Energy-saving electricity feedback device and method for an elevator

An elevator electricity feedback device includes a sampling unit, a transmitting unit, and a central processing unit. The sampling unit is electrically connected with an energy supply network of the elevator and the CPU, the transmitting unit is electrically connected with a motor driver of the elevator and electrically connected with the energy supply network through an AC resistor; and the CPU is electrically connected with the transmitting unit. The transmitting unit is electrically connected with the motor driver of the elevator to feed back an energy of the motor driver to the energy supply network when the motor driver is in an energy generating state so that an effect of conserving energy is achieved. In the energy generating state, a DC current produced by the motor driver is converted into AC current which is transmitted to the energy supply network.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a field of automatic control, and more particularly to, an elevator electricity feedback device, an elevator electricity feedback method and an elevator thereof.

BACKGROUND OF THE INVENTION

According to statistical reports by China's elevator association, in China the number of elevators being used is now 1.5 million, and the number of sold elevators is increasing by more than 150 thousand per year. This means China has become an elevator superpower in the world. With increasing number of elevators used in China, an electricity consumption amount of a typical elevator is approximate 50-100 kWh/day. By electricity consumption per day of 80 kWh for each elevator, with the conservative estimated elevator numbers of 1.5 million, the total electricity consumption per day is calculated approximate 120 million KWh, and hence the total electricity consumption per year is 43.8 billion KWh. In this manner, the energy consumption per year of the whole China elevators is equivalent to seven-month energy generation by the Three Gorges' Hydropower Station. Evidently, the elevator energy consumption is tremendous. Therefore, this brings an elevator energy-conservation demand without a moment delay. Energy-conserving elevators are the inevitable trends in the future elevator development.

The elevator travel regulation is very special, primarily including ascending and descending movements each for 50%. When the elevator is in an ascending condition without load, the counter-weight of the elevator pulls the elevator so that a tractor of the elevator is in an energy generating state; similarly, when the elevator is in a descending condition with a full load, the elevator is also in an energy generating state.

The tractor of the elevator is in the energy generating state when ascending in a no-load condition and descending in a full-load condition so that DC voltage of a driver is raised by the energy generated by the tractor. In order to ensure the driver operating normally, the energy generated by the tractor needs to be released. A traditional method is to add a braking unit and a braking resistor to the driver, namely a heat dissipation approach, to dissipate the energy generated by the tractor by the braking resistor.

Because the energy generated by the tractor is dissipated by the braking resistor in heat dissipation, the energy is not effectively utilized. Currently there are a few methods involving effective utilization of the dissipated energy, and three methods are discussed in the following.

1. A method of adopting a large capacitor is introduced. When the tractor of the elevator is in the energy generating state, the large capacitor is charged through a circuit so that the energy in the large capacitor can be utilized for a control circuit of the driver. The method adopting the large capacitor is an advancement of reutilization of the energy generated by the tractor but electric power of the control circuit of the driver is low, and the energy consumption the control circuit of the driver is also low so that a part of the energy generated by the tractor that cannot be completely stored in the large capacitor is still necessarily dissipated by the braking resistor in heat dissipation.

2. A method of adopting storing-energy batteries is introduced, the principle of which is the same as the large capacitor method described above.

3. A simpler energy-conserving method is to power-off the driver and a lighting power when the elevator is in a standby state. In fact, this energy-conserving method cannot completely solve the problem of elevator energy consumption.

The above-mentioned methods cannot completely accomplish purposes of conserving energy.

SUMMARY OF THE INVENTION

To solve the above-mentioned drawbacks, an objective of the present invention is to provide an elevator electricity feedback device, an elevator electricity feedback method and an elevator thereof.

In order to solve the above-mentioned problem, the present invention provides an elevator electricity feedback device which comprises a sampling unit, a transmitting unit and a central processing unit (CPU). The sampling unit which is electrically connected to an energy supply network of an elevator and the CPU is utilized for sampling alternating current (AC) signals of the energy supply network and inputting the sampled AC signals to the CPU. The transmitting unit which is electrically connected to a motor driver of the elevator is electrically connected with the energy supply network through an AC resistor, and when the motor driver is in an energy consuming state, the transmitting unit transmits energy produced by the energy supply network to the motor driver; when the motor driver is in an energy generating state, the transmitting unit feeds back energy produced by the motor driver to the energy supply network. The CPU which is electrically connected with the transmitting unit is utilized for inputting the AC signals obtained by the sampling unit to the transmitting unit.

Optionally, the transmitting unit further comprises a detector, a pulse width modulation (PWM) unit, and a switch. The switch is electrically connected with the motor driver and electrically connected with the energy supply network through the AC resistor, and when the motor driver is in the energy consuming state, the switch converts the AC current provided by the energy supply network into DC current which is transmitted to the motor driver; when the motor driver is in the energy generating state, the switch inverts the DC current produced by the motor drive into AC current which is transmitted to the energy supply network. The detector is electrically connected with the motor driver and the CPU, and the detector is utilized for detecting an operating state of the motor driver and inputting the detected operating state of the motor driver to the CPU. The PWM unit is electrically connected with the CPU and the switch, and the PWM unit is utilized for obtaining the AC signals of the energy supply network, and when the motor driver is in an energy generating state, the PWM unit synchronizes the current transmitted to the energy supply network by the switch and the existing current of the energy supply network.

Optionally, the detector further comprises a capacitor and a threshold value judgment unit such that the capacitor is electrically coupled with the motor drive, the threshold value judgment unit is electrically coupled with the capacitor and the CPU, and the detector is utilized for comparing a voltage between two ends of the capacitor with a voltage threshold value, and transmitting a control signal to the CPU according to a comparing result.

Optionally, the detector further comprises a communication port, and the communication port is electrically connected with the CPU and is utilized for reporting operating parameters of the electricity feedback device to a bus.

Optionally, the electricity feedback device has operation parameters which include operating times, total energy of the energy feedback, and feedback frequencies.

Optionally, the electricity feedback device further comprises an external multifunction terminal, such that the external multifunction terminal is electrically connected with the CPU and is utilized for controlling enablement and disablement of the electricity feedback device and obtaining a malfunction code of the electricity feedback device.

Optionally, the sampling unit comprises a voltage detector and a current detector, such that the voltage detector is utilized for sampling AC voltage signals of the energy supply network and the current detector is utilized for sampling AC signals of the energy supply network.

Optionally, the energy generating state of the motor driver corresponds to either an ascending no-load condition or a descending full-load condition of the elevator.

The present invention further provides an elevator electricity feedback method by adopting the above-mentioned device, which comprises the following steps; sampling the AC signals of the energy supply network by the sampling unit; detecting the operating state of the motor driver by the transmitting unit and transmitting the operating state of the motor driver to the CPU; and when the motor driver is in the energy generating state, the CPU controlling the transmitting unit to feed back energy produced by the motor driver to the energy supply network, a feedback current being controlled by a sampling signal of the sampling unit to ensure that the feedback current and the existing current of the energy supply network are synchronous.

Optionally, the electricity feedback device includes the transmitting unit further comprises a detector, a pulse width modulation (PWM) unit, and a switch. The step of detecting the operating state of the motor driver by the transmitting unit further adopts the operating state of the motor driver detected by the detector, and the detected operating state of the motor driver is transmitted to the CPU; the control method of the feedback current controlled by the signals sampled by the sampling unit comprises obtaining the AC signals from the CPU by the PWM unit, and controlling the AC current transmitted from the switch to the energy supply network to synchronize with the existing current of the energy supply network according to the AC signals.

Optionally, the transmitting unit includes the detector further comprises a capacitor and a threshold value judgment unit, such that the detector includes the capacitor is electrically coupled with the motor driver of the elevator, and the threshold value judgment unit is electrically coupled with the capacitor; the operating state of the motor driver of the elevator detected by the detector further comprises adopting the threshold value judgment unit to compare a voltage between two ends of the capacitor with a voltage threshold value, and transmitting an operating state signal of the motor driver to the CPU according to a comparing result.

Optionally, the detector includes the threshold value judgment unit transmits a high level signal to the CPU for representing the motor driver in the energy consuming state; the threshold value judgment unit transmits a low level signal to the CPU for representing the motor driver in the energy generating state.

The present invention further provides an elevator having a motor driver, an AC resistor, and the above-mentioned electricity feedback device.

The advantages of the present invention are as follows, the transmitting unit is electrically connected with the motor driver of the elevator to feed back the energy of the motor driver to the energy supply network when the motor driver is in an energy generating state, so that an effect of conserving energy is achieved.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of an elevator electricity feedback device, an elevator electricity feedback method and an elevator thereof provided by the present invention are described in detail with the following accompanying diagrams.

FIG. 1illustrates a schematic structural diagram of an elevator control system according to one embodiment of the present invention, which comprises a motor driver100, an AC resistor110and an electricity feedback device130. The motor driver100is electrically connected with the electricity feedback device130, and the electricity feedback device130is electrically connected with an energy supply network150through the AC resistor110.

The electricity feedback device130further comprises a sampling unit131, a transmitting unit133, a central processing unit (CPU)135, a communication port137and an external multifunction terminal139.

The sampling unit131is electrically connected with the energy supply network150and the CPU135and utilized for sampling alternating current (AC) signals of the energy supply network150, wherein the AC signals includes voltage signals and current signals for each phase of a three-phase alternating current in the energy supply network150. The sampling unit131is also electrically connected with the CPU135and thereby inputs the AC signals sampled from the energy supply network150to the CPU135so as to ensure successive synchronizations of the frequencies and phases between an existing current in the energy supply network150and a feedback current when the transmitting unit133feeds back the energy.

The transmitting unit133is electrically connected to the motor driver100, and through the AC resistor110, electrically connected to the energy supply network150. When the motor driver100is in an energy consuming state, the transmitting unit133transmits an energy provided by the energy supply network150to the motor driver150. When the motor driver100is in an energy generating state, the transmitting unit133feeds back an energy produced by the motor driver100to the energy supply network150. The energy generating state of the motor driver100corresponds to either an ascending no-load condition or a descending full-load condition of the elevator. The transmitting unit133is further electrically connected to the CPU135so that the CPU135can obtain the AC signals sampled by the sampling unit131from the energy supply network150to ensure successive synchronizations of the frequencies and phases between the existing current in the energy supply network150and the feedback current.

The communication port137is an optional element to be electrically connected with the CPU135and utilized for reporting a few operating parameters of the electricity feedback device130to a bus, for instance, a PROFIBUS. The operating parameters include operating times, total energy of the energy feedback, feedback frequency, and so on. The application of the communication port137can be utilized further for extending in environments using the device.

The external multifunction terminal139is an optional element to be electrically connected with the CPU135and utilized for connecting an external control device. For instance, a computer for controlling enablement and disablement of the electricity feedback device130, also pre-sets a set of malfunction code in the CPU135so that the external multifunction terminal139can obtain the set of malfunction code when the device has malfunctioned, so as to find out the malfunction reasons of the device.

Please refer toFIG. 2andFIG. 3.FIG. 2illustrates a concrete architectural diagram of the control system shown inFIG. 1, andFIG. 3illustrates a circuit wiring diagram which with relation toFIG. 2. The AC resistor110can be three inductors, each corresponds to the three-phase current of the energy supply network150respectively. The sampling unit131further comprises a voltage detector1311and a current detector1312, the voltage detector1311and the current detector1312are utilized for sampling the AC signals of the energy supply network150which comprise the voltage signals and the current signals of every phase of the three-phase AC current in the energy supply network150. More particularly, the voltage detector1311is utilized for sampling AC voltage signals of the energy supply network150, and the current detector1312is utilized for sampling AC current signals of the energy supply network150.

The transmitting unit133further comprises a detector2331, a pulse width modulation (PWM) unit2332, and a switch2333. The switch2333is electrically connected with the motor driver100, and through the AC resistor110, electrically connected with the energy supply network150, and when the motor driver100is in the energy consuming state, the switch2333converts a AC current provided by the energy supply network150into DC current which is transmitted to the motor driver100; and when the motor driver100is in the energy generating state, the switch2333inverts a DC current produced by the motor drive100into AC current which is transmitted to the energy supply network150. In this embodiment, the switch2333can be an Insulated Gate Bipolar Transistor (IGBT). In an inverting state, the switch2333inverts the DC current produced by the motor driver100to the AC current, and the frequencies and phases of the AC current are controlled by the PWM unit2332. The PWM unit2332is electrically connected with the CPU135and the switch2333and utilized for obtaining voltage and current states of the energy supply network150from the CPU135, especially for obtaining information of the frequencies and phases to ensure successive synchronizations between the AC current fed back to the energy supply network150by the switch2333and the existing current of the energy supply network150when the motor driver100is energy generating state.

The detector2331is electrically connected with the motor driver100and the CPU135and utilized for detecting an operating state of the motor driver100and thereby inputs the detected operating state of the motor driver100to the CPU135. In this embodiment, the detector2331further comprises a capacitor C and a threshold value judgment unit M, the capacitor C is electrically coupled with the motor drive100, and the threshold value judgment unit M is electrically coupled with the capacitor C and the CPU to determine a voltage between two ends of the capacitor C and transmits a control signal to the CPU135. In an exemplar of an Chinese standard city energy supply network as the energy supply network150, when the motor driver100is in the energy consuming state, a AC current provided from the energy supply network150is commutated to a DC current with 540V through the switch2333so that the voltage between two ends of the capacitor C is 540V. Therefore, when the voltage between two ends of the capacitor C is detected to 540V by the threshold value judgment unit M, the motor driver100is considered in the energy consuming state, and such a state of the motor driver100is reported to the CPU135. When the motor driver100is transferred from the energy consuming state to the energy generating state, the capacitor C is through a discharging and a charging processes, that is, the voltage between two ends of the capacitor C will fall and then rise. With the motor driver100generating energy constantly, the voltage between two ends of the capacitor C also raises constantly, and when the voltage between two ends of the capacitor C reaches a pre-set threshold value, for instance 600V, the motor driver100is considered in the energy generating state, and the state of the motor driver100is reported to the CPU135. Then, the PWM unit2332and the switch2333are controlled by the CPU135to feed back the energy generated by the motor driver100to the energy supply network150. In the process of the motor driver100transforming from energy generation to energy consuming, the threshold value judgment unit M adopts the similar operating mode.

Referring toFIG. 4, a flow chart of an electricity feedback method according to an embodiment of the present invention by adopting the devices shown inFIG. 1toFIG. 3are illustrated, which comprises the steps are as follows: In step S40, the AC signals of the energy supply network150are sampled by the sampling unit131. The step particularly comprises utilizing sampled voltage signals and current signals of each phase of a three-phase alternating current in the energy supply network150to ensure successive synchronizations of the frequencies and phases between the existing current in the energy supply network150and the feedback current.

In step S41, the operating state of the motor driver100is detected by the transmitting unit133. The step particularly comprises comparing a voltage between two ends of the capacitor with a voltage threshold value. In an exemplar of a Chinese standard city energy supply network as the energy supply network150, when the motor driver100is in the energy consuming state, the voltage between two ends of the capacitor C is 540V so that the motor driver100is considered in the energy consuming state. When the motor driver100is transferred from the energy consuming state to the energy generating state, the capacitor C undergoes a discharging and a charging processes, and when the threshold value judgment unit M detects the voltage between two ends of the capacitor C reaches the pre-set threshold value, for instance, a larger than 540V, 600V or 650V, the motor driver100is considered in the energy generating state.

In step S42, an operating state signal of the motor driver100is transmitted to the CPU135according to a comparing result. More particularly, as long as the motor driver100is considered in the energy consuming state as the step S41, a signal for representing the motor driver100being in the energy consuming state is transmitted to the CPU135, and as long as the motor driver100is considered in the energy generating state in step S41, a signal for representing the motor driver100being in the energy generating state is transmitted to the CPU135. For example, a high level electrical signal and a low level electrical signal can represent the two states of the motor driver100, respectively. The threshold value judgment unit M transmits a high level electrical signal to CPU135to represent the motor driver100being in the energy consuming state; and the threshold value judgment unit M transmits a low level electrical signal to CPU135to represent the motor driver100being in the energy generating state.

In step S43, the CPU135determines the operating state of the motor driver100according to the received signals. If the motor driver100is in the energy generating state, the step S44is executed, and if the motor driver100is in the energy consuming state, the process of the electricity feedback method returns to step S40, that is, no action is executed, so that the detecting and sampling of above-mentioned are executed, continually.

In step S44, the PWM unit2332and the switch2333of the transmitting unit133are controlled by the CPU135to feed back the energy generated by the motor driver100to the energy supply network150, and the PWM unit2332obtains sampled signals from the CPU135, so as to control synchronization between the AC current transmitted from the switch2333to the energy supply network150and the existing current of the energy supply network150.

The present invention has been disclosed as the preferred embodiments above, however, the above preferred embodiments are not described for limiting the present invention, various modifications, alterations and improvements can be made by persons skilled in this art without departing from the spirits and principles of the present invention, and therefore the protection scope of claims of the present invention is based on the range defined by the claims.