Segmented Chopper Bridge Arms for High-Current DC Drive
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Solution Overview
Problem
High-power DC motors face challenges in achieving consistent current sharing among parallel power switch tubes, leading to potential damage and restricted current values, especially when using ordinary low-current power switch tubes, which is costly and difficult to maintain, especially in applications like electric vehicles and military equipment.
Innovation Solution
A DC electric drive apparatus with 2j armature winding branches and k bridge arm portions, each comprising j bridge arm units connected to j power lines, allowing each bridge arm unit to output current for two armature winding branches, reducing the impact of inconsistent switching characteristics among power switch tubes and enabling higher current values without the need for extremely consistent power switch tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If parallel current sharing technology is adopted with j power switch tubes connected in parallel to carry high current, then the current capacity of the chopper can be increased, but the consistency of working characteristics among power switch tubes becomes difficult to ensure, leading to potential damage and high cost
Solution Approach 1:
The invention divides the chopper into k bridge arm portions, each with j bridge arm units that independently control current to 2j armature winding branches. This segmentation isolates the current paths so that inconsistencies in one bridge arm unit do not affect others, allowing ordinary power switch tubes to be used without requiring extreme consistency while maintaining high current capacity through the aggregated 2j parallel branches.
2Power
If the number of power switch tubes connected in parallel is increased to achieve higher current values, then the current sharing effect improves when fully on, but the difficulty of ensuring consistent switching characteristics increases, resulting in worse current sharing during ON and OFF processes
Solution Approach 1:
The chopper structure is segmented into k bridge arm portions with j bridge arm units each, controlling current to 2j independent armature winding branches. This creates 2j isolated current paths where each branch receives controlled current from dedicated bridge arm units, eliminating the need for extremely consistent switching characteristics among all power switch tubes while achieving high current output through the aggregated parallel branches.
3Ease of manufacture
If ordinary low-current power switch tubes are used with parallel current sharing, then the cost is reduced, but the system requires careful selection from a large number of tubes to ensure high consistency, resulting in high use cost and complex selection process
Solution Approach 1:
The invention segments the current path into 2j independent armature winding branches controlled by j bridge arm units each. This segmentation allows the use of ordinary low-current power switch tubes without requiring careful selection for high consistency, as the isolated current paths prevent inconsistency from causing damage. The structure inherently tolerates variations in switching characteristics among power switch tubes.
4Power
If power switch tubes are converted from OFF to ON state, and they cannot turn on at the same time due to inconsistent characteristics, then current sharing fails and high current damages the single power switch tube turned on in advance
Solution Approach 1:
The chopper is divided into k bridge arm portions with j bridge arm units each, controlling current to 2j independent armature winding branches. This segmentation creates isolated current paths where each branch is controlled by dedicated bridge arm units. When power switch tubes switch with inconsistent timing, the isolated paths prevent current concentration on a single tube, as the current distributes across multiple independent branches, eliminating the damage risk from non-simultaneous switching.
5Power
If power switch tubes are converted from ON to OFF state, and they cannot turn off at the same time due to inconsistent characteristics, then current sharing fails and high current damages the power switch tube turned off last
Solution Approach 1:
The invention segments the current path into 2j independent armature winding branches, each controlled by dedicated bridge arm units. This segmentation isolates the current paths so that when power switch tubes turn off at different times, the current does not concentrate on the last turning-off tube. Instead, the current distributes across multiple independent branches, preventing damage from non-simultaneous switching during turn-off.
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 design allows for increased current capacity without damaging individual power switch tubes, reduces the cost and complexity of selecting highly consistent power switch tubes, and enhances the performance and reliability of high-current electric drive devices, including heavy-duty applications like electric vehicles and combat vehicles.
Implementation Method 1
the controller controls the ON and OFF of the power switch tube of the chopper bridge arm unit through the driving signal from the driving portion to obtain the output DC voltage with controllable voltage magnitude and polarity
Implementation Method 2
loads the output DC voltage into the armature winding of the DC motor... the armature winding branches generate output torques to drive the electric device
Implementation Method 3
2j ×m commutator segments connected to the windings, and two brush sets respectively connected to two power line sets of the DC motor and in contact with the commutator segments
Data Source
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AI summary
A DC electric drive apparatus and an electric device. The DC electric drive apparatus (10) is provided in an electric device to drive the electric device, comprising: a DC motor (11), for driving the electric device; a DC power source, for outputting constant-voltage DC power to the DC motor; and a chopper (12), for converting constant-voltage DC power into variable-voltage DC power according to a driving signal and providing variable-voltage DC power for the DC motor, wherein, the DC motor has 2j armature winding branches (16) each composed of m windings (16a), 2j × m commutator segments connected to the windings, and two brush sets (17) respectively connected to two power line sets of the DC motor and in contact with the commutator segments; each of the brush sets comprises j brushes (18); each of the power line sets comprises j power lines; the chopper has k bridge arm portions (19), and each of the bridge arm portions comprises j bridge arm units (20) connected to j power lines of one power line set in one-to-one correspondence; each of bridge arm units outputs a current for two armature winding branches through correspondingly connected power lines, and the armature winding branches generate output torques to drive the electric device. Both j and m are positive integers not less than 2, and k is 1 or 2.