Active Brake Unit for Regenerative Energy Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing regenerative devices for feeding energy back into the supply network from braking electric motors are hindered by the need for a large and costly isolating transformer, which increases volume and cost.
Innovation Solution
An active brake unit is implemented, comprising a forward branch with a rectifier and first inverter connected to the motor, and a reverse branch with a second intermediate circuit, current-compensated chokes, and a regulated second inverter, which feeds back braking energy into the supply network via a line adapter circuit, minimizing the need for an isolating transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an isolating transformer is used to feed braking energy back into the supply network, then galvanic isolation and safety are improved, but device volume and cost increase significantly
Solution Approach 1:
The patent extracts and eliminates the isolating transformer from the regenerative braking circuit. Instead of using a transformer for galvanic isolation, the invention uses a direct coupling approach with the supply network, removing the bulky and expensive transformer component while maintaining the essential function of feeding braking energy back into the network.
Solution Approach 2:
The forward branch circuit components (rectifier, intermediate circuit, inverter) are designed to serve dual functions: driving the motor during normal operation and feeding braking energy back into the supply network during regenerative braking. This multi-functionality eliminates the need for separate isolation equipment.
2Reliability
If an isolating transformer is used to prevent high circulating currents, then safety is improved, but device cost increases
Solution Approach 1:
The patent removes the isolating transformer from the circuit configuration. Safety is maintained through alternative means including proper design of the inverter switching elements, use of freewheeling diodes, and controlled commutation of currents, eliminating the need for expensive transformer-based isolation.
Solution Approach 2:
The patent introduces intermediate circuit elements such as freewheeling diodes and carefully designed switching sequences as mediators to manage circulating currents safely without requiring a transformer. The inverter bridge acts as an intermediary that controls current flow direction and magnitude.
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 recovers braking energy and feeds it back into the supply network, reducing costs and volume by eliminating the need for an isolating transformer, while maintaining efficient energy compensation and minimizing harmonics through PWM control.
Implementation Method 1
The forward branch consists of a rectifier (32) which is connected to the supply network (1)
Implementation Method 2
each pole of the second intermediate circuit (42) being connected to the output of the first intermediate circuit (33) via a series connection of a current-compensated choke (61, 62) and a diode (64, 65)
Implementation Method 3
the second inverter (41) is controlled with pulse width modulated (PWM) signals, so that the harmonics are minimized
Data Source
Figure 1
AI summary
The invention relates to a circuit arrangement for recirculating the energy produced during the braking of electric motors into a supply system. The object of the invention is to implement the feeding of the energy that can be obtained when braking electric motors to the supply system without the use of an isolating transformer. Said object is solved by a forward branch (3), comprising a rectifier (32) connected to the supply system (1). The rectifier is guided via a first intermediate circuit (33) to a first inverter (34) that is connected to the motor (2), and a backward branch (4), comprising a second intermediate circuit (42) connected to the output of the first intermediate circuit (33), wherein a second inverter (41) is connected to the second intermediate circuit, and the second inverter in turn is connected to the supply system (1) via a mains circuit (5). Each pole of the second intermediate circuit (42) is connected via a series connection of a current-compensated throttle (61, 62) and a diode (64, 65) to the output of the first intermediate circuit (33).