Elevator Power Supply
With more and more elevators being installed, building codes require at least 90 minutes of backup power to ensure the safety of passengers in the event of a utility power failure.
Historically, standby generators have been used to fulfill this requirement but due to maintenance requirements and new air quality control regulations, UPS (Uninterruptible Power Supply) battery backup systems are becoming increasingly popular.
SMPS
The SMPS or switch mode power supply is a type of power supply that produces a regulated dc output signal by using semiconductor switching techniques. It is used for many different applications and is a relatively new technology that has emerged in recent years.
Unlike a linear power supply, an SMPS is much more efficient and has low heat generation. This is because the switching transistor dissipates little power during its operation, unlike the current-dissipating pass transistor in a linear regulator.
An SMPS can be used for a wide range of electronics including computers, chargers and laboratory equipment. In addition, they are also widely used in electronic devices for home appliances like television sets and motor drives.
There are a number of different types of SMPS. Some of the most common include buck-boost and flyback converters.
In general, these types of SMPS use a single switching transistor (power MOSFET) for the purpose of voltage regulation. When the input power is turned on, this transistor changes to a high-dissipation state and then back to a low-dissipation state. This allows the transistor to be switched on and off very quickly, which in turn minimizes the amount of power wasted.
This is an important advantage in a SMPS because it allows the device to be more compact. This is especially true for SMPS with very high switching frequencies, which can reduce the size of the components on the board by up to four times.
Another key advantage of SMPSs is that they can handle a wider range of input current and voltage than traditional linear power supplies. This can help to save energy and reduce the cost of a device.
A power factor correction circuit is also commonly included in a SMPS. This corrects the current flow in the input circuit to follow the sinusoidal shape of the output voltage. This helps to keep the shunt resistors in the power supply at a more constant voltage level and therefore reduces the power factor.
The SMPS can be built to operate from either mains or battery power. This can be useful for an elevator drive where the mains power is often unavailable but the batteries can provide emergency power when required.
Controller
Elevators require a power supply to operate properly. This power can be 3-phase 380 V or single-phase 220 V AC power. Frequent power failures can damage SMPS components and affect the efficiency of the system. Maintaining an emergency power source can help ensure that the elevator will continue operating properly in any situation.
Typically, an elevator power supply includes a controller that coordinates the operation of the different parts of an elevator. It can control various functions such as Elevator power supply speed, door opening speed and delay, lighting, fan, and alarm systems.
For example, the controller may use a power storage device to store power delivered through a travelling cable to the elevator car for future use. This allows the controller to meet peak power demands by supplying low voltage DC power to the system and then delivering the accumulated power at higher voltage levels when needed.
An elevator power supply can also include a DC converter that provides AC for the elevator motor when needed. This converter converts the DC power from a battery to the desired voltage level, e.g., a three-phase 200/400 V commercial power line.
A conventional elevator power supply of this type typically requires three sets of converters and inverters. This increases the cost of the system and reduces efficiency.
To eliminate this cost, a new design can be used that uses only two sets of converters and inverters to provide both normal power supply and emergency backup power. This invention can also simplify the structure of the power supply and improve efficiency.
Another benefit of using a power storage device is that it makes it easier to open and close the elevator doors. Using this method, a controller can power the elevator doors with a DC motor that is powered by the stored power.
This method of powering an elevator door controller system is similar to that described above for the elevator motor and can be implemented with a variety of different devices. However, a preferred embodiment of the invention incorporates a solid-state drive (SSD) in place of a motor-generator set. The SSD can be any suitable device that can meet the specific requirements of the elevator door control system.
Batteries
Elevators are a very important feature in most tall buildings. They help people get from one floor to another with ease and convenience, but they also require a power supply in the event of an outage or other problems.
Historically, most tall buildings have used generators to provide backup power for their elevators. However, due to new building code enforcement and the need for maintenance and air quality control, many building owners are requiring battery backup systems as an alternative.
Batteries are a relatively inexpensive option and can easily be installed to power an elevator. They are especially effective in situations where the electrical grid is unavailable or not functioning properly.
Battery backed up elevators are available in both rack and pinion and cable traction models. Both have traveling cables extending from the battery to a junction box that provides power to a drive motor that drives the hoistway pulleys and sheaves, allowing the elevator car to be raised or lowered.
The system preferably includes solar power for charging the batteries as well as alternative power supplied by a conventional electric power grid in the event of insufficient solar energy. The solar power is redirected from the batteries to the junction box via fixed and traveling power cables.
In addition to the batteries, the system may include a regenerative braking system for capturing electrical energy as the elevator is descending and feeding this back to the batteries when they are fully charged. This can help to ensure that the battery backup system will function as expected even in the event of a power outage or other problems.
Load Capacity
The load capacity of an elevator battery or similar power supply must not only handle the normal operating current but also the inrush/peak current of the ancillary equipment, such as the exhaust fans that can be found on most elevators. This is to prevent damage to the batteries that could be caused by excessive heat dissipation during continuous use.
Some cities require that any battery backup system containing more than 50 gallons of electrolyte be contained in a fire-rated room to ensure the safety of the system. This should be considered when evaluating the system to determine whether it meets local requirements and will be safe to operate in the event of an outage or other problem.
Chargers
An elevator power supply, for example a charger, is used to provide emergency power for an elevator in case of an interruption in the main input power source. This type of power supply, often called an Uninterruptible Elevator power supply Power System (UPS), is especially useful for elevators because it provides a quick transition from a power outage to the back-up power.
One of the advantages of a UPS is that it can be designed to be easily and inexpensively installed in an elevator. An elevator UPS can be a stand alone unit or part of a larger power supply system.
Various factors such as the length of a common power cut, a capacity of a lift motor, the type of elevator, and whether it would be used in a residential or commercial area are taken into account while designing an elevator UPS.
The main disadvantage of the commonly available back-up power systems is their high dv/dt output waveform, which can cause a lot of load current to exceed the output of the dc inverter stage. To solve this problem, the present invention uses a stepped square wave output from an inverter.
Another advantage of this type of UPS is that it can be used in both residential and commercial buildings. It can also be adapted to different power requirements, such as the frequency and voltage required for the elevator motor controller and its motors.
In one embodiment, the charger 5 is provided on the cage 6 of the elevator 6. When the cage is stopped at a hall of the floor 1F-3F, it is moved automatically by communication means such as wireless ones toward the floor to charge the drive batteries 1 provided in the corresponding halls.
While the drive batteries are charged, a charging device provided on the cage is also charged by the charger 5. This is done using an electromagnetic induction between the receptors 3 at each of the halls and the feeders 4 located in the elevator hall, for example, at the floor where the cage is stopped.
The electric power supplied to the hall devices from the charger is a part of the power supplied through the tail cord 7 from the charger 5 for illuminating the cage and driving the door motor. The feeders and receptors are made of a high conductivity metal to ensure the power delivered is of good quality and high efficiency.
