and nocturnal cooling as an additional heat source or heat sink means when such are available to further improve the coefficient of performance. The system also incorporates individual temperature control mechanisms in each room to circulate an adequate amount of water from the storage tank in accordance with the heat demand of each room, thus contributing to realization of an energy efficient central air conditioning system.